# kb

id: chemical-vapor-deposition-20260505-1
file: data/en.wikipedia.org/wiki/Chemical_vapor_deposition-1.md
category: reference
title: Chemical vapor deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_vapor_deposition
date_saved: 2026-05-05T10:46:39.791808+00:00
instance: kb-cron
parent: chemical-vapor-deposition-20260505-0
summary:
== Uses == CVD is commonly used to deposit conformal films and augment substrate surfaces in ways that more traditional surface modification techniques are not capable of. CVD is extremely useful in the process of atomic layer deposition at depositing extremely thin layers of material. A variety of applications for such films exist. Gallium arsenide is used in some integrated circuits (ICs) and photovoltaic devices. Amorphous polysilicon is used in photovoltaic devices. Certain carbides and nitrides confer wear-resistance. Polymerization by CVD, perhaps the most versatile of all applications, allows for super-thin coatings which possess some very desirable qualities, such as lubricity, hydrophobicity and weather-resistance to name a few. The CVD of metal-organic frameworks, a class of crystalline nanoporous materials, has recently been demonstrated. Recently scaled up as an integrated cleanroom process depositing large-area substrates, the applications for these films are anticipated in gas sensing and low-κ dielectrics. CVD techniques are advantageous for membrane coatings as well, such as those in desalination or water treatment, as these coatings can be sufficiently uniform (conformal) and thin that they do not clog membrane pores. == Commercially important materials prepared by CVD == === Polysilicon === Polycrystalline silicon is deposited from trichlorosilane (SiHCl3) or


id: chemical-vapor-deposition-20260505-2
file: data/en.wikipedia.org/wiki/Chemical_vapor_deposition-2.md
category: reference
title: Chemical vapor deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_vapor_deposition
date_saved: 2026-05-05T10:46:39.791808+00:00
instance: kb-cron
parent: chemical-vapor-deposition-20260505-0
summary:
==== Titanium nitride ==== Titanium nitride (TiN) is a commonly used as a wear resistant coating to increase the lifetime of cutting tools due to its hardness and chemical resistance. A common gas mixture used for depositing titanium nitride with CVD is: TiCl4 + 1/2 N2 + 2 H2 → TiN(s) + 4 HCl Other gas mixtures used to deposit titanium nitride with CVD includes TiCl4 + NH3 + H2. === Metals === Tungsten CVD, used for forming conductive contacts, vias, and plugs on a semiconductor device, is achieved from tungsten hexafluoride (WF6), which may be deposited in two ways: WF6 → W + 3 F2 WF6 + 3 H2 → W + 6 HF Other metals, notably aluminium and copper, can be deposited by CVD. As of 2010, commercially cost-effective CVD for copper did not exist, although volatile sources exist, such as Cu(hfac)2. Copper is typically deposited by electroplating. Aluminium can be deposited from triisobutylaluminium (TIBAL) and related organoaluminium compounds. CVD for molybdenum, tantalum, titanium, nickel is widely used. These metals can form useful silicides when deposited onto silicon. Mo, Ta, and Ti are deposited by LPCVD, from their pentachlorides. However, nickel, molybdenum, and tungsten can be deposited at


id: chemical-vapor-deposition-20260505-3
file: data/en.wikipedia.org/wiki/Chemical_vapor_deposition-3.md
category: reference
title: Chemical vapor deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_vapor_deposition
date_saved: 2026-05-05T10:46:39.791808+00:00
instance: kb-cron
parent: chemical-vapor-deposition-20260505-0
summary:
==== Methods of analysis of results ==== Raman spectroscopy, X-ray spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM) are used to examine and characterize the graphene samples. Raman spectroscopy is used to characterize and identify the graphene particles; X-ray spectroscopy is used to characterize chemical states; TEM is used to provide fine details regarding the internal composition of graphene; SEM is used to examine the surface and topography. Sometimes, atomic force microscopy (AFM) is used to measure local properties such as friction and magnetism. X-ray diffraction methods are useful techniques to analyze thin films. X-ray diffraction methods such as Grazing incidence X-ray diffraction can be used to qualify the phases present in deposited films. Additionally, X-ray reflectivity (XRR) can be used to measure the thickness and roughness of deposited films. Pole figure measurements are useful and can be used to investigate textures and preferential orientations in deposited films. Cold wall CVD technique can be used to study the underlying surface science involved in graphene nucleation and growth as it allows unprecedented control of process parameters like gas flow rates, temperature and pressure as demonstrated in a recent study. The study was carried out in a home-built vertical cold


id: chloralkali-process-20260505-0
file: data/en.wikipedia.org/wiki/Chloralkali_process-0.md
category: reference
title: Chloralkali process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chloralkali_process
date_saved: 2026-05-05T10:46:40.961258+00:00
instance: kb-cron
parent: chloralkali-process-20260505-0
summary:
The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are commodity chemicals required by industry. Thirty five million tons of chlorine were prepared by this process in 1987. In 2022, this had increased to about 97 million tonnes. The chlorine and sodium hydroxide produced in this process are widely used in the chemical industry. Usually the process is conducted on a brine (an aqueous solution of concentrated NaCl), in which case sodium hydroxide (NaOH), hydrogen, and chlorine result. When using calcium chloride or potassium chloride, the products contain calcium or potassium instead of sodium. Related processes are known that use molten NaCl to give chlorine and sodium metal or condensed hydrogen chloride to give hydrogen and chlorine. The process has a high energy consumption, for example around 2,500 kWh (9,000 MJ) of electricity per tonne of sodium hydroxide produced. Because the process yields equivalent amounts of chlorine and sodium hydroxide (two moles of sodium hydroxide per mole of chlorine), it is necessary to find a use for these products in the same proportion. For every


id: chloralkali-process-20260505-1
file: data/en.wikipedia.org/wiki/Chloralkali_process-1.md
category: reference
title: Chloralkali process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chloralkali_process
date_saved: 2026-05-05T10:46:40.961258+00:00
instance: kb-cron
parent: chloralkali-process-20260505-0
summary:
In the mercury-cell process, also known as the Castner–Kellner process, the "outer" electrolytic cells each contain an anode immersed in brine, which floats on a layer of mercury. The "inner" cells each contain a cathode in a sodium hydroxide solution, floating on the same mercury layer. The walls dividing the cells have gaps below the surface of the mercury layer. This allows mercury to flow between cells, while preventing the aqueous solutions from doing so. In the "outer" cell, chloride ions are oxidized at the anode, producing chlorine gas which bubbles out of the cell. The mercury layer acts as the cathode, here sodium ions in the brine are reduced and form an amalgam with the mercury. Once in the amalgam, sodium atoms are free to move to the "inner" cell. In the "inner" cell, the mercury layer now acts as the anode. Sodium atoms in the amalgam are oxidized and enter aqueous solution. Meanwhile at the cathode, water is split into hydrogen gas and hydroxide ions. Mercury cells are being phased out due to concerns about the high toxicity of mercury and mercury poisoning from mercury cell pollution such as occurred in Canada (see Ontario Minamata disease) and Japan


id: chloride-process-20260505-0
file: data/en.wikipedia.org/wiki/Chloride_process-0.md
category: reference
title: Chloride process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chloride_process
date_saved: 2026-05-05T10:46:42.118981+00:00
instance: kb-cron
parent: chloride-process-20260505-0
summary:
The chloride process is used to separate titanium from its ores. The goal of the process is to win high purity titanium dioxide from ores such as ilmenite (FeTiO3) and rutile (TiO2). The strategy exploits the volatility of TiCl4, which is readily purified and converted to the dioxide. Millions of tons of TiO2 are produced annually by this process, mainly for use as white pigments. As of 2017, the chloride process is used alongside the older sulfate process, which relies on hot sulfuric acid to extract iron and other impurities from ores. == Process chemistry == In this process, the feedstock is treated at 1000 °C with carbon and chlorine gas, giving titanium tetrachloride. Typical is the conversion starting from the ore ilmenite: 2 FeTiO3 + 7 Cl2 + 6 C → 2 TiCl4 + 2 FeCl3 + 6 CO The process is a variant of a carbothermic reaction, which exploits the reducing power of carbon. The titanium tetrachloride is purified by distillation. Other impurities are converted to the respective chlorides as well, but most are less volatile than TiCl4. Vanadium tetrachloride and vanadium oxytrichloride codistill with TiCl4, but these impurities can be removed by chemical reduction. It can be


id: chlorine-free-germanium-processing-20260505-0
file: data/en.wikipedia.org/wiki/Chlorine-free_germanium_processing-0.md
category: reference
title: Chlorine-free germanium processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chlorine-free_germanium_processing
date_saved: 2026-05-05T10:46:43.311129+00:00
instance: kb-cron
parent: chlorine-free-germanium-processing-20260505-0
summary:
Chlorine-free germanium processing are methods of germanium activation to form useful germanium precursors in a more energy efficient and environmentally friendly way compared to traditional synthetic routes. Germanium tetrachloride is a valuable intermediate for the synthesis of many germanium complexes. Normal synthesis of it involves an energy-intensive dehydration of germanium oxide, GeO 2 {\displaystyle {\ce {GeO2}}} , with hydrogen chloride, HCl {\displaystyle {\ce {HCl}}} Due to the environmental and safety impact of non-recyclable, high energy reactions with HCl {\displaystyle {\ce {HCl}}} , an alternative synthesis of a shelf-stable germanium intermediate precursor without chlorine is of interest. In 2017, a synthesis of organogermanes, GeR 4 {\displaystyle {\ce {GeR4}}} without using chloride species was reported, allowing for a much more environmentally friendly and low energy synthesis using GeO 2 {\displaystyle {\ce {GeO2}}} , Ge ( 0 ) {\displaystyle {\ce {Ge(0)}}} , and even selectively activating germanium in the presence of zinc oxide ( ZnO {\displaystyle {\ce {ZnO}}} ), resulting in products that are bench stable and solid. == Synthesis of organogermanes == === Oxidation of germanium metal === Glavinović et al. have synthesized organogermanes using ortho-quinone, which is both redox "non-innocent" and acts as a pseudo-halide, resulting in an air and moisture


id: chlorine-free-germanium-processing-20260505-1
file: data/en.wikipedia.org/wiki/Chlorine-free_germanium_processing-1.md
category: reference
title: Chlorine-free germanium processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chlorine-free_germanium_processing
date_saved: 2026-05-05T10:46:43.311129+00:00
instance: kb-cron
parent: chlorine-free-germanium-processing-20260505-0
summary:
The substitution reaction described above is thought to process via a mechanism in which steric strain of the complex is slowly alleviated over the course of the reaction. The first Grignard reagent substitutes the most sterically hindered oxygen position, where the t-butyl group of the catechol ligand is alpha to the oxygen. The second Grignard reagent substitutes the now uni-dentate catechol-grignard adduct, removing the ligand and resulting in two complete substitutions. Referring to the scheme below, treating intermediate 2 with an additional equivalent of Grignard reagent yields 3 at a faster rate than the rate to make 2, and treatment of 3 with two equivalents of reagent yields 4 at even more quickly. This is starkly different from the substitution reactions of GeCl 4 {\displaystyle {\ce {GeCl4}}} , in which the germanium center becomes more sterically hindered over the course of the reaction as ligand exchange of the carbons and the chlorides progresses, making the substitution more difficult. The stereochemical selectivity of the substitution reaction is further enforced by the identity of the auxiliary amine ligand. By using a more sterically encumbered amine ligand such as triethylamine, a 1.67:1 mixture of dibutyl-germane-η2-catecholate and tributylgermyl-η1-catecholate is produced after substitution with two


id: coal-pollution-mitigation-20260505-0
file: data/en.wikipedia.org/wiki/Coal_pollution_mitigation-0.md
category: reference
title: Coal pollution mitigation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coal_pollution_mitigation
date_saved: 2026-05-05T10:46:44.547833+00:00
instance: kb-cron
parent: coal-pollution-mitigation-20260505-0
summary:
Coal pollution mitigation is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment. The combustion of coal releases diverse chemicals into the air. The main products are water and carbon dioxide, just like the combustion of petroleum. Also released are sulfur dioxide and nitrogen oxides, as well as some mercury. The residue remaining after combustion, coal ash often contains arsenic, mercury, and lead. Finally, the burning of coal, especially anthracite, can release radioactive materials. == Mitigation technologies == Mitigation of coal-based pollution can be divided into several distinct approaches. Coal pollution mitigation seek to minimize negative impacts of coal combustion. === Precombustion === Prior to its combustion, coal can be cleaned by physical and by chemical means. Physical cleaning of coal usually involves gravimetric processes, often in conjunction with froth flotation Such processes remove minerals and other


id: coal-pollution-mitigation-20260505-1
file: data/en.wikipedia.org/wiki/Coal_pollution_mitigation-1.md
category: reference
title: Coal pollution mitigation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coal_pollution_mitigation
date_saved: 2026-05-05T10:46:44.547833+00:00
instance: kb-cron
parent: coal-pollution-mitigation-20260505-0
summary:
An early example of a coal-based plant using (oxy-fuel) carbon-capture technology is Swedish company Vattenfall’s Schwarze Pumpe power station located in Spremberg, Germany, built by German firm Siemens, which went on-line in September 2008. The facility captures CO2 and acid rain producing pollutants, separates them, and compresses the CO2 into a liquid. Plans are to inject the CO2 into depleted natural gas fields or other geological formations. Vattenfall opines that this technology is considered not to be a final solution for CO2 reduction in the atmosphere, but provides an achievable solution in the near term while more desirable alternative solutions to power generation can be made economically practical. Other examples of oxy-combustion carbon capture are in progress. Callide Power Station has retrofitted a 30-MWth existing PC-fired power plant to operate in oxy-fuel mode; in Ciuden, Spain, Endesa has a newly built 30-MWth oxy-fuel plant using circulating fluidized bed combustion (CFBC) technology. Babcock-ThermoEnergy's Zero Emission Boiler System (ZEBS) is oxy-combustion-based; this system features near 100% carbon-capture and according to company information virtually no air-emissions. Other carbon capture and storage technologies include those that dewater low-rank coals. Low-rank coals often contain a higher level of moisture content which contains a lower energy


id: coal-pollution-mitigation-20260505-2
file: data/en.wikipedia.org/wiki/Coal_pollution_mitigation-2.md
category: reference
title: Coal pollution mitigation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coal_pollution_mitigation
date_saved: 2026-05-05T10:46:44.547833+00:00
instance: kb-cron
parent: coal-pollution-mitigation-20260505-0
summary:
In the United States, clean coal was mentioned by former President George W. Bush on several occasions, including his 2007 State of the Union Address. Bush's position was that carbon capture and storage technologies should be encouraged as one means to reduce the country's dependence on foreign oil. During the US Presidential campaign for 2008, both candidates John McCain and Barack Obama expressed interest in the development of CCS technologies as part of an overall comprehensive energy plan. The development of pollution mitigation technologies could also create export business for the United States or any other country working on it. The American Reinvestment and Recovery Act allocated $3.4 billion for advanced carbon capture and storage technologies, including demonstration projects. Former Secretary of State Hillary Clinton has said that "we should strive to have new electricity generation come from other sources, such as clean coal and renewables", and former Energy Secretary Dr. Steven Chu has said that "It is absolutely worthwhile to invest in carbon capture and storage", noting that even if the U.S. and Europe turned their backs on coal, developing nations like India and China would likely not. During the first 2012 United States presidential election debate, Mitt Romney


id: coalbed-methane-extraction-20260505-0
file: data/en.wikipedia.org/wiki/Coalbed_methane_extraction-0.md
category: reference
title: Coalbed methane extraction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coalbed_methane_extraction
date_saved: 2026-05-05T10:46:45.718283+00:00
instance: kb-cron
parent: coalbed-methane-extraction-20260505-0
summary:
Coalbed methane extraction (CBM extraction) is a method for extracting methane from a coal deposit. Coal bed methane (CBM) is one of the factors restricting the safe production of coal in underground coal mines. It is also a form of high-quality energy that can be used in many fields such as power generation, heating, and chemical industries. CBM extraction is therefore carried out before extraction with a view of increasing the safety of mining coal beds, and as a useful energy resource to be exploited. == Basic principles == Methane adsorbed into a solid coal matrix (coal macerals) will be released if the coal seam is depressurized. Methane may be extracted by drilling wells into the coal seam. The goal is to decrease the water pressure by pumping water from the well. The decrease in pressure allows methane to desorb from the coal and flow as a gas up the well to the surface. Methane is then compressed and piped to market. The objective is to avoid putting methane into the water line but allow it to flow up the backside of the well (casing) to the compressor station. If the water level is pumped too low during dewatering, methane


id: coated-fabrics-20260505-0
file: data/en.wikipedia.org/wiki/Coated_fabrics-0.md
category: reference
title: Coated fabrics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coated_fabrics
date_saved: 2026-05-05T10:46:46.879165+00:00
instance: kb-cron
parent: coated-fabrics-20260505-0
summary:
Coated fabrics are those that have undergone a coating procedure to become more functional and hold the added properties, such as cotton fabrics becoming impermeable or waterproof. Coated textiles are used in a variety of applications, including blackout curtains and the development of waterproof fabrics for raincoats. == Coating == The coating is an application of chemical substances on the surface of fabric that is to be made functional or decorative. Coatings use less material than other types of applications, such as exhaust or padding on stenter. == History == The earliest known coated fabric is Oilcloth. Oilcloth is produced by the application of boiled linseed oil. The use of boiled oils can be traced back to 200 AD. == Types == Coated fabrics can be made in a variety of ways, depending on the coating ingredients used, such as chemical and particles. Rubber, plastic, and vinyl coatings are just a few examples. Nanofabrics are coated with a wide range of nanoparticles to make the fabrics capable of enhanced properties such as ultrahydrophobicity, medical textiles (antimicrobial resistance), Ultraviolet protection, and elasticity. === Use === The applications and uses of coated fabrics are numerous. In manufacturing of pristine clothes. Self cleaning


id: coated-paper-20260505-0
file: data/en.wikipedia.org/wiki/Coated_paper-0.md
category: reference
title: Coated paper
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coated_paper
date_saved: 2026-05-05T10:46:48.102584+00:00
instance: kb-cron
parent: coated-paper-20260505-0
summary:
Coated paper (also known as enamel paper, gloss paper, and thin paper) is paper that has been coated with a mixture of materials or a polymer to impart certain qualities to the paper, including weight, surface gloss, smoothness, or reduced ink absorbency. Various materials, including kaolinite, calcium carbonate, bentonite, and talc, can be used to coat paper for high-quality printing, such as that used in the packaging industry and in magazines. The chalk or china clay is bound to the paper with synthetic viscosifiers, such as styrene-butadiene latexes and natural organic binders such as starch. The coating formulation may also contain chemical additives as dispersants, resins, or polyethylene to give water resistance and wet strength to the paper, or to protect against ultraviolet radiation. Coated papers have been traditionally used for printing magazines. == History == Waterproof paper was described in Scientific American in 1884. == Varieties == === Machine-finished coated paper === Machine-finished coated paper (MFC) has a basis weight of 48–80 g/m2. They have good surface properties, high print gloss and adequate sheet stiffness. MFC papers are made of 60–85% groundwood or thermomechanical pulp (TMP) and 15–40% chemical pulp with a total pigment content of 20–30%. The paper


id: cobalt-extraction-20260505-0
file: data/en.wikipedia.org/wiki/Cobalt_extraction-0.md
category: reference
title: Cobalt extraction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cobalt_extraction
date_saved: 2026-05-05T10:46:49.259891+00:00
instance: kb-cron
parent: cobalt-extraction-20260505-0
summary:
Cobalt extraction refers to the techniques used to extract cobalt from its ores and other compound ores. Several methods exist for the separation of cobalt from copper and nickel. They depend on the concentration of cobalt and the exact composition of the ore used. == Recovery from copper-cobalt sulfide concentrates == The ores are treated by a sulfatizing roast in a fluidized bed furnace to convert copper and cobalt sulfides into soluble sulfates and iron into insoluble hematite. The calcine is subsequently leached with sulfuric acid from the spent copper recovery electrolyte. Oxide concentrates are introduced at this leaching step to maintain the acid balance in the circuit. Iron and aluminum are removed from the leach solution by the addition of lime, and copper is electrowon on copper cathodes. A part of the spent electrolyte enters the cobalt recovery circuit and is purified by the removal of iron, copper, nickel, and zinc prior to the precipitation of cobalt as its hydroxide. This is accomplished by the addition of more lime to raise the pH until the remaining copper precipitates. This copper is sent back to the copper circuit. As more lime is then added, a copper-cobaltite precipitates and is fed


id: cohobation-20260505-0
file: data/en.wikipedia.org/wiki/Cohobation-0.md
category: reference
title: Cohobation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cohobation
date_saved: 2026-05-05T10:46:50.352179+00:00
instance: kb-cron
parent: cohobation-20260505-0
summary:
In pre-modern chemistry and alchemy, cohobation was the process of repeated distillation of the same matter, with the liquid drawn from it (successive redistillation); that liquid being poured again and again upon the matter left at the bottom of the vessel. Cohobation is a kind of circulation, only differing from it in this, that the liquid is drawn off in cohobation, as in common distillation, and thrown back again; whereas in circulation, it rises and falls in the same vessel, without ever being drawn out. Cohobation is not recognized as a useful process in modern chemistry. Indeed, it is equivalent to performing the same distillation a number of times and does not increase the purity of the distillate or alter the residue any more than would be done by maintaining it at elevated temperature for the same period of time. The Dean-Stark trap does involve returning some distillate to the reaction flask: a solution is distilled and the condensed liquid is collected in a tube wherein water settles to the bottom and is drained out, while an organic solvent returns to the boiling solution. However, the process is not manual, most of the solvent does not leave the reaction flask,


id: contact-process-20260505-0
file: data/en.wikipedia.org/wiki/Contact_process-0.md
category: reference
title: Contact process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Contact_process
date_saved: 2026-05-05T10:46:51.498069+00:00
instance: kb-cron
parent: contact-process-20260505-0
summary:
The contact process is a method for manufacturing sulfuric acid in the high concentrations needed for industrial processes. Platinum was originally used as the catalyst for this reaction; however, because it is susceptible to reacting with arsenic impurities in the sulfur feedstock, vanadium(V) oxide (V2O5) has since been preferred. == History == This process was patented in 1831 by British vinegar merchant Peregrine Phillips. In addition to being a far more economical process for producing concentrated sulfuric acid than the previous lead chamber process, the contact process also produces sulfur trioxide and oleum. In 1890 John Brown Francis Herreshoff developed a form of the contact catalytic process for the company of which he was a partner. In 1901 Eugen de Haën patented the basic process involving combining sulfur dioxide and oxygen in the presence of vanadium oxides, producing sulfur trioxide which was easily absorbed into water, producing sulfuric acid. This process was improved remarkably by shrinking the particle size of the catalyst (e.g. ≤ 5000 microns), a process discovered by two chemists of BASF in 1914. == Process == The process can be divided into four stages: Combining of sulfur and oxygen (O2) to form sulfur dioxide, then purify the


id: continuous-foam-separation-20260505-0
file: data/en.wikipedia.org/wiki/Continuous_foam_separation-0.md
category: reference
title: Continuous foam separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continuous_foam_separation
date_saved: 2026-05-05T10:46:52.712893+00:00
instance: kb-cron
parent: continuous-foam-separation-20260505-0
summary:
Continuous foam separation is a chemical process closely related to foam fractionation in which foam is used to separate components of a solution when they differ in surface activity. In any solution, surface active components tend to adsorb to gas-liquid interfaces while surface inactive components stay within the bulk solution. When a solution is foamed, the most surface active components collect in the foam and the foam can be easily extracted. This process is commonly used in large-scale projects such as water waste treatment due to a continuous gas flow in the solution. There are two types of foam that can form from this process. They are wet foam (or kugelschaum) and dry foam (or polyederschaum). Wet foam tends to form at the lower portion of the foam column, while dry foam tends to form at the upper portion. The wet foam is more spherical and viscous, and the dry foam tends to be larger in diameter and less viscous. Wet foam forms closer to the originating liquid, while dry foam develops at the outer boundaries. As such, what most people usually understand as foam is actually only dry foam. The setup for continuous foam separation consists of securing a


id: continuous-foam-separation-20260505-1
file: data/en.wikipedia.org/wiki/Continuous_foam_separation-1.md
category: reference
title: Continuous foam separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continuous_foam_separation
date_saved: 2026-05-05T10:46:52.712893+00:00
instance: kb-cron
parent: continuous-foam-separation-20260505-0
summary:
Δ P = γ ∘ ( 1 R 1 + 1 R 2 ) {\displaystyle \Delta P=\gamma ^{\circ }({\frac {1}{R_{1}}}+{\frac {1}{R_{2}}})} As pressure grows inside the bubbles, the liquid lamellae shown in the figure above will forced to move toward plateau borders causing a collapse of the lamellae. ==== Gibbs adsorption isotherm ==== The Gibbs adsorption isotherm can be used to determine the change in surface tension with changing concentration. Since chemical potential varies with a change in concentration, the following equation can be used to estimate the change in surface tension where dγ is the change in surface tension of the interface, Γ1 is the surface excess of the solvent, Γ2 is the surface excess of the solute (surfactant), dμ1 is the change in chemical potential of the solvent, and dμ2 is the change in chemical potential of the solute: d γ = Γ 1 d μ 1 + Γ 2 d μ 2 {\displaystyle \mathrm {d} \gamma =\Gamma _{1}\mathrm {d} \mu _{1}+\Gamma _{2}\mathrm {d} \mu _{2}} For ideal cases, Γ1 = 0 and the created foam is dependent on the change in chemical potential of the solute. During foaming, the solute experiences a change in chemical potential as


id: continuous-foam-separation-20260505-2
file: data/en.wikipedia.org/wiki/Continuous_foam_separation-2.md
category: reference
title: Continuous foam separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Continuous_foam_separation
date_saved: 2026-05-05T10:46:52.712893+00:00
instance: kb-cron
parent: continuous-foam-separation-20260505-0
summary:
Recovery is how efficiently the protein is removed from the solution into the foam state, the higher the percentage, the better the process is at recovering protein from solute into the foam state. Foam hydrodynamics as well as many of the variables that affect the success of foaming have limited understanding. This complicates using mathematical calculations to predict protein recovery by foaming. However some trends have been determined; high recovery rates have been linked to high concentrations of protein in the initial solution, high gas flow rates, and high feed flow rates. Enrichment is also known to increase when foaming is performed using shallow pools. Using pools with low heights allows for only a small amount of protein to adsorb from the solution to the surface of the bubbles in the foam resulting in lower surface viscosity. This leads to coalescence of the unstable foam higher up in the column causing an increase in the bubble size and an increase in the reflux of the protein in the foam. However, an increased velocity of the gas being pumped into the system has been shown to lead to a decrease in the enrichment ratio. Since these calculations are difficult to predict,


id: copper-sweetening-20260505-0
file: data/en.wikipedia.org/wiki/Copper_sweetening-0.md
category: reference
title: Copper sweetening
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Copper_sweetening
date_saved: 2026-05-05T10:46:53.893344+00:00
instance: kb-cron
parent: copper-sweetening-20260505-0
summary:
Copper sweetening is a petroleum refining process using a slurry of clay and cupric chloride to oxidize mercaptans. The resulting disulfides are less odorous and usually very viscous, and are usually removed from the lower-boiling fractions and left in the heavy fuel oil fraction. Copper sweetening introduces trace amount of copper into the resulting products, which tends to have detrimental effects as it leads to formation of gummy residues. Other sources of copper include contact with refinery parts made of copper and copper alloys. Copper is one of the most active instability promoters, and concentrations as low as 0.1 ppm can have marked negative effect. To combat these, metal deactivators are added to some fuels. == References == == See also == Sour crude oil Sweet crude oil


id: coprecipitation-20260505-0
file: data/en.wikipedia.org/wiki/Coprecipitation-0.md
category: reference
title: Coprecipitation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Coprecipitation
date_saved: 2026-05-05T10:46:55.032742+00:00
instance: kb-cron
parent: coprecipitation-20260505-0
summary:
In chemistry, coprecipitation (CPT) or co-precipitation is the carrying down by a precipitate of substances normally soluble under the conditions employed. Analogously, in medicine, coprecipitation (referred to as immunoprecipitation) is specifically "an assay designed to purify a single antigen from a complex mixture using a specific antibody attached to a beaded support". Coprecipitation is an important topic in chemical analysis, where it can be undesirable, but can also be usefully exploited. In gravimetric analysis, which consists on precipitating the analyte and measuring its mass to determine its concentration or purity, coprecipitation is a problem because undesired impurities often coprecipitate with the analyte, resulting in excess mass. This problem can often be mitigated by "digestion" (waiting for the precipitate to equilibrate and form larger and purer particles) or by redissolving the sample and precipitating it again. On the other hand, in the analysis of trace elements, as is often the case in radiochemistry, coprecipitation is often the only way of separating an element. Since the trace element is too dilute (sometimes less than a part per trillion) to precipitate by conventional means, it is typically coprecipitated with a carrier, a substance that has a similar crystalline structure that can incorporate the


id: cracking-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Cracking_(chemistry)-0.md
category: reference
title: Cracking (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cracking_(chemistry)
date_saved: 2026-05-05T10:46:56.249729+00:00
instance: kb-cron
parent: cracking-chemistry-20260505-0
summary:
In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon–carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of large hydrocarbons into smaller, more useful alkanes and alkenes. Simply put, hydrocarbon cracking is the process of breaking long-chain hydrocarbons into short ones. This process requires high temperatures. More loosely, outside the field of petroleum chemistry, the term "cracking" is used to describe any type of splitting of molecules under the influence of heat, catalysts and solvents, such as in processes of destructive distillation or pyrolysis. Fluid catalytic cracking produces a high yield of petrol and LPG, while hydrocracking is a major source of jet fuel, diesel fuel, naphtha, and again yields LPG. == History and patents == Among several variants of thermal cracking methods (variously known as the "Shukhov cracking process", "Burton cracking process", "Burton–Humphreys cracking process", and "Dubbs cracking process") Vladimir Shukhov, a Russian engineer, invented and patented the first in 1891 (Russian Empire, patent


id: cracking-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Cracking_(chemistry)-1.md
category: reference
title: Cracking (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cracking_(chemistry)
date_saved: 2026-05-05T10:46:56.249729+00:00
instance: kb-cron
parent: cracking-chemistry-20260505-0
summary:
Steam cracking is a petrochemical process in which saturated hydrocarbons are broken down into smaller, often unsaturated, hydrocarbons. It is the principal industrial method for producing the lighter alkenes (or commonly olefins), including ethene (or ethylene) and propene (or propylene). Steam cracker units are facilities in which a feedstock such as naphtha, liquefied petroleum gas (LPG), ethane, propane or butane is thermally cracked through the use of steam in a bank of pyrolysis furnaces to produce lighter hydrocarbons. In steam cracking, a gaseous or liquid hydrocarbon feed like naphtha, LPG or ethane is diluted with steam and briefly heated in a furnace without the presence of oxygen. Typically, the reaction temperature is very high, at around 850 °C (1,560 °F), but the reaction is only allowed to take place very briefly. In modern cracking furnaces, the residence time is reduced to milliseconds to improve yield, resulting in gas velocities up to the speed of sound. After the cracking temperature has been reached, the gas is quickly quenched to stop the reaction in a transfer line heat exchanger or inside a quenching header using quench oil. The products produced in the reaction depend on the composition of the feed, the hydrocarbon-to-steam


id: cracking-chemistry-20260505-2
file: data/en.wikipedia.org/wiki/Cracking_(chemistry)-2.md
category: reference
title: Cracking (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cracking_(chemistry)
date_saved: 2026-05-05T10:46:56.249729+00:00
instance: kb-cron
parent: cracking-chemistry-20260505-0
summary:
==== Hydrocracking ==== Hydrocracking is a catalytic cracking process assisted by the presence of added hydrogen gas. Unlike a hydrotreater, hydrocracking uses hydrogen to break C–C bonds (hydrotreatment is conducted prior to hydrocracking to protect the catalysts in a hydrocracking process). In 2010, 265 million tonnes (261,000,000 long tons; 292,000,000 short tons) of petroleum was processed with this technology. The main feedstock is vacuum gas oil, a heavy fraction of petroleum. The products of this process are saturated hydrocarbons; depending on the reaction conditions (temperature, pressure, catalyst activity) these products range from ethane and LPG to heavier hydrocarbons consisting mostly of isoparaffins. Hydrocracking is normally facilitated by a bifunctional catalyst that is capable of rearranging and breaking hydrocarbon chains as well as adding hydrogen to aromatics and olefins to produce naphthenes and alkanes. The major products from hydrocracking are jet fuel and diesel, but low sulphur naphtha fractions and LPG are also produced. All these products have a very low content of sulfur and other contaminants with a goal of reducing the gasoil and naphtha range material to 10 PPM sulfur or lower. It is very common in Europe and Asia because those regions have high demand for diesel and


id: cronak-process-20260505-0
file: data/en.wikipedia.org/wiki/Cronak_process-0.md
category: reference
title: Cronak process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cronak_process
date_saved: 2026-05-05T10:46:57.426906+00:00
instance: kb-cron
parent: cronak-process-20260505-0
summary:
The Cronak process is a conventional chromate conversion coating process developed in 1933 by The New Jersey Zinc Company. It involves immersing a zinc or zinc-plated article for 5 to 15 seconds in a chromate solution, typically prepared from sodium dichromate and sulfuric acid. The process was patented in the United States on March 24, 1936 with USPTO number 2,035,380. == References == == External links == https://web.archive.org/web/20141211093127/http://www.innovateus.net/science/what-zinc-chromate-used


id: cryogenic-gas-plant-20260505-0
file: data/en.wikipedia.org/wiki/Cryogenic_gas_plant-0.md
category: reference
title: Cryogenic gas plant
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cryogenic_gas_plant
date_saved: 2026-05-05T10:46:58.587610+00:00
instance: kb-cron
parent: cryogenic-gas-plant-20260505-0
summary:
A cryogenic gas plant is an industrial facility that creates molecular oxygen, molecular nitrogen, argon, krypton, helium, and xenon at relatively high purity. As air is made up of nitrogen, the most common gas in the atmosphere, at 78%, with oxygen at 19%, and argon at 1%, with trace gasses making up the rest, cryogenic gas plants separate air inside a distillation column at cryogenic temperatures (about 100 K/-173 °C) to produce high purity gases such as argon, nitrogen, oxygen, and many more with 1 ppm or less impurities. The process is based on the general theory of the Hampson-Linde cycle of air separation, which was invented by Carl von Linde in 1895. == Purpose == The main purpose of a cryogenic nitrogen plant is to provide a customer with high purity gaseous nitrogen (GAN), liquid nitrogen (LIN), liquid argon (LAR) and high purity argon PLAR at high purities, along with extracting trace gasses like krypton, xenon and helium. High purity liquid material such as oxygen or nitrogen produced by cryogenic plants is stored in a local tank and used as a strategic reserve. This liquid can be vaporised to cover peaks in demand or for use when the plant


id: crystallization-of-polymers-20260505-0
file: data/en.wikipedia.org/wiki/Crystallization_of_polymers-0.md
category: reference
title: Crystallization of polymers
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crystallization_of_polymers
date_saved: 2026-05-05T10:46:59.767344+00:00
instance: kb-cron
parent: crystallization-of-polymers-20260505-0
summary:
Crystallization of polymers is a process associated with partial alignment of their molecular chains. These chains fold together and form ordered regions called lamellae, which compose larger spheroidal structures named spherulites. Polymers can crystallize upon cooling from melting, mechanical stretching or solvent evaporation. Crystallization affects optical, mechanical, thermal and chemical properties of the polymer. The degree of crystallinity is estimated by different analytical methods and it typically ranges between 10 and 80%, with crystallized polymers often called "semi-crystalline". The properties of semi-crystalline polymers are determined not only by the degree of crystallinity, but also by the size and orientation of the molecular chains. == Crystallization mechanisms == === Solidification from the melt === Polymers are composed of long molecular chains which form irregular, entangled coils in the melt. Some polymers retain such a disordered structure upon freezing and readily convert into amorphous solids. In other polymers, the chains rearrange upon freezing and form partly ordered regions with a typical size of the order 1 micrometer. Although it would be energetically favorable for the polymer chains to align parallel, such alignment is hindered by the entanglement. Therefore, within the ordered regions, the polymer chains are both aligned and folded. Those regions


id: crystallization-of-polymers-20260505-1
file: data/en.wikipedia.org/wiki/Crystallization_of_polymers-1.md
category: reference
title: Crystallization of polymers
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crystallization_of_polymers
date_saved: 2026-05-05T10:46:59.767344+00:00
instance: kb-cron
parent: crystallization-of-polymers-20260505-0
summary:
=== Crystallization from solution === Polymers can also be crystallized from a solution or upon evaporation of a solvent. This process depends on the degree of dilution: in dilute solutions, the molecular chains have no connection with each other and exist as a separate polymer coil in the solution. Increase in concentration which can occur via solvent evaporation, induces interaction between molecular chains and a possible crystallization as in the crystallization from the melt. Crystallization from solution may result in the highest degree of polymer crystallinity. For example, highly linear polyethylene can form platelet-like single crystals with a thickness on the order 10–20 nm when crystallized from a dilute solution. The crystal shape can be more complex for other polymers, including hollow pyramids, spirals and multilayer dendritic structures. A very different process is precipitation; it uses a solvent which dissolves individual monomers but not the resulting polymer. When a certain degree of polymerization is reached, the polymerized and partially crystallized product precipitates out of the solution. The rate of crystallization can be monitored by a technique which selectively probes the dissolved fraction, such as nuclear magnetic resonance. === Confined crystallization === When polymers crystallize from an isotropic, bulk of melt


id: crystallization-of-polymers-20260505-2
file: data/en.wikipedia.org/wiki/Crystallization_of_polymers-2.md
category: reference
title: Crystallization of polymers
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Crystallization_of_polymers
date_saved: 2026-05-05T10:46:59.767344+00:00
instance: kb-cron
parent: crystallization-of-polymers-20260505-0
summary:
=== Thermal and mechanical properties === Below their glass transition temperature, amorphous polymers are usually hard and brittle because of the low mobility of their molecules. Increasing the temperature induces molecular motion resulting in the typical rubber-elastic properties. A constant force applied to a polymer at temperatures above Tg results in a viscoelastic deformation, i.e., the polymer begins to creep. Heat resistance is usually given for amorphous polymers just below the glass transition temperature. Relatively strong intermolecular forces in semicrystalline polymers prevent softening even above the glass transition temperature. Their elastic modulus changes significantly only at high (melting) temperature. It also depends on the degree of crystallinity: higher crystallinity results in a harder and more thermally stable, but also more brittle material, whereas the amorphous regions provide certain elasticity and impact resistance. Another characteristic feature of semicrystalline polymers is strong anisotropy of their mechanical properties along the direction of molecular alignment and perpendicular to it. Above the glass transition temperature amorphous chains in a semi-crystalline polymer are ductile and are able to deform plastically. Crystalline regions of the polymer are linked by the amorphous regions. Tie molecules prevent the amorphous and crystalline phases from separating under an applied load. When


id: crystasulf-20260505-0
file: data/en.wikipedia.org/wiki/CrystaSulf-0.md
category: reference
title: CrystaSulf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/CrystaSulf
date_saved: 2026-05-05T10:47:00.974642+00:00
instance: kb-cron
parent: crystasulf-20260505-0
summary:
CrystaSulf is the trade name for a chemical process used for removing hydrogen sulfide (H2S) from natural gas, synthesis gas and other gas streams in refineries and chemical plants. CrystaSulf uses a modified liquid-phase Claus reaction to convert the hydrogen sulfide (H2S) into elemental sulfur which is then removed from the process by filtration. CrystaSulf is used in the energy industry as a mid-range process to handle sulfur amounts between 0.1 and 20 short tons (0.091 and 18.144 t) per day. Below 0.1 short tons (0.091 t) of sulfur per day is typically managed by H2S Scavengers and applications above 20 short tons (18 t) per day are typically treated with the Amine – Claus process. == Process chemistry == In the CrystaSulf process, a heavy hydrocarbon liquid is pumped through an absorber where the liquid contacts the gas stream that contains H2S. The H2S is absorbed from the gas stream and the clean gas stream then exits the absorber. The H2S in the liquid reacts with sulfur dioxide (SO2) to form elemental sulfur and water according to the following chemical equation. 2 H2S + SO2 → 3 S + 2 H2O The formed elemental sulfur remains dissolved in the


id: cumene-process-20260505-0
file: data/en.wikipedia.org/wiki/Cumene_process-0.md
category: reference
title: Cumene process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cumene_process
date_saved: 2026-05-05T10:47:02.146629+00:00
instance: kb-cron
parent: cumene-process-20260505-0
summary:
The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It was invented by Rūdolfs Ūdris and Pyotr Sergeyev in 1942 in the Soviet Union, and independently by Heinrich Hock in 1944. This process converts two relatively cheap starting materials, benzene and propylene, into two more valuable ones, phenol and acetone. Other reactants required are oxygen from air and small amounts of a radical initiator. Most of the worldwide production of phenol and acetone is now based on this method. In 2022, nearly 10.8 million tonnes of phenol was produced by the cumene process. In order for this process to be economical, there must also be demand for the acetone by-product as well as the phenol. == Steps of the process == Cumene is formed in the gas-phase Friedel–Crafts alkylation of benzene by propene. Benzene and propene are compressed together to a pressure of 30 bar at 250 °C in presence of a catalytic Lewis acid. Phosphoric acid is often favored over aluminium halides. Cumene is oxidized in air, which removes the tertiary benzylic hydrogen from cumene


id: curing-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Curing_(chemistry)-0.md
category: reference
title: Curing (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Curing_(chemistry)
date_saved: 2026-05-05T10:47:03.298418+00:00
instance: kb-cron
parent: curing-chemistry-20260505-0
summary:
Curing is a chemical process employed in polymer chemistry and process engineering that produces the toughening or hardening of a polymer material by cross-linking of polymer chains. Even if it is strongly associated with the production of thermosetting polymers, the term "curing" can be used for all the processes where a solid product is obtained from a liquid solution, such as with PVC plastisols. == Curing process == During the curing process, single monomers and oligomers, mixed with or without a curing agent, react to form a tridimensional polymeric network. In the very first part of the reaction branches of molecules with various architectures are formed, and their molecular weight increases in time with the extent of the reaction until the network size is equal to the size of the system. The system has lost its solubility and its viscosity tends to infinite. The remaining molecules start to coexist with the macroscopic network until they react with the network creating other crosslinks. The crosslink density increases until the system reaches the end of the chemical reaction. Curing can be induced by heat, radiation, electron beams, or chemical additives. To quote from IUPAC: curing "might or might not require mixing with


id: curing-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Curing_(chemistry)-1.md
category: reference
title: Curing (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Curing_(chemistry)
date_saved: 2026-05-05T10:47:03.298418+00:00
instance: kb-cron
parent: curing-chemistry-20260505-0
summary:
=== Thermal analysis === If the reactions occurring during crosslinking are exothermic, the crosslinking rate can be related to the heat released during the process. The higher the number of bonds created, the higher is the heat released in the reaction. At the end of the reaction, no more heat will be released. To measure the heat flow differential scanning calorimetry can be used. Assuming that each bond formed during the crosslinking releases the same amount of energy, the degree of curing, α {\displaystyle \alpha } , can be defined as follows: α = Q Q T = ∫ 0 s Q ˙ d t ∫ 0 s f Q ˙ d t {\displaystyle \alpha ={\frac {Q}{Q_{T}}}={\frac {\int _{0}^{s}{\dot {Q}}\,dt}{\int _{0}^{s_{f}}{\dot {Q}}\,dt}}} where Q {\displaystyle Q} is the heat released up to a certain time s {\displaystyle s} , Q ˙ {\displaystyle {\dot {Q}}} is the instantaneous rate of heat and Q T {\displaystyle Q_{T}} is the total amount of heat released in s f {\displaystyle s_{f}} , when the reaction finishes. Also in this case the degree of curing goes from zero (no bonds created) to one (no more reactions occur) with a slope that changes in time and


id: deacon-process-20260505-0
file: data/en.wikipedia.org/wiki/Deacon_process-0.md
category: reference
title: Deacon process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deacon_process
date_saved: 2026-05-05T10:47:04.478228+00:00
instance: kb-cron
parent: deacon-process-20260505-0
summary:
The Deacon process, invented by Henry Deacon, is a process used during the manufacture of alkalis (the initial end product was sodium carbonate) by the Leblanc process. Hydrogen chloride gas was converted to chlorine gas, which was then used to manufacture a commercially valuable bleaching powder, and at the same time the emission of waste hydrochloric acid was curtailed. To some extent this technically sophisticated process superseded the earlier manganese dioxide process. == Process == The process was based on the oxidation of hydrogen chloride: 4 HCl + O2 → 2 Cl2 + 2H2O The reaction takes place at about 400 to 450 °C in the presence of a variety of catalysts, including copper chloride (CuCl2). Three companies developed commercial processes for producing chlorine based on the Deacon reaction: The Kel-Chlor process developed by the M. W. Kellogg Company, which utilizes nitrosylsulfuric acid. The Shell-Chlor process developed by the Shell Oil Company, which utilizes copper catalysts. The MT-Chlor process developed by the Mitsui Toatsu Company, which utilizes chromium-based catalysts. The Deacon process is now outdated technology. Most chlorine today is produced by using electrolytic processes. New catalysts based on ruthenium(IV) oxide have been developed by Sumitomo. == Leblanc-Deacon process ==


id: decaffeination-20260505-0
file: data/en.wikipedia.org/wiki/Decaffeination-0.md
category: reference
title: Decaffeination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decaffeination
date_saved: 2026-05-05T10:47:06.751518+00:00
instance: kb-cron
parent: decaffeination-20260505-0
summary:
Decaffeination is the removal of caffeine from coffee beans, cocoa, tea leaves, and other caffeine-containing materials. Decaffeinated products are commonly termed by the abbreviation decaf. To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low. A caffeine content reduction of at least 97% is required under United States FDA standards. A 2006 study found decaffeinated drinks to contain typically 1–2% of the original caffeine content, but sometimes as much as 20%. == Decaffeinated coffee == Friedlieb Ferdinand Runge performed the first isolation of caffeine from coffee beans in 1820, after the German poet Goethe heard about his work on belladonna extract, and requested he perform an analysis on coffee beans. Though Runge was able to isolate the compound, he did not learn much about the chemistry of caffeine itself, nor did he seek to use the process commercially to produce decaffeinated coffee. === Processes === Various methods can be used for decaffeination of coffee. These methods take place prior to roasting and may use organic solvents such as dichloromethane or ethyl acetate, supercritical CO2, or water to extract caffeine from the beans, while leaving flavour precursors in


id: decaffeination-20260505-1
file: data/en.wikipedia.org/wiki/Decaffeination-1.md
category: reference
title: Decaffeination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decaffeination
date_saved: 2026-05-05T10:47:06.751518+00:00
instance: kb-cron
parent: decaffeination-20260505-0
summary:
==== Supercritical CO2 ==== Food scientists have also turned to supercritical carbon dioxide (sCO2) as a means of decaffeination. Developed by Kurt Zosel, a scientist of the Max Planck Institute, it uses CO2 (carbon dioxide), heated and pressurised above its critical point, to extract caffeine. Green coffee beans are steamed and then added to a high pressure vessel. A mixture of water and CO2 is circulated through the vessel at 300 atm and 65 °C (149 °F). At this pressure and temperature CO2 is a supercritical fluid, with properties midway between a gas and a liquid. Caffeine dissolves into the CO2; but compounds contributing to the flavour of the brewed coffee are largely insoluble in CO2 and remain in the bean. In a separate vessel, caffeine is scrubbed from the CO2 with additional water. The CO2 is then recirculated to the pressure vessel. === Caffeine content of coffee === According to a 1979 analysis, coffee has the following caffeine content, depending on how it is prepared: === Caffeine content of decaffeinated coffee === To ensure product quality, manufacturers are required to test the newly decaffeinated coffee beans to make sure that caffeine concentration is relatively low. A caffeine content reduction


id: decrepitation-20260505-0
file: data/en.wikipedia.org/wiki/Decrepitation-0.md
category: reference
title: Decrepitation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Decrepitation
date_saved: 2026-05-05T10:47:07.908092+00:00
instance: kb-cron
parent: decrepitation-20260505-0
summary:
Decrepitation can be: the noise produced when certain chemical compounds are heated the cracking, or breaking up of compounds (such as lumps of limestone) during heating. Such compounds may also include lead nitrate and calcine. == Mineralogy == Decrepitation is one of the most accurate ways to calculate a mineral-deposit scale so that the analysis of the hydrothermal system is advanced and improved. Fluid inclusions are important in regard to decrepitation because they are the microscopic areas of gas and liquid within crystals that are decrepitated, or broken, with the application of heat. When decrepitating the crystal or salt, the liquid pressure is released which can result in a crack. However, in some cases the fluid inclusions are not fully decrepitated, in which case other methods must be used. Despite this shortcoming, decrepitation is the preferred procedure for identifying minerals because it allows for the quickest and greatest number of inclusions to be measured. The pressure necessary to spur decrepitation is reliant upon the size of the fluid inclusions; bigger inclusions decrepitate more easily at pressures between 700 and 900 atmospheres, while smaller fluid inclusions may require upwards of 1200 atmospheres, contrastingly, when fluid inclusions become even smaller, the amount


id: dehydrogenation-of-amine-boranes-20260505-0
file: data/en.wikipedia.org/wiki/Dehydrogenation_of_amine-boranes-0.md
category: reference
title: Dehydrogenation of amine-boranes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dehydrogenation_of_amine-boranes
date_saved: 2026-05-05T10:47:09.099059+00:00
instance: kb-cron
parent: dehydrogenation-of-amine-boranes-20260505-0
summary:
Dehydrogenation of amine-boranes or dehydrocoupling of amine-boranes is a chemical process wherein dihydrogen is released from amine-boranes. This process was once of some interest for hydrogen storage. == Substrates == Ammonia-borane, the parent amine-borane, is a molecule with the formula H3B−NH3. The hydrogen content for double dehydrogenation of ammonia-borane is nearly 12% ((4/33.7)x100): H3B−NH3 → 2 H2 + (HBNH) The amine boranes have the formula H3B−NH2R where R = alkyl. Their hydrogen content is necessarily lower, but the dehydrogenated product is more processable. == Catalysis == Many metal complexes catalyze the dehydrogenation of amine-borane (AB). Catalysis in the absence of metals has also been observed. === Pathways === The dehydrogenation of AB would in principle afford (H2BNH2)n and (HBNH)n. The monomers (n = 1) are highly unstable with respect to oligomerization. === Metal carbonyl catalysts === Group 6 metal carbonyls upon photolytic activation catalyze dehydrogenation of AB. Secondary amine-boranes dehydrogenate to form cyclic dimers, or monomeric aminoboranes in the case of more bulky groups on the amine. Similarly, primary amine-boranes dehydrogenate through a two step intramolecular process to give aminoborane polymers, which further dehydrogenate to form borazines. [CpFe(CO)2]2 is also an effective precatalyst, requiring photolytic activation. The two step process


id: deicing-20260505-0
file: data/en.wikipedia.org/wiki/Deicing-0.md
category: reference
title: Deicing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deicing
date_saved: 2026-05-05T10:47:10.308341+00:00
instance: kb-cron
parent: deicing-20260505-0
summary:
De-icing is the process of removing snow, ice or frost from a surface. Anti-icing is the application of chemicals that not only de-ice but also remain on a surface and continue to delay the reformation of ice for a certain period of time, or prevent adhesion of ice to make mechanical removal easier. De-icing can be accomplished by mechanical methods (scraping, pushing); through the application of heat; by use of dry or liquid chemicals designed to lower the freezing point of water (various salts or brines, alcohols, glycols); or by a combination of these different techniques. == Application areas == === Roadways === In 2013, an estimated 14 million tons of salt were used for de-icing roads in North America. De-icing of roads has traditionally been done with salt, spread by snowplows or dump trucks designed to spread it, often mixed with sand and gravel, on slick roads. Sodium chloride (rock salt) is normally used, as it is inexpensive and readily available in large quantities. However, since salt water still freezes at −18 °C (0 °F), it is of no help when the temperature falls below this point. It also has a tendency to cause corrosion, rusting the steel used


id: deicing-20260505-1
file: data/en.wikipedia.org/wiki/Deicing-1.md
category: reference
title: Deicing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deicing
date_saved: 2026-05-05T10:47:10.308341+00:00
instance: kb-cron
parent: deicing-20260505-0
summary:
==== Airport pavement ==== De-icing operations for airport pavement (runways, taxiways, aprons, taxiway bridges) may involve several types of liquid and solid chemical products, including propylene glycol, ethylene glycol, calcium magnesium acetate and other organic compounds. Chloride-based compounds (e.g. salt) are not used at airports, due to their corrosive effect on aircraft and other equipment. Urea mixtures have also been used for pavement de-icing, due to their low cost. However, urea is a significant pollutant in waterways and wildlife, as it degrades to ammonia after application, and it has largely been phased out at U.S. airports. In 2012 the U.S. Environmental Protection Agency (EPA) prohibited use of urea-based de-icers at most commercial airports. === Water agitator de-icer === Water agitators are electric motors put under water that propel up warmer water and agitate the surface with it to de-ice aquatic structures on rivers and lakes in freezing temperatures. There are also agitator bubblers that use compressed air, run through a hose, and released to agitate the water. == De-icing chemicals == All de-icers share a common working mechanism: they prevent water molecules from binding above a certain temperature. The effect depends on the concentration. This temperature is below 0 °C,


id: deposition-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Deposition_(chemistry)-0.md
category: reference
title: Deposition (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Deposition_(chemistry)
date_saved: 2026-05-05T10:47:11.449691+00:00
instance: kb-cron
parent: deposition-chemistry-20260505-0
summary:
In chemistry, deposition occurs when molecules settle out of a solution. Deposition can be viewed as a reverse process to dissolution or particle re-entrainment. == See also == Atomic layer deposition Chemical vapor deposition Deposition (physics) Fouling Physical vapor deposition Thin-film deposition Fused filament fabrication Precipitation (chemistry) == References ==


id: derivatization-20260505-0
file: data/en.wikipedia.org/wiki/Derivatization-0.md
category: reference
title: Derivatization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Derivatization
date_saved: 2026-05-05T10:47:12.625681+00:00
instance: kb-cron
parent: derivatization-20260505-0
summary:
Derivatization is a technique used in chemistry which converts a chemical compound into a product (the reaction's derivate) of similar chemical structure, called a derivative. Generally, a specific functional group of the compound participates in the derivatization reaction and transforms the educt to a derivate of deviating reactivity, solubility, boiling point, melting point, aggregate state, or chemical composition. Resulting new chemical properties can be used for quantification or separation of the educt. Derivatization techniques are frequently employed in chemical analysis of mixtures and in surface analysis, e.g. in X-ray photoelectron spectroscopy where newly incorporated atoms label characteristic groups. == Derivatization reactions == Several characteristics are desirable for a derivatization reaction: The reaction is reliable and proceeds to completion. Less unreacted starting material will simplify analysis. Also, this allows a small amount of analyte to be used. The reaction is general, allowing a wide range of substrates, yet specific to a single functional group, reducing complicating interference. The products are relatively stable, and form no degradation products within a reasonable period, facilitating analysis. Some examples of good derivatization reactions are the formation of esters and amides via acyl chlorides. == Classical qualitative organic analysis == Classical qualitative organic analysis usually involves


id: desiccation-20260505-0
file: data/en.wikipedia.org/wiki/Desiccation-0.md
category: reference
title: Desiccation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Desiccation
date_saved: 2026-05-05T10:47:13.812962+00:00
instance: kb-cron
parent: desiccation-20260505-0
summary:
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. The word desiccation comes from Latin de- 'thoroughly' and siccare 'to dry'. == Industry == Desiccation is widely employed in the oil and gas industry. These materials are obtained in a hydrated state, but the water content leads to corrosion or is incompatible with downstream processing. Removal of water is achieved by cryogenic condensation, absorption into glycols, and absorption onto desiccants such as silica gel. == Laboratory == A desiccator is a heavy glass or plastic container, now somewhat antiquated, used in practical chemistry for drying or keeping small amounts of materials very dry. The material is placed on a shelf, and a drying agent or desiccant, such as dry silica gel or anhydrous sodium hydroxide, is placed below the shelf. Often some sort of humidity indicator is included in the desiccator to show, by color changes, the level of humidity. These indicators are in the form of indicator plugs or indicator cards. The active chemical is cobalt chloride (CoCl2). Anhydrous


id: detonation-spraying-20260505-0
file: data/en.wikipedia.org/wiki/Detonation_spraying-0.md
category: reference
title: Detonation spraying
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Detonation_spraying
date_saved: 2026-05-05T10:47:14.991060+00:00
instance: kb-cron
parent: detonation-spraying-20260505-0
summary:
Detonation spraying is one of the many forms of thermal spraying techniques that are used to apply a protective coating at supersonic velocities to a material in order to change its surface characteristics. This is primarily to improve the durability of a component. It was first invented in 1955 by H.B. Sargent, R.M. Poorman and H. Lamprey and is applied to a component using a specifically designed detonation gun (D-gun). The component being sprayed must be prepared correctly by removing all surface oils, greases, debris and roughing up the surface in order to achieve a strongly bonded detonation spray coating. This process involves the highest velocities (≈3500 m/s shockwave that propels the coating materials) and temperatures (≈4000 °C) of coating materials compared to all other forms of thermal spraying techniques. Because of these characteristics, detonation spraying is able to apply low porous (below 1%) and low oxygen content (between 0.1 and 0.5%) protective coatings that protect against corrosion, abrasion and adhesion under low load. This process allows the application of very hard and dense surface coatings which are useful as wear resistant coatings. For this reason, detonation spraying is commonly used for protective coatings in aircraft engines, plug and ring


id: detonation-spraying-20260505-1
file: data/en.wikipedia.org/wiki/Detonation_spraying-1.md
category: reference
title: Detonation spraying
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Detonation_spraying
date_saved: 2026-05-05T10:47:14.991060+00:00
instance: kb-cron
parent: detonation-spraying-20260505-0
summary:
For cases where a very strong mechanical bond is required (such as for components that are going to be used to machine with) the components surface is often machined to create grooves for the coating to bond to. Dovetail grooves offer strong positive bonding but can be laboursome and costly. A cheaper method is to cut simple partially open grooves, yet this method produces an inferior final bond strength. The edges and corners of a component present possible weak points in the coating structure, as they can break off from the component. To increase the bond strength at these points the corners and edges of the component should be rounded off. If the coating does not need to reach the edges of a component, then an undercut can be used (as shown in the diagram to the right) to secure the coating to the substrate. Although undercuts can also be used in other scenarios. Coatings often have a tendency to shrink after being applied due to the cooling process. This means steps need to be taken in order to minimise the negative effects of shrinking. If not, the coating can suffer from stress due to tension which will weaken the


id: detonation-spraying-20260505-2
file: data/en.wikipedia.org/wiki/Detonation_spraying-2.md
category: reference
title: Detonation spraying
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Detonation_spraying
date_saved: 2026-05-05T10:47:14.991060+00:00
instance: kb-cron
parent: detonation-spraying-20260505-0
summary:
Detonation spraying creates a coating that is mostly mechanically bonded as opposed to being metallurgically bonded, which is a much stronger type of bond. Detonation spraying is a 'line of sight' process meaning that components generally need to be coated before being put to use or assembled. This is because the detonation gun needs to be able to access the surface to be able to apply an effective coating. The coatings despite being considerably strong in compression are weak under tension, meaning they can't be applied to malleable or expanding components. The coatings tend to fatigue under pinpoint loading. Detonation guns are quite large and loud. Detonation spraying has to be performed at a location specifically designed for it, as the gun is reasonable large and it is a loud process that produces substantial noise. For this reason, it is usually installed in a sound-proof room (with concrete walls 45 cm thick). The process involves a considerable amount of mechanisation and automation because the operator can't be in the room whilst the D-gun is in operation. == Safety == Detonation gun spraying like any other industrial process carries with it a number of safety hazards that need to be managed


id: dihydroxylation-20260505-0
file: data/en.wikipedia.org/wiki/Dihydroxylation-0.md
category: reference
title: Dihydroxylation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dihydroxylation
date_saved: 2026-05-05T10:47:16.177321+00:00
instance: kb-cron
parent: dihydroxylation-20260505-0
summary:
Dihydroxylation is the process by which an alkene is converted into a vicinal diol. Although there are many routes to accomplish this oxidation, the most common and direct processes use a high-oxidation-state transition metal (typically osmium or manganese). The metal is often used as a catalyst, with some other stoichiometric oxidant present. In addition, other transition metals and non-transition metal methods have been developed and used to catalyze the reaction. == Osmium catalyzed reactions == Osmium tetroxide (OsO4) is a popular oxidant used in the dihydroxylation of alkenes because of its reliability and efficiency with producing syn-diols. Since it is expensive and toxic, catalytic amounts of OsO4 are used in conjunction with a stoichiometric oxidizing agent. The Milas hydroxylation, Upjohn dihydroxylation, and Sharpless asymmetric dihydroxylation reactions all use osmium as the catalyst as well as varying secondary oxidizing agents. The Milas dihydroxylation was introduced in 1930, and uses hydrogen peroxide as the stoichiometric oxidizing agent. Although the method can produce diols, overoxidation to the dicarbonyl compound has led to difficulties isolating the vicinal diol. Therefore, the Milas protocol has been replaced by the Upjohn and Sharpless asymmetric dihydroxylation. Upjohn dihydroxylation was reported in 1973 and uses OsO4 as the active


id: disproportionation-20260505-0
file: data/en.wikipedia.org/wiki/Disproportionation-0.md
category: reference
title: Disproportionation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disproportionation
date_saved: 2026-05-05T10:47:17.360434+00:00
instance: kb-cron
parent: disproportionation-20260505-0
summary:
In chemistry, disproportionation, sometimes called dismutation (the French word), is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionation, such as when a compound in an intermediate oxidation state is formed from precursors of lower and higher oxidation states, is called comproportionation, also known as symproportionation. More generally, the term can be applied to any desymmetrizing reaction where two molecules of one type react to give one each of two different types: 2 A → A' + A" This expanded definition is not limited to redox reactions, but also includes some molecular autoionization reactions, such as the self-ionization of water. In contrast, some authors use the term redistribution to refer to reactions of this type (in either direction) when only ligand exchange but no redox is involved and distinguish such processes from disproportionation and comproportionation.For example, the Schlenk equilibrium 2 RMgX → R2Mg + MgX2 is an example of a redistribution reaction. == History == The first disproportionation reaction to be studied in detail was: 2 Sn2+ → Sn4+ + Sn This was examined using tartrates by Johan Gadolin in 1788.


id: disproportionation-20260505-1
file: data/en.wikipedia.org/wiki/Disproportionation-1.md
category: reference
title: Disproportionation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Disproportionation
date_saved: 2026-05-05T10:47:17.360434+00:00
instance: kb-cron
parent: disproportionation-20260505-0
summary:
2 CH3COCOOH + H2O → CH3CH(OH)COOH + CH3COOH + CO2 The dismutation of pyruvic acid into other small organic molecules (ethanol + CO2, or lactate and acetate, depending on the environmental conditions) is also a key step in fermentation reactions. Fermentation reactions can also be considered as disproportionation or dismutation biochemical reactions. Indeed, the donor and acceptor of electrons in the redox reactions supplying the chemical energy in these complex biochemical systems are the same organic molecules simultaneously acting as reductant or oxidant. Another example of biochemical dismutation reaction is the disproportionation of acetaldehyde into ethanol and acetic acid. In cellular respiration, electrons are transferred from substrate (electron donor) to an electron acceptor; in fermentation, part of the substrate molecule itself accepts the electrons. Fermentation is therefore a type of disproportionation, and does not involve an overall change in oxidation state of the substrate. Most of the fermentative substrates are organic molecules. === Disproportionation of sulfur intermediates === Another example is microbial sulfur disproportionation (MSD), a type of energy metabolism involving the disproportionation of inorganic sulfur compounds, that exists often alongside reduction of sulfate in certain bacteria. Sulfur isotopes of sediments are often measured for studying environments in the Earth's


id: dissociation-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Dissociation_(chemistry)-0.md
category: reference
title: Dissociation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dissociation_(chemistry)
date_saved: 2026-05-05T10:47:18.544926+00:00
instance: kb-cron
parent: dissociation-chemistry-20260505-0
summary:
Dissociation in chemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into other things such as atoms, ions, or radicals, usually in a reversible manner. For instance, when an acid dissolves in water, a covalent bond between an electronegative atom and a hydrogen atom is broken by heterolytic fission, which gives a proton (H+) and a negative ion. Dissociation is the opposite of association or recombination. == Dissociation constant == For reversible dissociations in a chemical equilibrium AB ↽ − − ⇀ A + B {\displaystyle {\ce {AB <=> A + B}}} the dissociation constant Kd is the ratio of dissociated to undissociated compound K d = [ A ] [ B ] [ A B ] {\displaystyle K_{d}=\mathrm {\frac {[A][B]}{[AB]}} } where the brackets denote the equilibrium concentrations of the species. == Dissociation degree == The dissociation degree α {\displaystyle \alpha } is the fraction of original solute molecules that have dissociated. It is usually indicated by the Greek symbol α. More accurately, degree of dissociation refers to the amount of solute dissociated into ions or radicals per mole. In case of very strong acids and bases, degree of


id: dissociation-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Dissociation_(chemistry)-1.md
category: reference
title: Dissociation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dissociation_(chemistry)
date_saved: 2026-05-05T10:47:18.544926+00:00
instance: kb-cron
parent: dissociation-chemistry-20260505-0
summary:
where HA is a proton acid such as acetic acid, CH3COOH. The double arrow means that this is an equilibrium process, with dissociation and recombination occurring at the same time. This implies that the acid dissociation constant K a = [ H + ] [ A − ] [ HA ] {\displaystyle K_{\ce {a}}={\ce {\frac {[H^{+}][A^{-}]}{[HA]}}}} However a more explicit description is provided by the Brønsted–Lowry acid–base theory, which specifies that the proton H+ does not exist as such in solution but is instead accepted by (bonded to) a water molecule to form the hydronium ion H3O+. The reaction can therefore be written as HA + H 2 O ↽ − − ⇀ H 3 O + + A − {\displaystyle {\ce {HA + H2O <=> H3O+ + A-}}} and better described as an ionization or formation of ions (for the case when HA has no net charge). The equilibrium constant is then K a = [ H 3 O + ] [ A − ] [ HA ] {\displaystyle K_{\ce {a}}={\ce {\frac {[H_{3}O^{+}][A^{-}]}{[HA]}}}} where [ H 2 O ] {\displaystyle {\ce {[H_2O]}}} is not included because in dilute solution the solvent is essentially a pure liquid with a thermodynamic


id: dow-process-bromine-20260505-0
file: data/en.wikipedia.org/wiki/Dow_process_(bromine)-0.md
category: reference
title: Dow process (bromine)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dow_process_(bromine)
date_saved: 2026-05-05T10:47:19.700222+00:00
instance: kb-cron
parent: dow-process-bromine-20260505-0
summary:
The Dow process is the method of bromine extraction from brine, and was Herbert Henry Dow's second revolutionary process for generating bromine commercially. This process was patented in 1891. In the original invention, bromide-containing brines are treated with sulfuric acid and bleaching powder to oxidize bromide to bromine, which remains dissolved in the water. Other oxidizers, such as electric current or chlorine, may be used instead of bleach. The aqueous solution is dripped onto burlap, and air is blown through causing bromine to volatilize. Bromine is trapped with iron turnings to give a solution of ferric bromide. Treatment with more iron metal converted the ferric bromide to ferrous bromide via comproportionation. Where desired, free bromine may be obtained by thermal decomposition of ferrous bromide. Before Dow entered the bromine business, brine was evaporated by heating with wood scraps and then crystallized sodium chloride was removed. An oxidizing agent was added, and bromine was formed in the solution. Then bromine was distilled. This was a very complicated and costly process. == References ==


id: dow-process-phenol-20260505-0
file: data/en.wikipedia.org/wiki/Dow_process_(phenol)-0.md
category: reference
title: Dow process (phenol)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dow_process_(phenol)
date_saved: 2026-05-05T10:47:20.858802+00:00
instance: kb-cron
parent: dow-process-phenol-20260505-0
summary:
The Dow process process is a method of phenol production through the hydrolysis of chlorobenzene. == Details == Benzene can be readily converted to chlorobenzene by nucleophilic aromatic substitution via a benzyne intermediate. Chlorobenzene is treated with aqueous sodium hydroxide at 350 °C and 300 bar or molten sodium hydroxide at 350 °C to convert it to sodium phenoxide, which yields phenol upon acidification. When 1-[14C]-1-chlorobenzene was subjected to aqueous NaOH at 395 °C, ipso the substitution product 1-[14C]-phenol was formed in 54% yield, while the cine substitution product 2-[14C]-phenol was formed in 43% yield. This indicates that an elimination-addition (benzyne) mechanism is predominant, with perhaps a small amount of product from addition-elimination (SNAr). == References ==


id: downs-cell-20260505-0
file: data/en.wikipedia.org/wiki/Downs_cell-0.md
category: reference
title: Downs cell
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Downs_cell
date_saved: 2026-05-05T10:47:22.050487+00:00
instance: kb-cron
parent: downs-cell-20260505-0
summary:
Downs' process is an electrochemical method for the commercial preparation of metallic sodium, in which molten NaCl is electrolyzed in a special apparatus called the Downs cell. The Downs cell was invented in 1923 (patented: 1924) by the American chemist James Cloyd Downs (1885–1957). == Operation == The Downs cell uses a carbon anode and an iron cathode, with molten sodium chloride as the electrolyte. Although solid sodium chloride is a poor conductor of electricity, when molten, the sodium and chloride ions are mobilized. These become charge carriers and allow conduction of electric current. Some calcium chloride and/or chlorides of barium (BaCl2) and strontium (SrCl2), and, in some processes, sodium fluoride (NaF) are added to the electrolyte to reduce the temperature required to keep the electrolyte liquid. Sodium chloride (NaCl) melts at 801 °C (1074 Kelvin), but a salt mixture can be kept liquid at a temperature as low as 600 °C at the mixture containing, by weight: 33.2% NaCl and 66.8% CaCl2. Using pure sodium chloride causes an inseparable metallic sodium emulsion to form in the molten NaCl. Therefore, one option is to have a NaCl (42%) and CaCl2 (58%) mixture. The anode reaction is: 2Cl− → Cl2 (g)


id: downstream-processing-20260505-0
file: data/en.wikipedia.org/wiki/Downstream_processing-0.md
category: reference
title: Downstream processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Downstream_processing
date_saved: 2026-05-05T10:47:23.244801+00:00
instance: kb-cron
parent: downstream-processing-20260505-0
summary:
Downstream processing refers to the recovery and the purification of biosynthetic products, particularly pharmaceuticals, from natural sources such as animal tissue, plant tissue or fermentation broth, including the recycling of salvageable components as well as the proper treatment and disposal of waste. It is an essential step in the manufacture of pharmaceuticals such as antibiotics, hormones (e.g. insulin and human growth hormone), antibodies (e.g. infliximab and abciximab) and vaccines; antibodies and enzymes used in diagnostics; industrial enzymes; and natural fragrance and flavor compounds. Downstream processing is usually considered a specialized field in biochemical engineering, which is itself a specialization within chemical engineering. Many of the key technologies were developed by chemists and biologists for laboratory-scale separation of biological and synthetic products, whilst the role of biochemical and chemical engineers is to develop the technologies towards larger production capacities. Downstream processing and analytical bioseparation both refer to the separation or purification of biological products, but at different scales of operation and for different purposes. Downstream processing implies manufacture of a purified product fit for a specific use, generally in marketable quantities, while analytical bioseparation refers to purification for the sole purpose of measuring a component or components of a mixture, and


id: dust-explosion-20260505-0
file: data/en.wikipedia.org/wiki/Dust_explosion-0.md
category: reference
title: Dust explosion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dust_explosion
date_saved: 2026-05-05T10:47:24.448574+00:00
instance: kb-cron
parent: dust-explosion-20260505-0
summary:
A dust explosion is the rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere or other oxidizing gaseous medium, such as pure oxygen. In cases when fuel plays the role of a combustible material, the explosion is known as a fuel-air explosion. Dust explosions are a frequent hazard in coal mines, grain elevators and silos, and other industrial environments. They are also commonly used by special effects artists, filmmakers, and pyrotechnicians, given their spectacular appearance and ability to be safely contained under certain carefully controlled conditions. Thermobaric weapons exploit this principle by rapidly saturating an area with an easily combustible material and then igniting it to produce explosive force. These weapons are the most powerful non-nuclear explosives in existence. == Terminology == If rapid combustion occurs in a confined space, enormous overpressures can build up, causing major structural damage and flying debris. The sudden release of energy from a "detonation" can produce a shockwave, either in open air or in a confined space. If the spread of flame is at subsonic speed, the phenomenon is sometimes called a


id: dust-explosion-20260505-1
file: data/en.wikipedia.org/wiki/Dust_explosion-1.md
category: reference
title: Dust explosion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dust_explosion
date_saved: 2026-05-05T10:47:24.448574+00:00
instance: kb-cron
parent: dust-explosion-20260505-0
summary:
electrostatic discharge (e.g. an improperly installed conveyor belt, which can act like a Van de Graaff generator) friction electrical arcing from machinery or other equipment hot surfaces (e.g. overheated bearings) fire self-ignition However, it is often difficult to determine the exact source of ignition when investigating after an explosion. When a source cannot be found, ignition will often be attributed to static electricity. Static charges can be generated by external sources, or can be internally generated by friction at the surfaces of particles themselves as they collide or move past one another. == Mechanism == Dust has a very large surface area compared to its mass. Since burning can only occur at the surface of a solid or liquid, where it can react with oxygen, this causes dust to be much more flammable than bulk materials. For example, a 1 kg (2.2 lb) sphere of a combustible material with a density of 1 g/cm3 would be about 12.4 cm (4.9 in) in diameter, and have a surface area of 0.048 m2 (0.52 sq ft). However, if it were broken up into spherical dust particles 50 μm in diametre (about the size of flour particles) it would have a surface area


id: effervescence-20260505-0
file: data/en.wikipedia.org/wiki/Effervescence-0.md
category: reference
title: Effervescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Effervescence
date_saved: 2026-05-05T10:47:25.598156+00:00
instance: kb-cron
parent: effervescence-20260505-0
summary:
Effervescence is the escape of gas from an aqueous solution and the foaming or fizzing that results from that release. The word effervescence is derived from the Latin verb fervere (to boil), preceded by the adverb ex. It has the same linguistic root as the word fermentation . Effervescence can also be observed when opening a bottle of champagne, beer or carbonated soft drink. The visible bubbles are produced by the escape from solution of the dissolved gas (which itself is not visible while dissolved in the liquid). == In beverages == Although CO2 is most common for beverages, nitrogen gas is sometimes deliberately added to certain beers. The smaller bubble size creates a smoother beer head. Due to the poor solubility of nitrogen in beer, kegs or widgets are used for this. == Chemistry == In the laboratory, a common example of effervescence is seen if hydrochloric acid is added to a block of limestone. If a few pieces of marble or an antacid tablet are put in hydrochloric acid in a test tube fitted with a bung, effervescence of carbon dioxide can be witnessed. CaCO3 + 2 HCl → CaCl2 + H2O + CO2↑ This process is generally


id: efflorescence-20260505-0
file: data/en.wikipedia.org/wiki/Efflorescence-0.md
category: reference
title: Efflorescence
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Efflorescence
date_saved: 2026-05-05T10:47:26.794814+00:00
instance: kb-cron
parent: efflorescence-20260505-0
summary:
In chemistry, efflorescence (Derived from the Latin verb 'efflorescere' roughly meaning 'to flower') is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water or occasionally, in another solvent. The water, with the salt now held in solution, migrates to the surface, then evaporates, leaving a coating of the salt. In what has been described as "primary efflorescence", the water is the invader and the salt was already present internally, and a reverse process, where the salt is originally present externally and is then carried inside in solution, is referred to as "secondary efflorescence". Efflorescences can occur in natural and built environments. On porous construction materials it may present a cosmetic outer problem only (primary efflorescence causing staining), but can sometimes indicate internal structural weakness (migration/degradation of component materials). Efflorescence may clog the pores of porous materials, resulting in the destruction of those materials by internal water pressure, as seen in the spalling of brick. == Examples == A 5 molar concentration aqueous droplet of NaCl will spontaneously crystallize at 45% relative humidity (298 K) to form an NaCl cube


id: electrochemical-engineering-20260505-0
file: data/en.wikipedia.org/wiki/Electrochemical_engineering-0.md
category: reference
title: Electrochemical engineering
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrochemical_engineering
date_saved: 2026-05-05T10:47:27.979873+00:00
instance: kb-cron
parent: electrochemical-engineering-20260505-0
summary:
Electrochemical engineering is the branch of chemical engineering dealing with the technological applications of electrochemical phenomena, such as electrosynthesis of chemicals, electrowinning and refining of metals, flow batteries and fuel cells, surface modification by electrodeposition, electrochemical separations and corrosion. According to the IUPAC, the term electrochemical engineering is reserved for electricity-intensive processes for industrial or energy storage applications and should not be confused with applied electrochemistry, which comprises small batteries, amperometric sensors, microfluidic devices, microelectrodes, solid-state devices, voltammetry at disc electrodes, etc. More than 6% of the electricity is consumed by large-scale electrochemical operations in the US. == Scope == Electrochemical engineering combines the study of heterogeneous charge transfer at electrode/electrolyte interphases with the development of practical materials and processes. Fundamental considerations include electrode materials and the kinetics of redox species. The development of the technology involves the study of the electrochemical reactors, their potential and current distribution, mass transport conditions, hydrodynamics, geometry and components as well as the quantification of its overall performance in terms of reaction yield, conversion efficiency, and energy efficiency. Industrial developments require further reactor and process design, fabrication methods, testing, and product development. Electrochemical engineering considers current distribution, fluid flow, mass transfer, and the kinetics


id: electrochemical-engineering-20260505-1
file: data/en.wikipedia.org/wiki/Electrochemical_engineering-1.md
category: reference
title: Electrochemical engineering
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrochemical_engineering
date_saved: 2026-05-05T10:47:27.979873+00:00
instance: kb-cron
parent: electrochemical-engineering-20260505-0
summary:
== Bibliography == T.F. Fuller, John N. Harb, Electrochemical Engineering, John Wiley & Sons, 2018. H. Wright (ed.), Electrochemical Engineering: Emerging Technologies and Applications, Willford Press, 2016. D. Stolten, B. Emonts, Fuel Cell Science and Engineering: Materials, Processes, Systems and Technology, John Wiley & Sons, 2012. D.D. Macdonald, P. Schmuki (eds.), Electrochemical Engineering, in Encyclopedia of Electrochemistry, Vol. 5, Wiley-VCH, 2007. J. Newman, K.E. Thomas-Alyea, Electrochemical Systems, 3rd ed., John Wiley & Sons, Hoboken NJ, 2004. (1st ed. 1973). V.M. Schmidt, Elektrochemische Verfahrenstechnik, Wiley-VCH, 2003. H. Pütter, Industrial Electroorganic Chemistry, in Organic Electrochemistry, 4th ed., H. Lund, O. Hammerich (eds.), Marcel Dekker, New York, 2001. F.C. Walsh, Un Primer Curso de Ingeniería Electroquímica, Editorial Club Universitario, Alicante, España, 2000. M.P. Grotheer, Electrochemical Processing, Inorganic, in Kirk-Othmer Encyclopedia of Chemical Technology, 5th ed., Vol. 9, P. 618, John Wiley & Sons, 2000. H. Wendt, G. Kreysa, Electrochemical Engineering: Science and Technology in Chemical and Other Industries, Springer, Berlin 1999. R.F. Savinell, Tutorials in Electrochemical Engineering - Mathematical Modeling, Pennington, The Electrochemical Society, 1999. A. Geoffrey, Electrochemical Engineering Principles, Prentice Hall, 1997. F. Goodrige, K. Scott Electrochemical Process Engineering - A Guide to the Design of Electrolytic Plant, Plenum Press, New York


id: electrochemical-fluorination-20260505-0
file: data/en.wikipedia.org/wiki/Electrochemical_fluorination-0.md
category: reference
title: Electrochemical fluorination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrochemical_fluorination
date_saved: 2026-05-05T10:47:29.158870+00:00
instance: kb-cron
parent: electrochemical-fluorination-20260505-0
summary:
Electrochemical fluorination (ECF), or electrofluorination, is a foundational organofluorine chemistry method for the preparation of fluorocarbon-based organofluorine compounds. The general approach represents an application of electrosynthesis. The fluorinated chemical compounds produced by ECF are useful because of their distinctive solvation properties and the relative inertness of carbon–fluorine bonds. Two ECF synthesis routes are commercialized and commonly applied: the Simons process and the Phillips Petroleum process. It is also possible to electrofluorinate in various organic media. Prior to the development of these methods, fluorination with fluorine, a dangerous oxidizing agent, was a dangerous and wasteful process. ECF can be cost-effective, but it may also result in low yields. == Simons process == The Simons process, named after Joseph H. Simons entails electrolysis of a solution of an organic compound in a solution of hydrogen fluoride. An individual reaction can be described as: R3C–H + HF → R3C–F + H2 In the course of a typical synthesis, this reaction occurs once for each C–H bond in the precursor. The cell potential is maintained near 5–6 V. The anode is nickel-plated. Simons discovered the process in the 1930s at Pennsylvania State College (U.S.), under the sponsorship of the 3M Corporation. The results were


id: electrodialysis-20260505-0
file: data/en.wikipedia.org/wiki/Electrodialysis-0.md
category: reference
title: Electrodialysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrodialysis
date_saved: 2026-05-05T10:47:30.386561+00:00
instance: kb-cron
parent: electrodialysis-20260505-0
summary:
Electrodialysis (ED) is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference. This is done in a configuration called an electrodialysis cell. The cell consists of a feed (dilute) compartment and a concentrate (brine) compartment formed by an anion exchange membrane and a cation exchange membrane placed between two electrodes. In almost all practical electrodialysis processes, multiple electrodialysis cells are arranged into a configuration called an electrodialysis stack, with alternating anion and cation-exchange membranes forming the multiple electrodialysis cells. Electrodialysis processes are different from distillation techniques and other membrane based processes (such as reverse osmosis (RO)) in that dissolved species are moved away from the feed stream, whereas other processes move away the water from the remaining substances. Because the quantity of dissolved species in the feed stream is far less than that of the fluid, electrodialysis offers the practical advantage of much higher feed recovery in many applications. == Method == In an electrodialysis stack, the dilute (D) feed stream, brine or concentrate (C) stream, and electrode (E) stream are allowed to flow through the appropriate cell compartments formed by the ion-exchange membranes. Under the


id: electrodialysis-20260505-1
file: data/en.wikipedia.org/wiki/Electrodialysis-1.md
category: reference
title: Electrodialysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrodialysis
date_saved: 2026-05-05T10:47:30.386561+00:00
instance: kb-cron
parent: electrodialysis-20260505-0
summary:
== Applications == In application, electrodialysis systems can be operated as continuous production or batch production processes. In a continuous process, feed is passed through a sufficient number of stacks placed in series to produce the final desired product quality. In batch processes, the diluate and/or concentrate streams are re-circulated through the electrodialysis systems until the final product or concentrate quality is achieved. Electrodialysis is usually applied to deionization of aqueous solutions. However, desalting of sparingly conductive aqueous organic and organic solutions is also possible. Some applications of electrodialysis include: Large scale brackish and seawater desalination and salt production. Small and medium scale drinking water production (e.g., towns & villages, construction & military camps, nitrate reduction, hotels & hospitals) Water reuse (e.g., desalination brine treatment, industrial laundry wastewater, produced water from oil/gas production, cooling tower makeup & blowdown, metals industry fluids, wash-rack water) Pre-demineralization (e.g., boiler makeup & pretreatment, ultrapure water pretreatment, process water desalination, power generation, semiconductor, chemical manufacturing, food and beverage) Food processing Agricultural water (e.g., water for greenhouses, hydroponics, irrigation, livestock) Glycol desalting (e.g., antifreeze / engine-coolants, capacitor electrolyte fluids, oil and gas dehydration, conditioning and processing solutions, industrial heat transfer fluids, secondary coolants from heating, venting,


id: electrolysis-20260505-0
file: data/en.wikipedia.org/wiki/Electrolysis-0.md
category: reference
title: Electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolysis
date_saved: 2026-05-05T10:47:31.576904+00:00
instance: kb-cron
parent: electrolysis-20260505-0
summary:
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous biological and physical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity." == Etymology == The word "electrolysis" was introduced by Michael Faraday in 1834, using the Greek words ἤλεκτρον [ɛ̌ːlektron] "amber", which since the 17th century was associated with electrical phenomena, and λύσις [lýsis] meaning "dissolution". Nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure elements, precedes the coinage of the term and formal description by Faraday. == History == In the early nineteenth century, William Nicholson and Anthony Carlisle sought to further Volta's experiments. They attached two wires to either side of a voltaic pile and placed the other ends in a tube filled with water. They noticed when the wires were brought together that each wire produced bubbles. One type was hydrogen, the other was oxygen. In 1785 a


id: electrolysis-20260505-1
file: data/en.wikipedia.org/wiki/Electrolysis-1.md
category: reference
title: Electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolysis
date_saved: 2026-05-05T10:47:31.576904+00:00
instance: kb-cron
parent: electrolysis-20260505-0
summary:
Solvation or reaction of an ionic compound with a solvent (such as water) to produce mobile ions An ionic compound melted by heating The electrodes are immersed separated by a distance such that a current flows between them through the electrolyte and are connected to the power source which completes the electrical circuit. A direct current supplied by the power source drives the reaction causing ions in the electrolyte to be attracted toward the respective oppositely charged electrode. Electrodes of metal, graphite and semiconductor material are widely used. Choice of suitable electrode depends on chemical reactivity between the electrode and electrolyte and manufacturing cost. Historically, when non-reactive anodes were desired for electrolysis, graphite (called plumbago in Faraday's time) or platinum were chosen. They were found to be some of the least reactive materials for anodes. Platinum erodes very slowly compared to other materials, and graphite crumbles and can produce carbon dioxide in aqueous solutions but otherwise does not participate in the reaction. Cathodes may be made of the same material, or they may be made from a more reactive one since anode wear is greater due to oxidation at the anode. === Process of electrolysis === The key process of


id: electrolysis-20260505-2
file: data/en.wikipedia.org/wiki/Electrolysis-2.md
category: reference
title: Electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolysis
date_saved: 2026-05-05T10:47:31.576904+00:00
instance: kb-cron
parent: electrolysis-20260505-0
summary:
=== Energy changes during electrolysis === The amount of electrical energy that must be added equals the change in Gibbs free energy of the reaction plus the losses in the system. The losses can (in theory) be arbitrarily close to zero, so the maximum thermodynamic efficiency equals the enthalpy change divided by the free energy change of the reaction. In most cases, the electric input is larger than the enthalpy change of the reaction, so some energy is released in the form of heat. In some cases, for instance, in the electrolysis of steam into hydrogen and oxygen at high temperature, the opposite is true and heat energy is absorbed. This heat is absorbed from the surroundings, and the heating value of the produced hydrogen is higher than the electric input. === Variations === Pulsating current results in products different from DC. For example, pulsing increases the ratio of ozone to oxygen produced at the anode in the electrolysis of an aqueous acidic solution such as dilute sulphuric acid. Electrolysis of ethanol with pulsed current evolves an aldehyde instead of primarily an acid. === Related processes === Galvanic cells and batteries use spontaneous, energy-releasing redox reactions to generate an electrical


id: electrolysis-20260505-3
file: data/en.wikipedia.org/wiki/Electrolysis-3.md
category: reference
title: Electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolysis
date_saved: 2026-05-05T10:47:31.576904+00:00
instance: kb-cron
parent: electrolysis-20260505-0
summary:
the electrode potential for the reduction producing hydrogen is −0.41 V, the electrode potential for the oxidation producing oxygen is +0.82 V. Comparable figures calculated in a similar way, for 1 M zinc bromide, ZnBr2, are −0.76 V for the reduction to Zn metal and +1.10 V for the oxidation producing bromine. The conclusion from these figures is that hydrogen should be produced at the cathode and oxygen at the anode from the electrolysis of water—which is at variance with the experimental observation that zinc metal is deposited and bromine is produced. The explanation is that these calculated potentials only indicate the thermodynamically preferred reaction. In practice, many other factors have to be taken into account such as the kinetics of some of the reaction steps involved. These factors together mean that a higher potential is required for the reduction and oxidation of water than predicted, and these are termed overpotentials. Experimentally it is known that overpotentials depend on the design of the cell and the nature of the electrodes. For the electrolysis of a neutral (pH 7) sodium chloride solution, the reduction of sodium ion is thermodynamically very difficult and water is reduced evolving hydrogen leaving hydroxide ions in


id: electrolysis-20260505-4
file: data/en.wikipedia.org/wiki/Electrolysis-4.md
category: reference
title: Electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolysis
date_saved: 2026-05-05T10:47:31.576904+00:00
instance: kb-cron
parent: electrolysis-20260505-0
summary:
=== Electrolysis of seawater === A 2020 study investigated direct electrolysis of seawater, alkaline electrolysis, proton-exchange membrane electrolysis, and solid oxide electrolysis. Direct electrolysis of seawater follows known processes, forming an electrolysis cell in which the seawater acts as the electrolyte to allow for the reaction at the anode, 2 Cl−(aq) → Cl2(g) + 2e− and the reaction at the cathode, 2 H2O(l) + 2 e− → H2(g) + 2OH−(aq). The inclusion of magnesium and calcium ions in the seawater makes the production of alkali hydroxides possible that could form scales in the electrolyser cell, cutting down on lifespan and increasing the need for maintenance. The alkaline electrolysers operate with the following reactions at the anode, 2 OH−(aq) → 1/2 O2(g) + H2O(l) + 2 e−, and at the cathode, 2 H2O(l) + 2 e− → H2(g) + 2 OH−(aq), and use high base solutions as electrolytes, operating at 60–90 °C (140–194 °F) and need additional separators to ensure the gas phase hydrogen and oxygen remain separate. The electrolyte can easily get contaminated, but the alkaline electrolyser can operate under pressure to improve energy consumption. The electrodes can be made of inexpensive materials and there's no requirement for an expensive


id: electrolytic-process-20260505-0
file: data/en.wikipedia.org/wiki/Electrolytic_process-0.md
category: reference
title: Electrolytic process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrolytic_process
date_saved: 2026-05-05T10:47:32.744806+00:00
instance: kb-cron
parent: electrolytic-process-20260505-0
summary:
An electrolytic process is the use of electrolysis industrially to refine metals or compounds at a high purity and low cost. Some examples are the Hall-Héroult process used for aluminium, or the production of hydrogen from water. == Overview == Electrolysis is usually done in bulk using hundreds of sheets of metal connected to an electric power source. In the production of copper, these pure sheets of copper are used as starter material for the cathodes, and are then lowered into a solution such as copper sulfate with the large anodes that are cast from impure (97% pure) copper. The copper from the anodes is electroplated on to the cathodes, while any impurities settle to the bottom of the tank. This forms cathodes of 99.999% pure copper. == See also == Electrolysis of water Electroplating == References ==


id: electrometallurgy-20260505-0
file: data/en.wikipedia.org/wiki/Electrometallurgy-0.md
category: reference
title: Electrometallurgy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrometallurgy
date_saved: 2026-05-05T10:47:33.905872+00:00
instance: kb-cron
parent: electrometallurgy-20260505-0
summary:
Electrometallurgy is a method in metallurgy that uses electrical energy to produce metals by electrolysis. It is usually the last stage in metal production and is therefore preceded by pyrometallurgical or hydrometallurgical operations. The electrolysis can be done on a molten metal oxide (smelt electrolysis) which is used for example to produce aluminium from aluminium oxide via the Hall-Hérault process. Electrolysis can be used as a final refining stage in pyrometallurgical metal production (electrorefining) and it is also used for reduction of a metal from an aqueous metal salt solution produced by hydrometallurgy (electrowinning). == Processes == Electrometallurgy is the field concerned with the processes of metal electrodeposition. There are seven categories of these processes: Electrolysis Electrowinning, the extraction of metal from ores Electrorefining, the purification of metals. Metal powder production by electrodeposition is included in this category, or sometimes electrowinning, or a separate category depending on application. Electroplating, the deposition of a layer of one metal on another Electroforming, the manufacture of, usually thin, metal parts through electroplating Electropolishing, the removal of material from a metallic workpiece Etching, industrially known to Wikipedia as chemical milling == Research trends == === Molten oxide electrolysis === Molten Oxide Electrolysis in steelmaking


id: electropolishing-20260505-0
file: data/en.wikipedia.org/wiki/Electropolishing-0.md
category: reference
title: Electropolishing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electropolishing
date_saved: 2026-05-05T10:47:35.094163+00:00
instance: kb-cron
parent: electropolishing-20260505-0
summary:
Electropolishing, also known as electrochemical polishing, anodic polishing, or electrolytic polishing (especially in the metallography field), is an electrochemical process that removes material from a metallic workpiece, reducing the surface roughness by levelling micro-peaks and valleys, improving the surface finish. Electropolishing is often compared to, but distinctly different from, electrochemical machining. It is used to polish, passivate, and deburr metal parts. It is often described as the reverse of electroplating. It may be used in lieu of abrasive fine polishing in microstructural preparation. == Mechanism == Typically, the workpiece is immersed in a temperature-controlled bath of electrolyte and serves as the anode. At the cathode, a reduction reaction occurs, which normally produces hydrogen. The tiny hydrogen bubbles forming on the surface of the workpiece exert a scrubbing action which can be used to clean and polish the part. Electrolytes used for electropolishing are most often concentrated acid solutions such as mixtures of sulfuric acid and phosphoric acid. Other electropolishing electrolytes reported in the literature include mixtures of perchloric acid with acetic anhydride (which has caused fatal explosions), and methanolic solutions of sulfuric acid. To electropolish a rough surface, the protruding parts of a surface profile must dissolve faster than the


id: electrotyping-20260505-0
file: data/en.wikipedia.org/wiki/Electrotyping-0.md
category: reference
title: Electrotyping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrotyping
date_saved: 2026-05-05T10:47:36.311227+00:00
instance: kb-cron
parent: electrotyping-20260505-0
summary:
Electrotyping (also galvanoplasty) is a chemical method for forming metal parts that exactly reproduce a model. The method was invented by a Prussian engineer Moritz von Jacobi in Russia in 1838, and was immediately adopted for applications in printing and several other fields. As described in an 1890 treatise, electrotyping produces "an exact facsimile of any object having an irregular surface, whether it be an engraved steel- or copper-plate, a wood-cut, or a form of set-up type, to be used for printing; or a medal, medallion, statue, bust, or even a natural object, for art purposes." In art, several important "bronze" sculptures created in the 19th century are actually electrotyped copper, and not bronze at all; sculptures were executed using electrotyping at least into the 1930s. In printing, electrotyping had become a standard method for producing plates for letterpress printing by the late 1800s. It complemented the older technology of stereotyping, which involved metal casting. By 1901, stereotypers and electrotypers in several countries had formed labor unions around these crafts. The unions persisted into the 1970s, but by the late 20th century, after more than a century in widespread use for preparing plates, the two technologies had been bypassed by


id: electrotyping-20260505-1
file: data/en.wikipedia.org/wiki/Electrotyping-1.md
category: reference
title: Electrotyping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrotyping
date_saved: 2026-05-05T10:47:36.311227+00:00
instance: kb-cron
parent: electrotyping-20260505-0
summary:
One of the first applications of electrotyping was in printing. Initially, electrotyping was used to make copper reproductions of engraved metal plates or wooden carvings, which were used to print artwork. The electrotypes could be incorporated along with movable type to compose the formes for printing. Jacobi published his first account of electrotyping in October 1838. In 1839, electrotyping was used by Russian printers for government documents; the Russian Czar Nicholas I had immediately become an enthusiastic supporter and patron of the technology. In England, the first use of electrotyping for printing appeared in the London Journal of April 1840, and other English examples are known from later in that year. The image to the right shows one of the earliest uses of electrotyping in the United States; it is a comparison done by Joseph Alexander Adams in 1841 of the printed image prepared directly from a wood carving and of the image printed from a copper electrotype copy. Electrotyped copper plates could be formed into cylinders, which was valuable for use in magazine and newspaper printing. Electrotyping was also used to produce entire printing plates directly from the formes composed from movable type and illustrations. In this application, electrotyping


id: electrotyping-20260505-2
file: data/en.wikipedia.org/wiki/Electrotyping-2.md
category: reference
title: Electrotyping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrotyping
date_saved: 2026-05-05T10:47:36.311227+00:00
instance: kb-cron
parent: electrotyping-20260505-0
summary:
Electrotyping has been used for the production of metal sculptures, where it is an alternative to the casting of molten metal. These sculptures are sometimes called "galvanoplastic bronzes", although the actual metal is usually copper. It was possible to apply essentially any patina to these sculptures; gilding was also readily accomplished in the same facilities as electrotyping by using electroplating. Electrotyping has been used to reproduce valuable objects such as ancient coins, and in some cases electrotype copies have proven more durable than fragile originals. One of the earliest documented large-scale (1.67 metres (5.5 ft)) electrotype sculptures was John Evan Thomas's Death of Tewdric Mawr, King of Gwent (1849). The electrotype was done by Elkington, Mason, & Co. for the Great Exhibition of 1851. Among the most spectacular early examples are Josef Hermann's twelve angels (1858) at the base of the cupola of Saint Isaac's Cathedral in St. Petersburg, Russia (see photograph A below). As described by Théophile Gautier in 1867, "They are twenty-one feet high, and were made by the galvanoplastic process in four pieces, whose welding together is invisible. They could in this manner be made so light that, in spite of their dimensions, they would not be


id: electrowinning-20260505-0
file: data/en.wikipedia.org/wiki/Electrowinning-0.md
category: reference
title: Electrowinning
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Electrowinning
date_saved: 2026-05-05T10:47:37.469306+00:00
instance: kb-cron
parent: electrowinning-20260505-0
summary:
Electrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process to remove impurities from a metal. However, in electrorefining, the overall electron balance is zero, whereas electrowinning shows a net positive electron consumption in the overall reaction. Both processes use electroplating on a large scale and are important techniques for the economical and straightforward purification of non-ferrous metals. The resulting metals are said to be electrowon. In electrowinning, an electrical current is passed from an inert anode through a leach solution containing the dissolved metal ions so that the metal is recovered as it is reduced and deposited in an electroplating process onto the cathode. In electrorefining, the anode consists of the impure metal (e.g., copper) to be refined. The impure metallic anode is oxidized and the metal dissolves into solution. The metal ions migrate through the electrolyte towards the cathode where the pure metal is deposited. Insoluble solid impurities sedimenting below the anode often contain valuable rare elements such as gold, silver and selenium. == History == Electrowinning is the oldest industrial electrolytic process. The English chemist Humphry


id: emulsion-polymerization-20260505-0
file: data/en.wikipedia.org/wiki/Emulsion_polymerization-0.md
category: reference
title: Emulsion polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_polymerization
date_saved: 2026-05-05T10:47:38.679050+00:00
instance: kb-cron
parent: emulsion-polymerization-20260505-0
summary:
In polymer chemistry, emulsion polymerization is a type of radical polymerization that usually starts with an emulsion incorporating water, monomers, and surfactants. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer (the oil) are emulsified (with surfactants) in a continuous phase of water. Water-soluble polymers, such as certain polyvinyl alcohols or hydroxyethyl cellulose, can also be used to act as emulsifiers/stabilizers. The name "emulsion polymerization" is a misnomer that arises from a historical misconception. Rather than occurring in emulsion droplets, polymerization takes place in the latex/colloid particles that form spontaneously in the first few minutes of the process. These latex particles are typically 100 nm in size, and are made of many individual polymer chains. The particles are prevented from coagulating with each other because each particle is surrounded by the surfactant ('soap'); the charge on the surfactant repels other particles electrostatically. When water-soluble polymers are used as stabilizers instead of soap, the repulsion between particles arises because these water-soluble polymers form a 'hairy layer' around a particle that repels other particles, because pushing particles together would involve compressing these chains. Emulsion polymerization is used to make several commercially important polymers. Many of


id: emulsion-polymerization-20260505-1
file: data/en.wikipedia.org/wiki/Emulsion_polymerization-1.md
category: reference
title: Emulsion polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_polymerization
date_saved: 2026-05-05T10:47:38.679050+00:00
instance: kb-cron
parent: emulsion-polymerization-20260505-0
summary:
The Smith-Ewart-Harkins theory for the mechanism of free-radical emulsion polymerization is summarized by the following steps: A monomer is dispersed or emulsified in a solution of surfactant and water, forming relatively large droplets in water. Excess surfactant creates micelles in the water. Small amounts of monomer diffuse through the water to the micelle. A water-soluble initiator is introduced into the water phase where it reacts with monomer in the micelles. (This characteristic differs from suspension polymerization where an oil-soluble initiator dissolves in the monomer, followed by polymer formation in the monomer droplets themselves.) This is considered Smith-Ewart interval 1. The total surface area of the micelles is much greater than the total surface area of the fewer, larger monomer droplets; therefore the initiator typically reacts in the micelle and not the monomer droplet. Monomer in the micelle quickly polymerizes and the growing chain terminates. At this point the monomer-swollen micelle has turned into a polymer particle. When both monomer droplets and polymer particles are present in the system, this is considered Smith-Ewart interval 2. More monomer from the droplets diffuses to the growing particle, where more initiators will eventually react. Eventually the free monomer droplets disappear and all remaining monomer


id: emulsion-polymerization-20260505-2
file: data/en.wikipedia.org/wiki/Emulsion_polymerization-2.md
category: reference
title: Emulsion polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_polymerization
date_saved: 2026-05-05T10:47:38.679050+00:00
instance: kb-cron
parent: emulsion-polymerization-20260505-0
summary:
[ P ∙ ] = N m i c e l l e s 2 N A {\displaystyle [\mathrm {P} ^{\bullet }]={\frac {N_{\mathrm {micelles} }}{2N_{\mathrm {A} }}}} where N m i c e l l e s {\displaystyle N_{\mathrm {micelles} }} is number concentration of micelles (number of micelles per unit volume), and N A {\displaystyle N_{\mathrm {A} }} is the Avogadro constant (6.02×1023 mol−1). Consequently, the rate of polymerization is then R p = k p [ M ] N m i c e l l e s 2 N A . {\displaystyle R_{p}=k_{p}[\mathrm {M} ]{\frac {N_{\mathrm {micelles} }}{2N_{\mathrm {A} }}}.} === Interval 3 === Separate monomer droplets disappear as the reaction continues. Polymer particles in this stage may be sufficiently large enough that they contain more than 1 radical per particle. == Process considerations == Emulsion polymerizations have been used in batch, semi-batch, and continuous processes. The choice depends on the properties desired in the final polymer or dispersion and on the economics of the product. Modern process control schemes have enabled the development of complex reaction processes, with ingredients such as initiator, monomer, and surfactant added at the beginning, during, or at the end of the reaction.


id: emulsion-polymerization-20260505-3
file: data/en.wikipedia.org/wiki/Emulsion_polymerization-3.md
category: reference
title: Emulsion polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_polymerization
date_saved: 2026-05-05T10:47:38.679050+00:00
instance: kb-cron
parent: emulsion-polymerization-20260505-0
summary:
=== Non-surfactant stabilizers === Some grades of polyvinyl alcohol and other water-soluble polymers can promote emulsion polymerization even though they do not typically form micelles and do not act as surfactants (for example, they do not lower surface tension). It is believed that growing polymer chains graft onto these water-soluble polymers, which stabilize the resulting particles. Dispersions prepared with such stabilizers typically exhibit excellent colloidal stability (for example, dry powders may be mixed into the dispersion without causing coagulation). However, they often result in products that are very water sensitive due to the presence of the water-soluble polymer. === Other ingredients === Other ingredients found in emulsion polymerization include chain transfer agents, buffering agents, and inert salts. Preservatives are added to products sold as liquid dispersions to retard bacterial growth. These are usually added after polymerization, however. == Applications == Polymers produced by emulsion polymerization can roughly be divided into three categories. Synthetic rubber Some grades of styrene-butadiene (SBR) Some grades of Polybutadiene Polychloroprene (Neoprene) Nitrile rubber Acrylic rubber Fluoroelastomer (FKM) Plastics Some grades of PVC Some grades of polystyrene Some grades of PMMA Acrylonitrile-butadiene-styrene terpolymer (ABS) Polyvinylidene fluoride Polyvinyl fluoride PTFE Dispersions (i.e. polymers sold as aqueous dispersions) polyvinyl


id: emulsion-stabilization-using-polyelectrolytes-20260505-0
file: data/en.wikipedia.org/wiki/Emulsion_stabilization_using_polyelectrolytes-0.md
category: reference
title: Emulsion stabilization using polyelectrolytes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_stabilization_using_polyelectrolytes
date_saved: 2026-05-05T10:47:39.907152+00:00
instance: kb-cron
parent: emulsion-stabilization-using-polyelectrolytes-20260505-0
summary:
Polyelectrolytes are charged polymers capable of stabilizing (or destabilizing) colloidal emulsions through electrostatic interactions. Their effectiveness can be dependent on molecular weight, pH, solvent polarity, ionic strength, and the hydrophilic-lipophilic balance (HLB). Stabilized emulsions are useful in many industrial processes, including deflocculation, drug delivery, petroleum waste treatment, and food technology. == Types of polyelectrolytes == Polyelectrolytes are made up of positively or negatively charged repeat units. The charge on a polyelectrolyte depends on the different properties of the solution, such as the degree of dissociation of the monomer units, the solvent properties, salt concentration, pH, and temperature. Polymers become charged through the dissociation of the monomer side groups. If more monomer side groups are dissociated, the polymer has a higher charge. In turn, the charge of the polymer classifies the polyelectrolyte, which can be positive (cationic) or negative (anionic). The polymer charge and ionic strength of the polyelectrolyte in question dictate how thick a polyelectrolyte layer will be. The thickness of a polyelectrolyte then affects its adsorption ability. For more information on polyelectrolyte adsorption, look here. Some examples of polyelectrolytes can be found in the table below. The properties of the polymers vary with molecular weight and degree of polymerization.


id: emulsion-stabilization-using-polyelectrolytes-20260505-1
file: data/en.wikipedia.org/wiki/Emulsion_stabilization_using_polyelectrolytes-1.md
category: reference
title: Emulsion stabilization using polyelectrolytes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Emulsion_stabilization_using_polyelectrolytes
date_saved: 2026-05-05T10:47:39.907152+00:00
instance: kb-cron
parent: emulsion-stabilization-using-polyelectrolytes-20260505-0
summary:
λ B = e 2 4 π ε r ε 0 k B T , {\displaystyle \lambda _{B}={\frac {e^{2}}{4\pi \varepsilon _{r}\varepsilon _{0}k_{\text{B}}T}},} where e {\displaystyle e} = elementary charge, ε 0 {\displaystyle \varepsilon _{0}} = vacuum permittivity, ε r {\displaystyle \varepsilon _{r}} = relative dielectric constant. === Surface charge density === The factors discussed above can influence the charge on the surface of the polyelectrolyte. The surface charge density of these surfaces, at low surface potentials, can be modeled using a simplified version of the Grahame equation (eq. 3): σ = ε r ε 0 ϕ 0 K , {\displaystyle \sigma ={\varepsilon _{r}\varepsilon _{0}\phi _{0}}{K},} where ϕ 0 {\displaystyle \phi _{0}} = surface potential. Examples of polymers and their surface charge densities can be found in the table below. == Applications == === Deflocculation === Depending on the situation, polyelectrolytes can function as either flocculants or deflocculants. To stabilize emulsion, deflocculant polyelectrolytes are required. When repulsive forces between particles overcome the intermolecular forces in solution and the loose flocculated aggregates separate, deflocculation occurs. As opposed to the loose and easily separated sediments formed in flocculation, sediments formed in deflocculation are tightly packed and difficult to redisperse. The repelling forces in


id: equilibrium-catalyst-20260505-0
file: data/en.wikipedia.org/wiki/Equilibrium_catalyst-0.md
category: reference
title: Equilibrium catalyst
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Equilibrium_catalyst
date_saved: 2026-05-05T10:47:41.072600+00:00
instance: kb-cron
parent: equilibrium-catalyst-20260505-0
summary:
Equilibrium catalyst usually refers to the catalyst mix use in fluid catalytic cracking (FCC), but includes other petrochemical processes that use large amounts (many tons) of catalysts. The catalyst is a zeolite. During the FCC, the catalyst "inventory" is regularly removed from operation and reactivated by combusting the accumulated coke, which is a catalyst poison. Some of the catalyst is irreversibly deactivated by metal contaminants and by degradation of the alumino silicate backbone of the zeolite. To compensate for these changes, some inventory is removed and some fresh catalyst is added. Thus, the inventory consists of a catalytic particles with a range of activities. This mixture is referred to as the equilibrium catalyst. In addition to FCC, equilibrium catalyst concept applies to hydroprocessing and hydrocracking. == Spent catalyst disposal == The disposal of spent catalyst is gaining importance, particularly because of strict environmental regulations and high prices of fresh catalyst. Landfills and approved dumping sites have been predominantly used to get rid of the spent catalyst. Catalysts containing metals (nickel, vanadium, molybdenum) classified as hazardous are pre-treated before disposal. Sale of spent catalyst to the cement industry or its reuse in construction sites, metal casting industry, in road building offers


id: etching-20260505-0
file: data/en.wikipedia.org/wiki/Etching-0.md
category: reference
title: Etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Etching
date_saved: 2026-05-05T10:47:42.331695+00:00
instance: kb-cron
parent: etching-20260505-0
summary:
Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types of material. As a method of printmaking, it is, along with engraving, the most important technique for old master prints, and remains in wide use today. In a number of modern variants such as microfabrication etching and photochemical milling, it is a crucial technique in modern technology, including circuit boards. In traditional pure etching, a metal plate (usually of copper, zinc or steel) is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with a pointed etching needle where the artist wants a line to appear in the finished piece, exposing the bare metal. The échoppe, a tool with a slanted oval section, is also used for "swelling" lines. The plate is then dipped in a bath of acid, known as the mordant (French for "biting") or etchant, or has acid washed over it. The acid "bites" into the metal (it undergoes a redox reaction) to a depth depending on


id: etching-20260505-1
file: data/en.wikipedia.org/wiki/Etching-1.md
category: reference
title: Etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Etching
date_saved: 2026-05-05T10:47:42.331695+00:00
instance: kb-cron
parent: etching-20260505-0
summary:
Callot also appears to have been responsible for an improved, harder, recipe for the etching ground, using lute-makers' varnish rather than a wax-based formula. This enabled lines to be more deeply bitten, prolonging the life of the plate in printing, and also greatly reducing the risk of "foul-biting", where acid gets through the ground to the plate where it is not intended to, producing spots or blotches on the image. Previously the risk of foul-biting had always been at the back of an etcher's mind, preventing too much time on a single plate that risked being ruined in the biting process. Now etchers could do the highly detailed work that was previously the monopoly of engravers, and Callot made full use of the new possibilities. Callot also made more extensive and sophisticated use of multiple "stoppings-out" than previous etchers had done. This is the technique of letting the acid bite lightly over the whole plate, then stopping-out those parts of the work which the artist wishes to keep light in tone by covering them with ground before bathing the plate in acid again. He achieved unprecedented subtlety in effects of distance and light and shade by careful control of this


id: etching-20260505-2
file: data/en.wikipedia.org/wiki/Etching-2.md
category: reference
title: Etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Etching
date_saved: 2026-05-05T10:47:42.331695+00:00
instance: kb-cron
parent: etching-20260505-0
summary:
The second way to apply hard ground is by liquid hard ground. This comes in a can and is applied with a brush upon the plate to be etched. Exposed to air the hard ground will harden. Some printmakers use oil/tar based asphaltum or bitumen as hard ground, although often bitumen is used to protect steel plates from rust and copper plates from aging. Soft ground also comes in liquid form and is allowed to dry but it does not dry hard like hard ground and is impressionable. After the soft ground has dried the printmaker may apply materials such as leaves, objects, hand prints and so on which will penetrate the soft ground and expose the plate underneath. The ground can also be applied in a fine mist, using powdered rosin or spraypaint. This process is called aquatint, and allows for the creation of tones, shadows, and solid areas of color. The design is then drawn (in reverse) with an etching-needle or échoppe. An "echoppe" point can be made from an ordinary tempered steel etching needle, by grinding the point back on a carborundum stone, at a 45–60 degree angle. The "echoppe" works on the same principle that makes


id: etching-20260505-3
file: data/en.wikipedia.org/wiki/Etching-3.md
category: reference
title: Etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Etching
date_saved: 2026-05-05T10:47:42.331695+00:00
instance: kb-cron
parent: etching-20260505-0
summary:
Growing concerns about the health effects of acids and solvents led to the development of less toxic etching methods in the late 20th century. An early innovation was the use of floor wax as a hard ground for coating the plate. Others, such as printmakers Mark Zaffron and Keith Howard, developed systems using acrylic polymers as a ground and ferric chloride for etching. The polymers are removed with sodium carbonate (washing soda) solution, rather than solvents. When used for etching, ferric chloride does not produce a corrosive gas, as acids do, thus eliminating another danger of traditional etching. The traditional aquatint, which uses either powdered rosin or enamel spray paint, is replaced with an airbrush application of the acrylic polymer hard ground. Again, no solvents are needed beyond the soda ash solution, though a ventilation hood is needed due to acrylic particulates from the air brush spray. The traditional soft ground, requiring solvents for removal from the plate, is replaced with water-based relief printing ink. The ink receives impressions like traditional soft ground, resists the ferric chloride etchant, yet can be cleaned up with warm water and either soda ash solution or ammonia. Anodic etching has been used in industrial


id: etching-20260505-4
file: data/en.wikipedia.org/wiki/Etching-4.md
category: reference
title: Etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Etching
date_saved: 2026-05-05T10:47:42.331695+00:00
instance: kb-cron
parent: etching-20260505-0
summary:
=== Aquatint === Aquatint is a variation giving only tone rather than lines when printed. Particulate resin is evenly distributed on all or parts of the plate, then heated to form a screen ground of uniform, but less than perfect, density. After etching, any exposed surface will result in a roughened (i.e., darkened) surface. Areas that are to be light in the final print are protected by varnishing between acid baths. Successive turns of varnishing and placing the plate in acid create areas of tone difficult or impossible to achieve by drawing through a wax ground. === Sugar lift === Designs in a syrupy solution of sugar or Camp Coffee are painted onto the metal surface prior to it being coated in a liquid etching ground or 'stop out' varnish. When the plate is placed in hot water the sugar dissolves, leaving the image. The plate can then be etched. === Spit bite === A mixture of nitric acid and gum arabic (or, very rarely, saliva) which can be dripped, spattered or painted onto a metal surface giving interesting results. A mixture of nitric acid and rosin may also be used. == Printing == Printing the plate is done by


id: ether-cleavage-20260505-0
file: data/en.wikipedia.org/wiki/Ether_cleavage-0.md
category: reference
title: Ether cleavage
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ether_cleavage
date_saved: 2026-05-05T10:47:43.647978+00:00
instance: kb-cron
parent: ether-cleavage-20260505-0
summary:
Ether cleavage refers to chemical substitution reactions that lead to the cleavage of ethers. Due to the high chemical stability of ethers, the cleavage of the C-O bond is uncommon in the absence of specialized reagents or under extreme conditions. In organic chemistry, ether cleavage is an acid catalyzed nucleophilic substitution reaction. Depending on the specific ether, cleavage can follow either SN1 or SN2 mechanisms. Distinguishing between both mechanisms requires consideration of inductive and mesomeric effects that could stabilize or destabilize a potential carbocation in the SN1 pathway. Usage of hydrohalic acids takes advantage of the fact that these agents are able to protonate the ether oxygen atom and also provide a halide anion as a suitable nucleophile. However, as ethers show similar basicity as alcohols (pKa of approximately 16), the equilibrium of protonation lies on the side of the unprotonated ether and cleavage is usually very slow at room temperature. Ethers can be cleaved by strongly basic agents, e.g. organolithium compounds. Cyclic ethers are especially susceptible to base cleavage, but acyclic ethers can be cleaved as well. == Mechanism in acid == Ethers cleave in polar, acidic solutions. Provided that a carbocation intermediate can be adequately stabilized, the cleavage


id: exfoliation-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Exfoliation_(chemistry)-0.md
category: reference
title: Exfoliation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Exfoliation_(chemistry)
date_saved: 2026-05-05T10:47:44.913762+00:00
instance: kb-cron
parent: exfoliation-chemistry-20260505-0
summary:
In chemistry, Exfoliation is a process that separates layered materials into nanomaterials by breaking the bonds between layers using mechanical, chemical, or thermal procedures. While exfoliation has historical roots dating back centuries, significant advances and widespread research gained momentum after Novoselov and Geim's discovery of graphene using Scotch tape in 2004. Their Nobel Prize-winning research primarily relied on mechanical exfoliation for the production of graphene which sparked an immediate interest in the exfoliation process. Today, exfoliation is regarded as the most widely used nanomaterial production technique. Exfoliation typically involves breaking weak bonds called van der Waals bonds to create two-dimensional materials, such as graphene or transition metal dichalcogenide monolayers. While various reversible chemical processes, such as intercalation can disrupt the weak bonds in a lamellar structure and introduce guest species, many of them fail to produce single-sheet materials as the processes are not strong enough to cancel the interlayer attractions. However, during exfoliation, the high energy input leads to an extreme bond-breaking process that irreversibly separates the layers into single sheets. Lately, it has been shown that if the energy input is substantial enough, the procedure can even break much stronger, bonds such as metallic or ionic bonds to create


id: exfoliation-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Exfoliation_(chemistry)-1.md
category: reference
title: Exfoliation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Exfoliation_(chemistry)
date_saved: 2026-05-05T10:47:44.913762+00:00
instance: kb-cron
parent: exfoliation-chemistry-20260505-0
summary:
==== Micromechanical Cleavage ==== Micromechanical Cleavage is the original graphene production method proposed by Novoselov and Geim. This process involves using sticky tape to get graphite samples and separating the layers until getting a single layer. Although the process yielded high-purity single-layered materials, it fell out of favor quickly as it required several repetitions for a single layer of graphene and was likely to damage the graphene layers during the process. ==== Liquid Phase Separation ==== Liquid phase separation is one of the most widely used exfoliation methods. Its high yields, high purity, and scalability make it one of the most preferred exfoliation methods. It works by providing a liquid medium for the mechanical exfoliation methods. The liquid medium significantly reduces the strength of the bonds in the material compared to vacuum conditions, making it easier for mechanical forces to break the weak bonds in the material. However, due to the interfacial tension forces, liquid phase separation does not always yield uniform results. When the tension forces do not balance out, graphene single layers may break due to the tension forces. To achieve relatively uniform results, the overall energy of the system must be minimized. The best way to optimize


id: exfoliation-chemistry-20260505-2
file: data/en.wikipedia.org/wiki/Exfoliation_(chemistry)-2.md
category: reference
title: Exfoliation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Exfoliation_(chemistry)
date_saved: 2026-05-05T10:47:44.913762+00:00
instance: kb-cron
parent: exfoliation-chemistry-20260505-0
summary:
==== Oxide Reduction ==== The oxide reduction method is particularly widely used with graphite to create graphene. It involves introducing oxide functional groups into the lamellar structure, which doubles the distance between graphite layers and reduces van der Waals attractions. These functional groups are then removed using reductants, resulting in single graphene layers from the graphite, which can now be easily exfoliated due to reduced van der Waals attractions. This method is especially valuable for fine-tuning the band gap properties of graphene, which naturally lacks a band gap. While this method was widely used over the last decade, its impurity levels led to its decline in popularity. The presence of a large number of holes and defects made the produced graphene unsuitable for electronics, and the chemicals used were hazardous. In 2014, a research group succeeded in isolating graphene layers without the use of oxidants, significantly increasing the purity of the samples and eliminating the need for further processing of the products. This advancement is expected to reignite interest in oxide reduction exfoliation. ==== Electrochemical Exfoliation ==== One of the most promising exfoliation methods is electrochemical exfoliation, which has been popular among researchers since its introduction in 2008. This method


id: exfoliation-chemistry-20260505-3
file: data/en.wikipedia.org/wiki/Exfoliation_(chemistry)-3.md
category: reference
title: Exfoliation (chemistry)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Exfoliation_(chemistry)
date_saved: 2026-05-05T10:47:44.913762+00:00
instance: kb-cron
parent: exfoliation-chemistry-20260505-0
summary:
==== Low Temperature Thermal Exfoliation ==== Low-temperature thermal exfoliation aims to retain the benefits of high-temperature thermal exfoliation while avoiding unexpected outcomes such as high costs and impurities. For this purpose, low-temperature thermal exfoliation employs relatively lower temperatures of 200°C-550°C to decompose the functional groups. These temperatures yield purer results than high-temperature thermal exfoliation because the chemicals produced at this temperature do not readily react with the layered material itself. Although this decrease in temperature affects reaction times, it is usually favored to achieve purer results. Even though the reaction time is shorter in low-temperature thermal exfoliation compared to high-temperature, it is still significantly shorter than in other methods. Additionally, low-temperature thermal exfoliation allows for fine-tuning of the bandgap properties of materials, making it an ideal method for electronic applications. Microwave Irradiation Exfoliation: Microwave Irradiation Exfoliation is another exfoliation method that would decrease the complexity of the exfoliation experiments greatly. First utilized for the production of exfoliated graphite, it was later adapted for other nanomaterials. In the microwave irradiation exfoliation method, materials partially intercalated through chemical processes are exposed to microwave radiation. Ions and molecules trapped between layers absorb microwaves, leading to local temperature changes. These local changes trigger significant


id: fajans-paneth-hahn-law-20260505-0
file: data/en.wikipedia.org/wiki/Fajans–Paneth–Hahn_Law-0.md
category: reference
title: Fajans–Paneth–Hahn Law
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fajans–Paneth–Hahn_Law
date_saved: 2026-05-05T10:47:46.067851+00:00
instance: kb-cron
parent: fajans-paneth-hahn-law-20260505-0
summary:
The Fajans–Paneth–Hahn Law (also Fajans precipitation rule, Fajans-Peneth precipitation and adsorption rule, Hahn law of precipitation and adsorption, Fajans Law), in chemistry, is a rule governing how a small amount of one substance (tracer) is carried down to a precipitate of another substance present in much larger amount (carrier) by coprecipitation or adsorption. The rule states that: the lower the solubility of the tracer cation with the anion of the carrier, the greater the amount of the tracer carried down by the carrier through co-precipitates or adsorption; when the tracer substance forms a mixed crystal, then the separation by co-precipitation only weakly depends on the conditions; the tracer will adsorb on the surface of the carrier precipitate if the precipitate acquired a surface charge opposite to that of the carrier ions in the solution; and then the separation strongly depends on the condition of precipitation. The amount carried down is strongly affected by presence of complexing species regardless if it occurs by formation of mixed crystals or adsorption. The law is named after chemists Kazimierz Fajans, Friedrich Paneth and Otto Hahn. The Fajans-Paneth-Hahn law is essential for understanding the behaviour of minute amounts of substances (e.g., carrier-free radionuclides) in solutions.


id: fasil-process-20260505-0
file: data/en.wikipedia.org/wiki/Fasil_process-0.md
category: reference
title: Fasil process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fasil_process
date_saved: 2026-05-05T10:47:47.236908+00:00
instance: kb-cron
parent: fasil-process-20260505-0
summary:
The fasil process (named from "formaldehyde silver") is an industrial method for producing formaldehyde from methanol, utilizing a silver catalyst. It is one of the two primary large-scale formaldehyde production methods, alongside the metal oxide process. The name fasil is a registered trademark owned by Dynea AS. Dynea started to produce formaldehyde in Norway in 1947 and has developed the process since then. More than 40 fasil formaldehyde plants have been installed worldwide. == Process description == Methanol, air and water is the primary feedstock for formaldehyde production. The feedstock is mixed in a vaporizer, and passed over a silver catalyst bed in an adiabatic reactor. Due to the methanol/oxygen ratio, the reaction gas mixture is above the upper flammability limit (UFL) for methanol/air mixtures and therefore inherently safe. The formaldehyde produced is separated from unreacted methanol and byproducts through absorption in water, using a selective absorber. In the fasil process, formaldehyde is synthesized through the catalytic oxidation of methanol. The primary reactions are partial oxidation of methanol (1), and methanol dehydrogenation (2). (1) CH3OH + ½ O2 → CH2O + H2O (2) CH3OH → CH2O + H2 This exothermic chemical reaction is facilitated by the silver catalyst at high


id: ffc-cambridge-process-20260505-0
file: data/en.wikipedia.org/wiki/FFC_Cambridge_process-0.md
category: reference
title: FFC Cambridge process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/FFC_Cambridge_process
date_saved: 2026-05-05T10:47:48.419173+00:00
instance: kb-cron
parent: ffc-cambridge-process-20260505-0
summary:
The FFC Cambridge process is an electrochemical method for producing Titanium (Ti) from titanium oxide by electrolysis in molten calcium salts. == History == A process for electrochemical production of titanium through the reduction of titanium oxide in a calcium chloride solution was first described in a 1904 German patent, and in 1954 U.S. patent 2845386A was awarded to Carl Marcus Olson for the production of metals like titanium by reduction of the metal oxide by a molten salt reducing agent in a specific gravity apparatus. The FFC Cambridge process was developed by George Chen, Derek Fray, and Thomas Farthing between 1996 and 1997 at the University of Cambridge. (The name FFC derives from the first letters of the last names of the inventors). The intellectual property relating to the technology has been acquired by Metalysis, (Sheffield, UK). == Process == The process typically takes place between 900 and 1100 °C, with an anode (typically carbon) and a cathode (the oxide being reduced) in a solution of molten CaCl2. Depending on the nature of the oxide it will exist at a particular potential relative to the anode, which is dependent on the quantity of CaO present in CaCl2. === Cathode


id: fischer-assay-20260505-0
file: data/en.wikipedia.org/wiki/Fischer_assay-0.md
category: reference
title: Fischer assay
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fischer_assay
date_saved: 2026-05-05T10:47:49.547161+00:00
instance: kb-cron
parent: fischer-assay-20260505-0
summary:
The Fischer assay is a standardized laboratory test for determining the oil yield from oil shale to be expected from a conventional shale oil extraction. A 100 gram oil shale sample crushed to <2.38 mm is heated in a small aluminum retort to 500 °C (930 °F) at a rate of 12°C/min (22°F/min), and held at that temperature for 40 minutes. The distilled vapors of oil, gas, and water are passed through a condenser and cooled with ice water into a graduated centrifuge tube. The oil yields achieved by other technologies are often reported as a percentage of the Fischer Assay oil yield. The original Fischer Assay test was developed in the early low temperature coal retorting research by Franz Joseph Emil Fischer and Hans Schrader. It was adapted for evaluating oil shale yields in 1949 by K. E. Stanfield and I. C. Frost. == See also == Fischer–Tropsch process == References ==


id: flash-vacuum-pyrolysis-20260505-0
file: data/en.wikipedia.org/wiki/Flash_vacuum_pyrolysis-0.md
category: reference
title: Flash vacuum pyrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Flash_vacuum_pyrolysis
date_saved: 2026-05-05T10:47:50.716075+00:00
instance: kb-cron
parent: flash-vacuum-pyrolysis-20260505-0
summary:
In organic chemistry. flash vacuum pyrolysis (FVP) is a technique that entails heating a precursor molecule intensely and briefly. The method is used to induce transformations that cannot readily be achieved in solution methods such as in refluxing solvents. The technique is uncommon due in part to limitations on the scale on which reactions can be carried out. In terms of implementation of FVP, two key parameters are the temperature and duration (or residence time). Often the experiment entails volatilizing a precursor, which is drawn through a "hot zone" followed by rapid condensation. The apparatus typically is conducted under dynamic vacuum. The hot zone must impart heat to the gaseous molecules, so it is packed with solids to induce gas-solid collisions. The packing material is generally chemically inert, such as quartz. The precursor (i) volatilizes with gentle heating and under vacuum, (ii) the precursor fragments or rearranges in the hot zone, and finally (iii) the products are collected by rapid cooling. Rapid post-reaction cooling and the dilution inherent in gases both suppress bimolecular degradation pathways. The technique is applied to conversions that proceed via unimolecular pathways. == Examples == 2-Acetoxydioxane, when heated at 425 °C converts to the highly reactive


id: flocculation-20260505-0
file: data/en.wikipedia.org/wiki/Flocculation-0.md
category: reference
title: Flocculation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Flocculation
date_saved: 2026-05-05T10:47:51.876651+00:00
instance: kb-cron
parent: flocculation-20260505-0
summary:
In colloidal chemistry, flocculation is a process by which colloidal particles come out of suspension to sediment in the form of floc or flake, either spontaneously or due to the addition of a clarifying agent. The action differs from precipitation in that, prior to flocculation, colloids are merely suspended, under the form of a stable dispersion (where the internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation) and are not truly dissolved in solution. Coagulation and flocculation are important processes in fermentation and water treatment with coagulation aimed to destabilize and aggregate particles through chemical interactions between the coagulant and colloids, and flocculation to sediment the destabilized particles by causing their aggregation into floc. == Term definition == According to the IUPAC definition, flocculation is "a process of contact and adhesion whereby the particles of a dispersion form larger-size clusters". Flocculation is synonymous with agglomeration and coagulation/coalescence. Basically, coagulation is a process of addition of coagulant to destabilize a stabilized charged particle. Meanwhile, flocculation is a technique that promotes agglomeration and assists in the settling of particles. The most common used coagulant is alum, Al2(SO4)3·14H2O. The chemical reaction involved: Al2(SO4)3 · 14 H2O → 2 Al(OH)3(s)


id: flocculation-20260505-1
file: data/en.wikipedia.org/wiki/Flocculation-1.md
category: reference
title: Flocculation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Flocculation
date_saved: 2026-05-05T10:47:51.876651+00:00
instance: kb-cron
parent: flocculation-20260505-0
summary:
Flocculation and sedimentation are widely employed in the purification of drinking water as well as in sewage treatment, storm-water treatment and treatment of industrial wastewater streams. For drinking water, typical treatment processes consist of grates, coagulation, flocculation, sedimentation, granular filtration and disinfection. The coagulation and flocculation steps are similar, causing particles to aggregate and fall out of solution, but may use different chemicals or physical movement of water. A variety of salts may be added to adjust the pH and act as clarifying agents, depending on the water chemistry. These include sodium hydroxide, calcium hydroxide, aluminum sulfate, aluminum oxide, ferric sulfate, ferric chloride, sodium aluminate, with flocculant aids polyaluminum chloride, polyferric chloride. A variety of cationic, anionic, and non-ionic polymers are also used, typically with a molecular weight below 500,000. Polydiallyldimethyl ammonium chloride (polyDADMAC) and epiDMA (a copolymer of epichlorohydrin and dimethylamine) are common choices, though these can produce carcinogenic nitrosamines. Sand, powerdered activated carbon, and clay may also be used as nucleating agents; in some cases, these are re-used after extraction. Biopolymers, especially, chitosan, are increasingly popular as environmentally friendly flocculants. Chitosan is not only biodegradable but also exhibits a unique ability to bind with a wide range of


id: fluid-catalytic-cracking-20260505-0
file: data/en.wikipedia.org/wiki/Fluid_catalytic_cracking-0.md
category: reference
title: Fluid catalytic cracking
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
date_saved: 2026-05-05T10:47:53.104203+00:00
instance: kb-cron
parent: fluid-catalytic-cracking-20260505-0
summary:
Fluid catalytic cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum (crude oils) into gasoline, alkene gases, and other petroleum products. The cracking of petroleum hydrocarbons was originally done by thermal cracking, now virtually replaced by catalytic cracking, which yields greater volumes of high octane rating gasoline; and produces by-product gases, with more carbon-carbon double bonds (i.e. alkenes), that are of greater economic value than the gases produced by thermal cracking. The feedstock to the FCC conversion process usually is heavy gas oil (HGO), which is that portion of the petroleum (crude oil) that has an initial boiling-point temperature of 340 °C (644 °F) or higher, at atmospheric pressure, and that has an average molecular weight that ranges from about 200 to 600 or higher; heavy gas oil also is known as "heavy vacuum gas oil" (HVGO). In the fluid catalytic cracking process, the HGO feedstock is heated to a high temperature and to a moderate pressure, and then is placed in contact with a hot, powdered catalyst, which breaks the long-chain molecules of the high-boiling-point hydrocarbon liquids into short-chain molecules, which then are collected as a vapor.


id: fluid-catalytic-cracking-20260505-1
file: data/en.wikipedia.org/wiki/Fluid_catalytic_cracking-1.md
category: reference
title: Fluid catalytic cracking
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
date_saved: 2026-05-05T10:47:53.104203+00:00
instance: kb-cron
parent: fluid-catalytic-cracking-20260505-0
summary:
=== Main column === The reaction product vapors (at 535 °C and a pressure of 1.72 bar) flow from the top of the reactor to the bottom section of the main column (commonly referred to as the main fractionator where feed splitting takes place) where they are distilled into the FCC end products of cracked petroleum naphtha, fuel oil, and offgas. After further processing for removal of sulfur compounds, the cracked naphtha becomes a high-octane component of the refinery's blended gasolines. The main fractionator offgas is sent to what is called a gas recovery unit where it is separated into butanes and butylenes, propane and propylene, and lower molecular weight gases (hydrogen, methane, ethylene and ethane). Some FCC gas recovery units may also separate out some of the ethane and ethylene. Although the schematic flow diagram above depicts the main fractionator as having only one sidecut stripper and one fuel oil product, many FCC main fractionators have two sidecut strippers and produce a light fuel oil and a heavy fuel oil. Likewise, many FCC main fractionators produce a light cracked naphtha and a heavy cracked naphtha. The terminology light and heavy in this context refers to the product boiling ranges,


id: fluid-catalytic-cracking-20260505-2
file: data/en.wikipedia.org/wiki/Fluid_catalytic_cracking-2.md
category: reference
title: Fluid catalytic cracking
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
date_saved: 2026-05-05T10:47:53.104203+00:00
instance: kb-cron
parent: fluid-catalytic-cracking-20260505-0
summary:
=== Catalysts === FCC units continuously withdraw and replace some of the catalyst in order to maintain a steady level of activity. Modern FCC catalysts are fine powders with a bulk density of 0.80 to 0.96 g/cm3 and having a particle size distribution ranging from 10 to 150 μm and an average particle size of 60 to 100 μm. The design and operation of an FCC unit is largely dependent upon the chemical and physical properties of the catalyst. The desirable properties of an FCC catalyst are: Good stability to high temperature and to steam High activity Large pore sizes Good resistance to attrition Low coke production A modern FCC catalyst has four major components: crystalline zeolite, matrix, binder, and filler. Zeolite is the active component and can comprise from about 15% to 50%, by weight, of the catalyst. Faujasite (aka Type Y) is the zeolite used in FCC units. The zeolites are strong solid acids (equivalent to 90% sulfuric acid). The alumina matrix component of an FCC catalyst also contributes to catalytic activity sites. The binder and filler components provide the physical strength and integrity of the catalyst. The binder is usually silica sol and the filler is usually


id: fluid-catalytic-cracking-20260505-3
file: data/en.wikipedia.org/wiki/Fluid_catalytic_cracking-3.md
category: reference
title: Fluid catalytic cracking
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
date_saved: 2026-05-05T10:47:53.104203+00:00
instance: kb-cron
parent: fluid-catalytic-cracking-20260505-0
summary:
== History == The first commercial use of catalytic cracking occurred in 1915 when Almer M. McAfee of Gulf Refining Company developed a batch process using aluminium chloride (a Friedel–Crafts catalyst known since 1877) to catalytically crack heavy petroleum oils. However, the prohibitive cost of the catalyst prevented the widespread use of McAfee's process at that time. In 1922, a French mechanical engineer named Eugene Jules Houdry and a French pharmacist named E. A. Prudhomme set up a laboratory near Paris to develop a catalytic process for converting lignite coal to gasoline. Supported by the French government, they built a small demonstration plant in 1929 that processed about 60 tons per day of lignite coal. The results indicated that the process was not economically viable and it was subsequently shut down. Houdry had found that Fuller's earth, a clay mineral containing aluminosilicates, could convert oil derived from the lignite to gasoline. He then began to study the catalysis of petroleum oils and had some success in converting vaporized petroleum oil to gasoline. In 1930, the Vacuum Oil Company invited him to come to the United States and he moved his laboratory to Paulsboro, New Jersey. In 1931, the Vacuum Oil


id: fluid-catalytic-cracking-20260505-4
file: data/en.wikipedia.org/wiki/Fluid_catalytic_cracking-4.md
category: reference
title: Fluid catalytic cracking
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
date_saved: 2026-05-05T10:47:53.104203+00:00
instance: kb-cron
parent: fluid-catalytic-cracking-20260505-0
summary:
== Typical modern yields == == See also == Cracking (chemistry) == References == == External links == Valero Refinery Tour (Houston, TX) Description and diagram of power train CD Tech website discussion of Lummus FCC and hydrotreating of catalytically cracked naphtha. The FCC Network Recovery of CO from a FCC using the COPureSM Process North American Catalysis Society Fluid Catalytic Cracking (University of British Columbia, Quak Foo, Lee ) CFD Simulation of a Full-Scale Commercial FCC Regenerator


id: fluidization-20260505-0
file: data/en.wikipedia.org/wiki/Fluidization-0.md
category: reference
title: Fluidization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluidization
date_saved: 2026-05-05T10:47:54.289691+00:00
instance: kb-cron
parent: fluidization-20260505-0
summary:
Fluidization (or fluidisation) is a process similar to liquefaction whereby a granular material is converted from a static solid-like state to a dynamic fluid-like state. This process occurs when a fluid (liquid or gas) is passed up through the granular material. When a gas flow is introduced through the bottom of a bed of solid particles, it will move upwards through the bed via the empty spaces between the particles. At low gas velocities, aerodynamic drag on each particle is also low, and thus the bed remains in a fixed state. Increasing the velocity, the aerodynamic drag forces will begin to counteract the gravitational forces, causing the bed to expand in volume as the particles move away from each other. Further increasing the velocity, it will reach a critical value at which the upward drag forces will exactly equal the downward gravitational forces, causing the particles to become suspended within the fluid. At this critical value, the bed is said to be fluidized and will exhibit fluidic behavior. By further increasing gas velocity, the bulk density of the bed will continue to decrease, and its fluidization becomes more intense until the particles no longer form a bed and are "conveyed"


id: fluidization-20260505-1
file: data/en.wikipedia.org/wiki/Fluidization-1.md
category: reference
title: Fluidization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluidization
date_saved: 2026-05-05T10:47:54.289691+00:00
instance: kb-cron
parent: fluidization-20260505-0
summary:
Fluidized solids can be easily transferred between reactors. The intense mixing within a fluidized bed means that its temperature is uniform. There is excellent heat transfer between a fluidized bed and heat exchangers immersed in the bed. In the 1920s, the Winkler process was developed to gasify coal in a fluidized bed, using oxygen. It was not commercially successful. The first large scale commercial implementation, in the early 1940s, was the fluid catalytic cracking (FCC) process, which converted heavier petroleum cuts into gasoline. Carbon-rich "coke" deposits on the catalyst particles and deactivates the catalyst in less than 1 second. The fluidized catalyst particles are shuttled between the fluidized bed reactor and a fluidized bed burner where the coke deposits are burned off, generating heat for the endothermic cracking reaction. By the 1950s, fluidized bed technology was being applied to mineral and metallurgical processes such as drying, calcining, and sulfide roasting. In the 1960s, several fluidized bed processes dramatically reduced the cost of some important monomers. Examples are the Sohio process for acrylonitrile and the oxychlorination process for vinyl chloride. These chemical reactions are highly exothermic and fluidization ensures a uniform temperature, minimizing unwanted side reactions, and efficient heat transfer to


id: fluidized-bed-combustion-20260505-0
file: data/en.wikipedia.org/wiki/Fluidized_bed_combustion-0.md
category: reference
title: Fluidized bed combustion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluidized_bed_combustion
date_saved: 2026-05-05T10:47:55.510744+00:00
instance: kb-cron
parent: fluidized-bed-combustion-20260505-0
summary:
Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels. In its most basic form, fuel particles are suspended in a hot, bubbling fluidity bed of ash and other particulate materials (sand, limestone etc.) through which jets of air are blown to provide the oxygen required for combustion or gasification. The resultant fast and intimate mixing of gas and solids promotes rapid heat transfer and chemical reactions within the bed. FBC plants are capable of burning a variety of low-grade solid fuels, including most types of coal, coal waste and woody biomass, at high efficiency and without the necessity for expensive fuel preparation (e.g., pulverising). In addition, for any given thermal duty, FBCs are smaller than the equivalent conventional furnace, so may offer significant advantages over the latter in terms of cost and flexibility. FBC reduces the amount of sulfur emitted in the form of SOx emissions. Limestone is used to precipitate out sulfate during combustion, which also allows more efficient heat transfer from the boiler to the apparatus used to capture the heat energy (usually water tubes). The heated precipitate coming in direct contact with the tubes (heating by conduction) increases the efficiency. This allows coal


id: fluoroether-e-1-20260505-0
file: data/en.wikipedia.org/wiki/Fluoroether_E-1-0.md
category: reference
title: Fluoroether E-1
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fluoroether_E-1
date_saved: 2026-05-05T10:47:56.739256+00:00
instance: kb-cron
parent: fluoroether-e-1-20260505-0
summary:
Fluoroether E-1 (known chemically as heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, is a chemical compound that is among the class of per- and polyfluoroalkyl substances (PFAS). This synthetic fluorochemical is used in the GenX process, and may arise from the degradation of GenX chemicals including FRD-903. == Production == The main production of Fluoroether E-1 is within the GenX process where FRD-903 (2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoic acid) is used to generate (FRD-902) ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate, and Fluoroether E-1 (heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether). == Properties == Fluoroether E-1 is a colorless liquid that is practically insoluble in water. It is volatile and has a low boiling point. == References ==


id: 6-2-fluorotelomersulfonic-acid-20260505-0
file: data/en.wikipedia.org/wiki/6:2-Fluorotelomersulfonic_acid-0.md
category: reference
title: 6:2-Fluorotelomersulfonic acid
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/6:2-Fluorotelomersulfonic_acid
date_saved: 2026-05-05T10:47:57.862696+00:00
instance: kb-cron
parent: 6-2-fluorotelomersulfonic-acid-20260505-0
summary:
6:2-fluorotelomersulfonic acid (6:2-FTS) is a chemical compound that belongs to the group of fluorotelomersulfonic acids within the broader class of per- and polyfluorinated alkyl compounds (PFAS). Due to its structural similarity to perfluorooctanesulfonic acid (PFOS), it is also called H4PFOS. == Production == 6:2-Fluorotelomersulfonic acid is produced via telomerization. In addition, it is also formed, for example, from some perfluorocarboxybetaines after their splitting. == Usage == 6:2-Fluorotelomersulfonic acid and its derivatives are used as a replacement product for perfluorooctanesulfonic acid (PFOS) or its salts in fire-fighting foams. 6:2-FTS has also been used in the chromium plating industry to reduce mist formation during plating. == References ==


id: foam-separation-20260505-0
file: data/en.wikipedia.org/wiki/Foam_separation-0.md
category: reference
title: Foam separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Foam_separation
date_saved: 2026-05-05T10:47:59.013110+00:00
instance: kb-cron
parent: foam-separation-20260505-0
summary:
Foam separation is a chemical process which falls into a category of separation techniques called "Adsorptive bubble separation methods". It is further divided into froth flotation and foam fractionation. Foam separation is essential in order to prevent contamination of fermentation medium through the foam by external microbes. == References ==


id: formox-process-20260505-0
file: data/en.wikipedia.org/wiki/Formox_process-0.md
category: reference
title: Formox process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Formox_process
date_saved: 2026-05-05T10:48:00.187149+00:00
instance: kb-cron
parent: formox-process-20260505-0
summary:
The Formox process produces formaldehyde. Formox is a registered trademark owned by Johnson Matthey. The process was originally invented jointly by Swedish chemical company Perstorp and Reichhold Chemicals. Industrially, formaldehyde is produced by catalytic oxidation of methanol. The most commonly used catalysts are silver metal or a mixture of an iron oxide with molybdenum and/or vanadium. In the recently more commonly used Formox process using iron oxide and molybdenum and/or vanadium, methanol and oxygen react at 300-400°C to produce formaldehyde according to the chemical equation: CH3OH + ½ O2 → H2CO + H2O. The silver-based catalyst (see also: the Fasil process) is usually operated at a higher temperature, about 650 °C. On it, two chemical reactions simultaneously produce formaldehyde: the one shown above, and the dehydrogenation reaction: CH3OH → H2CO + H2 Further oxidation of the formaldehyde product during its production usually gives formic acid that is found in formaldehyde solution, found in parts per million values. == References ==


id: fowler-process-20260505-0
file: data/en.wikipedia.org/wiki/Fowler_process-0.md
category: reference
title: Fowler process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fowler_process
date_saved: 2026-05-05T10:48:01.371535+00:00
instance: kb-cron
parent: fowler-process-20260505-0
summary:
The Fowler process is an industry and laboratory route to fluorocarbons, by fluorinating hydrocarbons or their partially fluorinated derivatives in the vapor phase over cobalt(III) fluoride. == Background == The Manhattan Project required the production and handling of uranium hexafluoride for uranium enrichment, whether by diffusion or centrifuge. Uranium hexafluoride is very corrosive, oxidising, volatile solid (sublimes at 56 °C). To handle this material, several new materials were required, including a coolant liquid that could survive contact with uranium hexafluoride. Perfluorocarbons were identified as ideal materials, but at that point no method was available to produce them in any significant quantity. The problem is that fluorine gas is extremely reactive. Simply exposing a hydrocarbon to fluorine will cause the hydrocarbon to ignite. A way to moderate the reaction was required, and the method developed was to react the hydrocarbon with cobalt(III) fluoride, rather than fluorine itself. After World War II, much of the technology that had been kept secret was released into the public domain. The March 1947 issue of Industrial and Engineering Chemistry presented a collection of articles about fluorine chemistry, starting with the generation and handling of fluorine, and going on to discuss the synthesis of organofluorides and


id: frank-caro-process-20260505-0
file: data/en.wikipedia.org/wiki/Frank–Caro_process-0.md
category: reference
title: Frank–Caro process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Frank–Caro_process
date_saved: 2026-05-05T10:48:02.549271+00:00
instance: kb-cron
parent: frank-caro-process-20260505-0
summary:
The Frank–Caro process, also called cyanamide process, is the nitrogen fixation reaction of calcium carbide with nitrogen gas in a reactor vessel at about 1,000 °C. The reaction is exothermic and self-sustaining once the reaction temperature is reached. Originally the reaction took place in large steel cylinders with an electrical resistance element providing initial heat to start the reaction. Modern production uses rotating ovens. The synthesis produces a solid mixture of calcium cyanamide (CaCN2), also known as nitrolime, and carbon. CaC2 + N2 → CaCN2 + C == History == The Frank–Caro process was the first commercial process that was used worldwide to fix atmospheric nitrogen. The product was used as fertilizer and commercially known as Lime-Nitrogen. Nitrolim or Kalkstickstoff in German. The method was developed by the German chemists Adolph Frank and Nikodem Caro between 1895 and 1899. In its first decades, the world market for inorganic fertilizer was dominated by factories utilizing the cyanamide process. === Production facilities === The first full-scale factories were established in 1905 in Piano d´Orta (Italy) and Westeregeln (Germany). From 1908 the Frank–Caro process was used at North Western Cyanamide Company at Odda, Norway. With an annual production capacity of 12,000 ton from


id: galvanization-20260505-0
file: data/en.wikipedia.org/wiki/Galvanization-0.md
category: reference
title: Galvanization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Galvanization
date_saved: 2026-05-05T10:48:03.729256+00:00
instance: kb-cron
parent: galvanization-20260505-0
summary:
Galvanization (also spelled galvanisation) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are coated by submerging them in a bath of hot, molten zinc. Galvanized steel is widely used in applications where corrosion resistance is needed without the cost of stainless steel, and is considered superior in terms of cost and life-cycle. It can be identified by the crystallization patterning on the surface (often called a "spangle"). Galvanized steel can be welded; however, welding gives off toxic zinc fumes. Galvanized fumes are released when the galvanized metal reaches a certain temperature. This temperature varies by the galvanization process used. In long-term, continuous exposure, the recommended maximum temperature for hot-dip galvanized steel is 200 °C (392 °F), according to the American Galvanizers Association. The use of galvanized steel at temperatures above this will result in peeling of the zinc at the inter-metallic layer. Like other corrosion protection systems, galvanizing protects steel by acting as a barrier between steel and the atmosphere. However, zinc is a more electropositive (active) metal in comparison to steel. This is a unique characteristic for galvanizing, which means


id: chemical-garden-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_garden-0.md
category: reference
title: Chemical garden
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_garden
date_saved: 2026-05-05T10:48:04.929522+00:00
instance: kb-cron
parent: chemical-garden-20260505-0
summary:
A chemical garden is a set of complex biological-looking structures created by mixing inorganic chemicals. This experiment in chemistry is usually performed by adding metal salts, such as copper sulfate or cobalt(II) chloride, to an aqueous solution of sodium silicate (otherwise known as waterglass). This results in the growth of plant-like forms in minutes to hours. The chemical garden was first observed and described by Johann Rudolf Glauber in 1646. In its original form, the chemical garden involved the introduction of ferrous chloride (FeCl2) crystals into a solution of potassium silicate (K2SiO3). == Process == The chemical garden relies on most transition metal silicates being insoluble in water and colored. When a metal salt, such as cobalt chloride, is added to a sodium silicate solution, it will start to dissolve. It will then form insoluble cobalt silicate by a double displacement reaction. This cobalt silicate is a semipermeable membrane. Because the ionic strength of the cobalt solution inside the membrane is higher than the sodium silicate solution's, which forms the bulk of the tank contents, osmotic effects will increase the pressure within the membrane. This will cause the membrane to tear, forming a hole. The cobalt cations will react with


id: glycol-dehydration-20260505-0
file: data/en.wikipedia.org/wiki/Glycol_dehydration-0.md
category: reference
title: Glycol dehydration
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Glycol_dehydration
date_saved: 2026-05-05T10:48:06.124014+00:00
instance: kb-cron
parent: glycol-dehydration-20260505-0
summary:
Glycol dehydration is a liquid desiccant system for the removal of water from natural gas and natural gas liquids (NGL). It is the most common and economical means of water removal from these streams. Glycols typically seen in industry include triethylene glycol (TEG), diethylene glycol (DEG), ethylene glycol (MEG), and tetraethylene glycol (TREG). TEG is the most commonly used glycol in industry. == Purpose == The purpose of a glycol dehydration unit is to remove water from natural gas and natural gas liquids. When produced from a reservoir, natural gas usually contains a large amount of water and is typically completely saturated or at the water dew point. This water can cause several problems for downstream processes and equipment. At low temperatures the water can either freeze in piping or, as is more commonly the case, form hydrates with CO2 and hydrocarbons (mainly methane hydrates). Depending on composition, these hydrates can form at relatively high temperatures plugging equipment and piping. Glycol dehydration units depress the hydrate formation point of the gas through water removal. Without dehydration, a free water phase (liquid water) could also drop out of the natural gas as it is either cooled or the pressure is lowered


id: haber-process-20260505-0
file: data/en.wikipedia.org/wiki/Haber_process-0.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
The Haber process, also called the Haber–Bosch process, is the main industrial procedure for the production of ammonia. It converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using finely divided iron metal as a catalyst: N 2 + 3 H 2 ↽ − − ⇀ 2 NH 3 Δ H 298 K ∘ = − 92.28 kJ per mole of N 2 {\displaystyle {\ce {N2 + 3H2 <=> 2NH3}}\qquad {\Delta H_{\mathrm {298~K} }^{\circ }=-92.28~{\text{kJ per mole of }}{\ce {N2}}}} This reaction is exothermic but disfavored in terms of entropy because four equivalents of reactant gases are converted into two equivalents of product gas. However, due to the extremely high kinetic barriers to bond cleavage, high pressures and temperatures are needed to drive the reaction forward. The German chemists Fritz Haber and Carl Bosch developed the process in the first decade of the 20th century, and its improved efficiency over existing methods such as the Birkeland–Eyde and Frank–Caro processes was a major advancement in the industrial production of ammonia. The Haber process can be combined with steam reforming to produce ammonia with just three chemical inputs: water, natural gas, and atmospheric nitrogen. Both Haber and Bosch


id: haber-process-20260505-1
file: data/en.wikipedia.org/wiki/Haber_process-1.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
Combined with the energy needed to produce hydrogen and purified atmospheric nitrogen, ammonia production is energy-intensive, accounting for 1–2% of global energy consumption, 3% of global carbon emissions, and 3% to 5% of natural gas consumption. Hydrogen required for ammonia synthesis is most often produced through gasification of hydrocarbons, mostly natural gas, but other potential hydrogen sources include coal, petroleum, peat, biomass, or waste. As of 2012, the global production of ammonia produced from natural gas using the steam reforming process was 72%; however, in China as of 2022, natural gas and coal were responsible for 20% and 75% respectively. Hydrogen can also be produced from water and electricity using electrolysis: at one time, most of Europe's ammonia was produced from the Hydro plant at Vemork. Other possibilities include biological hydrogen production or photolysis, but at present, steam reforming of natural gas is the most economical means of mass-producing hydrogen. The choice of catalyst is important for synthesizing ammonia. In 2012, Hideo Hosono's group reported ammonia synthesis using Ru-loaded calcium-aluminium oxide C12A7:e− electride, describing the electride as an electron donor and reversible hydrogen store. Subsequent work studied nitrogen dissociation and catalytic mechanisms on Ru-loaded C12A7:e−. This method is implemented in


id: haber-process-20260505-2
file: data/en.wikipedia.org/wiki/Haber_process-2.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
where ϕ ^ i {\displaystyle {\hat {\phi }}_{i}} is the fugacity coefficient of species i {\displaystyle i} , y i {\displaystyle y_{i}} is the mole fraction of the same species, P {\displaystyle P} is the reactor pressure, and P ∘ {\displaystyle P^{\circ }} is standard pressure, typically 1 bar (0.10 MPa). Economically, reactor pressurization is expensive: pipes, valves, and reaction vessels need to be strong enough, and safety considerations affect operating at 20 MPa. Compressors take considerable energy, as work must be done on the (compressible) gas. Thus, the compromise used gives a single-pass yield of around 15%. While removing the ammonia from the system increases the reaction yield, this step is not used in practice, since the temperature is too high; instead it is removed from the gases leaving the reaction vessel. The hot gases are cooled under high pressure, allowing the ammonia to condense and be removed as a liquid. Unreacted hydrogen and nitrogen gases are returned to the reaction vessel for another round. While most ammonia is removed (typically down to 2–5 mol.%), some ammonia remains in the recycle stream. In academic literature, a more complete separation of ammonia has been proposed by absorption in metal halides,


id: haber-process-20260505-3
file: data/en.wikipedia.org/wiki/Haber_process-3.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
=== Catalysts other than iron === Many efforts have been made to improve the Haber–Bosch process. Many metals were tested as catalysts. The requirement for suitability is the dissociative adsorption of nitrogen (i. e. the nitrogen molecule must be split into nitrogen atoms upon adsorption). If the binding of the nitrogen is too strong, the catalyst is blocked and the catalytic ability is reduced (self-poisoning). The elements in the periodic table to the left of the iron group show such strong bonds. Further, the formation of surface nitrides makes, for example, chromium catalysts ineffective. Metals to the right of the iron group, in contrast, adsorb nitrogen too weakly for ammonia synthesis. Haber initially used catalysts based on osmium and uranium. Uranium reacts to its nitride during catalysis, while osmium oxide is rare. According to theoretical and practical studies, improvements over pure iron are limited. The activity of iron catalysts is increased by the inclusion of cobalt. ==== Ruthenium ==== Ruthenium forms highly active catalysts. Allowing milder operating pressures and temperatures, Ru-based materials are referred to as second-generation catalysts. Such catalysts are prepared by the decomposition of triruthenium dodecacarbonyl on graphite. A drawback of activated-carbon-supported ruthenium-based catalysts is the methanation of


id: haber-process-20260505-4
file: data/en.wikipedia.org/wiki/Haber_process-4.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
The methane gas reacts in the primary reformer only partially. To increase the hydrogen yield and keep the content of inert components (i. e. methane) as low as possible, the remaining methane gas is converted in a second step with oxygen to hydrogen and carbon monoxide in the secondary reformer. The secondary reformer is supplied with air as the oxygen source. Also, the required nitrogen for the subsequent ammonia synthesis is added to the gas mixture. 2 CH 4 ( g ) + O 2 ( g ) ⟶ 2 CO ( g ) + 4 H 2 ( g ) Δ H ∘ = − 71 kJ / mol {\displaystyle {\ce {{2CH4_{(g)}}+O2_{(g)}->{2CO_{(g)}}+4H2_{(g)}}}\qquad {\Delta H^{\circ }=-71\ {\ce {kJ/mol}}}} In the third step, the carbon monoxide is oxidized to carbon dioxide, which is called CO conversion or water–gas shift reaction. CO ( g ) + H 2 O ( g ) ⟶ CO 2 ( g ) + H 2 ( g ) Δ H ∘ = − 41 kJ / mol {\displaystyle {\ce {{CO_{(g)}}+H2O(g)->{CO2_{(g)}}+H2_{(g)}}}\qquad {\Delta H^{\circ }=-41\ {\ce {kJ/mol}}}} Carbon monoxide and carbon dioxide would form carbamates with ammonia, which would clog (as solids) pipelines and apparatus within a short


id: haber-process-20260505-5
file: data/en.wikipedia.org/wiki/Haber_process-5.md
category: reference
title: Haber process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haber_process
date_saved: 2026-05-05T10:48:07.304456+00:00
instance: kb-cron
parent: haber-process-20260505-0
summary:
N2 → S*–N2 (γ-species) → S*–N2–S* (α-species) → 2 S*–N (β-species, surface nitride) The adsorption of nitrogen is similar to the chemisorption of carbon monoxide. On a Fe(111) surface, the adsorption of nitrogen first leads to an adsorbed γ-species with an adsorption energy of 24 kJmol−1 and an N-N stretch vibration of 2100 cm−1. Since the nitrogen is isoelectronic to carbon monoxide, it adsorbs in an on-end configuration in which the molecule is bound perpendicular to the metal surface at one nitrogen atom. This has been confirmed by photoelectron spectroscopy. Ab-initio-MO calculations have shown that, in addition to the σ binding of the free electron pair of nitrogen to the metal, there is a π binding from the d orbitals of the metal to the π* orbitals of nitrogen, which strengthens the iron-nitrogen bond. The nitrogen in the α state is more strongly bound with 31 kJmol−1. The resulting N–N bond weakening could be experimentally confirmed by a reduction of the wave numbers of the N–N stretching oscillation to 1490 cm−1. Further heating of the Fe(111) area covered by α-N2 leads to both desorption and the emergence of a new band at 450 cm−1. This represents a metal-nitrogen oscillation, the


id: hall-h-roult-process-20260505-0
file: data/en.wikipedia.org/wiki/Hall–Héroult_process-0.md
category: reference
title: Hall–Héroult process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hall–Héroult_process
date_saved: 2026-05-05T10:48:24.583650+00:00
instance: kb-cron
parent: hall-h-roult-process-20260505-0
summary:
The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite, aluminium's chief ore, through the Bayer process) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell. The process, conducted at an industrial scale, happens at 940–980 °C (1700–1800 °F) and produces aluminium with a purity of 99.5–99.8%. Recycling aluminum, which does not require electrolysis, is thus not treated using this method. The Hall–Héroult process consumes substantial electrical energy, and its electrolysis stage can produce significant amounts of carbon dioxide if the electricity is generated from high-emission sources. Furthermore, the process generates fluorocarbon compounds as byproducts, contributing to both air pollution and climate change. == Process == === Difficulties faced === Elemental aluminium cannot be produced by the electrolysis of an aqueous aluminium salt, because hydronium ions readily oxidize elemental aluminium. Although a molten aluminium salt could be used instead, aluminium oxide has a melting point of 2072 °C (3762 °F) so electrolysing it is impractical. In the Hall–Héroult process, alumina, Al2O3, is dissolved in molten synthetic cryolite, Na3AlF6, to lower its melting point for easier electrolysis. The carbon source is generally a coke


id: hall-h-roult-process-20260505-1
file: data/en.wikipedia.org/wiki/Hall–Héroult_process-1.md
category: reference
title: Hall–Héroult process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hall–Héroult_process
date_saved: 2026-05-05T10:48:24.583650+00:00
instance: kb-cron
parent: hall-h-roult-process-20260505-0
summary:
=== Electrodes === Electrodes in cells are mostly coke which has been purified at high temperatures. Pitch resin or tar is used as a binder. The materials most often used in anodes, coke and pitch resin, are mainly residues from the petroleum industry and need to be of high enough purity so no impurities end up into the molten aluminum or the electrolyte. There are two primary anode technologies using the Hall–Héroult process: Söderberg technology and prebaked technology. In cells using Söderberg or self-baking anodes, there is a single anode per electrolysis cell. The anode is contained within a frame and, as the bottom of the anode turns mainly into CO2 during the electrolysis, the anode loses mass and, being amorphous, it slowly sinks within its frame. More material to the top of the anode is continuously added in the form of briquettes made from coke and pitch. The lost heat from the smelting operation is used to bake the briquettes into the carbon form required for the reaction with alumina. The baking process in Söderberg anodes during electrolysis releases more carcinogenic PAHs and other pollutants than electrolysis with prebaked anodes and, partially for this reason, prebaked anode-using cells have


id: hall-h-roult-process-20260505-2
file: data/en.wikipedia.org/wiki/Hall–Héroult_process-2.md
category: reference
title: Hall–Héroult process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hall–Héroult_process
date_saved: 2026-05-05T10:48:24.583650+00:00
instance: kb-cron
parent: hall-h-roult-process-20260505-0
summary:
=== Economic impact === Aluminium produced via the Hall–Héroult process, in combination with cheaper electric power, helped make aluminium (and incidentally magnesium) an inexpensive commodity rather than a precious metal. This, in turn, helped make it possible for pioneers like Hugo Junkers to utilize aluminium and aluminium-magnesium alloys to make items like metal airplanes by the thousands, or Howard Lund to make aluminium fishing boats. In 2012 it was estimated that 12.7 tons of CO2 emissions are generated per ton of aluminium produced. In the 20th and 21st century the aluminum industry due to its large-scale requirements for cheap electricity has often been sited in locations where such electricity is available. For example Iceland, a country with no notable bauxite reserves and a population of less than half a million, is the world's twelfth largest aluminum producer due to the availability of cheap and plentiful electricity, particularly hydropower. Similarly Aluminerie Alouette in Sept-Îles, Quebec, is dependent for its electricity needs on the 5,428 MW Churchill Falls Generating Station operated by Churchill Falls (Labrador) Corporation Limited. The company town of Kitimat in British Columbia was built by Alcan to meet the growing demand for aluminum in the postwar era. It makes


id: haworth-synthesis-20260505-0
file: data/en.wikipedia.org/wiki/Haworth_synthesis-0.md
category: reference
title: Haworth synthesis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Haworth_synthesis
date_saved: 2026-05-05T10:48:25.748094+00:00
instance: kb-cron
parent: haworth-synthesis-20260505-0
summary:
The Haworth synthesis is a multistep preparation of alkyl-substituted polycyclic aromatic hydrocarbons developed by the British chemist Robert Downs Haworth in 1932. == References ==


id: holt-dern-process-20260505-0
file: data/en.wikipedia.org/wiki/Holt-Dern_process-0.md
category: reference
title: Holt-Dern process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Holt-Dern_process
date_saved: 2026-05-05T10:48:26.909442+00:00
instance: kb-cron
parent: holt-dern-process-20260505-0
summary:
The Holt-Dern process is a method by which silver and gold can be extracted from low-grade ores. The method was applied in mining at Park City, Utah, and in the Tintic Mining District at the Tintic Smelter Site. It was named for George Dern and T.P. Holt. == References ==


id: hydrochloric-acid-regeneration-20260505-0
file: data/en.wikipedia.org/wiki/Hydrochloric_acid_regeneration-0.md
category: reference
title: Hydrochloric acid regeneration
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrochloric_acid_regeneration
date_saved: 2026-05-05T10:48:29.162088+00:00
instance: kb-cron
parent: hydrochloric-acid-regeneration-20260505-0
summary:
Hydrochloric acid regeneration or HCl regeneration is a chemical process for the reclamation of bound and unbound HCl from metal chloride solutions such as hydrochloric acid. == Field of application == The commercially most relevant field of application for HCl regeneration processes is the recovery of HCl from waste pickle liquors from carbon-steel pickling lines. Other applications include the production of metal oxides such as, but not limited, to Al2O3 and MgO, as well as rare-earth oxides, by pyrohydrolysis of aqueous metal chloride or rare-earth chloride solutions. A number of different process routes are available. The most widely used is based on pyrohydrolysis and adiabatic absorption of hydrogen chloride in water, a process invented in the 1960s. However tightening environmental standards and stringent air permit policies render it increasingly difficult to establish new pyrohydrolysis-based acid regeneration plants. == Known processes == The following processes for the regeneration of HCl from spent pickle liquors have been adopted by the ferrous metals processing industry: === Regeneration === Pyrohydrolysis Spray roaster pyrohydrolysis Fluidised bed pyrohydrolysis Hydrothermal regeneration Electrolytic Fe precipitation === Recovery of free HCl === Retardation Dialysis Ion exchange === Transformation of FeCl2 to FeCl3 === Electrolytic oxidation Chemical oxidation == Hydrothermal


id: hydrodenitrogenation-20260505-0
file: data/en.wikipedia.org/wiki/Hydrodenitrogenation-0.md
category: reference
title: Hydrodenitrogenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodenitrogenation
date_saved: 2026-05-05T10:48:30.335190+00:00
instance: kb-cron
parent: hydrodenitrogenation-20260505-0
summary:
Hydrodenitrogenation (HDN) is an industrial process for the removal of nitrogen from petroleum. Organonitrogen compounds, even though they occur at low levels, are undesirable because they cause poisoning of downstream catalysts. Furthermore, upon combustion, organonitrogen compounds generate NOx, a pollutant. HDN is effected as general hydroprocessing, which traditionally focuses on hydrodesulfurization (HDS) because sulfur compounds are even more problematic. To some extent, hydrodeoxygenation (HDO) is also effected. Typical organonitrogen compounds in petroleum include quinolines and porphyrins and their derivatives. The total nitrogen content is typically less than 1% and the targeted levels are in the ppm range. As described in organic geochemistry, organonitrogen compounds are derivatives or degradation products of the compounds in the living matter that comprised the precursor to fossil fuels. In HDN, the organonitrogen compounds are treated at high temperatures with hydrogen in the presence of a catalyst, the net transformation being: R3N + 3 H2 → 3 RH + NH3 The catalysts generally consist of cobalt and nickel as well as molybdenum disulfide or less often tungsten disulfide supported on alumina. The precise composition of the catalyst, i.e. Co/Ni and Mo/W ratios, are tuned for particular feedstocks. A wide variety of catalyst compositions have been considered,


id: hydrodeoxygenation-20260505-0
file: data/en.wikipedia.org/wiki/Hydrodeoxygenation-0.md
category: reference
title: Hydrodeoxygenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodeoxygenation
date_saved: 2026-05-05T10:48:31.469693+00:00
instance: kb-cron
parent: hydrodeoxygenation-20260505-0
summary:
Hydrodeoxygenation (HDO) is a hydrogenolysis process for removing oxygen from oxygen-containing compounds. Typical HDO catalysts commonly are sulfided nickel-molybdenum or cobalt-molybdenum on gamma alumina. An idealized reaction is: R2O + 2 H2 → H2O + 2 RH The first review on HDO was published in 1983. HDO is of interest in producing biofuels, which are derived from oxygen-rich precursors like sugars or lipids. An example of a biomass refining process employing hydrodeoxygenation is the NEXBTL process. HDO of biomass fast pyrolysis vapors under low hydrogen pressures have recently attracted a lot of attention. Bulk molybdenum trioxide (MoO3) was used as catalyst and found to completely deoxygenate cellulose, corn stover, and lignin pyrolysis vapors and produce a stream of hydrocarbons including aromatics, alkenes, and alkanes. From an economic viewpoint, only aromatics and alkenes should ideally be produced to enable product incorporation into the existing infrastructure. == References ==


id: hydrodesulfurization-20260505-0
file: data/en.wikipedia.org/wiki/Hydrodesulfurization-0.md
category: reference
title: Hydrodesulfurization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodesulfurization
date_saved: 2026-05-05T10:48:32.694698+00:00
instance: kb-cron
parent: hydrodesulfurization-20260505-0
summary:
Hydrodesulfurization (HDS), also called hydrotreatment or hydrotreating, is a catalytic chemical process widely used to remove sulfur (S) from natural gas and from refined petroleum products, such as gasoline or petrol, jet fuel, kerosene, diesel fuel, and fuel oils. The purpose of removing the sulfur, and creating products such as ultra-low-sulfur diesel, is to reduce the sulfur dioxide (SO2) emissions that result from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, gas or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion. Another important reason for removing sulfur from the naphtha streams within a petroleum refinery is that sulfur, even in extremely low concentrations, poisons the noble metal catalysts (platinum and rhenium) in the catalytic reforming units that are subsequently used to upgrade the octane rating of the naphtha streams. The industrial hydrodesulfurization processes include facilities for the capture and removal of the resulting hydrogen sulfide (H2S) gas. In petroleum refineries, the hydrogen sulfide gas is then subsequently converted into byproduct, sulfur (S) or sulfuric acid (H2SO4). In fact, the vast majority of the 64,000,000 metric tons of sulfur produced worldwide in 2005 was byproduct sulfur from refineries and other hydrocarbon processing plants.


id: hydrodesulfurization-20260505-1
file: data/en.wikipedia.org/wiki/Hydrodesulfurization-1.md
category: reference
title: Hydrodesulfurization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodesulfurization
date_saved: 2026-05-05T10:48:32.694698+00:00
instance: kb-cron
parent: hydrodesulfurization-20260505-0
summary:
The liquid feed (at the bottom left in the diagram) is pumped up to the required elevated pressure and is joined by a stream of hydrogen-rich recycle gas. The resulting liquid-gas mixture is preheated by flowing through a heat exchanger. The preheated feed then flows through a fired heater where the feed mixture is totally vaporized and heated to the required elevated temperature before entering the reactor and flowing through a fixed-bed of catalyst where the hydrodesulfurization reaction takes place. The hot reaction products are partially cooled by flowing through the heat exchanger where the reactor feed was preheated and then flows through a water-cooled heat exchanger before it flows through the pressure controller (PC) and undergoes a pressure reduction down to about 3 to 5 atmospheres. The resulting mixture of liquid and gas enters the gas separator pressure vessel at about 35 °C and 3 to 5 atmospheres of absolute pressure. Most of the hydrogen-rich gas from the gas separator vessel is recycle gas, which is routed through an amine contactor for removal of the reaction product H2S that it contains. The H2S-free hydrogen-rich gas is then recycled back for reuse in the reactor section. Any excess gas from


id: hydrodesulfurization-20260505-2
file: data/en.wikipedia.org/wiki/Hydrodesulfurization-2.md
category: reference
title: Hydrodesulfurization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodesulfurization
date_saved: 2026-05-05T10:48:32.694698+00:00
instance: kb-cron
parent: hydrodesulfurization-20260505-0
summary:
== Other uses == The basic hydrogenolysis reaction has a number of uses other than hydrodesulfurization. === Hydrodenitrogenation === The hydrogenolysis reaction is also used to reduce the nitrogen content of a petroleum stream in a process referred to as hydrodenitrogenation (HDN). The process flow is the same as that for an HDS unit. Using pyridine (C5H5N), a nitrogen compound present in some petroleum fractionation products, as an example, the hydrodenitrogenation reaction has been postulated as occurring in three steps: C 5 H 5 N Pyridine + 5 H 2 Hydrogen ⟶ C 5 H 11 N Piperdine + 2 H 2 Hydrogen ⟶ C 5 H 11 NH 2 Amylamine + H 2 Hydrogen ⟶ C 5 H 12 Pentane + NH 3 Ammonia {\displaystyle {\ce {{\overset {Pyridine}{C5H5N}}+ {\overset {Hydrogen}{5H2}}-> {\overset {Piperdine}{C5H11N}}+ {\overset {Hydrogen}{2H2}}-> {\overset {Amylamine}{C5H11NH2}}+ {\overset {Hydrogen}{H2}}-> {\overset {Pentane}{C5H12}}+ {\overset {Ammonia}{NH3}}}}} and the overall reaction may be simply expressed as: C 5 H 5 N Pyridine + 5 H 2 Hydrogen ⟶ C 5 H 12 Pentane + NH 3 Ammonia {\displaystyle {\ce {{\overset {Pyridine}{C5H5N}}+ {\overset {Hydrogen}{5H2}}-> {\overset {Pentane}{C5H12}}+ {\overset {Ammonia}{NH3}}}}} Many HDS units for desulfurizing naphthas within petroleum refineries are actually simultaneously denitrogenating to some extent as


id: hydrodimerization-20260505-0
file: data/en.wikipedia.org/wiki/Hydrodimerization-0.md
category: reference
title: Hydrodimerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrodimerization
date_saved: 2026-05-05T10:48:33.825740+00:00
instance: kb-cron
parent: hydrodimerization-20260505-0
summary:
Hydrodimerization is an organic reaction that couples two alkenes to give a symmetrical hydrocarbon. The reaction is often implemented electrochemically; in that case the reaction is called electrodimerization. The reaction can also be induced with samarium diiodide, a one-electron reductant. Hydrodimerization is the basis of the Monsanto adiponitrile synthesis: 2 CH2=CHCN + 2 e− + 2 H+ → NCCH2CH2CH2CH2CN The reaction applies to a number electrophilic alkenes (Michael acceptors). == References ==


id: hydrogen-assisted-magnesiothermic-reduction-20260505-0
file: data/en.wikipedia.org/wiki/Hydrogen_assisted_magnesiothermic_reduction-0.md
category: reference
title: Hydrogen assisted magnesiothermic reduction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrogen_assisted_magnesiothermic_reduction
date_saved: 2026-05-05T10:48:35.041974+00:00
instance: kb-cron
parent: hydrogen-assisted-magnesiothermic-reduction-20260505-0
summary:
The hydrogen assisted magnesiothermic reduction ("HAMR") process is a thermochemical process to obtain titanium metal from titanium oxides. A technical challenge in the production of titanium metal is the formation of oxide impurities. The Kroll process, which is widely used commercially, addresses this challenge by converting titanium ore (an oxide) into titanium tetrachloride (TiCl4). This intermediate is readily purified. It is reduced to titanium metal with magnesium. This technology is both capital, energy, and carbon-intensive. One advantage of the Kroll process, and several like it, is that it starts with titanium ores (e.g., illmenite), not a purified dioxide. The HAMR technology also entails a two step process, starting with TiO2 under an atmosphere of hydrogen gas. The product TiH2 can be further processed to titanium metal through standard methods. The reduction of titanium oxides to titanium metal using magnesium does not occur. The novelty of the HAMR process is the inclusion of hydrogen. == References == "HAMR Process for Titanium Production Powder Research Lab - Department of Metallurgical Engineering - The University of Utah". powder.metallurgy.utah.edu.


id: hydrometallurgy-20260505-0
file: data/en.wikipedia.org/wiki/Hydrometallurgy-0.md
category: reference
title: Hydrometallurgy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrometallurgy
date_saved: 2026-05-05T10:48:36.216112+00:00
instance: kb-cron
parent: hydrometallurgy-20260505-0
summary:
Hydrometallurgy is a technique within the field of extractive metallurgy, the obtaining of metals from their ores. Hydrometallurgy uses solutions to recover metals from ores, concentrates, and recycled or residual materials. Usually the extracting solution is aqueous (water-based), often containing additives such as acids. In select cases, the extracting solvent is nonaqueous. Processing techniques that complement hydrometallurgy are pyrometallurgy, vapour metallurgy, and molten salt electrometallurgy. Hydrometallurgy is typically divided into three general areas: Leaching Solution concentration and purification Metal or metal compound recovery == Leaching == Leaching involves the use of aqueous solutions to extract metal from metal-bearing materials. The extracting solution is called a lixiviant. The lixiviant is optimized in terms of pH, oxidation-reduction potential, presence of chelating agents, and temperature. In a simple implementation, a slurry of the pulverized ore in the lixiviant solution is filtered to yield a solution containing the metal ion(s) of interest. For example copper in its carbonate minerals such as malachite dissolve in aqueous sulfuric acid. On the other hand, copper sulfide minerals, which are more prevalent, are not amenable to hydrometallurgy, at least until they have been roasted. Hydrometallurgy is used to extract rare earths. By using chelating agents, one can selectively


id: hydrothermal-liquefaction-20260505-0
file: data/en.wikipedia.org/wiki/Hydrothermal_liquefaction-0.md
category: reference
title: Hydrothermal liquefaction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrothermal_liquefaction
date_saved: 2026-05-05T10:48:37.443697+00:00
instance: kb-cron
parent: hydrothermal-liquefaction-20260505-0
summary:
Hydrothermal liquefaction (HTL) is a thermal depolymerization process used to convert wet biomass, and other macromolecules, into crude-like oil under moderate temperature and high pressure. The crude-like oil has high energy density with a lower heating value of 33.8-36.9 MJ/kg and 5-20 wt% oxygen and renewable chemicals. The process has also been called hydrous pyrolysis. The reaction usually involves homogeneous and/or heterogeneous catalysts to improve the quality of products and yields. Carbon and hydrogen of an organic material, such as biomass, peat or low-ranked coals (lignite) are thermo-chemically converted into hydrophobic compounds with low viscosity and high solubility. Depending on the processing conditions, the fuel can be used as produced for heavy engines, including marine and rail or upgraded to transportation fuels, such as diesel, gasoline or jet-fuels. The process may be significant in the creation of fossil fuels. Simple heating without water, anhydrous pyrolysis has long been considered to take place naturally during the catagenesis of kerogens to fossil fuels. In recent decades it has been found that water under pressure causes more efficient breakdown of kerogens at lower temperatures than without it. The carbon isotope ratio of natural gas also suggests that hydrogen from water has been added


id: hydrothermal-liquefaction-20260505-1
file: data/en.wikipedia.org/wiki/Hydrothermal_liquefaction-1.md
category: reference
title: Hydrothermal liquefaction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrothermal_liquefaction
date_saved: 2026-05-05T10:48:37.443697+00:00
instance: kb-cron
parent: hydrothermal-liquefaction-20260505-0
summary:
=== Feedstock === Theoretically, any biomass can be converted into bio-oil using hydrothermal liquefaction regardless of water content, and various different biomasses have been tested, from forestry and agriculture residues, sewage sludges, food process wastes, to emerging non-food biomass such as algae. The composition of cellulose, hemicellulose, protein, and lignin in the feedstock influence the yield and quality of the oil from the process. Zhang et al., at the University of Illinois, report on a hydrous pyrolysis process in which swine manure is converted to oil by heating the swine manure and water in the presence of carbon monoxide in a closed container. For that process they report that a temperatures of at least 275 °C (527 °F) is required to convert the swine manure to oil, and temperatures above about 335 °C (635 °F) reduces the amount of oil produced. The Zhang et al. process produces pressures of about 7 to 18 Mpa (1000 to 2600 psi - 69 to 178 atm), with higher temperatures producing higher pressures. Zhang et al. used a retention time of 120 minutes for the reported study, but report at higher temperatures a time of less than 30 minutes results in significant production of


id: hydrothermal-liquefaction-20260505-2
file: data/en.wikipedia.org/wiki/Hydrothermal_liquefaction-2.md
category: reference
title: Hydrothermal liquefaction
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Hydrothermal_liquefaction
date_saved: 2026-05-05T10:48:37.443697+00:00
instance: kb-cron
parent: hydrothermal-liquefaction-20260505-0
summary:
== Comparison with pyrolysis and other biomass to liquid technologies == The HTL process differs from pyrolysis as it can process wet biomass and produce a bio-oil that contains approximately twice the energy density of pyrolysis oil. Pyrolysis is a related process to HTL, but biomass must be processed and dried in order to increase the yield. The presence of water in pyrolysis drastically increases the heat of vaporization of the organic material, increasing the energy required to decompose the biomass. Typical pyrolysis processes require a water content of less than 40% to suitably convert the biomass to bio-oil. This requires considerable pretreatment of wet biomass such as tropical grasses, which contain a water content as high as 80-85%, and even further treatment for aquatic species, which can contain higher than 90% water content. The HTL oil can contain up to 80% of the feedstock carbon content (single pass). HTL oil has good potential to yield bio-oil with "drop-in" properties that can be directly distributed in existing petroleum infrastructure. The energy returned on energy invested (EROEI) of these processes is uncertain and/or has not been measured. Furthermore, products of hydrous pyrolysis might not meet current fuel standards. Further processing may


id: integrated-gasification-combined-cycle-20260505-0
file: data/en.wikipedia.org/wiki/Integrated_gasification_combined_cycle-0.md
category: reference
title: Integrated gasification combined cycle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle
date_saved: 2026-05-05T10:48:38.638828+00:00
instance: kb-cron
parent: integrated-gasification-combined-cycle-20260505-0
summary:
An integrated gasification combined cycle (IGCC) is a technology using a high pressure gasifier to turn coal and other carbon based fuels into pressurized synthesis gas. This enables removal of impurities from the fuel prior to generating electricity, reducing emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. Some of these impurities, such as sulfur, can be turned into re-usable byproducts through the Claus process. With additional process equipment, carbon monoxide can be converted to carbon dioxide via water-gas shift reaction, enabling it to be sequestered and increasing gasification efficiency. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, producing additional electricity. This process results in improved thermodynamic efficiency, compared to conventional pulverized coal combustion. == Significance == Coal can be found in abundance in the USA and many other countries and its price has remained relatively constant in recent years. Of the traditional hydrocarbon fuels - oil, coal, and natural gas - coal is used as a feedstock for 40% of global electricity generation. Fossil fuel consumption and its contribution to large-scale CO2 emissions is becoming a pressing issue because of the adverse effects of climate change. In


id: integrated-gasification-combined-cycle-20260505-1
file: data/en.wikipedia.org/wiki/Integrated_gasification_combined_cycle-1.md
category: reference
title: Integrated gasification combined cycle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle
date_saved: 2026-05-05T10:48:38.638828+00:00
instance: kb-cron
parent: integrated-gasification-combined-cycle-20260505-0
summary:
== Installations == The DOE Clean Coal Demonstration Project helped construct 3 IGCC plants: Edwarsport Power Station in Edwardsport, Indiana, Polk Power Station in Tampa, Florida (online 1996), and Pinon Pine in Reno, Nevada. In the Reno demonstration project, researchers found that then-current IGCC technology would not work more than 300 feet (100m) above sea level. The DOE report in reference 3 however makes no mention of any altitude effect, and most of the problems were associated with the solid waste extraction system. The Polk Power station is currently operating, following resolution of demonstration start-up problems, but the Piñon Pine project encountered significant problems and was abandoned. The US DOE's Clean Coal Power Initiative (CCPI Phase 2) selected the Kemper Project as one of two projects to demonstrate the feasibility of low emission coal-fired power plants. Mississippi Power began construction on the Kemper Project in Kemper County, Mississippi, in 2010 and is poised to begin operation in 2016, though there have been many delays. In March, the projected date was further pushed back from early 2016 to August 31, 2016, adding $110 million to the total and putting the project 3 years behind schedule. The electrical plant is a flagship


id: integrated-gasification-combined-cycle-20260505-2
file: data/en.wikipedia.org/wiki/Integrated_gasification_combined_cycle-2.md
category: reference
title: Integrated gasification combined cycle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle
date_saved: 2026-05-05T10:48:38.638828+00:00
instance: kb-cron
parent: integrated-gasification-combined-cycle-20260505-0
summary:
== Cost and reliability == A key issue in implementing IGCC is its high capital cost, which prevents it from competing with other power plant technologies. Currently, ordinary pulverized coal plants are the lowest cost power plant option. The advantage of IGCC comes from the ease of retrofitting existing power plants that could offset the high capital cost. In a 2007 model, IGCC with CCS is the lowest-cost system in all cases. This model compared estimations of levelized cost of electricity, showing IGCC with CCS to cost 71.9 $US2005/MWh, pulverized coal with CCS to cost 88 $US2005/MWh, and natural gas combined cycle with CCS to cost 80.6 $US2005/MWh. The levelized cost of electricity was noticeably sensitive to the price of natural gas and the inclusion of carbon storage and transport costs. The potential benefit of retrofitting has so far, not offset the cost of IGCC with carbon capture technology. A 2013 report by the U.S. Energy Information Administration demonstrates that the overnight cost of IGCC with CCS has increased 19% since 2010. Amongst the three power plant types, pulverized coal with CCS has an overnight capital cost of $5,227 (2012 dollars)/kW, IGCC with CCS has an overnight capital cost of


id: integrated-gasification-combined-cycle-20260505-3
file: data/en.wikipedia.org/wiki/Integrated_gasification_combined_cycle-3.md
category: reference
title: Integrated gasification combined cycle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle
date_saved: 2026-05-05T10:48:38.638828+00:00
instance: kb-cron
parent: integrated-gasification-combined-cycle-20260505-0
summary:
None of these facilities use advanced technology (F type) gas turbines. All refinery-based plants use refinery residues, rather than coal, as the feedstock. This eliminates coal handling and coal preparation equipment and its problems. Also, there is a much lower level of ash produced in the gasifier, which reduces cleanup and downtime in its gas cooling and cleaning stages. These non-utility plants have recognized the need to treat the gasification system as an up-front chemical processing plant, and have reorganized their operating staff accordingly. Another IGCC success story has been the 250 MW Buggenum plant in The Netherlands, which was commissioned in 1994 and closed in 2013, had good availability. This coal-based IGCC plant was originally designed to use up to 30% biomass as a supplemental feedstock. The owner, NUON, was paid an incentive fee by the government to use the biomass. NUON has constructed a 1,311 MW IGCC plant in the Netherlands, comprising three 437 MW CCGT units. The Nuon Magnum IGCC power plant was commissioned in 2011, and was officially opened in June 2013. Mitsubishi Heavy Industries has been awarded to construct the power plant. Following a deal with environmental organizations, NUON has been prohibited from using the


id: integrated-gasification-combined-cycle-20260505-4
file: data/en.wikipedia.org/wiki/Integrated_gasification_combined_cycle-4.md
category: reference
title: Integrated gasification combined cycle
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Integrated_gasification_combined_cycle
date_saved: 2026-05-05T10:48:38.638828+00:00
instance: kb-cron
parent: integrated-gasification-combined-cycle-20260505-0
summary:
== Testing == National and international test codes are used to standardize the procedures and definitions used to test IGCC Power Plants. Selection of the test code to be used is an agreement between the purchaser and the manufacturer, and has some significance to the design of the plant and associated systems. In the United States, The American Society of Mechanical Engineers published the Performance Test Code for IGCC Power Generation Plants (PTC 47) in 2006 which provides procedures for the determination of quantity and quality of fuel gas by its flow rate, temperature, pressure, composition, heating value, and its content of contaminants. == IGCC emission controversy == In 2007, the New York State Attorney General's office demanded full disclosure of "financial risks from greenhouse gases" to the shareholders of electric power companies proposing the development of IGCC coal-fired power plants. "Any one of the several new or likely regulatory initiatives for CO2 emissions from power plants - including state carbon controls, EPA's regulations under the Clean Air Act, or the enactment of federal global warming legislation - would add a significant cost to carbon-intensive coal generation"; U.S. Senator Hillary Clinton from New York has proposed that this full risk


id: intramolecular-vibrational-energy-redistribution-20260505-0
file: data/en.wikipedia.org/wiki/Intramolecular_vibrational_energy_redistribution-0.md
category: reference
title: Intramolecular vibrational energy redistribution
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Intramolecular_vibrational_energy_redistribution
date_saved: 2026-05-05T10:48:39.763766+00:00
instance: kb-cron
parent: intramolecular-vibrational-energy-redistribution-20260505-0
summary:
Intramolecular vibrational energy redistribution (IVR) is a process in which energy is redistributed between different quantum states of a vibrationally excited molecule, which is required by successful theories explaining unimolecular reaction rates such as RRKM theory. Such theories assume a full statistical redistribution between all vibrational modes, but restricted redistribution could enable bond selective chemistry for which deposited energy must remain in a particular mode for as long as it takes for the required reaction to take place. == References ==


id: inverse-vulcanization-20260505-0
file: data/en.wikipedia.org/wiki/Inverse_vulcanization-0.md
category: reference
title: Inverse vulcanization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Inverse_vulcanization
date_saved: 2026-05-05T10:48:40.977282+00:00
instance: kb-cron
parent: inverse-vulcanization-20260505-0
summary:
Inverse vulcanization is a process that produces polysulfide polymers, which also contain some organic linkers. In contrast, sulfur vulcanization produces material that is predominantly organic but has a small percentage of polysulfide crosslinks. == Synthesis == Like Thiokols and sulfur-vulcanization, inverse vulcanization uses the tendency of sulfur catenate. The polymers produced by inverse vulcanization consist of long sulfur linear chains interspersed with organic linkers. Traditional sulfur vulcanization produces a cross-linked material with short sulfur bridges, down to one or two sulfur atoms. The polymerization process begins with the heating of elemental sulfur above its melting point (115.21 °C), to favor the ring-opening polymerization process (ROP) of the S8 monomer, occurring at 159 °C. As a result, the liquid sulfur is constituted by linear polysulfide chains with diradical ends, which can be easily bridged together with small dienes, such as 1,3-Diisopropylbenzene(DIB), 1,4-diphenylbutadiyne, limonene, divinylbenzene (DVB), dicyclopentadiene, styrene, 4-vinylpyridine, cycloalkene and ethylidene norbornene, or longer organic molecules as polybenzoxazines, squalene and triglyceride. Chemically, the diene carbon-carbon double bond (C=C) of the substitutional group disappears, forming the carbon-sulfur single bond (C-S) which binds together the sulfur linear chains. The advantage of such a polymerization is the absence of a solvent; Sulphur acts as


id: ion-beam-mixing-20260505-0
file: data/en.wikipedia.org/wiki/Ion_beam_mixing-0.md
category: reference
title: Ion beam mixing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ion_beam_mixing
date_saved: 2026-05-05T10:48:42.165521+00:00
instance: kb-cron
parent: ion-beam-mixing-20260505-0
summary:
Ion beam mixing is the atomic intermixing and alloying that can occur at the interface separating two different materials during ion irradiation. It is applied as a process for adhering two multilayers, especially a substrate and deposited surface layer. The process involves bombarding layered samples with doses of ion radiation in order to promote mixing at the interface, and generally serves as a means of preparing electrical junctions, especially between non-equilibrium or metastable alloys and intermetallic compounds. Ion implantation equipment can be used to achieve ion beam mixing. == Mechanism == The unique effects that stem from ion beam mixing are primarily a result of ballistic effects; that is, impinging ions have high kinetic energies that are transferred to target atoms on collision. Ion energies can be seen on the order of 1 keV to 200 keV. When accelerated, such ion energies are sufficiently high to break intra- and especially inter-molecular bonds, and initiate relocations within an atomic lattice. The sequence of collisions is known as a collision cascade. During this ballistic process, energies of impinging ions displace atoms and electrons of the target material several lattice sites away, resulting in relocations there and interface mixing at the boundary layer.


id: ion-plating-20260505-0
file: data/en.wikipedia.org/wiki/Ion_plating-0.md
category: reference
title: Ion plating
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ion_plating
date_saved: 2026-05-05T10:48:43.354201+00:00
instance: kb-cron
parent: ion-plating-20260505-0
summary:
Ion plating (IP) is a physical vapor deposition (PVD) process that is sometimes called ion assisted deposition (IAD) or ion vapor deposition (IVD) and is a modified version of vacuum deposition. Ion plating uses concurrent or periodic bombardment of the substrate, and deposits film by atomic-sized energetic particles called ions. Bombardment prior to deposition is used to sputter clean the substrate surface. During deposition the bombardment is used to modify and control the properties of the depositing film. It is important that the bombardment be continuous between the cleaning and the deposition portions of the process to maintain an atomically clean interface. If this interface is not properly cleaned, then it can result into a weaker coating or poor adhesion. They are many different processes to vacuum deposited coatings in which they are used for various applications such as corrosion resistance and wear on the material. == Process == In ion plating, the energy, flux and mass of the bombarding species along with the ratio of bombarding particles to depositing particles are important processing variables. The depositing material may be vaporized either by evaporation, sputtering (bias sputtering), arc vaporization or by decomposition of a chemical vapor precursor chemical vapor deposition


id: isakidd-refining-technology-20260505-0
file: data/en.wikipedia.org/wiki/IsaKidd_refining_technology-0.md
category: reference
title: IsaKidd refining technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/IsaKidd_refining_technology
date_saved: 2026-05-05T10:48:44.550207+00:00
instance: kb-cron
parent: isakidd-refining-technology-20260505-0
summary:
The IsaKidd Technology is a copper electrorefining and electrowinning technology that was developed independently by Copper Refineries Proprietary Limited (“CRL”), a Townsville, Queensland, subsidiary of MIM Holdings (which is now part of Glencore, and at the Falconbridge Nickel Mines now-dismantled Kidd Creek refinery that was at Timmins, Ontario. It is based around the use of reusable cathode starter sheets for copper electrorefining and the automated stripping of the deposited “cathode copper” from them. == Overview == === The old way of electrorefining copper (pre-1978) === The usual process of electrorefining copper consists of placing a copper anode (about 99.5–99.7% pure copper) in sulfuric acid (H2SO4) bath of copper electrolyte, together with a cathode, and passing a current between the anode and cathode through an external circuit. At the applied electropotential, copper and less noble elements dissolve in the electrolyte, while elements more noble than copper, such as gold (Au) and silver (Ag), do not. Under the influence of the applied electrical potential, copper ions migrate from the anode and deposit on the cathode, forming cathode copper. The current IsaKidd technology represents the merger of the copper refining technologies developed by the two different organisations. The initial Isa Process development in


id: isakidd-refining-technology-20260505-1
file: data/en.wikipedia.org/wiki/IsaKidd_refining_technology-1.md
category: reference
title: IsaKidd refining technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/IsaKidd_refining_technology
date_saved: 2026-05-05T10:48:44.550207+00:00
instance: kb-cron
parent: isakidd-refining-technology-20260505-0
summary:
Over time, the formation of starter sheets was improved by mechanisation, but there was still a high labour input. Once the starter sheets were formed, they had to be flattened, to reduce the likelihood of short circuits, and then cut, formed and punched to make loops from which the starter sheets are hung from conductive copper hanger bars in the electrolytic cells (see Figure 1). The starter sheets are inserted in the refining cells and dissolved copper electrodeposits on them to produce the cathode copper product (see Figure 2). Because of the manufacturing cost of the starter sheets, refineries using them tend to keep them in the cells as long as possible, usually 12–14 days. On the other hand, the anodes normally reside in the cells for 24–28 days, meaning that there are two cathodes produced from each anode. The starter sheets have a tendency to warp, due to the mechanical stresses they encounter and often need to be removed from the refining cells after about two days to be straightened in presses before being returned to the cells. The tendency to warp leads to frequent short-circuiting. Due to their limitations, it is difficult for copper produced on starter sheets


id: isakidd-refining-technology-20260505-2
file: data/en.wikipedia.org/wiki/IsaKidd_refining_technology-2.md
category: reference
title: IsaKidd refining technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/IsaKidd_refining_technology
date_saved: 2026-05-05T10:48:44.550207+00:00
instance: kb-cron
parent: isakidd-refining-technology-20260505-0
summary:
=== Moving into electrowinning plants === The Isa Process was originally developed for the CRL copper electrorefinery in Townsville. It was subsequently licensed to the Copper Range Company for its White Pine copper refinery. The next licence issued was for an electrowinning application at the Broken Hill Associated Smelters (“BHAS”) lead smelter at Port Pirie, in South Australia. BHAS commissioned in 1985 a solvent extraction and electrowinning (“SX–EW”) to recover copper from copper–lead matte produced as a by-product of the lead smelting operations. The process used involves leaching the copper from the material using an acidic chloride–sulfate solution, followed by solvent extraction to concentrate the leached copper and electrowinning. Electrowinning copper differs from electrorefining in that electrorefining uses a copper anode that is dissolved and redeposited on the cathode, while in electrowinning the copper is already in solution and is extracted from the solution by passing a current through the solution using an inert lead-alloy anode, and a cathode. The chloride in the leach solution at Port Pirie proved to be a problem for the stainless steel cathodes of the Isa Process. A small amount of the chloride ions in the leach solution passed through the solvent into the electrolyte,


id: isakidd-refining-technology-20260505-3
file: data/en.wikipedia.org/wiki/IsaKidd_refining_technology-3.md
category: reference
title: IsaKidd refining technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/IsaKidd_refining_technology
date_saved: 2026-05-05T10:48:44.550207+00:00
instance: kb-cron
parent: isakidd-refining-technology-20260505-0
summary:
This was achieved by machining a 90° “V”-groove into the bottom edge of the cathode. The groove weakens the structure of the copper growing at the bottom edge of the cathode plate because the copper crystals grow perpendicular to the cathode plate from opposite sides of the groove, causing them to intersect at right angles to each other. A discontinuity in the structure is formed at the intersection that results in a weak zone, along which the copper splits during stripping. Figure 4 is a microscope view of the cross-section a copper cathode growing at the tip of a cathode plate. The yellow lines show the orientation and direction of crystal growth. ==== Low-resistance cathodes ==== The standard Isa Process cathodes have slightly higher electrical resistance than solid-copper hanger bar systems used by the Kidd Process, meaning that there is a higher power cost. However, this cost is offset by greater reliability and predictability in the increase in resistance over time, allowing for maintenance planning. The solid-copper hanger bars, on the other hand, lose electrical performance over a shorter period of time due to corrosive attack on the joint and sudden failure is possible. The maintenance costs of such systems


id: isakidd-refining-technology-20260505-4
file: data/en.wikipedia.org/wiki/IsaKidd_refining_technology-4.md
category: reference
title: IsaKidd refining technology
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/IsaKidd_refining_technology
date_saved: 2026-05-05T10:48:44.550207+00:00
instance: kb-cron
parent: isakidd-refining-technology-20260505-0
summary:
=== The birth of the combined IsaKidd technology === After Falconbridge’s 1992 decision to market the Kidd technology, the Falconbridge and the then MIM Process Technologies groups competed for the tank house technology market. Between 1992 and 2006, 25 Kidd technology licences were sold, while there were 52 Isa process licences sold in the same period. Xstrata plc (now Glencore) took over MIM Holdings in 2003. The Isa Process technology continued to be developed and marketed by Xstrata Technology. Xstrata subsequently took over Falconbridge in 2006. The Kidd Process technology consequently became part of the Xstrata Technology tank house package and together they began to be marketed as IsaKidd, a name that represents the dual heritage of the technology. The result has been a technology package that combined what were mutually regarded as the best of both versions. This combination led to the development of new stripping systems and new cathode designs are in development. The variation in copper deposits on the cathode plates was one of the difficulties encountered with the earlier stripping machines. Areas of thin copper on the cathode plates, which are caused by short circuits, are difficult to separate from the stainless steel plate due to


id: isothermal-microcalorimetry-20260505-0
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-0.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
Isothermal microcalorimetry (IMC) is a laboratory method for real-time monitoring and dynamic analysis of chemical, physical and biological processes. Over a period of hours or days, IMC determines the onset, rate, extent and energetics of such processes for specimens in small ampoules (e.g. 3–20 ml) at a constant set temperature (c. 15 °C–150 °C). IMC accomplishes this dynamic analysis by measuring and recording vs. elapsed time the net rate of heat flow (μJ/s = μW) to or from the specimen ampoule, and the cumulative amount of heat (J) consumed or produced. IMC is a powerful and versatile analytical tool for four closely related reasons: All chemical and physical processes are either exothermic or endothermic—produce or consume heat. The rate of heat flow is proportional to the rate of the process taking place. IMC is sensitive enough to detect and follow either slow processes (reactions proceeding at a few % per year) in a few grams of material, or processes which generate minuscule amounts of heat (e.g. metabolism of a few thousand living cells). IMC instruments generally have a huge dynamic range—heat flows as low as ca. 1 μW and as high as ca. 50,000 μW can be measured by the


id: isothermal-microcalorimetry-20260505-1
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-1.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
However, for most applications it is paramount to know, by some means, what process or processes are being measured by monitoring heat flow. In general this entails first having detailed physical, chemical and biological knowledge of the items placed in an IMC ampoule before it is placed in an IMC instrument for evaluation of heat flow over time. It is also then necessary to analyze the ampoule contents after IMC measurements of heat flow have been made for one or more periods of time. Also, logic-based variations in ampoule contents can be used to identify the specific source or sources of heat flow. When rate process and heat flow relationships have been established, it is then possible to rely directly on the IMC data. What IMC can measure in practice depends in part on specimen dimensions, and they are necessarily constrained by instrument design. A given commercial instrument typically accepts specimens of up to a fixed diameter and height. Instruments accepting specimens with dimensions of up to ca. 1 or 2 cm in diameter × ca. 5 cm in height are typical. In a given instrument larger specimens of a given type usually produce greater heat flow signals, and this


id: isothermal-microcalorimetry-20260505-2
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-2.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
== Instruments and measurement principles == === Instrument configurations === Modern IMC instruments are actually semi-adiabatic—i.e. heat transfer between the specimen and its surroundings is not zero (adiabatic), because IMC measurement of heat flow depends on the existence of a small temperature differential—ca. 0.001 °C. However, because the differential is so low, IMC measurements are essentially isothermal. Fig. 3. shows an overview of an IMC instrument which contains 48 separate heat flow measurement modules. One module is shown. The module's measuring unit is typically a Peltier-Seebeck device. The device produces a voltage proportional to the temperature difference between a specimen which is producing or consuming heat and a thermally inactive reference which is at the temperature of the heat sink. The temperature difference is in turn proportional to the rate at which the specimen is producing or consuming heat (see Calibration below). All the modules in an instrument use the same heat sink and thermostat and thus all produce data at the same set temperature. However, it is generally possible to start and stop measurements in each ampoule independently. In a highly parallel (e.g. 48-channel) instrument like the one shown in Fig. 3, this makes it possible to perform (start


id: isothermal-microcalorimetry-20260505-3
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-3.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
=== Ampoules === Many highly useful IMC measurements can be conducted in sealed ampoules (Fig. 1) which offer advantages of simplicity, protection from contamination and (where needed) a substantial margin of bio-safety for persons handling or exposed to the ampoules. A closed ampoule can contain any desired combination of solids, liquids, gasses or items of biologic origin. Initial gas composition in the ampoule head space can be controlled by sealing the ampoule in the desired gas environment. However, there are also IMC instrument/ampoule designs which permit controlled flow of gas or liquid through the ampoule during measurement and/or mechanical stirring. Also, with proper accessories, some IMC instruments can be operated as ITC (isothermal titration calorimetry) instruments. The topic of ITC is covered elsewhere (see Isothermal titration calorimetry). In addition some IMC instruments can record heat flow while the temperature is slowly changed (scanned) over time. The scanning rate has to be slow (ca. ± 2 °C/h) in order to keep IMC-scale specimens (e.g. a few grams) sufficiently close to the heat sink temperature (< ca. 0.1 °C). Fast scanning of temperature is the province of differential scanning calorimetry (DSC) instruments which generally use much smaller specimens. Some DSC instruments can


id: isothermal-microcalorimetry-20260505-4
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-4.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
==== Simple ==== For comparisons of the effect of experimental variables (e.g. initial concentrations) on rate processes, IMC does not require development and use of chemical or other assay methods. If absolute data are required (e.g. quantity of product produced by a process), then assays can be conducted in parallel on specimens identical to those used for IMC (and/or on IMC specimens after IMC runs). The resultant assay data is used to calibrate the rate data obtained by IMC. ==== Non-interfering ==== IMC does not require adding markers (e.g. fluorescent or radioactive substances) to capture rate processes. Unadulterated specimens can be used, and after an IMC run, the specimen is unchanged (except by the processes which have taken place). The post-IMC specimen can be subjected to any kind of physical, chemical, morphological or other evaluation of interest. === Caveats === ==== Missed data ==== As indicated in the methodology description, when the IMC method of inserting a sealed ampoule is used, it is not possible to capture heat flow during the first ca. 40 minutes while the specimen is slowly being brought to the set temperature. In this mode therefore, IMC is best suited to studying processes which start slowly


id: isothermal-microcalorimetry-20260505-5
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-5.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
===== Formation ===== IMC is widely used for studying the rates of formation of a variety of materials by various processes. It is best suited to study processes which occur slowly—i.e. over hours or days. A prime example is the study of hydration and setting reactions of calcium mineral cement formulations. One paper provides an overview (Gawlicki, et al. 2010) and another describes a simple approach (Evju 2003). Other studies focus on insights into cement hydration provided by IMC combined with IR spectroscopy (Ylmen et al. 2010) and on using IMC to study the influence of compositional variables on cement hydration and setting times (Xu et al. 2011). IMC can also be conveniently used to study the rate and amount of hydration (in air of known humidity) of calcium minerals or other minerals. To provide air of known humidity for such studies, small containers of saturated salt solutions can be placed in an IMC ampoule along with a non-hydrated mineral specimen. The ampoule is then sealed and introduced into an IMC instrument. The saturated salt solution keeps the air in the ampoule at a known rH, and various common salt solutions provide humidities ranging from e.g. 32-100% rH. Such studies


id: isothermal-microcalorimetry-20260505-6
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-6.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
===== Cell and tissue biology ===== Mammalian cells in culture have a metabolic rate of ca. 30×10−12 W/cell (Figs. 2 and 3 in Bibliography: West, Woodruff and Brown 2002). By definition, IMC instruments have a sensitivity of at least 1×10−6 W (i.e. 1 μW). Therefore, the metabolic heat of ca. 33,000 cells is detectable. Based on this sensitivity, IMC was used to perform a large number of pioneering studies of cultured mammalian cell metabolismics in the 1970s and 1980s in Sweden. One paper (Monti 1990) serves as an extensive guide to work done up until 1990. It includes explanatory text and 42 references to IMC studies of heat flow from cultured human erythrocytes, platelets, lymphocytes, lymphoma cells, granulocytes, adipocytes, skeletal muscle, and myocardial tissue. The studies were done to determine how and where IMC might be used as a clinical diagnostic method and/or provide insights into metabolic differences between cells from healthy persons and persons with various diseases or health problems. Developments since ca. 2000 in IMC (e.g. massively parallel instruments, real-time, computer-based storage and analysis of heat flow data) have stimulated further use of IMC in cultured cell biology. For example, IMC has been evaluated for assessing antigen-induced lymphocyte


id: isothermal-microcalorimetry-20260505-7
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-7.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
"The cytotoxicity of particulate materials such as bioactive glass and hydroxyapatite particles can be evaluated using the microcalorimetry method. This is a modern method for in vitro study of biomaterials biocompatibility and cytotoxicity which can be used alongside the old conventional assays." ===== Microbiology ===== Publications describing use of IMC in microbiology began in the 1980s (Jesperson 1982). While some IMC microbiology studies have been directed at viruses (Heng et al. 2005) and fungi (Antoci et al. 1997), most have been concerned with bacteria. A recent paper (Braissant et al. 2010) provides a general introduction to IMC metabolismic methods in microbiology and an overview of applications in medical and environmental microbiology. The paper also explains how heat flow vs. time data for bacteria in culture are an exact expression—as they occur over time—of the fluctuations in microorganism metabolic activity and replication rates in a given medium (Fig. 6). In general, bacteria are about 1/10 the size of mammalian cells and produce perhaps 1/10 as much metabolic heat-i.e. ca. 3×10−12 W/cell. Thus, compared to mammalian cells (see above) ca. 10X as many bacteria—ca. 330,000—must be present to produce detectable heat flow—i.e. 1 μW. However, many bacteria replicate orders of magnitude more


id: isothermal-microcalorimetry-20260505-8
file: data/en.wikipedia.org/wiki/Isothermal_microcalorimetry-8.md
category: reference
title: Isothermal microcalorimetry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Isothermal_microcalorimetry
date_saved: 2026-05-05T10:48:45.754826+00:00
instance: kb-cron
parent: isothermal-microcalorimetry-20260505-0
summary:
===== Environmental biology ===== Because of its versatility, IMC can be an effective tool in the fields of plant and environmental biology. In an early study (Hansen et al. 1989), the metabolic rate of larch tree clone tissue specimens was measured. The rate was predictive of long-term tree growth rates, was consistent for specimens from a given tree and was found to correlate with known variations in the long-term growth of clones from different trees. Bacterial oxalotrophic metabolism is common in the environment, particularly in soils. Oxalotrophic bacteria are capable of using oxalate as a sole carbon and energy source. Closed-ampoule IMC was used to study metabolism of oxalotrophic soil bacteria exposed to both an optimized medium containing potassium oxalate as the sole carbon source and a model soil (Bravo et al. 2011). Using an optimized medium, growth of six different strains of soil bacteria was easily monitored and reproducibly quantified and differentiated over a period days. IMC measurement of bacterial metabolic heat flow in the model soil was more difficult, but a proof of concept was demonstrated. Moonmilk is a white, creamy material found in caves. It is a non-hardening, fine crystalline precipitate from limestone and is composed mainly


id: kraft-process-20260505-0
file: data/en.wikipedia.org/wiki/Kraft_process-0.md
category: reference
title: Kraft process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kraft_process
date_saved: 2026-05-05T10:48:46.929805+00:00
instance: kb-cron
parent: kraft-process-20260505-0
summary:
The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component of paper. The kraft process involves treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes. The process name is derived from the German word Kraft, meaning 'strength' in this context, due to the strength of the kraft paper produced using this process. == History == A precursor of the kraft process was used during the Napoleonic Wars in England. The kraft process was invented by Carl F. Dahl in 1879 in Danzig, Prussia, Germany. U.S. patent 296,935 was issued in 1884, and a pulp mill using this technology began in Sweden in 1890. The invention of the recovery boiler by G. H. Tomlinson in the early 1930s


id: kraft-process-20260505-1
file: data/en.wikipedia.org/wiki/Kraft_process-1.md
category: reference
title: Kraft process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kraft_process
date_saved: 2026-05-05T10:48:46.929805+00:00
instance: kb-cron
parent: kraft-process-20260505-0
summary:
4. CaO + H2O → Ca(OH)2 The combination of reactions 1 through 4 form a closed cycle with respect to sodium, sulfur and calcium and is the main concept of the so-called recausticizing process where sodium carbonate is reacted to regenerate sodium hydroxide. The recovery boiler also generates high pressure steam which is fed to turbogenerators, reducing the steam pressure for the mill use and generating electricity. A modern kraft pulp mill is more than self-sufficient in its electrical generation and normally will provide a net flow of energy which can be used by an associated paper mill or sold to neighboring industries or communities through to the local electrical grid. Additionally, bark and wood residues are often burned in a separate power boiler to generate steam. Although recovery boilers using G.H. Tomlinson's invention have been in general use since the early 1930s, attempts have been made to find a more efficient process for the recovery of cooking chemicals. Weyerhaeuser has operated a Chemrec first generation black liquor entrained flow gasifier successfully at its New Bern plant in North Carolina, while a second generation plant is run in pilot scale at Smurfit Kappa's plant in Piteå, Sweden. An additional technology


id: kraft-process-20260505-2
file: data/en.wikipedia.org/wiki/Kraft_process-2.md
category: reference
title: Kraft process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kraft_process
date_saved: 2026-05-05T10:48:46.929805+00:00
instance: kb-cron
parent: kraft-process-20260505-0
summary:
== Comparison with other pulping processes == Pulp produced by the kraft process is stronger than that made by other pulping processes and maintains a high effective sulfur ratio (sulfidity), an important determiner of the strength of the paper. Acidic sulfite processes degrade cellulose more than the kraft process, which leads to weaker fibers. Kraft pulping removes most of the lignin present originally in the wood whereas mechanical pulping processes leave most of the lignin in the fibers. The hydrophobic nature of lignin interferes with the formation of the hydrogen bonds between cellulose (and hemicellulose) in the fibers needed for the strength of paper (strength refers to tensile strength and resistance to tearing). Kraft pulp is darker than other wood pulps, but it can be bleached to make very white pulp. Fully bleached kraft pulp is used to make high-quality paper where strength, whiteness, and resistance to yellowing are important. Kraft pulp's high cellulose and low lignin content is suited for paper for printing and writing, In contrast, mechanical pulp is produced by grinding wood without removing lignin. The lignin retained in mechanical pulp provides the opacity and bulk necessary for newsprint, but it results in lower tensile strength and


id: kroll-process-20260505-0
file: data/en.wikipedia.org/wiki/Kroll_process-0.md
category: reference
title: Kroll process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kroll_process
date_saved: 2026-05-05T10:48:48.073653+00:00
instance: kb-cron
parent: kroll-process-20260505-0
summary:
The Kroll process is a pyrometallurgical industrial process used to produce metallic titanium from titanium tetrachloride. As of 2001 William Justin Kroll's process replaced the Hunter process for almost all commercial production. == Process == In the Kroll process, titanium tetrachloride is reduced by liquid magnesium to give titanium metal: TiCl 4 + 2 Mg → 825 ∘ C Ti + 2 MgCl 2 {\displaystyle {\ce {{TiCl4}+2{Mg}->[825~^{\circ }\mathrm {C} ]{Ti}+2{MgCl2}}}} The reduction is conducted at 800–850 °C in a stainless steel retort. Complications result from partial reduction of the TiCl4, giving to the lower chlorides TiCl2 and TiCl3. The MgCl2 can be further refined back to magnesium. === Appurtenant processes === The resulting porous metallic titanium sponge is purified by leaching or vacuum distillation. The sponge is crushed, and pressed before it is melted in a consumable electrode vacuum arc furnace, "backfilled with pure gettered argon of a pressure high enough to avoid a glow discharge". The melted ingot is allowed to solidify under vacuum. It is often remelted to remove inclusions and ensure uniformity. These melting steps add to the cost of the product. Titanium is about six times as expensive as stainless steel: Potter noted in 2023 that


id: krupp-renn-process-20260505-0
file: data/en.wikipedia.org/wiki/Krupp–Renn_process-0.md
category: reference
title: Krupp–Renn process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Krupp–Renn_process
date_saved: 2026-05-05T10:48:49.362759+00:00
instance: kb-cron
parent: krupp-renn-process-20260505-0
summary:
The Krupp–Renn process was a direct reduction steelmaking process used from the 1930s to the 1970s. It used a rotary furnace and was one of the few technically and commercially successful direct reduction processes in the world, acting as an alternative to blast furnaces due to their coke consumption. The Krupp–Renn process consumed mainly hard coal and had the unique characteristic of partially melting the charge. This method is beneficial for processing low-quality or non-melting ores, as their waste material forms a protective layer that can be easily separated from the iron. It generates Luppen, nodules of pre-reduced iron ore, which can be easily melted down. The first industrial furnaces emerged in the 1930s, firstly in Nazi Germany and then in the Japanese Empire. During the 1950s, new facilities were constructed, notably in Czechoslovakia and West Germany. The process was discontinued in the early 1970s, with a few nuances. It was unproductive, intricate to master, and only pertinent to certain ores. In the beginning of the 21st century, Japan modernized the process to manufacture ferronickel, which is the sole surviving variant. == History == === Setting up === The direct reduction of iron ore principle was tested in the late


id: krupp-renn-process-20260505-1
file: data/en.wikipedia.org/wiki/Krupp–Renn_process-1.md
category: reference
title: Krupp–Renn process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Krupp–Renn_process
date_saved: 2026-05-05T10:48:49.362759+00:00
instance: kb-cron
parent: krupp-renn-process-20260505-0
summary:
The Krupp–Renn process is a direct reduction process that uses a long tubular furnace similar to those found in cement production. The most recent units constructed have a diameter of approximately 4.5 meters and a length of 110 meters. The residence time of the product is influenced by the slope and speed of rotation of the rotary kiln, which is inclined at an angle of roughly 2.5 percent. Prior to usage, the iron ore is crushed to less than 6 mm in particle size. The iron ore is introduced into the furnace upstream and mixed with a small amount of fuel, typically hard coal. After 6 to 8 hours, it exits the furnace as pre-reduced iron ore at 1,000 °C. The amount of iron recovered ranges from 94% to 97.5% of the initial iron in the ore. A burner located at the lower end of the furnace provides heat, transforming it into a counter-current reactor. The fuel comprises finely pulverized coal, which, upon high-temperature combustion, generates reducing gas primarily consisting of CO. Once the furnace reaches an optimal temperature, the ore-coal mixture can serve as the primary fuel source. The fumes exiting the furnace's upper end attain temperatures ranging from


id: krupp-renn-process-20260505-2
file: data/en.wikipedia.org/wiki/Krupp–Renn_process-2.md
category: reference
title: Krupp–Renn process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Krupp–Renn_process
date_saved: 2026-05-05T10:48:49.362759+00:00
instance: kb-cron
parent: krupp-renn-process-20260505-0
summary:
The furnace comprises three distinct zones: Firstly, the preheating zone heats the ore to 800 °C using the hot fumes within the furnace. Ore reduction occurs only if temperatures exceed 900-1,000 °C, while the coal releases its most volatile constituents. Secondly, the reduction zone is situated in the middle of the furnace, where coal and iron oxides combine to produce carbon monoxide. The carbon monoxide is released from the charge, generating a gaseous layer that shields the charge against the oxidizing air circulating above. As a consequence, this excessive gas is combusted, raising the temperature of the furnace walls, which then transfer the heat back to the charge due to rotary motion. The temperature eventually increases to 800 – 1,200 °C. Subsequently, the iron oxides are gradually altered into ferronickel or metallic iron. The metal produced is in the form of metallic sponge particles that are finely dispersed in the powdery gangue. Reduction is complete by the end of the furnace, and there is a minimal amount of CO produced. This is due to the fact that the charge is no longer protected from oxidation by the air blown in at the base of the furnace. As a result, a


id: krupp-renn-process-20260505-3
file: data/en.wikipedia.org/wiki/Krupp–Renn_process-3.md
category: reference
title: Krupp–Renn process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Krupp–Renn_process
date_saved: 2026-05-05T10:48:49.362759+00:00
instance: kb-cron
parent: krupp-renn-process-20260505-0
summary:
=== Productivity === Depending on the ore and plant size, a furnace can daily output 250 to 800 tons of pre-reduced iron ore. The biggest furnaces, up to 5 meters in diameter and 110 meters long, can process 950 to 1,000 tons of ore daily, excluding fuel. A properly operated plant typically runs for around 300 days per year. The internal refractory typically lasts 7 to 8 months in the most exposed part of the furnace and for 2 years elsewhere. In 1960, a Krupp-Renn furnace using low-grade ore yielded 100 kilotons of iron annually, while a contemporaneous modern blast furnace produced ten times as much cast iron. Direct reduction processes employing rotary furnaces frequently face a significant challenge due to the localized formation of iron and slag rings, which sinter together and gradually obstruct the furnace. Understanding the mechanism of lining formation is a complex process involving mineralogy, chemical reactions, and ore preparation. The formation of the lining ring, which progressively grows and poisons the furnace, is caused by a few elements in minute quantities. To remedy this, increasing the supply of combustion air or interrupting the furnace charging process are effective solutions. Otherwise, it may be necessary to


id: krupp-renn-process-20260505-4
file: data/en.wikipedia.org/wiki/Krupp–Renn_process-4.md
category: reference
title: Krupp–Renn process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Krupp–Renn_process
date_saved: 2026-05-05T10:48:49.362759+00:00
instance: kb-cron
parent: krupp-renn-process-20260505-0
summary:
The production of ferronickel from laterites takes place in a context that is much more favorable to the Krupp–Renn process than to the steel industry. Lateritic ores in the form of saprolite are poor, very basic and contain iron. Production volumes are moderate, and the nickel chemistry is remarkably amenable to rotary kiln reduction. The process is therefore attractive, but regardless of the metal extracted, mastering all the physical and chemical transformations in a single reactor is a real challenge. The failure of the Larco plant at Lárymna Greece, illustrates the risk involved in adopting this process: it was only when the ore was ready for industrial processing that it proved incompatible with the Krupp–Renn process. As a result, lower-temperature reduction followed by electric furnace smelting allows each stage to have its own dedicated tool for greater simplicity and efficiency. Developed in 1950 at Koniambo in New Caledonia, this combination has proven to be both cost-effective and, above all, more robust. Large rotating drums (5 m in diameter and 100 m or even 185 m long) are used to produce a dry powder from nickel ore concentrate. This powder contains 1.5 to 3% nickel. It leaves the drum at 800–900


id: kv-rner-process-20260505-0
file: data/en.wikipedia.org/wiki/Kværner_process-0.md
category: reference
title: Kværner process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Kværner_process
date_saved: 2026-05-05T10:48:50.554847+00:00
instance: kb-cron
parent: kv-rner-process-20260505-0
summary:
The Kværner process or the Kværner carbon black and hydrogen process (CB&H) is a method of producing carbon black and hydrogen gas from hydrocarbons such as methane, natural gas and biogas with no greenhouse gas pollution. The process was developed in the 1980s by the Norwegian engineering firm Kværner, and was first commercially exploited in 1999. Further refinement enabled the methane pyrolysis process for implementation at high-volume and low-cost. == Description == The endothermic reaction separates (i.e. decomposes) hydrocarbons into carbon and hydrogen in a plasma burner at around 1600 °C. The resulting components, carbon particles and hydrogen, are present as a mixture in form of an aerosol. C n H m ⟶ n C + m 2 H 2 {\displaystyle {\ce {C_{\mathit {n}}H_{\mathit {m}}->{{\mathit {n}}C}+{\frac {\mathit {m}}{2}}H2}}} In comparison to other reformation methods such as steam reforming and partial oxidation that have carbon dioxide as a by-product, there is no by-product in the Kværner process. The natural gas is efficiently and completely transformed into pure carbon and hydrogen and does not release carbon dioxide into the atmosphere. After separating the mixture, the carbon particles can be used for instance as activated carbon, graphite or industrial soot, special kinds of


id: leblanc-process-20260505-0
file: data/en.wikipedia.org/wiki/Leblanc_process-0.md
category: reference
title: Leblanc process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leblanc_process
date_saved: 2026-05-05T10:48:51.792778+00:00
instance: kb-cron
parent: leblanc-process-20260505-0
summary:
The Leblanc process was an early industrial process for making soda ash (sodium carbonate) used throughout the 19th century, named after its inventor, Nicolas Leblanc. It involved two stages: making sodium sulfate from sodium chloride, followed by reacting the sodium sulfate with coal and calcium carbonate to make sodium carbonate. The process gradually became obsolete after the development of the Solvay process. == Background == Soda ash (sodium carbonate) and potash (potassium carbonate), collectively termed alkali, are vital chemicals in the glass, textile, soap, and paper industries. The traditional source of alkali in western Europe had been potash obtained from wood ashes. However, by the 13th century, deforestation had rendered this means of production uneconomical, and alkali had to be imported. Potash was imported from North America, Scandinavia, and Russia, where large forests still stood. Soda ash was imported from Spain and the Canary Islands, where it was produced from the ashes of glasswort plants (called barilla ashes in Spain), or imported from Syria. The soda ash from glasswort plant ashes was mainly a mixture of sodium carbonate and potassium carbonate. In addition in Egypt, naturally occurring sodium carbonate, the mineral natron, was mined from dry lakebeds. In Britain, the


id: leblanc-process-20260505-1
file: data/en.wikipedia.org/wiki/Leblanc_process-1.md
category: reference
title: Leblanc process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leblanc_process
date_saved: 2026-05-05T10:48:51.792778+00:00
instance: kb-cron
parent: leblanc-process-20260505-0
summary:
== Industrial history == Leblanc established the first Leblanc process plant in 1791 in St. Denis. However, French Revolutionaries seized the plant, along with the rest of Louis Philip's estate, in 1794, and publicized Leblanc's trade secrets. Napoleon I returned the plant to Leblanc in 1801, but lacking the funds to repair it and compete against other soda works that had been established in the meantime, Leblanc committed suicide in 1806. By the early 19th century, French soda ash producers were making 10,000 - 15,000 tons annually. However, it was in Britain that the Leblanc process became most widely practiced. The first British soda works using the Leblanc process was built by the Losh family of iron founders at the Losh, Wilson and Bell works in Walker on the River Tyne in 1816, but steep British tariffs on salt production hindered the economics of the Leblanc process and kept such operations on a small scale until 1824. Following the repeal of the salt tariff, the British soda industry grew dramatically. The Bonnington Chemical Works was possibly the earliest production, and the chemical works established by James Muspratt in Liverpool and Flint, and by Charles Tennant near Glasgow became some of


id: leblanc-process-20260505-2
file: data/en.wikipedia.org/wiki/Leblanc_process-2.md
category: reference
title: Leblanc process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Leblanc_process
date_saved: 2026-05-05T10:48:51.792778+00:00
instance: kb-cron
parent: leblanc-process-20260505-0
summary:
== Pollution issues == The Leblanc process plants were quite damaging to the local environment. The process of generating salt cake from salt and sulfuric acid released hydrochloric acid gas, and because this acid was industrially useless in the early 19th century, it was simply vented into the atmosphere. Also, an insoluble smelly solid waste was produced. For every 8 tons of soda ash, the process produced 5.5 tons of hydrogen chloride and 7 tons of calcium sulfide waste. This solid waste (known as galligu) had no economic value, and was piled in heaps and spread on fields near the soda works, where it weathered to release hydrogen sulfide, the toxic gas responsible for the odor of rotten eggs. Because of their noxious emissions, Leblanc soda works became targets of lawsuits and legislation. An 1839 suit against soda works alleged, "the gas from these manufactories is of such a deleterious nature as to blight everything within its influence, and is alike baneful to health and property. The herbage of the fields in their vicinity is scorched, the gardens neither yield fruit nor vegetables; many flourishing trees have lately become rotten naked sticks. Cattle and poultry droop and pine away. It


id: linde-frank-caro-process-20260505-0
file: data/en.wikipedia.org/wiki/Linde–Frank–Caro_process-0.md
category: reference
title: Linde–Frank–Caro process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Linde–Frank–Caro_process
date_saved: 2026-05-05T10:48:52.991241+00:00
instance: kb-cron
parent: linde-frank-caro-process-20260505-0
summary:
The Linde–Frank–Caro process is a method for hydrogen production by removing hydrogen and carbon dioxide from water gas by condensation. The process was invented in 1909 by Adolf Frank and developed with Carl von Linde and Heinrich Caro. == Process description == Water gas is compressed to 20 bar and pumped into the Linde–Frank–Caro reactor. A water column removes most of the carbon dioxide and sulfur. Tubes with caustic soda then remove the remaining carbon dioxide, sulphur, and water from the gas stream. The gas enters a chamber and is cooled to −190 °C, resulting in the condensation of most of the gas to a liquid. The remaining gas is pumped to the next vessel where the nitrogen is liquefied by cooling to −205 °C, resulting in hydrogen gas as an end product. == See also == Water gas shift reaction Timeline of hydrogen technologies Frank–Caro process, another process used to produce cyanamide from calcium carbide and nitrogen gas in an electric furnace == References ==


id: list-of-purification-methods-in-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/List_of_purification_methods_in_chemistry-0.md
category: reference
title: List of purification methods in chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_purification_methods_in_chemistry
date_saved: 2026-05-05T10:48:54.214659+00:00
instance: kb-cron
parent: list-of-purification-methods-in-chemistry-20260505-0
summary:
Purification in a chemical context is the physical separation of a chemical substance of interest from foreign or contaminating substances. Pure results of a successful purification process are termed isolate. The following list of chemical purification methods should not be considered exhaustive. Affinity purification purifies proteins by retaining them on a column through their affinity to antibodies, enzymes, or receptors that have been immobilised on the column. Filtration is a mechanical method to separate solids from liquids or gases by passing the feed stream through a porous sheet such as a cloth or membrane, which retains the solids and allows the liquid to pass through. Centrifugation is a process that uses an electric motor to spin a vessel of fluid at high speed to make heavier components settle to the bottom of the vessel. Evaporation removes volatile liquids from non-volatile solutes, which cannot be done through filtration due to the small size of the substances. Liquid–liquid extraction removes an impurity or recovers a desired product by dissolving the crude material in a solvent in which other components of the feed material are soluble. Crystallization separates a product from a liquid feed stream, often in extremely pure form, by cooling the


id: list-of-wastewater-treatment-technologies-20260505-0
file: data/en.wikipedia.org/wiki/List_of_wastewater_treatment_technologies-0.md
category: reference
title: List of wastewater treatment technologies
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/List_of_wastewater_treatment_technologies
date_saved: 2026-05-05T10:48:55.394309+00:00
instance: kb-cron
parent: list-of-wastewater-treatment-technologies-20260505-0
summary:
This page consists of a list of wastewater treatment technologies: == See also == Agricultural wastewater treatment Industrial wastewater treatment List of solid waste treatment technologies Waste treatment technologies Water purification Sewage sludge treatment == References ==


id: chemical-looping-combustion-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_looping_combustion-0.md
category: reference
title: Chemical looping combustion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_looping_combustion
date_saved: 2026-05-05T10:48:56.584534+00:00
instance: kb-cron
parent: chemical-looping-combustion-20260505-0
summary:
Chemical looping combustion (CLC) is a technological process typically employing a dual fluidized bed system. CLC operated with an interconnected moving bed with a fluidized bed system, has also been employed as a technology process. In CLC, a metal oxide is employed as a bed material providing the oxygen for combustion in the fuel reactor. The reduced metal is then transferred to the second bed (air reactor) and re-oxidized before being reintroduced back to the fuel reactor completing the loop. Fig 1 shows a simplified diagram of the CLC process. Fig 2 shows an example of a dual fluidized bed circulating reactor system and a moving bed-fluidized bed circulating reactor system. Isolation of the fuel from air simplifies the number of chemical reactions in combustion. Employing oxygen without nitrogen and the trace gases found in air eliminates the primary source for the formation of nitrogen oxide (NOx), produces a flue gas composed primarily of carbon dioxide and water vapor; other trace pollutants depend on the fuel selected. == Description == Chemical looping combustion (CLC) uses two or more reactions to perform the oxidation of hydrocarbon-based fuels. In its simplest form, an oxygen-carrying species (normally a metal) is first oxidized in


id: chemical-looping-combustion-20260505-1
file: data/en.wikipedia.org/wiki/Chemical_looping_combustion-1.md
category: reference
title: Chemical looping combustion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_looping_combustion
date_saved: 2026-05-05T10:48:56.584534+00:00
instance: kb-cron
parent: chemical-looping-combustion-20260505-0
summary:
=== Variants and related technologies === A variant of CLC is Chemical-Looping Combustion with Oxygen Uncoupling (CLOU) where an oxygen carrier is used that releases gas-phase oxygen in the fuel reactor, e.g. CuO/Cu2O. This is helpful for achieving high gas conversion, and especially when using solid fuels, where slow steam gasification of char can be avoided. CLOU operation with solid fuels shows high performance Chemical Looping can also be used to produce hydrogen in Chemical-Looping Reforming (CLR) processes. In one configuration of the CLR process, hydrogen is produced from coal and/or natural gas using a moving bed fuel reactor integrated with a steam reactor and a fluidized bed air reactor. This configuration of CLR can produce greater than 99% purity H2 without the need for CO2 separation. Another CLR process is based on conventional steam methane reforming (SMR), with chemical-looping combustion replacing the reformer furnace. Thus, the heat for the reforming is transferred in fluidized-bed heat exchangers (FBHEs) connected to the air reactor and the fuel used is the off-gas from the reforming plus additional methane. This configuration can give higher energy efficiency than conventional SMR, because the furnace temperature can be reduced. Consequently, a negative CO2 capture cost could


id: chemical-looping-reforming-and-gasification-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification-0.md
category: reference
title: Chemical looping reforming and gasification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification
date_saved: 2026-05-05T10:48:57.792091+00:00
instance: kb-cron
parent: chemical-looping-reforming-and-gasification-20260505-0
summary:
Chemical looping reforming (CLR) and gasification (CLG) are the operations that involve the use of gaseous carbonaceous feedstock and solid carbonaceous feedstock, respectively, in their conversion to syngas in the chemical looping scheme. The typical gaseous carbonaceous feedstocks used are natural gas and reducing tail gas, while the typical solid carbonaceous feedstocks used are coal and biomass. The feedstocks are partially oxidized to generate syngas using metal oxide oxygen carriers as the oxidant. The reduced metal oxide is then oxidized in the regeneration step using air. The syngas is an important intermediate for generation of such diverse products as electricity, chemicals, hydrogen, and liquid fuels. The motivation for developing the CLR and CLG processes lies in their advantages of being able to avoid the use of pure oxygen in the reaction, thereby circumventing the energy intensive air separation requirement in the conventional reforming and gasification processes. The energy conversion efficiency of the processes can, thus, be significantly increased. Steam and carbon dioxide can also be used as the oxidants. As the metal oxide also serves as the heat transfer medium in the chemical looping process, the exergy efficiency of the reforming and gasification processes like that for the combustion process


id: chemical-looping-reforming-and-gasification-20260505-1
file: data/en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification-1.md
category: reference
title: Chemical looping reforming and gasification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification
date_saved: 2026-05-05T10:48:57.792091+00:00
instance: kb-cron
parent: chemical-looping-reforming-and-gasification-20260505-0
summary:
CH4 + H2O → CO + 3H2 Steam can be further used to convert CO to H2 via the water-gas shift reaction (WGS): H2O + CO → CO2 + H2 The SMR reaction is endothermic, which requires heat input. The state-of-art SMR system places the tubular catalytic reactors in a furnace, in which fuel gas is burned to provide the required heat. In the SMR with chemical looping combustion (CLC-SMR) concepts shown in Fig 2, the syngas production is carried out by the SMR in a tubular catalytic reactor while the chemical looping combustion system is used to provide the heat for the catalytic reaction. Depending on which chemical looping reactor is used to provide the SMR reaction heat, two CLC-SMR schemes can be configured. In Scheme 1 (Fig 2a), the reaction heat is provided by the reducer (fuel reactor). In Scheme 2 (Fig 2b), the reaction heat is provided by the combustor (air reactor). In either scheme, the combustion of metal oxide by air in the chemical looping system provides the heat source that sustains the endothermic SMR reactions. In the chemical looping system, natural gas and the recycled off-gas from the pressure swing adsorption (PSA) of the SMR


id: chemical-looping-reforming-and-gasification-20260505-2
file: data/en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification-2.md
category: reference
title: Chemical looping reforming and gasification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_looping_reforming_and_gasification
date_saved: 2026-05-05T10:48:57.792091+00:00
instance: kb-cron
parent: chemical-looping-reforming-and-gasification-20260505-0
summary:
=== Chemical looping gasification (CLG) === Chemical looping gasification (CLG) differs from the CLR in that it uses solid fuels such as coal and biomass instead of gaseous fuels as feedstocks. The operating principles for the CLG is similar to CLR. For solid feedstocks, devolatilization and pyrolysis of the solid fuel occur when the solid fuels are introduced into the reducer and mixed with the oxygen carrier particles. With the fluidized bed reducer, the released volatiles, including light organic compounds and tars, may channel through the reducer and exit with the syngas. The light organic compounds may reduce the purity of the syngas, while the tars may accumulate in downstream pipelines and instruments. For example, the carbon efficiency using the coal CLG fluidized bed reducer may vary from 55% to 81%, whereas the carbon efficiency using the coal moving bed reducer can reach 85% to 98%. The syngas derived from the biomass CLG fluidized bed reducer may consist of up to 15% methane, while the syngas derived from the biomass CLG moving bed reducer can reach a methane concentration of less than 5%. In general, increasing the temperature of the CLG system can promote volatile and char conversion. This may


id: mannheim-process-20260505-0
file: data/en.wikipedia.org/wiki/Mannheim_process-0.md
category: reference
title: Mannheim process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mannheim_process
date_saved: 2026-05-05T10:48:58.970059+00:00
instance: kb-cron
parent: mannheim-process-20260505-0
summary:
The Mannheim process is an industrial process for the production of hydrogen chloride and sodium sulfate from sulfuric acid and sodium chloride. The Mannheim furnace is also used to produce potassium sulfate from potassium chloride. The Mannheim process is a stage in the Leblanc process for the production of sodium carbonate. == Process == The process is named after Mannheim furnace, a large cast iron kiln in which it is conducted. The furnace was developed at Verein Chemischer Fabriken in Mannheim at the turn of the 20th century and superseded earlier furnace designs formerly used for the same purpose. Sodium chloride and sulfuric acid are first fed onto a stationary reaction plate where an initial reaction takes place. The stationary plate is up to 6 m (20 ft) in diameter. Rotating rabble arms constantly turn over the mixture and move the intermediate product to a lower plate. The kiln portion of the furnace is constructed with bricks that have high resistance to direct flame, temperature, and acid. The other parts of the furnace are heat and acid resistant. Hot flue gas passes up over the plates carrying out liberated hydrogen chloride gas. The intermediate product reacts with more sodium chloride


id: mass-deacidification-20260505-0
file: data/en.wikipedia.org/wiki/Mass_deacidification-0.md
category: reference
title: Mass deacidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mass_deacidification
date_saved: 2026-05-05T10:49:00.170656+00:00
instance: kb-cron
parent: mass-deacidification-20260505-0
summary:
Mass deacidification is a term used in library and information science as one possible measure against the degradation of paper in old books, the so-called "slow fires". The goal of the process is to increase the pH of acidic paper. Although acid-free paper has become more common, a large body of acidic paper still exists in books made after the 1850s; this is because of its cheaper and simpler production methods. Acidic paper, especially when exposed to light, air pollution, or high relative humidity, yellows and becomes brittle over time. During mass deacidification an alkaline agent is deposited in the paper to neutralize existing acid and prevent further decay. Mass deacidification is intended for objects on acidic paper that will be lost if no action is performed. == History of research and process development == Mass deacidification—along with microfilm and lamination—was developed during the early and mid-20th century as a response to the chemical process of hydrolysis by which the fibers that constitute paper, providing its structure and strength, have their bonds broken, resulting in paper that becomes increasingly brittle over time. Environmental pollutants can react with paper to form acids that promote oxidation, creating more acid as a by-product,


id: mass-deacidification-20260505-1
file: data/en.wikipedia.org/wiki/Mass_deacidification-1.md
category: reference
title: Mass deacidification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mass_deacidification
date_saved: 2026-05-05T10:49:00.170656+00:00
instance: kb-cron
parent: mass-deacidification-20260505-0
summary:
The BookKeeper process is a non-aqueous, liquid phase process that uses magnesium oxide. BookKeeper is available through Preservation Technologies, L.P. with plants in the U.S., Spain, Japan, Poland, The Netherlands, South Africa, Qatar. Another plant is available through Fratielivi in Italy. The CSC Book Saver uses carbonated magnesium propylate for deacidification. The CSC Book Saver is available in Europe through Conservación de Sustratos Celulósicos S.L. (CSC) (Barcelona, Spain). The Papersave process was developed by Battelle Ingenieurtechnik GmbH and is, therefore, sometimes referred to as "the Battelle Process". The process uses magnesium titanium alkoxide. The Papersave process is available in Europe through Nitrochemie Wimmis (Wimmis, Switzerland) under the name of Papersave Swiss and the Zentrum für Bucherhaltung (Leipzig, Germany). The Wei T'o process uses methoxy magnesium methyl carbonate, or isopropoxy magnesium isopropyl carbonate, and new products are coming out in 2008. Wei T'o is less commonly used for mass deacidification treatment than for single item deacidification. Wei T'o products are available through Wei T'o Associates Inc. (Matteson, US). BookKeeper, CSC Booksaver, Papersave, and Wei T'o are also available as hand-held sprays. == Adoption and costs == While deacidification has been adopted by major research libraries such as the Library of Congress


id: mercury-silvering-20260505-0
file: data/en.wikipedia.org/wiki/Mercury_silvering-0.md
category: reference
title: Mercury silvering
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mercury_silvering
date_saved: 2026-05-05T10:49:01.355366+00:00
instance: kb-cron
parent: mercury-silvering-20260505-0
summary:
Mercury silvering or fire gilding is a silvering technique for applying a thin layer of precious metal such as silver or gold (mercury gilding) to a base metal object. The process was invented during the renaissance and is documented in Vannoccio Biringuccio's 1540 book De la pirotechnia. An amalgam of mercury and the precious metal is prepared and applied to the object which is then heated, sometimes in oil, vaporizing most of the mercury. The technique is dangerous since mercury is highly toxic, especially in its vapor phase. Mercury silvering can be detected through a variety of methods. The technique was also used in Asia, for example tokin plating in Edo-period Japan. == See also == Mercury glass, internally silvered decorative glass products named for their resemblance to mercury Liquid-mirror telescope, may use a layer of reflective mercury == References ==


id: merox-20260505-0
file: data/en.wikipedia.org/wiki/Merox-0.md
category: reference
title: Merox
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Merox
date_saved: 2026-05-05T10:49:02.530750+00:00
instance: kb-cron
parent: merox-20260505-0
summary:
Merox is an acronym for mercaptan oxidation. It is a proprietary catalytic chemical process developed by UOP used in oil refineries and natural gas processing plants to remove mercaptans from LPG, propane, butanes, light naphthas, kerosene, and jet fuel by converting them to liquid hydrocarbon disulfides. The Merox process requires an alkaline environment which, in some process versions, is provided by an aqueous solution of sodium hydroxide (NaOH), a strong base, commonly referred to as caustic. In other versions of the process, the alkalinity is provided by ammonia, which is a weak base. The catalyst in some versions of the process is a water-soluble liquid. In other versions, the catalyst is impregnated into charcoal granules. Processes within oil refineries or natural gas processing plants that remove mercaptans and/or hydrogen sulfide (H2S) are commonly referred to as sweetening processes because they result in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide. The liquid hydrocarbon disulfides may remain in the sweetened products. These may be used as part of the refinery or natural gas processing plant fuel, or they may be processed further. When dealing with kerosene, the Merox process is usually more economical than using


id: merox-20260505-1
file: data/en.wikipedia.org/wiki/Merox-1.md
category: reference
title: Merox
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Merox
date_saved: 2026-05-05T10:49:02.530750+00:00
instance: kb-cron
parent: merox-20260505-0
summary:
=== Flow diagram === The flow diagram below depicts the equipment and the flow paths involved in the process. The LPG (or light naphtha) feedstock enters the prewash vessel and flows upward through a batch of caustic which removes any H2S that may be present in the feedstock. The coalescer at the top of the prewash vessel prevents caustic from being entrained and carried out of the vessel. The feedstock then enters the mercaptan extractor and flows upward through the contact trays where the LPG intimately contacts the downflowing Merox caustic that extracts the mercaptans from the LPG. The sweetened LPG exits the tower and flows through: a caustic settler vessel to remove any entrained caustic, a water wash vessel to further remove any residual entrained caustic and a vessel containing a bed of rock salt to remove any entrained water. The dry sweetened LPG exits the Merox unit. The caustic solution leaving the bottom of the mercaptan extractor ("rich" Merox caustic) flows through a control valve which maintains the extractor pressure needed to keep the LPG liquified. It is then injected with UOP's proprietary liquid catalyst (on an as needed basis), flows through a steam-heated heat exchanger and is


id: metal-vapor-synthesis-20260505-0
file: data/en.wikipedia.org/wiki/Metal_vapor_synthesis-0.md
category: reference
title: Metal vapor synthesis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Metal_vapor_synthesis
date_saved: 2026-05-05T10:49:03.899826+00:00
instance: kb-cron
parent: metal-vapor-synthesis-20260505-0
summary:
In chemistry, metal vapor synthesis (MVS) is a method for preparing metal complexes by combining freshly produced metal atoms or small particles with ligands. In contrast to the high reactivity of such freshly produced metal atoms, bulk metals typically are unreactive toward neutral ligands. The method has been used to prepare compounds that cannot be prepared by traditional synthetic methods, e.g. Ti(η6-toluene)2. The technique relies on a reactor that evaporates the metal, allowing the vapor to impinge on a cold reactor wall that is coated with the organic ligand. The metal evaporates upon being heated resistively or irradiated with an electron beam. The apparatus operates under high vacuum. In a common implementation, the metal vapor and the organic ligand are co-condensed at liquid nitrogen temperatures. In several case where compounds are prepared by MVS, related preparations employ conventional routes. Thus, tris(butadiene)molybdenum was first prepared by co-condensation of butadiene and Mo vapor, but yields are higher for the reduction of molybdenum(V) chloride in the presence of the diene. == References ==


id: metal-induced-crystallization-20260505-0
file: data/en.wikipedia.org/wiki/Metal-induced_crystallization-0.md
category: reference
title: Metal-induced crystallization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Metal-induced_crystallization
date_saved: 2026-05-05T10:49:05.059664+00:00
instance: kb-cron
parent: metal-induced-crystallization-20260505-0
summary:
Combined with certain metallic species, amorphous films can crystallize in a process known as metal-induced crystallization (MIC). The effect was discovered in 1969, when amorphous germanium (a-Ge) films crystallized at surprisingly low temperatures when in contact with aluminum, silver, copper, or tin. The effect was also verified in amorphous silicon (a-Si) films, as well as in amorphous carbon and various metal-oxide films. Likewise, the MIC evolved from simple temperature-driven annealing approaches to others involving lasers or microwave radiation, for example. A very common variant of the MIC procedure is the metal-induced lateral crystallization (MILC). In this case, the metal is deposited (onto the top or at the bottom) of some selected areas of the desired amorphous film. Upon annealing, crystallization starts from the portion of the amorphous film that is in contact with the metal species, and the MIC proceeds laterally. == References ==


id: methanation-20260505-0
file: data/en.wikipedia.org/wiki/Methanation-0.md
category: reference
title: Methanation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Methanation
date_saved: 2026-05-05T10:49:06.202076+00:00
instance: kb-cron
parent: methanation-20260505-0
summary:
Methanation is the conversion of carbon monoxide and carbon dioxide (COx) to methane (CH4) through hydrogenation. The methanation reactions of COx were first discovered by Sabatier and Senderens in 1902. COx methanation has many practical applications. It is a means of carbon oxide removal from process gases and is also being discussed as an alternative to PROX in fuel processors for mobile fuel cell applications. Methanation as a means of producing synthetic natural gas has been considered since the 1970s. More recently it has been considered as a way to store energy produced from solar or wind power using power-to-gas systems in conjunction with existing natural gas storage. == Chemical reactions == The following reactions describe the methanation of carbon monoxide and carbon dioxide respectively: CO + 3 H 2 ⟶ CH 4 + H 2 O {\displaystyle {\ce {CO + 3H2 -> CH4 + H2O}}} △H = -206 kJ/mol CO 2 + 4 H 2 ⟶ CH 4 + 2 H 2 O {\displaystyle {\ce {CO2 + 4H2 -> CH4 + 2 H2O}}} △H = -164 kJ/mol The methanation reactions are highly exothermic and release significant amounts of heat during reaction completion. There is disagreement on whether the CO2


id: micro-compounding-20260505-0
file: data/en.wikipedia.org/wiki/Micro-compounding-0.md
category: reference
title: Micro-compounding
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Micro-compounding
date_saved: 2026-05-05T10:49:07.395983+00:00
instance: kb-cron
parent: micro-compounding-20260505-0
summary:
Micro-compounding is the mixing or processing of polymer formulations in the melt on a small scale, typically milliliters. It is popular for research and development because it gives faster, more reliable results with smaller samples and less cost. Its applications include pharmaceutical, biomedical, and nutritional areas. == Design == Micro-compounding is typically performed with a tabletop, twin screw micro-compounder, or micro-extruder with a working volume of 5 or 15 milliliters. With such small volumes, it is difficult to have sufficient mixing in a continuous extruder. Therefore, micro-compounders typically have a batch mode (recirculation) and a conical shape. The L/D of a continuous twin screw extruder is mimicked in a batch micro-compounder by the recirculation mixing time, which is controlled by a manual valve. With this valve, the recirculation can be interrupted to unload the formulation in either a strand or an injection moulder, a film device or a fiber line. Typical recirculation times are one to three minutes, depending on the ease of dispersive and distributive mixing of the formulation. == Benefits == Micro-compounding can now produce films, fibers, and test samples (rods, rings, tablets) from mixtures as small as 5 ml in less than ten minutes. The small footprint


id: micro-pulling-down-20260505-0
file: data/en.wikipedia.org/wiki/Micro-pulling-down-0.md
category: reference
title: Micro-pulling-down
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Micro-pulling-down
date_saved: 2026-05-05T10:49:08.623875+00:00
instance: kb-cron
parent: micro-pulling-down-20260505-0
summary:
The micro-pulling-down (μ-PD) method is a crystal growth technique based on continuous transport of the melted substance through micro-channel(s) made in a crucible bottom. Continuous solidification of the melt is progressed on a liquid/solid interface positioned under the crucible. In a steady state, both the melt and the crystal are pulled-down with a constant (but generally different) velocity. Many different types of crystal are grown by this technique, including Y3Al5O12, Si, Si-Ge, LiNbO3, α-Al2O3, Y2O3, Sc2O3, LiF, CaF2, BaF2, etc. == Crystal growth routine == Standard routine procedure used in the growth of most of μ-PD crystals is well developed. The general stages of the growths include: Charging of the crucible with starting materials (mixture of powders) Heating of the crucible until starting materials in the crucible are completely melted Upward displacement of the seed until its contact with the meniscus or crucible Formation of the meniscus and partial melting of the seed top Correction of the shape of the meniscus through appropriate adjustment of crucible temperature and position of the seed crystal Crystal growth through pulling of the seed in downward direction Separation of the as grown crystal from the meniscus Cooling of the system (including the crystal and


id: molecular-laser-isotope-separation-20260505-0
file: data/en.wikipedia.org/wiki/Molecular_laser_isotope_separation-0.md
category: reference
title: Molecular laser isotope separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_laser_isotope_separation
date_saved: 2026-05-05T10:49:09.777690+00:00
instance: kb-cron
parent: molecular-laser-isotope-separation-20260505-0
summary:
Molecular laser isotope separation (MLIS) is a method of isotope separation, where specially tuned lasers are used to separate isotopes of uranium using selective ionization of hyperfine transitions of uranium hexafluoride molecules. It is similar to AVLIS. Its main advantage over AVLIS is low energy consumption and use of uranium hexafluoride instead of vaporized uranium. MLIS was conceived in 1971 at the Los Alamos National Laboratory. MLIS operates in cascade setup, like the gaseous diffusion process. Instead of vaporized uranium as in AVLIS the working medium of the MLIS is uranium hexafluoride which requires a much lower temperature to vaporize. The UF6 gas is mixed with a suitable carrier gas (a noble gas including some hydrogen) which allows the molecules to remain in the gaseous phase after being cooled by expansion through a supersonic de Laval nozzle. A scavenger gas (e.g. methane) is also included in the mixture to bind with the fluorine atoms after they are dissociated from the UF6 and inhibit their recombination with the enriched UF5 product. In the first stage, the expanded and cooled stream of UF6 is irradiated with an infrared laser operating at the wavelength of 16 μm. The mix is then irradiated with


id: molecular-layer-deposition-20260505-0
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-0.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
Molecular layer deposition (MLD) is a vapour phase thin film deposition technique based on self-limiting surface reactions carried out in a sequential manner. Essentially, MLD resembles the well established technique of atomic layer deposition (ALD) but, whereas ALD is limited to exclusively inorganic coatings, the precursor chemistry in MLD can use small, bifunctional organic molecules as well. This enables, as well as the growth of organic layers in a process similar to polymerization, the linking of both types of building blocks together in a controlled way to build up organic-inorganic hybrid materials. Even though MLD is a known technique in the thin film deposition sector, due to its relative youth it is not as explored as its inorganic counterpart, ALD, and a wide sector development is expected in the upcoming years. == History == Molecular layer deposition is a sister technique of atomic layer deposition. While the history of atomic layer deposition dates back to the 1970s, thanks to the independent work of Valentin Borisovich Aleskovskii. and Tuomo Suntola, the first MLD experiments with organic molecules were not published until 1991, when an article from Tetsuzo Yoshimura and co-workers appeared regarding the synthesis of polyimides using amines and anhydrides as


id: molecular-layer-deposition-20260505-1
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-1.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
== Process chemistry and surface reactions == Precursor chemistry plays a key role in MLD. The chemical properties of the precursor molecules drive the composition, structure and stability of the deposited hybrid material. To reach the saturation stage in a short time and ensure a reasonable deposition rate, precursors must chemisorb on the surface, react rapidly with the surface active groups and react with each other. The desired MLD reactions should have a large negative ∆G value. Organic compounds are employed as precursors for MLD. For their effective use, the precursor should have sufficient vapor pressure and thermal stability to be transported in the gas phase to the reaction zone without decomposing. Volatility is influenced by the molecular weight and intermolecular interactions. One of the challenges in MLD is to find an organic precursor that has sufficient vapor pressure, reactivity and thermal stability. Most organic precursors have low volatility, and heating is necessary to ensure the sufficient supply of vapor reaching the substrate. The backbone of the organic precursors can be flexible i.e., aliphatic, or rigid i.e., aromatics employed with the functional groups. The organic precursors usually are homo or heterobifunctional molecules with -OH, -COOH, -NH2, -CONH2, -CHO, -COCl, -SH,


id: molecular-layer-deposition-20260505-2
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-2.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
Molecule tilting: organic molecules with long chains are prone to not remaining completely perpendicular to the surface, lowering the number of surface sites. Bidentate ligands: when a reacting molecule has two functional groups, it may bend and react with two surface sites instead of remaining straight on the surface. This has been shown, for instance, for titanicones grown with ethylene glycol and glycerol. Because glycerol has an additional hydroxyl group compared to ethylene glycol and is able to provide an extra reactive hydroxyl group in the case of a double reaction of the terminal hydroxyl groups with the surface. Steric hindrance: organic precursors are often bulky, and can cover several surface groups when attached to the surface. Long pulsing times: organic precursors can have very low vapour pressures, and very long pulsing times may be necessary in order to achieve saturation. In addition, long purging times are usually needed to remove all unreacted molecules from the chamber afterward. Low temperatures: to increase the precursor vapor pressure, one might think of increasing its temperature. Nevertheless, organic precursors are usually very thermally fragile, and a temperature increase may induce decomposition. Gas-phase: many organic reactions are normally carried out in the liquid phase,


id: molecular-layer-deposition-20260505-3
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-3.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
==== Gaseous precursors ==== ALD/MLD are both gas phase processes. Hence, precursors are required to be introduced into the reaction zones in their gaseous form. A precursor already existing in a gaseous physical state would make its transport to the reactor very straightforward and hassle free. For example, there will be no need of heating the precursor thereby reducing the risk of condensation. However, precursors are seldom available in gaseous state. On the other hand, some ALD co-reactants are available in gaseous form. Examples include H2S used for sulphide films; NH3 used for nitride films; plasmas of O2 and O3 to produce oxides. The most common and straight forward way of regulating the supply of these co-reactants to the reactor is using a mass flow controller attached between the source and the reactor. They can also be diluted with an inert gas to control their partial pressure. == Film characterisation == Several characterisation techniques have evolved over time as the demand for creating ALD/MLD films for different applications has increased. This includes lab-based characterisation and efficient synchrotron-based x-ray techniques. === Lab-based characterisation === Since they both follow a similar protocol, almost all characterisation applicable to ALD generally applies to MLD


id: molecular-layer-deposition-20260505-4
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-4.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
==== High-k ==== Novel organic thin-film transistors require a high-performance dielectric layer, which should be thin and possess a high k-value. MLD makes tuning the high-k and dielectric strength possible by altering the amount and the ratio of the organic and inorganic components. Moreover, the usage of MLD allows to achieve better mechanical properties in terms of flexibility. Various hybrid dielectrics have already been developed: zincone hybrids from zirconium tert-butoxide (ZTB) and ethylene glycol (EG); Al2O3 based hybrids such as self-assembled MLD-deposited octenyltrichlorosilane (OTS) layers and Al2O3 linkers. Additionally, dielectric Ti-based hybrid from TiCl4 and fumaric acid proved its applicability in charge memory capacitors. === MLD for porous materials === MLD has high potential for the deposition of porous hybrid organic-inorganic and purely organic films, such as Metal-Organic Frameworks (MOFs) and Covalent-Organic Frameworks (COFs). Thanks to the defined pore structure and chemical tunability, thin films of these novel materials are expected to be incorporated in the next generation of gas sensors and low-k dielectrics. Conventionally, thin films of MOFs and COFs are grown via solvent-based routes, which are detrimental in a cleanroom environment and can cause corrosion of the pre-existing circuitry. As a cleanroom-compatible technique, MLD presents an attractive alternative,


id: molecular-layer-deposition-20260505-5
file: data/en.wikipedia.org/wiki/Molecular_layer_deposition-5.md
category: reference
title: Molecular layer deposition
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Molecular_layer_deposition
date_saved: 2026-05-05T10:49:10.956175+00:00
instance: kb-cron
parent: molecular-layer-deposition-20260505-0
summary:
==== Bioactive and biocompatible surfaces ==== MLD can also be applied to design of bioactive and biocompatible surfaces for targeted cell and tissue responses. Bioactive materials involve materials for regenerative medicine, tissue engineering (tissue scaffolds), biosensors etc. The important factors that can affect the cell-surface interaction, as well as the immune response of the system are surface chemistry (e.g. functional groups, surface charge and wettability) and surface topography. Understanding these properties is crucial in order to control the attachment and proliferation of the cell, and resultant bioactivity of the surfaces. Furthermore, the choice of organic building blocks and a type of biomolecules (e.g. proteins, peptides or polysaccharides) during the formation of bioactive surfaces is a key factor for cellular response of the surface. MLD allows for the building of bioactive, precise structures by combining such organic molecules with inorganic biocompatible elements like titanium. The use of MLD for biomedical applications is not widely studied and is a promising field of research. This method enables surface modification and thus, can functionalize a surface. A recent study published in 2017 used MLD to create bioactive scaffolds by combining titanium clusters with amino acids such as glycine, L-aspartic acid and L-arginine as organic


id: mond-process-20260505-0
file: data/en.wikipedia.org/wiki/Mond_process-0.md
category: reference
title: Mond process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Mond_process
date_saved: 2026-05-05T10:49:12.151423+00:00
instance: kb-cron
parent: mond-process-20260505-0
summary:
The Mond process, sometimes known as the carbonyl process, is a technique created by Ludwig Mond in 1890, to extract and purify nickel. The process was used commercially before the end of the 19th century, and particularly by the International Nickel Company in the Sudbury Basin. This process converts nickel oxides into nickel metal with very high purity being attainable in just a single step. == Synopsis == This process involves the fact that carbon monoxide combines with nickel readily and reversibly to give nickel carbonyl. Few other elements other than nickel, iron, and cobalt form carbonyl compounds under the mild conditions used in the process. This process has three steps: 1. Metal Feed (consisting of primarily Nickel oxide) reacts with hydrogen at 200 °C to give nickel. Other impurities including iron and cobalt are also reduced. NiO(s) + H2(g) → Ni(s) + H2O(g) 2. The impure nickel reacts with carbon monoxide at 50–60 °C to form the gas nickel carbonyl, leaving the impurities as solids. Ni(s) + 4 CO(g) → Ni(CO)4(g) 3. The mixture of nickel carbonyl and carbon monoxide is heated to 220–250 °C, resulting in decomposition back to nickel and carbon monoxide: Ni(CO)4(g) → Ni(s) + 4


id: monsanto-process-20260505-0
file: data/en.wikipedia.org/wiki/Monsanto_process-0.md
category: reference
title: Monsanto process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Monsanto_process
date_saved: 2026-05-05T10:49:13.296370+00:00
instance: kb-cron
parent: monsanto-process-20260505-0
summary:
The Monsanto process is an industrial method for the manufacture of acetic acid by catalytic carbonylation of methanol. The Monsanto process has largely been supplanted by the Cativa process, a similar iridium-based process developed by BP Chemicals Ltd, which is more economical and environmentally friendly. This process operates at a pressure of 30–60 atm and a temperature of 150–200 °C and gives a selectivity greater than 99%. It was developed in 1960 by the German chemical company BASF and improved by the Monsanto Company in 1966, which introduced a new catalyst system. == Catalytic cycle == The catalytically active species is the anion cis-[Rh(CO)2I2]− (top of scheme). The first organometallic step is the oxidative addition of methyl iodide to cis-[Rh(CO)2I2]− to form the hexacoordinate species [(CH3)Rh(CO)2I3]−. This anion rapidly transforms, via the migration of a methyl group to an adjacent carbonyl ligand, affording the pentacoordinate acetyl complex [(CH3CO)Rh(CO)I3]−. This five-coordinate complex then reacts with carbon monoxide to form the six-coordinate dicarbonyl complex, which undergoes reductive elimination to release acetyl iodide (CH3C(O)I). The catalytic cycle involves two non-organometallic steps: conversion of methanol to methyl iodide and the hydrolysis of the acetyl iodide to acetic acid and hydrogen iodide. The reaction has


id: natural-gas-processing-20260505-0
file: data/en.wikipedia.org/wiki/Natural-gas_processing-0.md
category: reference
title: Natural-gas processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural-gas_processing
date_saved: 2026-05-05T10:49:14.463304+00:00
instance: kb-cron
parent: natural-gas-processing-20260505-0
summary:
Natural-gas processing is a range of industrial processes designed to purify raw natural gas by removing contaminants such as solids, water, carbon dioxide (CO2), hydrogen sulfide (H2S), mercury and higher molecular mass hydrocarbons (condensate) to produce pipeline quality dry natural gas for pipeline distribution and final use. Some of the substances which contaminate natural gas have economic value and are further processed or sold. Hydrocarbons that are liquid at ambient conditions: temperature and pressure (i.e., pentane and heavier) are called natural-gas condensate (sometimes also called natural gasoline or simply condensate). Raw natural gas comes primarily from three types of wells: crude oil wells, gas wells, and condensate wells. Crude oil and natural gas are often found together in the same reservoir. Natural gas produced in wells with crude oil is generally classified as associated-dissolved gas as the gas had been associated with or dissolved in crude oil. Natural gas production not associated with crude oil is classified as “non-associated.” In 2009, 89 percent of U.S. wellhead production of natural gas was non-associated. Non-associated gas wells producing a dry gas in terms of condensate and water can send the dry gas directly to a pipeline or gas plant without undergoing any


id: natural-gas-processing-20260505-1
file: data/en.wikipedia.org/wiki/Natural-gas_processing-1.md
category: reference
title: Natural-gas processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural-gas_processing
date_saved: 2026-05-05T10:49:14.463304+00:00
instance: kb-cron
parent: natural-gas-processing-20260505-0
summary:
Be free of particulate solids and liquid water to prevent erosion, corrosion or other damage to the pipeline. Be dehydrated of water vapor sufficiently to prevent the formation of methane hydrates within the gas processing plant or subsequently within the sales gas transmission pipeline. A typical water content specification in the U.S. is that gas must contain no more than seven pounds of water per million standard cubic feet of gas. In the UK this is defined as <-10 °C @ 85barg for entry into the NTS. Contain no more than trace amounts of components such as hydrogen sulfide, carbon dioxide, mercaptans, and nitrogen. The most common specification for hydrogen sulfide content is 0.25 grain H2S per 100 cubic feet of gas, or approximately 4 ppm. Specifications for CO2 typically limit the content to no more than two or three percent. In the UK hydrogen sulfide is specified ≤5 mg/m3 and total sulfur as ≤50 mg/m3, carbon dioxide as ≤2.0% (molar), and nitrogen as ≤5.0% (molar) for entry into the NTS. Maintain mercury at less than detectable limits (approximately 0.001 ppb by volume) primarily to avoid damaging equipment in the gas processing plant or the pipeline transmission system from mercury


id: natural-gas-processing-20260505-2
file: data/en.wikipedia.org/wiki/Natural-gas_processing-2.md
category: reference
title: Natural-gas processing
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Natural-gas_processing
date_saved: 2026-05-05T10:49:14.463304+00:00
instance: kb-cron
parent: natural-gas-processing-20260505-0
summary:
Condensed liquid passes through a Joule-Thomson valve reducing the pressure to 20 bar and enters the demethanizer as the lower feed at -44.7 °C. Some of the vapour is routed through a turbo-expander and enters the demethanizer as the upper feed at -64 °C. The remaining vapor is chilled by the demethanizer overhead product and Joule-Thomson cooling (through a valve) and enters the column as reflux at -96 °C. The overhead product is mainly methane at 20 bar and -98 °C. This is heated and compressed to yield a sales gas at 20 bar and 40 °C. The bottom product is NGL at 20 barg which is fed to the deethanizer. The overhead product from the deethanizer is ethane and the bottoms are fed to the depropanizer. The overhead product from the depropanizer is propane and the bottoms are fed to the debutanizer. The overhead product from the debutanizer is a mixture of normal and iso-butane, and the bottoms product is a C5+ gasoline mixture. The operating conditions of the vessels in the NGL fractionation train are typically as follows. A typical composition of the feed and product is as follows. === Sweetening Units === The recovered streams of propane,


id: newbery-vautin-chlorination-process-20260505-0
file: data/en.wikipedia.org/wiki/Newbery–Vautin_chlorination_process-0.md
category: reference
title: Newbery–Vautin chlorination process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Newbery–Vautin_chlorination_process
date_saved: 2026-05-05T10:49:15.658889+00:00
instance: kb-cron
parent: newbery-vautin-chlorination-process-20260505-0
summary:
The Newbery–Vautin chlorination process is a method for extracting gold from its ore through the use of chlorination. This process was jointly developed by James Cosmo Newbery and Claude Theodore James Vautin. == Chlorination process == === History === A process for extracting gold from gold ores containing pyrite using chlorine gas was introduced by Karl Friedrich Plattner (1800–1858), around 1848. James Newbery and Claude Vautin began work on chlorination, at the United Pyrites Gold Extracting Co. in Bendigo, in 1878. They were awarded Victorian Patent No. 4484, in 1886, for their Newbery–Vautin chlorination process, which was faster than earlier chlorination processes. === Process description === Roasted gold-bearing pyrite concentrates and water were combined in a barrel, to which calcium chloride and sulphuric acid were added. The barrel was then made airtight. Compressed air was used to raise the internal pressure to four atmospheres, and the barrel was set in rotation. The sulphuric acid and calcium chloride reacted to form chlorine gas. The gold contained in the concentrate reacted with the chlorine to form gold chloride, which is a salt soluble in water. Once the extraction had occurred—after around four hours—the liquid containing the gold chloride was separated from the


id: nitrophosphate-process-20260505-0
file: data/en.wikipedia.org/wiki/Nitrophosphate_process-0.md
category: reference
title: Nitrophosphate process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Nitrophosphate_process
date_saved: 2026-05-05T10:49:16.886778+00:00
instance: kb-cron
parent: nitrophosphate-process-20260505-0
summary:
The nitrophosphate process (also known as the Odda process) is a method for the industrial production of nitrogen fertilizers invented by Erling Johnson in Odda Municipality, Norway. around 1927. The process involves acidifying phosphate rock with dilute nitric acid to produce a mixture of phosphoric acid and calcium nitrate. Ca 5 ( PO 4 ) 3 OH + 10 HNO 3 ⟶ 3 H 3 PO 4 + 5 Ca ( NO 3 ) 2 + H 2 O {\displaystyle {\ce {Ca5(PO4)3OH + 10 HNO3 -> 3 H3PO4 + 5 Ca(NO3)2 + H2O}}} The mixture is cooled to below 0 °C, where the calcium nitrate crystallizes and can be separated from the phosphoric acid. 2 H 3 PO 4 + 3 Ca ( NO 3 ) 2 + 12 H 2 O ⟶ 2 H 3 PO 4 + 3 Ca ( NO 3 ) 2 ⋅ 4 H 2 O {\displaystyle {\ce {2 H3PO4 + 3 Ca(NO3)2 + 12 H2O -> 2 H3PO4 + 3 Ca(NO3)2.4H2O}}} The resulting calcium nitrate produces nitrogen fertilizer. The filtrate is composed mainly of phosphoric acid with some nitric acid and traces of calcium nitrate, and this is neutralized with ammonia to produce a


id: oil-refinery-20260505-0
file: data/en.wikipedia.org/wiki/Oil_refinery-0.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefied petroleum gas and petroleum naphtha. Petrochemical feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. In 2020, the total capacity of global refineries for crude oil was about 101.2 million barrels per day. Oil refineries are typically large, sprawling industrial complexes with extensive piping running throughout, carrying streams of fluids between large chemical processing units, such as distillation columns. In many ways, oil refineries use many different technologies and can be thought of as types of chemical plants. Since December 2008, the world's largest oil refinery has been the Jamnagar Refinery owned by Reliance Industries, located in Gujarat, India, with a processing capacity of 1.24 million barrels (197,000


id: oil-refinery-20260505-1
file: data/en.wikipedia.org/wiki/Oil_refinery-1.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
== History == The Chinese were among the first civilizations to refine oil. As early as the first century, the Chinese were refining crude oil for use as an energy source. Between 512 and 518, in the late Northern Wei dynasty, the Chinese geographer, writer and politician Li Daoyuan introduced the process of refining oil into various lubricants in his famous work Commentary on the Water Classic. Crude oil was often distilled by Persian chemists, with clear descriptions given in handbooks such as those of Muhammad ibn Zakarīya Rāzi (c. 865–925). The streets of Baghdad were paved with tar, derived from petroleum that became accessible from natural fields in the region. In the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan. These fields were described by the Arab geographer Abu al-Hasan 'Alī al-Mas'ūdī in the 10th century, and by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads. Arab and Persian chemists also distilled crude oil in order to produce flammable products for military purposes. Through Islamic Spain, distillation became available in Western Europe by the 12th century. In the Northern Song dynasty (960–1127), a workshop called


id: oil-refinery-20260505-2
file: data/en.wikipedia.org/wiki/Oil_refinery-2.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
In the United States, for various complex economic and political reasons, the construction of new refineries came to a virtual stop in about the 1980s. However, many of the existing refineries in the United States have revamped many of their units and/or constructed add-on units in order to: increase their crude oil processing capacity, increase the octane rating of their product gasoline, lower the sulfur content of their diesel fuel and home heating fuels to comply with environmental regulations and comply with environmental air pollution and water pollution requirements. === United States === In the 19th century, refineries in the U.S. processed crude oil primarily to recover the kerosene. There was no market for the more volatile fraction, including gasoline, which was considered waste and was often dumped directly into the nearest river. The invention of the automobile shifted demand to gasoline and diesel, which remain the primary refined products today. Today, national and state legislation require refineries to meet stringent air and water cleanliness standards. In fact, oil companies in the U.S. perceive obtaining a permit to build a modern refinery to be so difficult and costly that no new refineries were built (though many have been expanded) in


id: oil-refinery-20260505-3
file: data/en.wikipedia.org/wiki/Oil_refinery-3.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. The majority of petroleum is converted to petroleum products, which includes several classes of fuels. Oil refineries also produce various intermediate products such as hydrogen, light hydrocarbons, reformate and pyrolysis gasoline. These are not usually transported but instead are blended or processed further on-site. Chemical plants are thus often adjacent to oil refineries or a number of further chemical processes are integrated into it. For example, light hydrocarbons are steam-cracked in an ethylene plant, and the produced ethylene is polymerized to produce polyethene. To ensure both proper separation and environmental protection, a very low sulfur content is necessary in all but the heaviest products. The crude sulfur contaminant is transformed to hydrogen sulfide via catalytic hydrodesulfurization and removed from the product stream via amine gas treating. Using the Claus process, hydrogen sulfide is afterward transformed to elementary sulfur to be sold to the chemical industry. The rather large heat energy freed by this process is directly used in the other parts of the refinery. Often an electrical power plant is combined into the whole refinery process to take up the excess heat. According to


id: oil-refinery-20260505-4
file: data/en.wikipedia.org/wiki/Oil_refinery-4.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
Desalter unit washes out salt, and other water-soluble contaminants, from the crude oil before it enters the atmospheric distillation unit. Pre-flash and/or pre-distillation which is found in most atmospheric crude oil units of more than 100,000 bpsd in capacity. Crude oil distillation unit distills the incoming crude oil into various fractions for further processing in other units. See continuous distillation. Vacuum distillation further distills the residue oil from the bottom of the crude oil distillation unit. The vacuum distillation is performed at a pressure well below atmospheric pressure. Naphtha hydrotreater unit uses hydrogen to desulfurize naphtha from atmospheric distillation. Naphtha must be desulfurized before sending it to a catalytic reformer unit. Catalytic reformer converts the desulfurized naphtha molecules into higher-octane molecules to produce reformate (reformer product). The reformate has higher content of aromatics and cyclic hydrocarbons which is a component of the end-product gasoline or petrol. An important byproduct of a reformer is hydrogen released during the catalyst reaction. The hydrogen is used either in the hydrotreaters or the hydrocracker. Distillate hydrotreater desulfurizes distillates (such as diesel) after atmospheric distillation. Uses hydrogen to desulfurize the naphtha fraction from the crude oil distillation or other units within the refinery. Distillate hydrotreaters


id: oil-refinery-20260505-5
file: data/en.wikipedia.org/wiki/Oil_refinery-5.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
== Crude oil distillation unit == The crude oil distillation unit (CDU) is the first processing unit in virtually all petroleum refineries. The CDU distills the incoming crude oil into various fractions of different boiling ranges, each of which is then processed further in the other refinery processing units. The CDU is often referred to as the atmospheric distillation unit because it operates at slightly above atmospheric pressure. Below is a schematic flow diagram of a typical crude oil distillation unit. The incoming crude oil is preheated by exchanging heat with some of the hot, distilled fractions and other streams. It is then desalted to remove inorganic salts (primarily sodium chloride). Following the desalter, the crude oil is further heated by exchanging heat with some of the hot, distilled fractions and other streams. It is then heated in a fuel-fired furnace (fired heater) to a temperature of about 398 °C and routed into the bottom of the distillation unit. The cooling and condensing of the distillation tower overhead is provided partially by exchanging heat with the incoming crude oil and partially by either an air-cooled or water-cooled condenser. Additional heat is removed from the distillation column by a pumparound system


id: oil-refinery-20260505-6
file: data/en.wikipedia.org/wiki/Oil_refinery-6.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
=== Background === Modern petroleum refining involves a complicated system of interrelated chemical reactions that produce a wide variety of petroleum-based products. Many of these reactions require precise temperature and pressure parameters. The equipment and monitoring required to ensure the proper progression of these processes is complex, and has evolved through the advancement of the scientific field of petroleum engineering. The wide array of high pressure and/or high temperature reactions, along with the necessary chemical additives or extracted contaminants, produces an astonishing number of potential health hazards to the oil refinery worker. Through the advancement of technical chemical and petroleum engineering, the vast majority of these processes are automated and enclosed, thus greatly reducing the potential health impact to workers. However, depending on the specific process in which a worker is engaged, as well as the particular method employed by the refinery in which he/she works, significant health hazards remain. Although occupational injuries in the United States were not routinely tracked and reported at the time, reports of the health impacts of working in an oil refinery can be found as early as the 1800s. For instance, an explosion in a Chicago refinery killed 20 workers in 1890. Since then,


id: oil-refinery-20260505-7
file: data/en.wikipedia.org/wiki/Oil_refinery-7.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
=== Hazard controls === The theory of hierarchy of controls can be applied to petroleum refineries and their efforts to ensure worker safety. Elimination and substitution are unlikely in petroleum refineries, as many of the raw materials, waste products, and finished products are hazardous in one form or another (e.g. flammable, carcinogenic). Examples of engineering controls include a fire detection/extinguishing system, pressure/chemical sensors to detect/predict loss of structural integrity, and adequate maintenance of piping to prevent hydrocarbon-induced corrosion (leading to structural failure). Other examples employed in petroleum refineries include the post-construction protection of steel components with vermiculite to improve heat/fire resistance. Compartmentalization can help to prevent a fire or other systems failure from spreading to affect other areas of the structure, and may help prevent dangerous reactions by keeping different chemicals separate from one another until they can be safely combined in the proper environment. Administrative controls include careful planning and oversight of the refinery cleaning, maintenance, and turnaround processes. These occur when many of the engineering controls are shut down or suppressed and may be especially dangerous to workers. Detailed coordination is necessary to ensure that maintenance of one part of the facility will not cause dangerous exposures to


id: oil-refinery-20260505-8
file: data/en.wikipedia.org/wiki/Oil_refinery-8.md
category: reference
title: Oil refinery
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Oil_refinery
date_saved: 2026-05-05T10:49:18.084931+00:00
instance: kb-cron
parent: oil-refinery-20260505-0
summary:
Corrosion of metallic components is a major factor of inefficiency in the refining process. Because it leads to equipment failure, it is a primary driver for the refinery maintenance schedule. Corrosion-related direct costs in the U.S. petroleum industry as of 1996 were estimated at US$3.7 billion. Corrosion occurs in various forms in the refining process, such as pitting corrosion from water droplets, embrittlement from hydrogen, and stress corrosion cracking from sulfide attack. From a materials standpoint, carbon steel is used for upwards of 80 percent of refinery components, which is beneficial due to its low cost. Carbon steel is resistant to the most common forms of corrosion, particularly from hydrocarbon impurities at temperatures below 205 °C, but other corrosive chemicals and environments prevent its use everywhere. Common replacement materials are low alloy steels containing chromium and molybdenum, with stainless steels containing more chromium dealing with more corrosive environments. More expensive materials commonly used are nickel, titanium, and copper alloys. These are primarily saved for the most problematic areas where extremely high temperatures and/or very corrosive chemicals are present. Corrosion is fought by a complex system of monitoring, preventative repairs, and careful use of materials. Monitoring methods include both offline checks


id: olin-raschig-process-20260505-0
file: data/en.wikipedia.org/wiki/Olin_Raschig_process-0.md
category: reference
title: Olin Raschig process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Olin_Raschig_process
date_saved: 2026-05-05T10:49:19.318530+00:00
instance: kb-cron
parent: olin-raschig-process-20260505-0
summary:
The Olin Raschig process is a chemical process for the production of hydrazine. The main steps in this process, patented by German chemist Friedrich Raschig in 1906 and one of three reactions named after him, are the formation of monochloramine from ammonia and hypochlorite, and the subsequent reaction of monochloramine with ammonia towards hydrazine. The process was further optimised and used by the Olin Corporation for the production of anhydrous hydrazine for aerospace applications. == Process == The commercially used Olin Raschig process consists of the following steps: First, sodium hypochlorite solution is mixed with a threefold excess of ammonia at 5 °C to give monochloramine. The primary reaction proceeds according to the idealised equation NaOCl + NH3 → NH2Cl + NaOH The monochloramine solution is then added to a 30-fold excess of ammonia at 130 °C and elevated pressure, causing a second reaction NH2Cl + NH3 → N2H4 + HCl The hydrochloric acid and sodium hydroxide byproducts undergo a secondary reaction to release the byproducts of water and sodium chloride. The overall reaction is thus NaOCl + 2NH3 → N2H4 + NaCl + H2O Excess ammonia and sodium chloride are removed by distillation, followed by azeotropic distillation with aniline


id: omega-process-20260505-0
file: data/en.wikipedia.org/wiki/OMEGA_process-0.md
category: reference
title: OMEGA process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/OMEGA_process
date_saved: 2026-05-05T10:49:20.520442+00:00
instance: kb-cron
parent: omega-process-20260505-0
summary:
The OMEGA process ("Only MEG Advantage") is a chemical process discovered by the Shell Global Solutions company that is used to produce ethylene glycol from ethylene. This process comprises two steps, the controlled oxidation of ethylene to ethylene oxide, and the net hydrolysis of ethylene oxide to monoethylene glycol (MEG). The first chemical plant using the OMEGA process was started in South Korea. Subsequent OMEGA plants have been started in Saudi Arabia and Singapore. Shell claims that this process, compared to conventional ones, does not produce higher glycols, uses less steam and water, and generates less waste. == Ethylene oxidation == To produce ethylene oxide, ethylene is oxidized with dioxygen in the presence of a silver catalyst. Some ethylene is over-oxidized to carbon dioxide and water, which is wasteful; early processes only gave ~ 65% selectivity for ethylene oxide as a result. In the OMEGA process, over-oxidation is reduced by including ethyl chloride as a moderator. == Ethylene oxide hydrolysis == Conventionally, monoethylene glycol (HOC2H4OH) is produced by the controlled hydrolysis of ethylene oxide (C2H4O). The monoethylene glycol product is also able to react with ethylene oxide to give diethylene glycol, and so on; sequential reaction with ethylene oxide is


id: organosolv-20260505-0
file: data/en.wikipedia.org/wiki/Organosolv-0.md
category: reference
title: Organosolv
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Organosolv
date_saved: 2026-05-05T10:49:21.669767+00:00
instance: kb-cron
parent: organosolv-20260505-0
summary:
In industrial paper-making processes, organosolv is a pulping technique that uses an organic solvent to solubilise lignin and hemicellulose. It has been considered in the context of both pulp and paper manufacture and biorefining for subsequent conversion of cellulose to fuel ethanol. The process was invented by Theodor Kleinert in 1968 as an environmentally benign alternative to kraft pulping. Organosolv has several advantages when compared to other popular methods such as kraft or sulfite pulping. In particular, the ability to obtain relatively high quality lignin adds value to a process stream otherwise considered as waste. Organosolv solvents are easily recovered by distillation, leading to less water pollution and elimination of the odour usually associated with kraft pulping. == Solvents == Organosolv pulping involves contacting a lignocellulosic feedstock such as chipped wood with an aqueous organic solvent at temperatures ranging from 140 to 220 °C. This causes lignin to break down by hydrolytic cleavage of alpha aryl-ether links into fragments that are soluble in the solvent system. Solvents used include acetone, methanol, ethanol, butanol, ethylene glycol, formic acid, and acetic acid. The concentration of solvent in water ranges from 40 to 80%. Higher boiling solvents have the advantage of a lower


id: organosolv-20260505-1
file: data/en.wikipedia.org/wiki/Organosolv-1.md
category: reference
title: Organosolv
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Organosolv
date_saved: 2026-05-05T10:49:21.669767+00:00
instance: kb-cron
parent: organosolv-20260505-0
summary:
=== Chempolis process === Chempolis Ltd in Oulu, Finland has developed, since 1995, a process concept where any lignocellulosic fibrous biomass sources are delignified with formic acid (biosolvent) in a compact process. The so-called "formico" technology incorporates full biosolvent recovery by evaporation and distillation in order to have a closed-loop process with minimal water need and effluent discharge. The delignification selectively fractionates lignocellulose components into cellulosic fibre, hemicellulose and lignin. Part of the hemicelluloses react to furfural and acetic acid, which are recovered in the distillation process to high-grade commercial products. The clean cellulosic fibre is used in various high-end packaging and textile purposes (bleached easily with hydrogen peroxide), or hydrolysed into high-purity glucose readily converted into biochemicals, or the glucose is easily fermented to bioethanol. The dissolved hemicelluloses and lignin after delignification are concentrated in evaporation and separated to produce hemicellulose fraction suitable for fermentation into ethanol or conversion to biochemicals. The separated lignin is sulfur-free and used in high-end applications replacing fossil aromatics. === American Science and Technology (AST) process === American Science and Technology (AST) based out of Chicago, Illinois, USA, has developed a process which uses a patented second generation Organosolv process to convert any kind


id: osmotic-dehydration-20260505-0
file: data/en.wikipedia.org/wiki/Osmotic_dehydration-0.md
category: reference
title: Osmotic dehydration
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Osmotic_dehydration
date_saved: 2026-05-05T10:49:22.820567+00:00
instance: kb-cron
parent: osmotic-dehydration-20260505-0
summary:
Osmotic dehydration is an operation used for the partial removal of water from plant tissues by immersion in a hypertonic (osmotic) solution. Sugar or salt solutions are used to reduce the moisture content of foods before actual drying process. This technique is used to give the product quality improvement over conventional drying process. Mild heat treatment after osmotic dehydration favours colour and flavour retention resulting in the product having superior organoleptic characteristics. It also increases resistance to heat treatment, prevents enzymatic browning and inhibits activities of polyphenol oxidase. The process is economical. Osmotic dehydration depends on: Temperature of osmotic solution. Concentration of the osmotic solution. Osmotic agent used. Process duration. Geometry of food material. David Baszucki == Process == Water removal is based on the natural and non-destructive phenomenon of osmosis across cell membranes. The driving force for the diffusion of water from the tissue into the solution is provided by the higher osmotic pressure of the hyper-tonic solution. The diffusion of water is accompanied by the simultaneous counter diffusion of solutes from the osmotic solution into the tissue. Since the cell membrane responsible for osmotic transport is not perfectly selective, solutes present in the cells (organic acids, reducing sugars,


id: ostwald-process-20260505-0
file: data/en.wikipedia.org/wiki/Ostwald_process-0.md
category: reference
title: Ostwald process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ostwald_process
date_saved: 2026-05-05T10:49:38.930345+00:00
instance: kb-cron
parent: ostwald-process-20260505-0
summary:
The Ostwald process is a chemical process used for making nitric acid (HNO3). The Ostwald process is a mainstay of the modern chemical industry, and it provides the main raw material for the most common type of fertilizer production. Historically and practically, the Ostwald process is closely associated with the Haber process, which provides the requisite raw material, ammonia (NH3). This method is preferred over other methods of nitric acid production because it is less expensive and more efficient. == Reactions == Ammonia is converted to nitric acid in 2 stages. === Initial oxidation of ammonia === The Ostwald process begins with burning ammonia. Ammonia burns in oxygen at temperature about 900 °C (1,650 °F) and pressure up to 8 standard atmospheres (810 kPa) in the presence of a catalyst such as platinum gauze, alloyed with 10% rhodium to increase its strength and nitric oxide yield, platinum metal on fused silica wool, copper, or nickel to form nitric oxide (nitrogen(II) oxide) and water (as steam). This reaction is strongly exothermic, making it a useful heat source once initiated: 4NH3 + 5O2 → 4NO + 6H2O (ΔH = −905.2 kJ/mol) ==== Side reactions ==== A number of side reactions compete with


id: oxfa-process-20260505-0
file: data/en.wikipedia.org/wiki/OxFA_process-0.md
category: reference
title: OxFA process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/OxFA_process
date_saved: 2026-05-05T10:49:40.132912+00:00
instance: kb-cron
parent: oxfa-process-20260505-0
summary:
The OxFA process is a process to produce formic acid from biomass by catalytic oxidation using molecular oxygen or air. Polyoxometalates of the Keggin-type are used as catalysts. == OxFA-Process == === General description === Formic acid is obtained by aqueous catalytic partial oxidation of wet biomass. A Keggin-type polyoxometalate (H5PV2Mo10O40) is used as the homogeneous catalyst to convert sugars, wood, waste paper or cyanobacteria to formic acid and CO2 as the sole byproduct. Yields of up to 53% formic acid can be achieved. It is possible to convert water-insoluble biomass in a suspension with the catalyst. After the reaction, formic acid is separated from the reaction mixture. Depending on the separation process, the formic acid can be further purified or used as it is. The remaining solution of the catalyst, residual formic acid and additives are recycled to the reaction. In this step, solids (e.g. soil from dirty biomass) or unreactive inorganics (e.g. inorganic salts from the natural salt content of the biomass) may be separated from the catalyst solution. The general reaction for a simple sugar like glucose can be summarized as follows: C6H12O6 + wO2 → xHCOOH + yCO2 + zH2O === Biomass pretreatment === Water-insoluble biomass


id: paper-chemicals-20260505-0
file: data/en.wikipedia.org/wiki/Paper_chemicals-0.md
category: reference
title: Paper chemicals
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paper_chemicals
date_saved: 2026-05-05T10:49:41.282318+00:00
instance: kb-cron
parent: paper-chemicals-20260505-0
summary:
Paper chemicals designate a group of chemicals that are used for paper manufacturing, or modify the properties of paper. These chemicals can be used to alter the paper in many ways, including changing its color and brightness, or by increasing its strength and resistance to water. The chemicals can be defined on basis of their usage in the process. Chemical usage is not only for imparting properties to paper but to handle the water cycles in the process, conditioning of fabrics, cleaning of equipment and several other applications. == Chemicals used in paper manufacturing == == Pulping == Chemical pulping involves dissolving lignin in order to extract the cellulose from the wood fiber. The different processes of chemical pulping include the Kraft process, which uses caustic soda and sodium sulfide and is the most common; alternatively, the use of sulfurous acid is known as the sulfite process, the neutral sulfite semichemical is treated as a third process separate from sulfite, and soda pulping which is the least ecologically hazardous utilizing sodium hydroxide or anthraquinone. Caustic soda is added to increase the pH in the pulping process of fibers. The higher pH of the paper-fiber solution causes the fibers to smoothen


id: paraffin-oxidation-20260505-0
file: data/en.wikipedia.org/wiki/Paraffin_oxidation-0.md
category: reference
title: Paraffin oxidation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paraffin_oxidation
date_saved: 2026-05-05T10:49:42.439928+00:00
instance: kb-cron
parent: paraffin-oxidation-20260505-0
summary:
Paraffin oxidation is a historical industrial process for the production of synthetic fatty acids. The fatty acids are further processed to consumer products such as soaps and fats as well as to lubricating greases for technical applications. Coal slack wax, a saturated, high molecular weight hydrocarbon mixture and by-product of the Fischer–Tropsch process was used as raw material. Side products were a wide range of carboxylic acids and oxidation products such as alcohols, aldehydes, esters, or ketones. The oxidation of paraffins was carried out in the liquid phase by molecular oxygen, e.g. by aerating with oxygen or atmospheric air, in the presence of catalysts such as permanganates, e.g. 0.1% - 0.3% potassium permanganate, at temperatures in the range of about 100 to 120 °C and under atmospheric pressure. == History == The process was commercially important from the mid-1930s on and was carried out until the first years after the Second World War on a large industrial scale. Paraffin oxidation enabled for first time the large-scale production of synthetic butter from coal by chemical means which was at that time seen as a sensation. Because of the high availability of inexpensive natural fats and the competition by petroleum-based fatty alcohols,


id: pechini-process-20260505-0
file: data/en.wikipedia.org/wiki/Pechini_process-0.md
category: reference
title: Pechini process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pechini_process
date_saved: 2026-05-05T10:49:43.636561+00:00
instance: kb-cron
parent: pechini-process-20260505-0
summary:
The Pechini process or liquid mix process as proposed in 1967 is a technique of depositing dielectric films of titanates and niobates of lead and alkaline-earth elements in the production of capacitors. Later, the process was customised for the in-lab synthesis of multicomponent finely dispersed oxide materials. It is named after its American inventor, Maggio Pechini. == Description == It is related to the sol-gel route. An aqueous solution of suitable oxides or salts is mixed with an alpha hydroxycarboxylic acid such as citric acid. Chelation takes place in the solution. A polyhydroxy alcohol is then added, and the liquid is heated to 150–250 °C (300–480 °F) to allow the chelates to polymerize, or form large, cross-linked networks. As excess water is removed by heating, a solid polymeric resin results. Eventually, at still higher temperatures of 500–900 °C (930–1,650 °F), the resin is decomposed or charred, and ultimately a mixed oxide is obtained. Particle size is extremely small, typically 20 to 50 nanometres (although there is agglomeration of these particles into larger clusters), with intimate mixing taking place on the atomic scale. == Uses == This method has been used for synthesizing over 100 mixed metal oxides including lanthanum manganite


id: pedersen-process-20260505-0
file: data/en.wikipedia.org/wiki/Pedersen_process-0.md
category: reference
title: Pedersen process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pedersen_process
date_saved: 2026-05-05T10:49:44.805341+00:00
instance: kb-cron
parent: pedersen-process-20260505-0
summary:
The Pederson process is a process of refining aluminum that first separates iron by reducing it to metal, and reacting alumina with lime to produce calcium aluminate, which is then leached with sodium hydroxide. It is more environmentally friendly than the more well-known Bayer process. This is because instead of producing alumina slag, also known as red mud, it produces pig iron as a byproduct. Red mud is considered both an economic and environmental challenge in the aluminum industry because it is considered a waste, with little benefit. It destroys the environment with its high pH, and is costly to maintain, even when in a landfill. Iron, however, is used in the manufacture of steel, and has structural uses in civil engineering and chemical uses as a catalyst. == History == The Pedersen process was invented by Harald Pedersen in the 1920s and used in Norway for over 40 years before shutting down due to the Pedersen process being less economically competitive than the Bayer process. However, it is believed a modern Pedersen process could be economically viable with "low-quality" bauxite, as even though "low-quality" bauxite has less alumina in the form of trihydrate gibbsite, it has more iron oxide


id: penex-20260505-0
file: data/en.wikipedia.org/wiki/Penex-0.md
category: reference
title: Penex
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Penex
date_saved: 2026-05-05T10:49:45.977817+00:00
instance: kb-cron
parent: penex-20260505-0
summary:
The Penex process is a continuous catalytic process used in the refining of crude oil. It isomerizes light naphtha (C5/C6) into higher-octane, branched C5/C6 molecules. It also reduces the concentration of benzene in the gasoline pool. It was first used commercially in 1958. Ideally, the isomerization catalyst converts normal pentane (nC5) to isopentane (iC5) and normal hexane (nC6) to 2,2- and 2,3-dimethylbutane. The thermodynamic equilibrium is more favorable at low temperature. == Background == In the petroleum industry, much research has been done on the upgrading of light hydrocarbons. The realisation that normal pentane is one of the most important remaining components of naphtha that can be easily upgraded prompted Phillips Petroleum to investigate the various processes for converting normal (linear) pentane into (branched) isopentane. The decisive factor in the isomerisation of normal pentane is an increase in the total octane number. This improvement in quality makes the result more valuable for blending with today's high-octane fuels. In addition, like other isoparaffins, isopentane has a low sensitivity (research octane minus engine octane) which means improved performance at street octane. Increasing the octane number also allows larger quantities of pentanes to be blended into premium petrol. In a refinery, light naphtha


id: peroxide-process-20260505-0
file: data/en.wikipedia.org/wiki/Peroxide_process-0.md
category: reference
title: Peroxide process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Peroxide_process
date_saved: 2026-05-05T10:49:47.106497+00:00
instance: kb-cron
parent: peroxide-process-20260505-0
summary:
The peroxide process is a method for the industrial production of hydrazine. In this process hydrogen peroxide is used as an oxidant instead of sodium hypochlorite, which is traditionally used to generate hydrazine. The main advantage of the peroxide process to hydrazine relative to the traditional Olin Raschig process is that it does not coproduce salt. In this respect, the peroxide process is an example of green chemistry. Since many millions of kilograms of hydrazine are produced annually, this method is of both commercial and environmental significance. == Production == === Ketazine formation === In the usual implementation, hydrogen peroxide is used together with acetamide. This mixture does not react with ammonia directly but does so in the presence of methyl ethyl ketone to give the oxaziridine. Balanced equations for the individual steps are as follows. Imine formation through condensation: Me(Et)C=O + NH3 → Me(Et)C=NH + H2O Oxidation of the imine to the oxaziridine: Me(Et)C=NH + H2O2 → Me(Et)CONH + H2O Condensation of the oxaziridine with a second molecule of ammonia to give the hydrazone: Me(Et)CONH + NH3 → Me(Et)C=NNH2 + H2O The hydrazone then condenses with a second equivalent of ketone to give the ketazine: Me(Et)C=O + Me(Et)C=NNH2 →


id: petersen-matrix-20260505-0
file: data/en.wikipedia.org/wiki/Petersen_matrix-0.md
category: reference
title: Petersen matrix
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Petersen_matrix
date_saved: 2026-05-05T10:49:48.296158+00:00
instance: kb-cron
parent: petersen-matrix-20260505-0
summary:
The Petersen matrix is a comprehensive description of systems of biochemical reactions used to model reactors for pollution control (engineered decomposition) as well as in environmental systems. It has as many columns as the number of relevant involved components (chemicals, pollutants, biomasses, gases) and as many rows as the number of involved processes (biochemical reactions and physical degradation). One further column is added to host the description of the kinetics of each transformation (rate equation). == Matrix structure == The mass conservation principle for each process is expressed in the rows of the matrix. If all components are included (none omitted) then the mass conservation principle states that, for each process: for all process i : ∑ j = 1 n a i j ρ j ˙ = 0 , {\displaystyle {\text{for all process }}i:\sum _{j=1}^{n}a_{ij}{\dot {\rho _{j}}}=0\;,} where ρ j ˙ {\displaystyle {\dot {\rho _{j}}}} is the density rate of each component. This can also be seen as the process stoichiometric relation. Moreover, the rate of variation of each component for all processes simultaneous effect can be easily assessed by summing the columns: for all component j : ∂ C j ∂ t = ∑ i = 1 m


id: phosphorolysis-20260505-0
file: data/en.wikipedia.org/wiki/Phosphorolysis-0.md
category: reference
title: Phosphorolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Phosphorolysis
date_saved: 2026-05-05T10:49:49.491683+00:00
instance: kb-cron
parent: phosphorolysis-20260505-0
summary:
Phosphorolysis is the cleavage of a compound in which inorganic phosphate is the attacking group. It is analogous to hydrolysis. An example of this is glycogen breakdown by glycogen phosphorylase, which catalyzes attack by inorganic phosphate on the terminal glycosyl residue at the nonreducing end of a glycogen molecule. If the glycogen chain has n glucose units, the products of a single phosphorolytic event are one molecule of glucose 1-phosphate and a glycogen chain of n-1 remaining glucose units. In addition, sometimes phosphorolysis is preferable to hydrolysis (like in the breakdown of glycogen or starch, as in the example above) because glucose 1-phosphate yields more ATP than does free glucose when subsequently catabolized to pyruvate. Another example of phosphorolysis is seen in the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate in glycolysis. The mechanism involves phosphorolysis. == See also == Phosphorylase == References == == External links == Media related to Phosphorolysis at Wikimedia Commons


id: photochlorination-20260505-0
file: data/en.wikipedia.org/wiki/Photochlorination-0.md
category: reference
title: Photochlorination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photochlorination
date_saved: 2026-05-05T10:49:50.686369+00:00
instance: kb-cron
parent: photochlorination-20260505-0
summary:
Photochlorination is a chlorination reaction that is initiated by light. Usually a C-H bond is converted to a C-Cl bond. Photochlorination is carried out on an industrial scale. The process is exothermic and proceeds as a chain reaction initiated by the homolytic cleavage of molecular chlorine into chlorine radicals by ultraviolet radiation. Many chlorinated solvents are produced in this way. == History == Chlorination is one of the oldest known substitution reactions in chemistry. The French chemist Jean-Baptiste Dumas investigated the substitution of hydrogen for chlorine by acetic acid in candle wax as early as 1830. He showed that for each mole of chlorine introduced into a hydrocarbon, one mole of hydrogen chloride is also formed and noted the light-sensitivity of this reaction. The idea that these reactions might be chain reactions is attributed to Max Bodenstein (1913). He assumed that in the reaction of two molecules not only the end product of the reaction can be formed, but also unstable, reactive intermediates which can continue the chain reaction. Photochlorination garnered commercial attention with the availability of cheap chlorine from chloralkali electrolysis. Chlorinated alkanes found an initial application in pharyngeal sprays. These contained chlorinated alkanes in relatively large quantities as


id: photochlorination-20260505-1
file: data/en.wikipedia.org/wiki/Photochlorination-1.md
category: reference
title: Photochlorination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photochlorination
date_saved: 2026-05-05T10:49:50.686369+00:00
instance: kb-cron
parent: photochlorination-20260505-0
summary:
=== Chloromethanes === An example of photochlorination at low temperatures and under ambient pressure is the chlorination of chloromethane to dichloromethane. The liquefied chloromethane (boiling point -24 °C) is mixed with chlorine in the dark and then irradiated with a mercury-vapor lamp. The resulting dichloromethane has a boiling point of 41 °C and is later separated by distillation from methyl chloride. The photochlorination of methane has a lower quantum yield than the chlorination of dichloromethane. Due to the high light intensity required, the intermediate products are directly chlorinated, so that mainly tetrachloromethane is formed. === Chlorinated paraffins === A major application of photochlorination is the production of chloroparaffins. Mixtures of complex composition consisting of several chlorinated paraffins are formed. Chlorinated paraffins have the general sum formula CxH(2x−y+2)Cly and are categorized into three groups: Low molecular weight chlorinated paraffins are short chain chloroparaffins (SCCP) with 10 to 13 carbon atoms, followed by medium chain chloroparaffins (MCCP) with carbon chain lengths of 14 to 17 carbon atoms and long chain chlorinated paraffins (LCCP), owing a carbon chainwith more than 17 carbon atoms. Approximately 70% of the chloroparaffins produced are MCCPs with a degree of chlorination from 45 to 52%. The remaining 30%


id: photochlorination-20260505-2
file: data/en.wikipedia.org/wiki/Photochlorination-2.md
category: reference
title: Photochlorination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photochlorination
date_saved: 2026-05-05T10:49:50.686369+00:00
instance: kb-cron
parent: photochlorination-20260505-0
summary:
== Further reading == H. Hartig: Einfache Dimensionierung, photochemischer Reaktoren. In: Chemie Ingenieur Technik – CIT. 42, 1970, p. 1241–1245, doi:10.1002/cite.330422002. Dieter Wöhrle, Michael W. Tausch, Wolf-Dieter Stohrer: Photochemie: Konzepte, Methoden, Experimente. Wiley & Sons, 1998, ISBN 978-3-527-29545-6, p. 271–275. US Grant 1379367, F. Sparre & W. E. Masland, "Process of Chlorination", issued 1921-05-24, assigned to Du Pont US Grant 1459777, R. Leiser & F. Ziffer, "Process and Apparatus for the Chlorination of Methane", issued 1920-02-14, assigned to Ziffer Fritz and Leiser Richard David A. Mixon, Michael P. Bohrer, Patricia A. O’Hara: Ultrapurification of SiCl4 by photochlorination in a bubble column reactor. In: AIChE Journal. 36, 1990, p. 216–226, doi:10.1002/aic.690360207. Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, p. 71, ISBN 0-12-352651-5 Hans Von Halban: Die Lichtabsorption des Chlors. In: Zeitschrift für Elektrochemie und angewandte physikalische Chemie. 28, 1922, p. 496–499, doi:10.1002/bbpc.19220282304. Arthur John Allmand: Part I.—Einstein’s law of photochemical equivalence. Introductory address to Part I. In: Trans. Faraday Soc. 21, 1926, p. 438, doi:10.1039/TF9262100438. Marion L. Sharrah, Geo. C. Feighner: Synthesis of Dodecylbenzen – Synthetic Detergent Intermediate. In: Industrial & Engineering Chemistry. 46, 1954, p.


id: photoelectrochemical-reduction-of-carbon-dioxide-20260505-0
file: data/en.wikipedia.org/wiki/Photoelectrochemical_reduction_of_carbon_dioxide-0.md
category: reference
title: Photoelectrochemical reduction of carbon dioxide
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Photoelectrochemical_reduction_of_carbon_dioxide
date_saved: 2026-05-05T10:49:51.841362+00:00
instance: kb-cron
parent: photoelectrochemical-reduction-of-carbon-dioxide-20260505-0
summary:
Photoelectrochemical reduction of carbon dioxide, also known as photoelectrolysis of carbon dioxide, is a chemical process whereby carbon dioxide is reduced to carbon monoxide or hydrocarbons by the energy of incident light. This process requires catalysts, most of which are semiconducting materials. The feasibility of this chemical reaction was first theorised by Giacomo Luigi Ciamician, an Italian photochemist. Already in 1912 he stated that "[b]y using suitable catalyzers, it should be possible to transform the mixture of water and carbon dioxide into oxygen and methane, or to cause other endo-energetic processes." Furthermore, the reduced species may prove to be a valuable feedstock for other processes. If the incident light utilized is solar then this process also potentially represents energy routes which combine renewable energy with CO2 reduction. == Thermodynamics == Thermodynamic potentials for the reduction of CO2 to various products is given in the following table versus NHE at pH = 7. Single electron reduction of CO2 to CO2●− radical occurs at E° = −1.90 V versus NHE at pH = 7 in an aqueous solution at 25 °C under 1 atm gas pressure. The reason behind the high negative thermodynamically unfavorable single electron reduction potential of CO2 is the


id: pidgeon-process-20260505-0
file: data/en.wikipedia.org/wiki/Pidgeon_process-0.md
category: reference
title: Pidgeon process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Pidgeon_process
date_saved: 2026-05-05T10:49:53.068885+00:00
instance: kb-cron
parent: pidgeon-process-20260505-0
summary:
The Pidgeon process is a practical method for smelting magnesium. The most common method involves the raw material, dolomite, being fed into an externally heated reduction tank and then thermally reduced to metallic magnesium using 75% ferrosilicon as a reducing agent in a vacuum. Overall the processes in magnesium smelting via the Pidgeon process involve dolomite calcination, grinding and pelleting, and vacuum thermal reduction. Besides the Pidgeon process, electrolysis of magnesium chloride for commercial production of magnesium is also used, especially for magnesite ores, which at one point in time accounted for 75% of the world's magnesium production. By 2000, it took between 17 and 20 kilowatt-hours per kilogram of magnesium produced by the Pidgeon process. The Pidgeon processes in Canada in the year 2000 all used sulfur hexafluoride (SF6) to cover the reaction so as not to introduce stray oxygen to it. Research to replace SF6 with boron trifluoride was underway in 2000. By 2011, magnesium production had departed under the Kyoto Protocol from Canada. Wu, Han and Liu claimed that "China is the world's largest producer of primary magnesium and has a magnesium smelting industry that is mainly based on the Pidgeon process" in an era in which


id: plasma-electrolytic-oxidation-20260505-0
file: data/en.wikipedia.org/wiki/Plasma_electrolytic_oxidation-0.md
category: reference
title: Plasma electrolytic oxidation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_electrolytic_oxidation
date_saved: 2026-05-05T10:49:54.290784+00:00
instance: kb-cron
parent: plasma-electrolytic-oxidation-20260505-0
summary:
Plasma electrolytic oxidation (PEO), also known as electrolytic plasma oxidation (EPO) or microarc oxidation (MAO), is an electrochemical surface treatment process for generating oxide coatings on metals. It is similar to anodizing, but it employs higher potentials, so that discharges occur and the resulting plasma modifies the structure of the oxide layer. This process can be used to grow thick (tens or hundreds of micrometers), largely crystalline, oxide coatings on metals such as aluminium, magnesium and titanium. Because they can present high hardness and a continuous barrier, these coatings can offer protection against wear, corrosion or heat as well as electrical insulation. The coating is a chemical conversion of the substrate metal into its oxide, and grows both inwards and outwards from the original metal surface. Because it grows inward into the substrate, it has excellent adhesion to the substrate metal. A wide range of substrate alloys can be coated, including all wrought aluminum alloys and most cast alloys, although high levels of silicon can reduce coating quality. The coating morphology and composition resulting from plasma electrolytic oxidation is largely dependent on the PEO parameters, including voltage, current density, and the electrolytic solution employed. == Process == Metals such as


id: plasma-polymerization-20260505-0
file: data/en.wikipedia.org/wiki/Plasma_polymerization-0.md
category: reference
title: Plasma polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_polymerization
date_saved: 2026-05-05T10:49:55.489163+00:00
instance: kb-cron
parent: plasma-polymerization-20260505-0
summary:
Plasma polymerization (or glow discharge polymerization) uses plasma sources to generate a gas discharge that provides energy to activate or fragment gaseous or liquid monomer, often containing a vinyl group, in order to initiate polymerization. Polymers formed from this technique are generally highly branched and highly cross-linked, and adhere to solid surfaces well. The biggest advantage to this process is that polymers can be directly attached to a desired surface while the chains are growing, which reduces steps necessary for other coating processes such as grafting. This is very useful for pinhole-free coatings of 100 picometers to 1-micrometer thickness with solvent insoluble polymers. == Introduction == In as early as the 1870s "polymers" formed by this process were known, but these polymers were initially thought of as undesirable byproducts associated with electric discharge, with little attention being given to their properties. It was not until the 1960s that the properties of these polymers were found to be useful. It was found that flawless thin polymeric coatings could be formed on metals, although for very thin films (<10 nm) this has recently been shown to be an oversimplification. By selecting the monomer type and the energy density per monomer, known as


id: plasma-polymerization-20260505-1
file: data/en.wikipedia.org/wiki/Plasma_polymerization-1.md
category: reference
title: Plasma polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_polymerization
date_saved: 2026-05-05T10:49:55.489163+00:00
instance: kb-cron
parent: plasma-polymerization-20260505-0
summary:
=== Kinetics === The kinetic rate of these reactions depends mostly on the monomer gas, which must be either gaseous or vaporized. However, other parameters are also important as well, such as power, pressure, flow rate, frequency, electrode gap, and reactor configuration. Low flow rates usually only depend on the number of reactive species present for polymerization, whereas high flow rates depend on the amount of time that is spent in the reactor. Therefore, the maximum rate of polymerization is somewhere in the middle. The fastest reactions tend to be in the order of triple-bonded > double-bonded > single bonded molecules, and also lower molecular weight molecules are faster than higher ones. So acetylene is faster than ethylene, and ethylene is faster than propene, etc. The molecular weight factor in polymer deposition is dependent on the monomer flow rate, in which a higher molecular weight monomer typically near 200 g/mol needs a much higher flow rate of 15×104 g/cm2, whereas lower molecular weights around 50 g/mol require a flow rate of only 5×104 g/cm2. A heavy monomer, therefore, needs a faster flow, and would likely lead to increased pressures, decreasing polymerization rates. Increased pressure tends to decrease polymerization rates reducing


id: plasma-polymerization-20260505-2
file: data/en.wikipedia.org/wiki/Plasma_polymerization-2.md
category: reference
title: Plasma polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_polymerization
date_saved: 2026-05-05T10:49:55.489163+00:00
instance: kb-cron
parent: plasma-polymerization-20260505-0
summary:
Polymerization is likely to take place through either ionic and/or radical processes which are initiated by plasma formed from the glow discharge. The classic view presented by Yasuda based upon thermal initiation of Parylene polymerization is that there are many propagating species present at any given time as shown in Figure 3. This figure shows two different pathways by which the polymerization may take place. The first pathway is a monofunctionalization process, which bears resemblance to a standard free radical polymerization mechanism (M•)- although with the caveat that the reactive species may be ionic and not necessarily radical. The second pathway refers to a difunctional mechanism, which for example may contain a cationic and a radical propagating center on the same monomer (•M•). A consequence is that 'polymer' can grow in multiple directions by multiple pathways off one species, such as a surface or other monomer. This possibility let Yasuda to term the mechanism as a very rapid step-growth polymerization. In the diagram, Mx refers to the original monomer molecule or any of many dissociation products such as chlorine, fluorine and hydrogen. The M• species refers to those that are activated and capable of participating in reactions to form new


id: plasma-polymerization-20260505-3
file: data/en.wikipedia.org/wiki/Plasma_polymerization-3.md
category: reference
title: Plasma polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_polymerization
date_saved: 2026-05-05T10:49:55.489163+00:00
instance: kb-cron
parent: plasma-polymerization-20260505-0
summary:
The most significant difference between conventional polymers and plasma polymers is that plasma polymers do not contain regular repeating units. Due to the number of different propagating species present at any one time as discussed above, the resultant polymer chains are highly branched and are randomly terminated with a high degree of cross-linking. An example of a proposed structure for plasma polymerized ethylene demonstrating a large extend of cross-linking and branching is shown in Figure 4. All plasma polymers contain free radicals as well. The amount of free radicals present varies between polymers and is dependent on the chemical structure of the monomer. Because the formation of the trapped free radicals is tied to the growth mechanism of the plasma polymers, the overall properties of the polymers directly correlate to the number of free radicals. Plasma polymers also contain internal stress. If a thick layer (e.g. 1 µm) of a plasma polymer is deposited on a glass slide, the plasma polymer will buckle and frequently crack. The curling is attributed to an internal stress formed in the plasma polymer during the polymer deposition. The degree of curling is dependent on the monomer as well as the conditions of the plasma


id: plasma-polymerization-20260505-4
file: data/en.wikipedia.org/wiki/Plasma_polymerization-4.md
category: reference
title: Plasma polymerization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Plasma_polymerization
date_saved: 2026-05-05T10:49:55.489163+00:00
instance: kb-cron
parent: plasma-polymerization-20260505-0
summary:
== Applications == The advantages offered by plasma polymerization have resulted in substantial research on the applications of these polymers. The vastly different chemical and mechanical properties offered by polymers formed with plasma polymerization means they can be applied to countless different systems. Applications ranging from adhesion, composite materials, protective coatings, printing, membranes, biomedical applications, water purification, and so on have all been studied. Of particular interest since the 1980s has been the deposition of functionalized plasma polymer films. For example, functionalized films are used as a means of improving biocompatibility for biological implants6 and for producing super-hydrophobic coatings. They have also been extensively employed in biomaterials for cell attachment, protein binding, and anti-fouling surfaces. Through the use of low-power and pressure plasma, high functional retention can be achieved which has led to substantial improvements in the biocompatibility of some products, a simple example being the development of extended-wear contact lenses. Due to these successes, the huge potential of functional plasma polymers is slowly being realized by workers in previously unrelated fields such as water treatment and wound management. Emerging technologies such as nanopatterning, 3D scaffolds, micro-channel coating, and microencapsulation are now also utilizing functionalized plasma polymers, areas for which


id: post-combustion-capture-20260505-0
file: data/en.wikipedia.org/wiki/Post-combustion_capture-0.md
category: reference
title: Post-combustion capture
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Post-combustion_capture
date_saved: 2026-05-05T10:49:56.679002+00:00
instance: kb-cron
parent: post-combustion-capture-20260505-0
summary:
Post-combustion capture refers to the removal of carbon dioxide (CO2) from a power station flue gas prior to its compression, transportation and storage in suitable geological formations, as part of carbon capture and storage. A number of different techniques are applicable, almost all of which are adaptations of acid gas removal processes used in the chemical and petrochemical industries. Many of these techniques existed before World War II and, consequently, post-combustion capture is the most developed of the various carbon-capture methodologies. Post-combustion capture plant should aim to maximise the capture of CO2 emissions from combustion plant and delivery it to secure sequestration in geological strata. Typically, a plant will aim to achieve a CO2 capture rate of >95%. To meet the required specification, the following should be monitored: CO2 mass balance CO2 in fuel combusted Total CO2 capture level (as a percentage) CO2 released to the environment CO2 quality CO2 can be transported either as gas phase at about 35 barg or as dense phase at 100 barg. The CO2 stream should meet or exceed gas quality standards. CO2 absorbents include primary amines which require more heat for regeneration than secondary amines However, secondary amines may form nitrosamines with Nitrogen


id: powder-coating-on-glass-20260505-0
file: data/en.wikipedia.org/wiki/Powder_coating_on_glass-0.md
category: reference
title: Powder coating on glass
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Powder_coating_on_glass
date_saved: 2026-05-05T10:49:57.832376+00:00
instance: kb-cron
parent: powder-coating-on-glass-20260505-0
summary:
Powder coating on glass is a specialized procedure related to traditional powder coating, which is the technique of applying electrostatically charged, dry powdered particles of pigment and resin to a solid item's surface. It requires its own unique process, however, because glass is a poor electrical conductor in comparison to metal, the traditional powder coating substrate. == Markets for glass applications == Powder coating on glass is used in industries such as cosmetics, fragrances, wine and spirits, where the contents inside of the glass containers require protection from ultraviolet (UV) rays, particularly UVA electromagnetic radiation, which is capable of penetrating glass. When applied with a dual-coat method, powder coating techniques on glass provide an opaque shield against the light's effects. == Cleaning preparation == Powder coating on glass requires specialized equipment. The biggest challenge is getting the powder to adhere to the glass surface since there is no natural electrostatic attraction like there is with different metals. A clean glass subsurface that will not interfere with the process is essential before beginning the powder coating procedure. Washing to remove oil, dirt and grease can be accomplished with solvents, wipes or a traditional wash system. Proper temperature control is critical from


id: process-20260505-0
file: data/en.wikipedia.org/wiki/Process-0.md
category: reference
title: Process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Process
date_saved: 2026-05-05T10:49:58.976748+00:00
instance: kb-cron
parent: process-20260505-0
summary:
A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: == Business and management == Business process, activities that produce a specific service or product for customers Business process modeling, activity of representing processes of an enterprise in order to deliver improvements Manufacturing process management, a collection of technologies and methods used to define how products are to be manufactured. Process architecture, structural design of processes, applies to fields such as computers, business processes, logistics, project management Process area, related processes within an area which together satisfies an important goal for improvements within that area Process costing, a cost allocation procedure of managerial accounting Process management (project management), a systematic series of activities directed towards planning, monitoring the performance and causing an end result in engineering activities, business process, manufacturing processes or project management Process-based management, is a management approach that views a business as a collection of processes == Law == Due process, the concept that governments must respect the rule of law Legal process, the proceedings and records of a legal case Service of process, the procedure of giving


id: process-chemistry-20260505-0
file: data/en.wikipedia.org/wiki/Process_chemistry-0.md
category: reference
title: Process chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Process_chemistry
date_saved: 2026-05-05T10:50:00.140905+00:00
instance: kb-cron
parent: process-chemistry-20260505-0
summary:
Process chemistry is the arm of pharmaceutical chemistry concerned with the development and optimization of a synthetic scheme and pilot plant procedure to manufacture compounds for the drug development phase. Process chemistry is distinguished from medicinal chemistry, which is the arm of pharmaceutical chemistry tasked with designing and synthesizing molecules on small scale in the early drug discovery phase. Medicinal chemists are largely concerned with synthesizing a large number of compounds as quickly as possible from easily tunable chemical building blocks (usually for SAR studies). In general, the repertoire of reactions utilized in discovery chemistry is somewhat narrow (for example, the Buchwald-Hartwig amination, Suzuki coupling, and reductive amination are commonplace reactions). In contrast, process chemists are tasked with identifying a chemical process that is safe, cost and labor efficient, “green,” and reproducible, among other considerations. Oftentimes, in searching for the shortest, most efficient synthetic route, process chemists must devise creative synthetic solutions that eliminate costly functional group manipulations and oxidation/reduction steps. This article focuses exclusively on the chemical and manufacturing processes associated with the production of small molecule drugs. Biological medical products (more commonly called “biologics”) represent a growing proportion of approved therapies. Additionally, the many complex factors associated with


id: process-chemistry-20260505-1
file: data/en.wikipedia.org/wiki/Process_chemistry-1.md
category: reference
title: Process chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Process_chemistry
date_saved: 2026-05-05T10:50:00.140905+00:00
instance: kb-cron
parent: process-chemistry-20260505-0
summary:
There are several strategies that are employed in the design of a process route to ensure the adequate overall yield of the pharmaceutical product. The first is the concept of convergent synthesis. Assuming a very good to excellent yield in each synthetic step, the overall yield of a multistep reaction can be maximized by combining several key intermediates at a late stage that are prepared independently from each other. Another strategy to maximize isolated yield (as well as time efficiency) is the concept of telescoping synthesis (also called one-pot synthesis). This approach describes the process of eliminating workup and purification steps from a reaction sequence, typically by simply adding reagents sequentially to a reactor. In this way, unnecessary losses from these steps can be avoided. Finally, to minimize overall cost, synthetic steps involving expensive reagents, solvents, or catalysts should be designed into the process route as late stage as possible, to minimize the amount of reagent used. In a pilot plant or manufacturing plant setting, yield can have a profound effect on the material cost of an API synthesis, so the careful planning of a robust route and the fine-tuning of reaction conditions are crucially important. After a synthetic route


id: process-chemistry-20260505-2
file: data/en.wikipedia.org/wiki/Process_chemistry-2.md
category: reference
title: Process chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Process_chemistry
date_saved: 2026-05-05T10:50:00.140905+00:00
instance: kb-cron
parent: process-chemistry-20260505-0
summary:
For this expression, the terms are inverted to reflect the desirability of shorter cycle times (as opposed to higher yields). The reproducibility of cycle times for critical processes such as reaction, centrifugation, or drying may be critical if these operations are rate-limiting in the manufacturing plant setting. For example, if an isolation step is particularly difficult or slow, it could become the bottleneck for API synthesis, in which case the reproducibility and optimization of that operation become critical. For an API manufacturing process, all PEI metrics (yield and cycle times) should be targeted at 98 to 100 percent. === EcoScale === In 2006, Van Aken, et al. developed a quantitative framework to evaluate the safety and ecological impact of a chemical process, as well as minor weighting of practical and economical considerations. Others have modified this EcoScale by adding, subtracting and adjusting the weighting of various metrics. Among other factors, the EcoScale takes into account the toxicity, flammability, and explosive stability of reagents used, any nonstandard or potentially hazardous reaction conditions (for example, elevated pressure or inert atmosphere), and reaction temperature. Some EcoScale criteria are redundant with previously considered criteria (e.g. E-factor). == Synthetic case studies == === Boehringer Ingelheim


id: process-chemistry-20260505-3
file: data/en.wikipedia.org/wiki/Process_chemistry-3.md
category: reference
title: Process chemistry
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Process_chemistry
date_saved: 2026-05-05T10:50:00.140905+00:00
instance: kb-cron
parent: process-chemistry-20260505-0
summary:
=== Biocatalysis and enzymatic engineering === Recently, large pharmaceutical process chemists have relied heavily on the development of enzymatic reactions to produce important chiral building blocks for API synthesis. Many varied classes of naturally occurring enzymes have been co-opted and engineered for process pharmaceutical chemistry applications. The widest range of applications come from ketoreductases and transaminases, but there are isolated examples from hydrolases, aldolases, oxidative enzymes, esterases and dehalogenases, among others. One of the most prominent uses of biocatalysis in process chemistry today is in the synthesis of Januvia®, a DPP-4 inhibitor developed by Merck for the management of type II diabetes. The traditional process synthetic route involved a late-stage enamine formation followed by rhodium-catalyzed asymmetric hydrogenation to afford the API sitagliptin. This process suffered from a number of limitations, including the need to run the reaction under a high-pressure hydrogen environment, the high cost of a transition-metal catalyst, the difficult process of carbon treatment to remove trace amounts of catalyst and insufficient stereoselectivity, requiring a subsequent recrystallization step before final salt formation. Merck's process chemistry department contracted Codexis, a medium-sized biocatalysis firm, to develop a large-scale biocatalytic reductive amination for the final step of its sitagliptin synthesis. Codexis engineered


