# kb

id: dorothy-cynthia-nampota-20260505-0
file: data/en.wikipedia.org/wiki/Dorothy_Cynthia_Nampota-0.md
category: reference
title: Dorothy Cynthia Nampota
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Dorothy_Cynthia_Nampota
date_saved: 2026-05-05T10:45:03.227880+00:00
instance: kb-cron
parent: dorothy-cynthia-nampota-20260505-0
summary:
Dorothy Cynthia Nampota is a Malawian educator and academic in science education. She is the executive director of the Malawi National Examinations Board (MANEB) and an associate professor at the University of Malawi. == Education == Nampota obtained a Bachelor of Education from the University of Malawi in 1991. In 1997, she received a Master of Arts degree from King's College, University of London, and completed her PhD in Science Education at the University of Bath in 2005. == Academic career == Dorothy joined the University of Malawi in 1992. She has served as Head of the Department of Curriculum and Teaching Studies (2005–2009), Deputy Dean of the Faculty of Education (2005–2006), and Director of the Centre for Educational Research and Training. In November 2020, Nampota was appointed Acting Executive Director of the Malawi National Examinations Board. She was confirmed as executive director in October 2021. == References ==


id: ian-nankervis-20260505-0
file: data/en.wikipedia.org/wiki/Ian_Nankervis-0.md
category: reference
title: Ian Nankervis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ian_Nankervis
date_saved: 2026-05-05T10:45:04.434711+00:00
instance: kb-cron
parent: ian-nankervis-20260505-0
summary:
Ian James Nankervis (born 3 January 1948) is a former Australian rules footballer for the Geelong Football Club in the Victorian Football League (VFL). Nankervis played for Geelong for 17 seasons and was captain from 1978 to 1981, and again in 1983. Nankervis held the record of most senior level games for Geelong with 325 VFL games. Nankervis also represented Victoria at state level on 12 occasions. == VFL career == Nankervis was recruited from Barwon. Initially he played mainly as a forward pocket-rover, scoring a creditable 203 goals. He later developed into one of the finest back pockets in the VFL after then coach Rodney Olsson shifted him to that end of the ground Nankervis was awarded the club's best and fairest award, the Carji Greeves Medal on three occasions in 1972, 1976 and 1977 and captained the team from 1978 until 1982 (110 games). Nankervis wore a guernsey with the number 40 during his tenure at the club. His brother Bruce Nankervis also played for Geelong. In 2001 he was named in the Geelong Football Club Team of the Century and in 2005 was inducted into the Australian Football Hall of Fame. == Honours == Individual: VFL: Victorian


id: malcolm-nokes-20260505-0
file: data/en.wikipedia.org/wiki/Malcolm_Nokes-0.md
category: reference
title: Malcolm Nokes
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Malcolm_Nokes
date_saved: 2026-05-05T10:45:05.596997+00:00
instance: kb-cron
parent: malcolm-nokes-20260505-0
summary:
Malcolm Cuthbert Nokes MC MA BSc (20 May 1897 – 22 November 1986) was a British schoolteacher, soldier, research scientist and Olympic athlete, who competed in the hammer throw and discus throw. == Biography == He won the bronze medal in the hammer throw at the 1924 Summer Olympics. Four years later he finished eleventh in the 1928 Olympic hammer throw competition. In 1923 he beat the British hammer throw record, but did so in a demonstration rather than a competition, so his throw did not count for record purposes. He won the gold medal for England in the 1930 British Empire Games in the hammer throw contest and finished fifth in the discus throw event. At the 1934 British Empire Games he won again the gold medal in the hammer throw competition. Nokes was the Amateur Athletic Association (AAA) Champion from 1923 to 1926 and placed second at the 1921 AAA Championships and 1922 AAA Championships and 1927–28. He was chairman of the AAA's Coaching Committee, and also a member of the Achilles Club. He was a graduate of Magdalen College, Oxford, where he studied chemistry and wrote a thesis on metaphenetidine. Nokes served in the Great War in


id: keith-o-brien-20260505-0
file: data/en.wikipedia.org/wiki/Keith_O'Brien-0.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
Keith Michael Patrick O'Brien (17 March 1938 – 19 March 2018) was a senior-ranking Catholic prelate in Scotland. He was the Archbishop of Saint Andrews and Edinburgh from 1985 to 2013. O'Brien was the leader of the Catholic Church in Scotland and had been the head of its conference of bishops until he stepped down as archbishop in February 2013. O'Brien's resignation followed publication of allegations that he had engaged in inappropriate and predatory sexual conduct with priests and seminarians under his jurisdiction and abused his power. O'Brien was opposed to homosexuality, which he described as "moral degradation", and a vehement opponent of same-sex marriage. On 20 March 2015, the Vatican announced that though he remained a member of the College of Cardinals, O'Brien would not exercise his rights or duties as a cardinal, in particular voting in papal conclaves; he had excused himself from participating in the 2013 conclave. O'Brien died after a fall, aged 80, on 19 March 2018. == Early life and education == O'Brien was born at Ballycastle, in County Antrim, Northern Ireland, on St. Patrick's Day, 17 March 1938. After primary education in Ballycastle, his family moved to Scotland where his father was serving with


id: keith-o-brien-20260505-1
file: data/en.wikipedia.org/wiki/Keith_O'Brien-1.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
=== Curial appointments === After his creation as cardinal, O'Brien was appointed a member of the Pontifical Council for Social Communications and also a member of the Pontifical Council for the Pastoral Care of Migrants and Itinerant People. He was President of the Bishops' Conference of Scotland and fulfilled various engagements at the request of other members of the Conference. He was sometimes referred to as the "Primate of Scotland"; however, this title or position has never existed. === Resignation as archbishop === O'Brien tendered his resignation from the governance of the Archdiocese of St Andrews and Edinburgh to the Pope some time in 2012, in view of his 75th birthday in March 2013; the Pope accepted it nunc pro tunc on 13 November 2012 and decided it would become effective on 25 February 2013. He remained a cardinal. The announcement of his resignation followed allegations initially in The Observer newspaper that O'Brien had engaged in inappropriate sexual conduct with junior clergy. The Pope appointed Philip Tartaglia as temporary apostolic administrator in O'Brien's place. In July, Leo Cushley, a priest from Motherwell, was named to succeed O'Brien as archbishop. == Sexual misconduct and consequences == In 2013 allegations became public


id: keith-o-brien-20260505-2
file: data/en.wikipedia.org/wiki/Keith_O'Brien-2.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
=== Ecclesiastical response === On 27 April 2013, The Scotsman reported that Cardinal Marc Ouellet would head an investigation into O'Brien, and that appointment of Scottish bishops had been halted until the inquiry was completed. This contradicted another report suggesting that the Vatican would not hold a formal investigation or publish any formal report because "The Church doesn't work that way." No decision had been made to demote or laicise O'Brien. O'Brien returned to Scotland and attempted to settle into the church-owned cottage he had planned as his retirement home in Dunbar, East Lothian. One of his accusers, a former seminarian, stated, "Keith O'Brien is giving the impression he wants a nice peaceful little retirement now. My experience hasn't left me for decades and as far as I'm concerned this brings things very much back into focus. I have an issue with Keith O'Brien and it needs to be dealt with." There were fears the cardinal's visibility would harm the church further. On 15 March 2013, it was confirmed that the Vatican had ordered O'Brien to leave Scotland, and he left for months of "prayer and penance". According to The Washington Post, "The statement did not specify that the decision


id: keith-o-brien-20260505-3
file: data/en.wikipedia.org/wiki/Keith_O'Brien-3.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
==== Apostolic visitation ==== After some delay, it was reported in The Observer on 23 June 2013 that the Vatican had decided to hold an apostolic visitation. This is a formal high-level inspection into the affair, in which the "visitator" is given authority directly by the pope. In this case the visitator was the archbishop of St Andrews and Edinburgh, who had not yet been appointed at the time. Papal nuncio Antonio Mennini told one of the complainants, a former priest known as "Lenny", of the decision. Anyone affected would be able to give evidence; if there was considered to be sufficient evidence, a deeper process would take place in Rome. Lenny was relieved that the facts would finally be examined, but said that the visitation also had to examine "whether any promotions were awarded to the cardinal's cronies". According to the article, senior figures in Rome said the visitation would also deal with the more general accusations of moral failings in the church in Scotland. There was criticism of the choice of O'Brien's successor as Archbishop of Edinburgh as visitator; Tom Doyle, a canon lawyer who had worked at the nunciature in Washington and later represented Catholic abuse victims


id: keith-o-brien-20260505-4
file: data/en.wikipedia.org/wiki/Keith_O'Brien-4.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
== Health and death == O'Brien said, while criticising a parliamentary bill on embryology in 2008, that he carried an organ donor card. O'Brien suffered from heart problems and was fitted with a pacemaker after complaining of dizzy spells and fainting prior to Passion Sunday Mass in March 2008. Following the acceptance of his resignation in February 2013 he said "Approaching the age of 75 and at times in indifferent health, I tendered my resignation as Archbishop of St Andrews and Edinburgh to Pope Benedict XVI some months ago." O'Brien died after a fall on 19 March 2018, two days after his 80th birthday. == Views == O'Brien was often forthright in his political and spiritual views. In 1999, at the European Synod of Bishops, O'Brien declared who he saw fit to be the next Archbishop of Westminster, following the death of Cardinal Basil Hume. He named his candidate, Timothy Radcliffe, Master General of the Dominican order (Black Friars). At the synod, Radcliffe had made an appeal to O'Brien, saying that there was a crisis of authority in the church, but the answer could not be more emphasis on authority. In the presence of the Pope, Radcliffe went on: the


id: keith-o-brien-20260505-5
file: data/en.wikipedia.org/wiki/Keith_O'Brien-5.md
category: reference
title: Keith O'Brien
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Keith_O'Brien
date_saved: 2026-05-05T10:45:06.748233+00:00
instance: kb-cron
parent: keith-o-brien-20260505-0
summary:
=== Abortion and embryo research === In May 2007 O'Brien urged Roman Catholics to reject political candidates who support what he called the "social evil" of abortion, and said that such Catholic politicians should not expect to remain full members of the church. During March 2008, O'Brien highlighted the issue of the Human Fertilisation and Embryology Bill being debated in Parliament, denouncing the government for a "monstrous attack on human rights" through its "evil" endorsement of "Frankenstein" experiments. Some scientists suggested that he intentionally used inflammatory language to stir up opposition to the bill; others argued he was sticking up for morals and forced the Government to allow MPs to vote freely on the issue. (Gordon Brown had originally imposed a three-line whip on Labour MPs, meaning they had to back the bill, regardless of personal convictions.) O'Brien himself narrated a five-minute video recording in which he stated the "many, many concerns" of the Catholic Church concerning the bill which was to be voted on in Parliament. It was posted on YouTube, and sent as a DVD to every member of Parliament. In the video O'Brien made clear he was not against medical research, and supported research with non-embryonic stem


id: peter-o-leary-referee-20260505-0
file: data/en.wikipedia.org/wiki/Peter_O'Leary_(referee)-0.md
category: reference
title: Peter O'Leary (referee)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Peter_O'Leary_(referee)
date_saved: 2026-05-05T10:45:07.943845+00:00
instance: kb-cron
parent: peter-o-leary-referee-20260505-0
summary:
Peter O'Leary (born 3 March 1972) is a New Zealand former Association football referee, previously of Wellington but now is residing in Hamilton. He operated in the Australian A-League and the New Zealand Football Championship, and his other occupation is as a teacher and deputy principal at Te Aroha College. He currently has the record for controlling the most matches in the FIFA Club World Cup. == Career == He first took up refereeing in 1994. He has officiated in many Oceania Football Confederation tournaments since becoming a FIFA referee in 2003, notably the OFC Nations Cup in 2004, and the Oceania Club Championship in 2006. In 2007, he was selected to officiate at the FIFA Under-20 World Cup in Canada during June and July of that year. He took charge of the Group F game between Nigeria and Costa Rica at the Royal Athletic Park in Victoria, British Columbia, on 1 July. He was then assigned the Group B match between Uruguay and Jordan at the Swangard Stadium in Burnaby, on 4 July. At the English Premiership tie between Aston Villa and Sunderland F.C. as a guest of top English referee Steve Bennett, O’Leary was summoned from the stands


id: alberto-oliverio-20260505-0
file: data/en.wikipedia.org/wiki/Alberto_Oliverio-0.md
category: reference
title: Alberto Oliverio
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alberto_Oliverio
date_saved: 2026-05-05T10:45:09.105432+00:00
instance: kb-cron
parent: alberto-oliverio-20260505-0
summary:
Alberto Oliverio (born December 1, 1938) is a biologist and psycho-biologist. He is currently professor of Psychobiology at the Sapienza University of Rome. He has been one of the main assistants of Nobel prize winner Daniel Bovet. == Publications == Oliverio is author or co-author of about 400 publications. He is author of about 30 chapters or general reviews in edited books or annual reviews. Has edited 6 books on animal behavior and behavioral genetics and is the author of many books on memory, brain and behavior. == Research fields == Neurochemical – neurophysiological correlates of memory. Genetic approaches to behavior. == Books == Oliverio A. & Oliverio Ferraris A., Lo sviluppo comparato del comportamento, Boringhieri, Turin, 1974. Oliverio A. & Oliverio Ferraris A., Psicologia: Basi biologiche, sviluppo, ambiente, Zanichelli, Bologna, 1976; 2nd Edition, 1980; 3rd Edition (Psicologia: I motivi del comportamento umano), 1986; 4th Edition, 1990; 5th edition 1996; 6th edition 2002; 7th edition 2007. Oliverio A., (Ed.) Zoologia 1: Comunicazione e comportamento sociale. Letture da Le Scienze, Le Scienze, Milan, 1977. Oliverio A., Maturità e vecchiaia, Feltrinelli, Milan, 1977. Oliverio A.. (Ed.) Genetics, Environment and Intelligence, North Holland, Amsterdam, 1977. Oliverio A. & Oliverio Ferraris A., Maschio/Femmina: Biologia,


id: albert-oppel-20260505-0
file: data/en.wikipedia.org/wiki/Albert_Oppel-0.md
category: reference
title: Albert Oppel
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Albert_Oppel
date_saved: 2026-05-05T10:45:10.267162+00:00
instance: kb-cron
parent: albert-oppel-20260505-0
summary:
Carl Albert Oppel (19 December 1831 – 23 December 1865) was a German paleontologist. == History == He was born at Hohenheim in Württemberg, on 19 December 1831. He first went to the University of Tübingen, where he graduated with a Ph.D. in 1853. The results of his work was published in Die Juraformation Englands, Frankreichs und des südwestlichen Deutschlands (1856–1858). He went to the Palaeontological Museum at Munich in 1858 and became an assistant there. It was in 1860 that he became the Professor of Palaeontology at the University of Munich. Then, a year later, he became the director of the Palaeontological Collection. Of his later works, it can be said that the most important was Paläontologische Mittheilungen aus dem Museum des Königlichen Bayerischen Staates (1862–1865). He died on 23 December 1865 at the age of 34. The wrinkle ridge Dorsum Oppel on the Moon is named after him, as is the fossil prawn genus Albertoppelia. == Studies == Oppel devoted his life to the study of fossils and the examination of the strata of the Jurassic period deposits. He is considered to have founded the study of zone stratigraphy and the use of index fossils, a term which


id: guadalupe-ortiz-de-land-zuri-fern-ndez-de-heredia-20260505-0
file: data/en.wikipedia.org/wiki/Guadalupe_Ortiz_de_Landázuri_Fernández_de_Heredia-0.md
category: reference
title: Guadalupe Ortiz de Landázuri Fernández de Heredia
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Guadalupe_Ortiz_de_Landázuri_Fernández_de_Heredia
date_saved: 2026-05-05T10:45:11.426485+00:00
instance: kb-cron
parent: guadalupe-ortiz-de-land-zuri-fern-ndez-de-heredia-20260505-0
summary:
Guadalupe Ortiz de Landázuri Fernández de Heredia (12 December 1916 – 16 July 1975) was a Spanish Catholic professor and a member of Opus Dei. She was one of the first women to join Opus Dei, after meeting the founder Josemaría Escrivá in 1944. She helped start Opus Dei in Mexico and also collaborated directly with Escrivá in Rome. A serious heart condition eventually claimed her life in 1975. After several requests from people who knew her during her life, her cause of canonization opened on 3 November 2001. In mid-2017, Pope Francis declared that she had lived a life of heroic virtue and named her Venerable. The same Pope confirmed a miracle attributed to her intercession (the healing of a cancer patient) in June 2018. Her beatification was celebrated on 18 May 2019 in Madrid. == Life == Guadalupe Ortiz de Landázuri Fernández de Heredia was born in Madrid on 12 December 1916 as the fourth of four children (and the only daughter) to Manuel Ortiz de Landázuri, a military officer, and Eulogia Fernández-Heredia. Her three elder siblings were Manuel, Eduardo, and Francisco, who died in childhood. Her brother Eduardo (who became a doctor and college professor) and his


id: guadalupe-ortiz-de-land-zuri-fern-ndez-de-heredia-20260505-1
file: data/en.wikipedia.org/wiki/Guadalupe_Ortiz_de_Landázuri_Fernández_de_Heredia-1.md
category: reference
title: Guadalupe Ortiz de Landázuri Fernández de Heredia
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Guadalupe_Ortiz_de_Landázuri_Fernández_de_Heredia
date_saved: 2026-05-05T10:45:11.426485+00:00
instance: kb-cron
parent: guadalupe-ortiz-de-land-zuri-fern-ndez-de-heredia-20260505-0
summary:
== Beatification == In 2001 the Opus Dei prelate Javier Echevarría Rodríguez started the steps needed to launch the beatification process. The forum for the diocesan process for the cause was transferred on 30 March 2001 from the Pamplona-Tudela diocese to the Madrid archdiocese at which point the Congregation for the Causes of Saints on 3 November issued the "nihil obstat" (no objections) edit to begin the cause and to title her as a Servant of God. Cardinal Antonio María Rouco Varela opened the diocesan process on 18 November and later closed it on 18 March 2005. From 2002 to 2003 there were 66 sessions held with 32 witnesses from Madrid being called to provide evidence and interrogatories while another week-long session in mid-2003 in Mexico saw 22 witnesses giving evidence in support of Ortiz de Landázuri's virtues in 37 sessions. The C.C.S. later received all the documents gathered during that process in 2005 (3008 pages in seven compiled volumes) and validated the process later on 17 February 2006. The postulation later compiled and submitted the Positio dossier to the C.C.S. in 2009 for evaluation. Theologians provided a positive vote to the cause on 7 June 2016 after having assessed


id: abraham-pais-20260505-0
file: data/en.wikipedia.org/wiki/Abraham_Pais-0.md
category: reference
title: Abraham Pais
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abraham_Pais
date_saved: 2026-05-05T10:45:12.672173+00:00
instance: kb-cron
parent: abraham-pais-20260505-0
summary:
Abraham Pais (; May 19, 1918 – July 28, 2000) was a Dutch-American physicist and science historian. Pais earned his Ph.D. from University of Utrecht just prior to a Nazi ban on Jewish participation in Dutch universities during World War II. When the Nazis began the forced relocation of Dutch Jews, he went into hiding, but was later arrested and saved only by the end of the war. He then served as an assistant to Niels Bohr in Denmark and was later a colleague of Albert Einstein at the Institute for Advanced Study in Princeton, New Jersey. His Subtle is the Lord, considered by many to be the definitive biography of Einstein, won the Science Writing Award. He followed it with Inwaard Bound: Of Matter and Forces in the Physical World, a history of modern physics, Niels Bohr's Times: In Physics, Philosophy, and Polity and Einstein Lived Here: Essays for the Layman. He was a physics professor at Rockefeller University until his retirement. He won the 1995 Lewis Thomas Prize for science writing. == Early life == Pais was born in Amsterdam, the first child of middle-class Dutch-Jewish parents. His father, Isaiah "Jacques" Pais, was the descendant of Sephardic Jewish


id: abraham-pais-20260505-1
file: data/en.wikipedia.org/wiki/Abraham_Pais-1.md
category: reference
title: Abraham Pais
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abraham_Pais
date_saved: 2026-05-05T10:45:12.672173+00:00
instance: kb-cron
parent: abraham-pais-20260505-0
summary:
== Higher education == In the fall of 1935 Pais began his studies at the University of Amsterdam without a clear idea regarding his desired career. With an interest in the exact sciences, he gradually gravitated to chemistry and physics as major subjects, and mathematics and astronomy as minor subjects. In the winter of 1936/1937 his career goals were defined by two guest lectures by George Uhlenbeck, professor of theoretical physics at University of Utrecht. Pais was fascinated by Uhlenbeck's discussion of Enrico Fermi's incorporation of the neutrino into the theory of beta radiation. On February 16, 1938, Pais was awarded two Bachelor of Science degrees in physics and mathematics, with minors in chemistry and astronomy. He began attending graduate courses in Amsterdam, including those in physics. He soon became disappointed by the only professor there in theoretical physics, Johannes Diderik van der Waals Jr. (the son of the 1910 Nobel laureate Johannes Diderik van der Waals), whom he found dull and averse to the new developments in physics. Pais soon wrote to Uhlenbeck at Utrecht and was granted an interview. During the remainder of the spring term he discontinued attending classes in Amsterdam and made several trips to visit


id: abraham-pais-20260505-2
file: data/en.wikipedia.org/wiki/Abraham_Pais-2.md
category: reference
title: Abraham Pais
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abraham_Pais
date_saved: 2026-05-05T10:45:12.672173+00:00
instance: kb-cron
parent: abraham-pais-20260505-0
summary:
During his student years Pais had been involved in the Zionist movement, through which he became acquainted with Trusha (Tirtsah) van Amerongen and Tina (Tineke) Strobos, and developed a close friendship with these two women and their families. The Germans began gradually to restrict the activities of the Dutch Jews and in early 1942 required them to wear yellow stars. At first Pais felt safe because his former university status exempted him from being sent to a labor camp. In early 1943, however, the Dutch secretary general of internal affairs, Frederiks, made arrangements for the university Jews to report to Barneveld for their own safety, where they would be housed in a chateau. Pais did not trust that and instead went into hiding. Those who reported to Barneveld were later sent to the Theresienstadt concentration camp where most of them did survive. His friend and for a time fiancée Tina Strobos was not Jewish and thus was freer of restrictions and threat of incarceration. She arranged hiding places for Pais and other Jews in Amsterdam. When the Germans began forcing the Dutch Jews into a ghetto in the old Jewish quarter of Amsterdam, his sister Annie and her husband Hermann


id: abraham-pais-20260505-3
file: data/en.wikipedia.org/wiki/Abraham_Pais-3.md
category: reference
title: Abraham Pais
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Abraham_Pais
date_saved: 2026-05-05T10:45:12.672173+00:00
instance: kb-cron
parent: abraham-pais-20260505-0
summary:
== Science historian == In the late 1970s Pais became interested in documenting the history of modern physics. He felt he was in a unique position to do so, having known many of the key people and with his knowledge of the language, culture, and science. Pais was perhaps best known for his biography of Albert Einstein, Subtle is the Lord: The Science and the Life of Albert Einstein, and its companion volume, Einstein Lived Here (Clarendon Press/Oxford University Press, 1994). Subtle is the Lord won the 1983 U.S. National Book Award in Science. His Inward Bound: Of matter and forces in the physical world (Clarendon Press/Oxford University Press, 1988) describes the events in physics during the preceding 100 years, and tries to explain why they happened as they did. In 1991 he published Niels Bohr's Times: In physics, philosophy, and polity (Clarendon Press/Oxford University Press, 1991) which describes the life and scientific contributions of Bohr. In 1995 he teamed with Laurie M. Brown and Sir Brian Pippard to compile a three-volume reference collection of articles portraying the scientific and cultural development of modern physics in Twentieth Century Physics (American Institute of Physics and the Institute of Physics, U.K., 1995).


id: efraim-racker-20260505-0
file: data/en.wikipedia.org/wiki/Efraim_Racker-0.md
category: reference
title: Efraim Racker
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Efraim_Racker
date_saved: 2026-05-05T10:45:13.985598+00:00
instance: kb-cron
parent: efraim-racker-20260505-0
summary:
Efraim Racker (June 28, 1913 – September 9, 1991) was an Austrian biochemist who was responsible for identifying and purifying Factor 1 (F1), the first part of the ATP synthase enzyme to be characterised. F1 is only a part of a larger ATP synthase complex known as Complex V. It is a peripheral membrane protein attached to component Fo, which is integral to the membrane. == Early life == Efraim Racker was born to a Jewish family in 1913 in Neu Sandez, Austrian Galicia, and grew up in Vienna. His elder brother, Heinrich Racker, was to become a famous psychoanalyst. Efraim Racker was studying medicine at the University of Vienna when Hitler invaded in 1938. Racker fled to Great Britain, where he took a job in a mental hospital in Wales. His research focused on the biochemical causes for mental diseases. During the war, Racker was given the opportunity to practice medicine, but he decided to move to the United States to continue his research. == Career == In the U.S., he accepted a position as a research associate in physiology at the University of Minnesota in Minneapolis from 1941 to 1942. While investigating the biochemical basis for brain diseases,


id: stefan-raunser-20260505-0
file: data/en.wikipedia.org/wiki/Stefan_Raunser-0.md
category: reference
title: Stefan Raunser
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Stefan_Raunser
date_saved: 2026-05-05T10:45:15.247958+00:00
instance: kb-cron
parent: stefan-raunser-20260505-0
summary:
Stefan Raunser (born 1976 in Landau in der Pfalz, Germany) is a German scientist and structural biologist specializing in membrane proteins, the cytoskeleton, toxins, and sarcomere structural biochemistry. Since 2014, he has been a director at the Max Planck Institute of Molecular Physiology in Dortmund, Germany. == Education and career == Raunser studied biology and chemistry at the Johannes Gutenberg-Universität Mainz and completed his Ph.D. in biochemistry at the Goethe University Frankfurt in 2004, under the supervision of Prof. Werner Kühlbrandt at the Max Planck Institute of Biophysics in Frankfurt/Main. He continued his research as a postdoctoral researcher at Harvard Medical School in Boston, USA, working with Thomas Walz from 2005 to 2008. He then became an "Emmy Noether group leader" at the Max Planck Institute of Molecular Physiology in Dortmund, serving in that position from 2008 to 2013. In 2014, Raunser held the Einstein Professorship for Membrane Biochemistry at Free University of Berlin from January to June before assuming his current role as a director at the Max Planck Institute of Molecular Physiology. In 2015, he became an honorary professor at the University of Duisburg-Essen, and later that same year, he became an adjunct professor at Technical University of


id: paul-reiter-20260505-0
file: data/en.wikipedia.org/wiki/Paul_Reiter-0.md
category: reference
title: Paul Reiter
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Paul_Reiter
date_saved: 2026-05-05T10:45:16.391182+00:00
instance: kb-cron
parent: paul-reiter-20260505-0
summary:
Paul Reiter is a professor of medical entomology at the Pasteur Institute in Paris, France. He is a member of the World Health Organization Expert Advisory Committee on Vector Biology and Control. He was an employee of the Centers for Disease Control (Dengue Branch) for 22 years. He is a specialist in the natural history, epidemiology and control of mosquito-borne diseases such as dengue fever, West Nile fever, and malaria. He is a Fellow of the Royal Entomological Society. == Criticism of the IPCC == Reiter says he was a contributor to the third IPCC Working Group II (Impacts, adaptation and vulnerability) report but resigned because he "found [himself] at loggerheads with persons who insisted on making authoritative pronouncements, although they had little or no knowledge of [his] speciality". After ceasing to contribute he says he struggled to get his name removed from the Third report "After much effort and many fruitless discussions, I decided to concentrate on the USGCCRP and resigned from the IPCC project. My resignation was accepted, but in a first draft I found that my name was still listed. I requested its removal, but was told it would remain because "I had contributed". It was only


id: john-rothwell-physiologist-20260505-0
file: data/en.wikipedia.org/wiki/John_Rothwell_(physiologist)-0.md
category: reference
title: John Rothwell (physiologist)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/John_Rothwell_(physiologist)
date_saved: 2026-05-05T10:45:18.723577+00:00
instance: kb-cron
parent: john-rothwell-physiologist-20260505-0
summary:
John C. Rothwell (born 1954) is a Professor of neurophysiology at the UCL Institute of Neurology. His main area of interest is transcranial magnetic stimulation and motor control. == Education == Rothwell was educated at the University of Cambridge. He completed his PhD at King's College London in 1980 which supervised by David Marsden. == Career and research == His group has pioneered the use of the paired-pulse technique (Kujirai et al. 1992), interhemispheric studies (Ferbert et al. 1992). Rothwell was appointed head of the Medical Research Council (MRC) Human Movement and Balance Unit after the untimely death of David Marsden. He has written over 400 papers and numerous chapters. == References ==


id: catherine-margaret-shachaf-20260505-0
file: data/en.wikipedia.org/wiki/Catherine_Margaret_Shachaf-0.md
category: reference
title: Catherine Margaret Shachaf
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catherine_Margaret_Shachaf
date_saved: 2026-05-05T10:45:19.894269+00:00
instance: kb-cron
parent: catherine-margaret-shachaf-20260505-0
summary:
Catherine Margaret Shachaf (Hebrew: קתרין מרגרט שחף) is an Indian cell biologist. She previously held an instructor position at Stanford University School of Medicine, and has made ground-breaking discoveries in cancer research. Shachaf has spoken at scientific conferences and has published more than 17 journal articles. Her leading work was published in Nature (2004), "MYC Inactivation Uncovers Pluripotent Differentiation and Tumor Dormancy in Hepatocellular Cancer." Shachaf is on the Editorial Board of the International Journal of Green Nanotechnology. == Education == Post doctorate fellow: Stanford University, Medical Oncology Ph.D: Israel Institute of Technology, Molecular Medicine M.Sc: Israel Institute of Technology, Genetics B.Sc.: University of Haifa, Israel, Biology Dr. Shachaf Technion PhD thesis http://www.graduate.technion.ac.il/Theses/Abstracts.asp?Id=10256 Archived 2020-09-27 at the Wayback Machine == Honors and awards == FOCIS Trainee Satellite Symposia Award, FOCIS (2008) AACR, Scholar in Training Award, Aflac (2008) Young Scientist Clinical Award, FAMRI (2004–2009) Comprehensive Cancer Center Translational Award, Stanford University (2005) Richard W. Weiland Fellowship, CCIS, Stanford University (2001–2004) == Key scientific contributions == Shachaf has researched how MYC expression induces cancer in mice and the effect of its inactivation in those tumors. She showed that removing MYC expression kills the tumor and that MYC reprograms the tumor cells.


id: alexander-smith-chemist-20260505-0
file: data/en.wikipedia.org/wiki/Alexander_Smith_(chemist)-0.md
category: reference
title: Alexander Smith (chemist)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alexander_Smith_(chemist)
date_saved: 2026-05-05T10:45:21.052856+00:00
instance: kb-cron
parent: alexander-smith-chemist-20260505-0
summary:
Alexander Smith (11 September 1865 – 8 September 1922) was a Scottish chemist, who spent his working life teaching in the universities of America. == Biography == He was born at 4 Nelson Street in Edinburgh's New Town, the son of Isabella (née Carter) and Alexander W. Smith, a music teacher. His paternal grandfather was the sculptor Alexander Smith. The family moved to 4 West Castle Road in the Merchiston district while he was young. He was educated at Edinburgh Collegiate School. He studied sciences (later specialising in chemistry) at the University of Edinburgh. He was taught mathematics by George Chrystal, physics by Peter Guthrie Tait and chemistry by Alexander Crum Brown. He obtained his B.Sc. in 1886 at the University of Edinburgh. During his university years, he showed a keen interest in astronomy and published four papers on the subject. He went to Germany in 1886 for further postgraduate studies and gained his doctorate at the Ludwig-Maximilians-Universität München under Prof Rainer Ludwig Claisen in Baeyer's laboratory in 1889. In 1890, aged 25, he was elected a Fellow of the Royal Society of Edinburgh. His proposers were Alexander Crum Brown, John Gibson, Leonard Dobbin and Ralph Stockman. In 1911, the


id: chris-smith-science-communicator-20260505-0
file: data/en.wikipedia.org/wiki/Chris_Smith_(science_communicator)-0.md
category: reference
title: Chris Smith (science communicator)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chris_Smith_(science_communicator)
date_saved: 2026-05-05T10:45:22.220841+00:00
instance: kb-cron
parent: chris-smith-science-communicator-20260505-0
summary:
Chris Smith (born 16 January 1975) - "the Naked Scientist" - is a British consultant virologist and a lecturer based at Cambridge University where he is a fellow of Queens' College. He is also a science radio broadcaster and writer, and presents the Naked Scientists, a programme which he founded in 2001, for BBC Radio and other networks internationally, as well as 5 Live Science on BBC Radio 5 Live. == Qualifications == Chris Smith has a Cambridge University medical degree (MB BChir) and a PhD in virology. He also gained a First Class Honours degree in neuroscience from University College London (UCL). He is a fellow of the Royal College of Pathologists (FRCPath) and on the General Medical Council (GMC) specialist register for medical microbiology and virology, practising as he does as a consultant clinical virologist at Addenbrooke's Hospital, Cambridge. == Naked Scientists podcast == Launched by Smith in 2001, and distributed as one of the first iTunes podcasts from 2005, it was also the first BBC local and regional programme to be published as a podcast and within its first twelve months it received 2 million programme downloads. In January 2010, Smith's The Naked Scientists group announced on


id: sami-solanki-20260505-0
file: data/en.wikipedia.org/wiki/Sami_Solanki-0.md
category: reference
title: Sami Solanki
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Sami_Solanki
date_saved: 2026-05-05T10:45:23.475442+00:00
instance: kb-cron
parent: sami-solanki-20260505-0
summary:
Sami Khan Solanki (born 1958 in Karachi, Pakistan) is director of the Max Planck Institute for Solar System Research (MPS), director of the Sun-Heliosphere Department of MPS, a scientific member of the Max Planck Society, and a Chair (and spokesperson) of the International Max Planck Research School on Physical Processes in the Solar System and Beyond at the Universities of Braunschweig and Göttingen. Solanki is also an Honorary Professor at the Institute of Astronomy at the Swiss Federal Institute of Technology Zurich, and (2) Institute for Geophysics and Extraterrestrial Physics at the Braunschweig University of Technology in Germany. In addition, he is a Distinguished Professor at the Kyung Hee University in Korea. He is the editor-in-chief of the Living Reviews in Solar Physics, an exclusively web-based, peer-reviewed journal, publishing reviews of research in all areas of solar and heliospheric physics. Living Reviews in Solar Physics was recently rated with an impact factor of 17.636 taking the third place in the "Astronomy & Astrophysics" category. Solanki's main topics of research are: Solar and heliospheric physics, in particular solar magnetism and Sun-Earth relations Stellar astrophysics, mainly stellar activity and magnetism Astronomical tests of theories of gravitation Atomic and molecular physics of astronomical


id: gerolf-steiner-20260505-0
file: data/en.wikipedia.org/wiki/Gerolf_Steiner-0.md
category: reference
title: Gerolf Steiner
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Gerolf_Steiner
date_saved: 2026-05-05T10:45:24.677600+00:00
instance: kb-cron
parent: gerolf-steiner-20260505-0
summary:
Gerolf Steiner (22 March 1908 – 14 August 2009) was a German zoologist. == Life and career == Steiner was born in Strasbourg, Alsace in March 1908. He earned his doctorate in 1931 at the University of Heidelberg. He completed his habilitation in 1942 at the Technical University Darmstadt and 1947 at the University of Heidelberg, where he was appointed as professor in 1949. In 1962, he was an associate professor at the Technical University of Karlsruhe, becoming full professor in 1966 and occupying the chair of zoology from 1962 to 1973. He died five months after his 101st birthday on August 14, 2009 in Heidelberg. == Rhinogradentia == Steiner is best known for a 1961 book authored pseudonymously as Harald Stümpke on the anatomy and habits of the rhinogradentia, a fictitious order of extinct mammals whose nose evolved in unusual ways. He has published also under the pseudonyms of Justus Andereich, Trotzhard Wiederumb, and Karl D.S. Geeste. == Publications == Die Automatie und die zentrale Beeinflussung des Herzens von Periplaneta americana. Heidelberg (1932). Methodische Untersuchungen über die Geruchsorientierung von Fleischfliegen. Springer, Berlin (1942). with Richard Sternfeld, Die Reptilien und Amphibien Mitteleuropas. Quelle & Meyer, Heidelberg (1952). Harald Stümpke (pseud.),


id: bengt-str-mgren-20260505-0
file: data/en.wikipedia.org/wiki/Bengt_Strömgren-0.md
category: reference
title: Bengt Strömgren
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bengt_Strömgren
date_saved: 2026-05-05T10:45:25.869306+00:00
instance: kb-cron
parent: bengt-str-mgren-20260505-0
summary:
Bengt Georg Daniel Strömgren (21 January 1908 – 4 July 1987) was a Danish astronomer and astrophysicist. == Life and career == Bengt Strömgren was born in Gothenburg. His parents were Hedvig Strömgren (née Lidforss) and Elis Strömgren, who was professor of astronomy at the University of Copenhagen and director of the University Observatory in Copenhagen. Bengt grew up in the professor's mansion surrounded with scientists, assistants, observers and guests. His father paced and promoted Bengt into a life with science, and Bengt's first paper was published already at the age of 14. He graduated from high school in 1925 and enrolled at the Copenhagen university. Only two years later, he graduated in astronomy and atomic physics, and during the following two years, he completed a doctoral degree, which was evaluated with the best marks in December 1929, when he was 21 years old. He gained a great deal of useful experience from his studies in theoretical physics at Niels Bohr's Institute close by, and he was at the right place at the right time. He soon found out that he intended to use the fresh theoretical framework of quantum physics in space, and investigate the applications of quantum mechanics


id: andrew-szydlo-20260505-0
file: data/en.wikipedia.org/wiki/Andrew_Szydlo-0.md
category: reference
title: Andrew Szydlo
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Andrew_Szydlo
date_saved: 2026-05-05T10:45:27.078565+00:00
instance: kb-cron
parent: andrew-szydlo-20260505-0
summary:
Andrew Zbigniew Szydlo ( SHID-low; born 1949) is a British chemist and chemistry teacher of Polish descent. Born in London, he is best known for his talks and lectures on chemistry. == Early life and education == Szydlo was born in London, England to Polish parents, Kazimierz and Daniela (née Suchecka). Daniela was one of many Polish children who were forcibly expatriated to Siberia by Soviet forces in 1942, and her experiences as an orphaned child in India have been described in an interview which she gave in 2011 and also in the book Poles in India. Szydlo attended Ellerslie Junior Mixed School in Shepherd's Bush, followed by Latymer Upper School, and then Imperial College London and University College London. He holds MSc, PhD, DIC, ACGI, and is a Fellow of the Royal Society of Chemistry, of which he is also a CChem. An expert on the history of alchemy, Szydlo is the author of the standard work on the Polish alchemist, Michael Sendivogius. The thesis of his book "Water that does not wet hands": The Alchemy of Michael Sendivogius, which argues that Sendivogius' role in the discovery of oxygen has not received proper attention, has won widespread acceptance within


id: fred-talbot-20260505-0
file: data/en.wikipedia.org/wiki/Fred_Talbot-0.md
category: reference
title: Fred Talbot
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Fred_Talbot
date_saved: 2026-05-05T10:45:28.298443+00:00
instance: kb-cron
parent: fred-talbot-20260505-0
summary:
Frederick Wilson Talbot (born 17 December 1949) is a British former television presenter and convicted sex offender. He grew up in north west England. == Early life and teaching == Born in Edinburgh, Talbot grew up in north west England, where he attended North Cestrian Grammar School in Altrincham, Cheshire. In 1964 he was a founding member of the Altrincham and District Astronomical Society, with which he co-discovered a meteor shower, the June Lyrids in June 1966. After teacher training in Gateshead in the late 1960s, he was employed to teach biology at Altrincham Grammar School for Boys until May 1984, when his schooling career came to "an abrupt end" following an indecent proposal he made to two pupils at his home. == Media career == Talbot began working for Granada Television in 1982, with The Final Frontier, an educational science series networked on ITV as part of their children's programming strand. In 1984, he began presenting for the regional news programme Granada Reports in North West England. He continued as a regular reporter for Granada Reports and became a weatherman for the ITV's This Morning in October 1988. Until production of This Morning was moved from the Albert Dock,


id: john-r-taylor-20260505-0
file: data/en.wikipedia.org/wiki/John_R._Taylor-0.md
category: reference
title: John R. Taylor
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/John_R._Taylor
date_saved: 2026-05-05T10:45:29.498732+00:00
instance: kb-cron
parent: john-r-taylor-20260505-0
summary:
John Robert Taylor is British-born emeritus professor of physics at the University of Colorado, Boulder. He received his B.A. in mathematics at Cambridge University, and his Ph.D. from the University of California, Berkeley in 1963 with thesis advisor Geoffrey Chew. Taylor has written several college-level physics textbooks. His bestselling book is An Introduction to Error Analysis, which has been translated into nine languages. His intermediate-level undergraduate textbook, Classical Mechanics, was well-reviewed. == Awards == Taylor was designated a Presidential Teaching Scholar in 1991. He has also received an Emmy Award for his television series Physics 4 Fun (1988–1990). == References ==


id: bruno-th-ring-20260505-0
file: data/en.wikipedia.org/wiki/Bruno_Thüring-0.md
category: reference
title: Bruno Thüring
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bruno_Thüring
date_saved: 2026-05-05T10:45:30.679560+00:00
instance: kb-cron
parent: bruno-th-ring-20260505-0
summary:
Bruno Jakob Thüring (7 September 1905, in Warmensteinach – 6 May 1989, in Karlsruhe) was a German physicist and astronomer. == Life and career == Thüring studied mathematics, physics, and astronomy at the Ludwig-Maximilians-Universität München and received his doctorate in 1928, under Alexander Wilkens. Wilkens was a professor of astronomy and director of the Munich Observatory, which was part of the university. From 1928 to 1933, Thüring was an assistant at the Munich Observatory. From 1934 to 1935, he was an assistant to Heinrich Vogt at Heidelberg University. Thüring completed his Habilitation there in 1935, whereupon he became an observator at the Munich Observatory. In 1937, Thüring became a lecturer (Dozent) at the Ludwig-Maximilians-Universität München. From 1940 to 1945, he held the chair for astronomy at the University of Vienna and was director of the Vienna Observatory. After 1945, Thüring lived as a private scholar in Karlsruhe. During the reign of Adolf Hitler, Thüring was a proponent of Deutsche Physik, as were the two Nobel Prize-winning physicists Johannes Stark and Philipp Lenard; Deutsche Physik, was anti-Semitic and had a bias against theoretical physics, especially quantum mechanics. He was also a student of the philosophy of Hugo Dingler. Thüring was an


id: suzy-urbaniak-20260505-0
file: data/en.wikipedia.org/wiki/Suzy_Urbaniak-0.md
category: reference
title: Suzy Urbaniak
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Suzy_Urbaniak
date_saved: 2026-05-05T10:45:32.933821+00:00
instance: kb-cron
parent: suzy-urbaniak-20260505-0
summary:
Suzy Urbaniak, OAM is an Australian science teacher and former geologist known for her teaching methods and the establishment of the Centre of Resources Excellence (CoRE) program. She has been teaching Earth sciences at Kent Street Senior High School in Perth, Western Australia since 2004. Urbaniak received the 2016 Prime Minister's Prize for Excellence in Science Teaching for her skills-based teaching program and contributions to the field of education. == Early life and education == Urbaniak attended the Australian National University from 1984 to 1988, where she studied geology and received several student accolades. She then graduated with a Diploma of Secondary Education from Edith Cowan University in 2003. == Career == Following her graduation, Urbaniak worked as a geologist for Newcrest. In 2004, she transitioned to a career in education, becoming a science teacher at Kent Street Senior High School in Perth. Her teaching approach focuses on developing young scientists by emphasizing hands-on learning, field trips, and real-world scientific practices. In addition to her teaching responsibilities, Urbaniak has launched various initiatives to promote earth sciences and STEM principles in her curriculum. She introduced the bi-annual Kent Street Women in Mining Day, which provides female students with networking opportunities and


id: virginia-uribe-20260505-0
file: data/en.wikipedia.org/wiki/Virginia_Uribe-0.md
category: reference
title: Virginia Uribe
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Virginia_Uribe
date_saved: 2026-05-05T10:45:34.134629+00:00
instance: kb-cron
parent: virginia-uribe-20260505-0
summary:
Dr. Virginia Uribe (December 20, 1933 - March 30, 2019) was an American educator, counselor and LGBT youth education outreach advocate. She was best known for founding the Los Angeles Unified School District's Project 10 program, an educational support and drop-out prevention program for LGBT youth, and the nonprofit arm of the Project 10 program, Friends of Project 10 Inc. == Personal life == Uribe was born in Los Angeles, and lived her entire life in Pasadena, California. She grew up in an Italian family, living with parents and her grandparents in the same household. She went to Catholic school throughout elementary school, high school, and college. Her grandparents were immigrants and "intensely" patriotic and believed the United States to be a land of opportunity. Their sense of fairness, working class sensibilities, and liberal ideals shaped her world view. Uribe felt that her family was supportive of her throughout her childhood, which gave her the mindset and strength needed to advocate for youth. Uribe felt her deepest attractions towards women. During her time as a student, she found herself sexually attracted to nuns at the Catholic schools she attended. While these desires remained mostly hidden, Uribe believed that some of


id: carl-von-voit-20260505-0
file: data/en.wikipedia.org/wiki/Carl_von_Voit-0.md
category: reference
title: Carl von Voit
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carl_von_Voit
date_saved: 2026-05-05T10:45:35.290076+00:00
instance: kb-cron
parent: carl-von-voit-20260505-0
summary:
Carl von Voit (31 October 1831 – 31 January 1908) was a German physiologist and dietitian. == Biography == Voit was born in Amberg, the son of August von Voit and Mathilde Burgett. From 1848 to 1854 he studied at the universities of Munich and Würzburg. At Munich, his teachers were Justus von Liebig and Max Joseph Pettenkofer, and at Würzburg, he was a pupil of Albert von Kölliker. In 1855 he furthered his education at the University of Göttingen under chemist Friedrich Wohler, and in 1856/57 served as an assistant to Theodor von Bischoff in Munich. In 1857, he obtained his habilitation, and from 1863 was a full professor of physiology, as well as curator of the physiological collection at the University of Munich. == Contributions == Carl von Voit is considered by many to be the "father" of modern dietetics. As a chemist and physiologist, he found that the amount of nitrogen in excreted urea is a measure for the protein turnover. Using a respiration calorimeter, he could measure the contribution of individual nutrients, known as Voitsche Kostmaß. He was also a successful teacher, attracting international students to the University of Munich and thus significantly influencing the US


id: wilhelm-heinrich-waagen-20260505-0
file: data/en.wikipedia.org/wiki/Wilhelm_Heinrich_Waagen-0.md
category: reference
title: Wilhelm Heinrich Waagen
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Wilhelm_Heinrich_Waagen
date_saved: 2026-05-05T10:45:36.497967+00:00
instance: kb-cron
parent: wilhelm-heinrich-waagen-20260505-0
summary:
Wilhelm Heinrich Waagen (23 June 1841 – 24 March 1900) was a German geologist and paleontologist. He was born in Munich and died in Vienna. He worked from 1870 to 1875 in the Geological Survey of India. He was a professor of paleontology at the University of Vienna from 1890. == Life and work == Waagen was born in Munich, the son of a Prussian councillor and his wife, Nanette (née Schechner), who had been a singer. He studied locally and attended the lectures of Karl Theodor Ernst von Siebold and Albert Oppel at the University of Munich before going to the University of Zurich where he studied natural sciences. His first work was on the Jurassic of France, Swabia and Switzerland published in 1864. He received a Doctor of Philosophy degree at the University of Munich under Albert Oppel where he studied the rocks and fossils of the Jurassic system, and published an elaborate work on geology (Versuch einer Allgemeinen Classification der Schichten des oberen Jura) that was crowned by the university. In 1866, he became an instructor in paleontology at the University of Munich and at the same time taught Princess Theresa and Prince Arnulf of Bavaria. In


id: johann-andreas-wagner-20260505-0
file: data/en.wikipedia.org/wiki/Johann_Andreas_Wagner-0.md
category: reference
title: Johann Andreas Wagner
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Johann_Andreas_Wagner
date_saved: 2026-05-05T10:45:37.685183+00:00
instance: kb-cron
parent: johann-andreas-wagner-20260505-0
summary:
Johann Andreas Wagner (21 March 1797 – 17 December 1861) was a German palaeontologist, zoologist and archaeologist who wrote several important works on palaeontology. He was also a pioneer of biogeographical theory. == Career == Wagner was born in Nuremberg and received a PhD from the University of Erlangen in 1826 after spending some time in the University of Wurzburg (1814–16). He worked as a privatdozent at Erlangen after a tour that included a visit to Paris. In 1832 he became an adjunct to Gotthilf Heinrich von Schubert at the Munich zoological collection. In 1835 he was elected to the Royal Bavarian Academy of Science. In 1845 he organized a survey of the distributions of 44 vertebrates (16 mammals, 27 birds, 1 reptile) across the districts of Bavaria under auspices of the Kingdom of Bavaria. In 1849 he was made third curator for the zoological collections. He was the author of Die Geographische Verbreitung der Säugethiere Dargestellt (1844–1846). In this work he recognized the zone around Mexico, Honduras and Nicaragua as being occupied by a mix of Nearctic and Neotropical fauna. This had also been suggested by Karl Illiger and Heinrich Lichtenstein. But Wagner produced some of the earliest biogeographical


id: alan-walker-anthropologist-20260505-0
file: data/en.wikipedia.org/wiki/Alan_Walker_(anthropologist)-0.md
category: reference
title: Alan Walker (anthropologist)
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alan_Walker_(anthropologist)
date_saved: 2026-05-05T10:45:38.834334+00:00
instance: kb-cron
parent: alan-walker-anthropologist-20260505-0
summary:
Alan Cyril Walker (23 August 1938 – 20 November 2017) was the Evan Pugh Professor of Biological Anthropology and Biology at the Pennsylvania State University and a research scientist for the National Museum of Kenya. == Life == He received his B.A. from Cambridge University in 1962, and his PhD from the University of London in 1967. In 2000 he received an honorary D.Sc. from the University of Chicago. Walker was a paleoanthropologist who worked on primate and human evolution. Walker was a member of the team led by Richard Leakey responsible for the 1984 discovery of the skeleton of the so-called Turkana Boy, and in 1985 Walker himself discovered the Black Skull near Lake Turkana in Kenya. == Awards == Walker was awarded a MacArthur Fellowship "genius grant" in 1988. In 1997 he received the Rhône-Poulenc Award from the Royal Society for The Wisdom of the Bones co-authored with Pat Shipman. During the award ceremony, Terry Pratchett, chairman of the judges, said "We were fascinated by the way the forensic net was spread out, bringing so many sciences to bear on the mystery of this million-year-old teenager." The following year he received the International Fondation Fyssen Prize in Paris.


id: christian-samuel-weiss-20260505-0
file: data/en.wikipedia.org/wiki/Christian_Samuel_Weiss-0.md
category: reference
title: Christian Samuel Weiss
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Christian_Samuel_Weiss
date_saved: 2026-05-05T10:45:39.985589+00:00
instance: kb-cron
parent: christian-samuel-weiss-20260505-0
summary:
Christian Samuel Weiss (26 February 1780 – 1 October 1856) was a German mineralogist born in Leipzig. Following graduation, he worked as a physics instructor in Leipzig from 1803 until 1808. and in the meantime, conducted geological studies of mountain formations in Tyrol, Switzerland and France (1806–08). In 1810 he became a professor of mineralogy at the University of Berlin, where in 1818/19 and 1832/33, he served as university rector. He died near Eger in Bohemia. Weiss is credited for creating parameters of modern crystallography, and was instrumental in making it a branch of mathematical science. He stressed the significance of direction in crystals, considering crystallographic axes to be a possible basis for classification of crystals. He is credited for introducing the categorization schema of crystal systems, and has a basic law of crystallography named after him called the "Weiss zone law". == Works by Weiss that have been translated into English == "On the methodical and natural distribution of the different systems of crystallisation" Edinburgh : Printed for A. Constable, 1823. "On the crystallographic discoveries and systems of Mohs and Weiss" (with Friedrich Mohs); Edinburgh : Printed for A. Constable, 1823. == See also == Geometrical crystallography before X-rays


id: alice-whitley-20260505-0
file: data/en.wikipedia.org/wiki/Alice_Whitley-0.md
category: reference
title: Alice Whitley
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alice_Whitley
date_saved: 2026-05-05T10:45:41.204508+00:00
instance: kb-cron
parent: alice-whitley-20260505-0
summary:
Dr Alice Whitley (6 February 1913 – 15 August 1990) was an Australian chemist and educator. Whitley focused on the science education of women and was for 50 years a faculty member at her alma mater Methodist Ladies' College (now known as the MLC School). She worked as a science teacher and headmistress. Whitley served as president of the Australian Science Teachers Association and the Association of Heads of Independent Girls' Schools. == Early life and education == Alice Whitley was born on 6 February 1913 to Alfred and May Whitley in Stanmore, New South Wales. She attended Methodist Ladies' College, Burwwod, commencing in 1921 and was Dux of College in 1930. She earned a degree in Science from the University of Sydney. == Teaching career == Whitley then taught mathematics at Brighton College, Manly and at SCEGGS Moss Vale, and was a science and mathematics teacher at MLC from 1941 to 1952. From 1952 to 1954, Whitley attended the University of London where she earned a PhD for her thesis in chemistry before returning to MLC as Head of Science and Deputy Headmistress from 1955 to 1959. She was Headmistress of MLC from 1960 until 1972. She was the


id: herbert-ward-wilson-20260505-0
file: data/en.wikipedia.org/wiki/Herbert_Ward_Wilson-0.md
category: reference
title: Herbert Ward Wilson
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Herbert_Ward_Wilson
date_saved: 2026-05-05T10:45:42.381372+00:00
instance: kb-cron
parent: herbert-ward-wilson-20260505-0
summary:
Herbert Ward Wilson (29 September 1877 – 1 October 1955) was an Australian science lecturer and naturalist. == Education == B.Com. 1sth computer eng. == World War 1 == Wilson's studies were interrupted by the First World War. Enlisting in the Australian Imperial Forces in 1915, he served at Gallipoli and in Egypt and France, being steadily promoted and rising to the rank of Major by the time of his demobilization in 1919. He was awarded the Military Cross, the Belgian Croix de guerre and was appointed to the OBE. == Career == After the war Wilson married Myra Hester Smith in 1920. Resuming his studies, he gained a BSc in 1920 and a MSc in 1925. This was followed by a career of lecturing on biological science, and especially botany. He was a member of the Royal Australasian Ornithologists Union, the Bird Observers Club, the Microscopical Society and the Field Naturalists Club of Victoria, from the latter of which he was awarded the Australian Natural History Medallion in 1943. He died at his home in Caulfield, being survived by a son. == References ==


id: h-dieter-zeh-20260505-0
file: data/en.wikipedia.org/wiki/H._Dieter_Zeh-0.md
category: reference
title: H. Dieter Zeh
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/H._Dieter_Zeh
date_saved: 2026-05-05T10:45:43.772996+00:00
instance: kb-cron
parent: h-dieter-zeh-20260505-0
summary:
Heinz-Dieter Zeh (German: [tseː]; 8 May 1932 – 15 April 2018) was theoretical physicist and professor emeritus of the University of Heidelberg. He is known for formalizing the theory of quantum decoherence. == Education and career == H. Dieter Zeh was born in Braunschweig and studied physics at the Technical University of Braunschweig and nuclear physics at the University of Heidelberg under J. Hans D. Jensen. At Heidelberg, he also investigated alpha particle formation in nuclei with Hans Jörg Mang and Zeh investigated the topic for his PhD thesis under Mang. Between 1964 and 1965, Zeh was a research assistant at California Institute of Technology and in 1965 and between 1967 and 1968 at the University of California, San Diego. He later became a professor in Heidelberg. == Research == Zeh is known for his work on decoherence, formally described in his 1970 seminal paper. He showed that the environment plays a central role in recovering the classical limit from quantum mechanics. In his paper he discussed applications, like explaining the emergence of chirality in sugar molecules. In 1973, with Olaf Kübler, Zeh explained using a reduced density matrix why coherent states are the most classical states, and why quantum


id: chemical-process-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_process-0.md
category: reference
title: Chemical process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_process
date_saved: 2026-05-05T10:45:45.373044+00:00
instance: kb-cron
parent: chemical-process-20260505-0
summary:
In a scientific sense, a chemical process is a method or means of changing one or more chemicals or chemical compounds. Such a process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an "engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry. Neither of these definitions are exact in the sense that one can always tell definitively what is a chemical process and what is not; they are practical definitions. There is also significant overlap in these two definition variations. Because of the inexactness of the definition, chemists and other scientists use the term "chemical process" only in a general sense or in the engineering sense. However, in the "process (engineering)" sense, the term "chemical process" is used extensively. The rest of the article will cover the engineering type of chemical processes. Although this type of chemical process may sometimes involve only one step, often multiple steps, referred to as unit


id: acheson-process-20260505-0
file: data/en.wikipedia.org/wiki/Acheson_process-0.md
category: reference
title: Acheson process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Acheson_process
date_saved: 2026-05-05T10:45:46.541191+00:00
instance: kb-cron
parent: acheson-process-20260505-0
summary:
The Acheson process is a method of synthesizing silicon carbide (SiC) and graphite invented by Edward Goodrich Acheson and patented by him in 1896. == Process == The process consists of heating a mixture of silicon dioxide (SiO2), in the form of silica or quartz sand, and carbon, in its elemental form as powdered coke, in an iron bowl. In the furnace, the silicon dioxide, which sometimes also contains other additives along with ferric oxide and saw dust is melted surrounding a graphite rod, which serves as a core. These rods are inserted in such a way that they are held in contact with each other through the particles of coke, which is commonly called coke bed. An electric current is passed through the graphite rods which heats the mixture to 1700–2500 °C. The result of the carbothermic reaction is a layer of silicon carbide (especially in its alpha and beta phases) forming around the rod and emission of carbon monoxide (CO). There are four chemical reactions in the production of silicon carbide: C + SiO2 → SiO + CO SiO2 + CO → SiO + CO2 C + CO2 → 2CO SiO + 2 C → SiC + CO


id: adsorption-20260505-0
file: data/en.wikipedia.org/wiki/Adsorption-0.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) is dissolved by or permeates a liquid or solid (the absorbent). While adsorption does often precede absorption, which involves the transfer of the absorbate into the volume of the absorbent material, alternatively, adsorption is distinctly a surface phenomenon, wherein the adsorbate does not penetrate through the material surface and into the bulk of the adsorbent. The term sorption encompasses both adsorption and absorption, and desorption is the reverse of sorption. Like surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of the material are fulfilled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak


id: adsorption-20260505-1
file: data/en.wikipedia.org/wiki/Adsorption-1.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
where P {\displaystyle P} is the partial pressure of the gas or the molar concentration of the solution. For very low pressures θ ≈ K P {\displaystyle \theta \approx KP} , and for high pressures θ ≈ 1 {\displaystyle \theta \approx 1} . The value of θ {\displaystyle \theta } is difficult to measure experimentally; usually, the adsorbate is a gas and the quantity adsorbed is given in moles, grams, or gas volumes at standard temperature and pressure (STP) per gram of adsorbent. If we call vmon the STP volume of adsorbate required to form a monolayer on the adsorbent (per gram of adsorbent), then θ = v v mon {\displaystyle \theta ={\frac {v}{v_{\text{mon}}}}} , and we obtain an expression for a straight line: 1 v = 1 K v mon 1 P + 1 v mon . {\displaystyle {\frac {1}{v}}={\frac {1}{Kv_{\text{mon}}}}{\frac {1}{P}}+{\frac {1}{v_{\text{mon}}}}.} Through its slope and y intercept we can obtain vmon and K, which are constants for each adsorbent–adsorbate pair at a given temperature. vmon is related to the number of adsorption sites through the ideal gas law. If we assume that the number of sites is just the whole area of the solid divided into the


id: adsorption-20260505-2
file: data/en.wikipedia.org/wiki/Adsorption-2.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
As SD is dictated by factors that are taken into account by the Langmuir model, SD can be assumed to be the adsorption rate constant. However, the rate constant for the Kisliuk model (R') is different from that of the Langmuir model, as R' is used to represent the impact of diffusion on monolayer formation and is proportional to the square root of the system's diffusion coefficient. The Kisliuk adsorption isotherm is written as follows, where θ(t) is fractional coverage of the adsorbent with adsorbate, and t is immersion time: d θ ( t ) d t = R ′ ( 1 − θ ) ( 1 + k E θ ) . {\displaystyle {\frac {d\theta _{(t)}}{dt}}=R'(1-\theta )(1+k_{\text{E}}\theta ).} Solving for θ(t) yields: θ ( t ) = 1 − e − R ′ ( 1 + k E ) t 1 + k E e − R ′ ( 1 + k E ) t . {\displaystyle \theta _{(t)}={\frac {1-e^{-R'(1+k_{\text{E}})t}}{1+k_{\text{E}}e^{-R'(1+k_{\text{E}})t}}}.} === Adsorption enthalpy === Adsorption constants are equilibrium constants, therefore they obey the Van 't Hoff equation: ( ∂ ln ⁡ K ∂ 1 T ) θ = − Δ H R . {\displaystyle \left({\frac {\partial \ln K}{\partial {\frac


id: adsorption-20260505-3
file: data/en.wikipedia.org/wiki/Adsorption-3.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
The plot of n a d s {\displaystyle n_{ads}} adsorbed versus χ {\displaystyle \chi } is referred to as the chi plot. For flat surfaces, the slope of the chi plot yields the surface area. Empirically, this plot was noticed as being a very good fit to the isotherm by Michael Polanyi and also by Jan Hendrik de Boer and Cornelis Zwikker but not pursued. This was due to criticism in the former case by Albert Einstein and in the latter case by Brunauer. This flat surface equation may be used as a "standard curve" in the normal tradition of comparison curves, with the exception that the porous sample's early portion of the plot of n a d s {\displaystyle n_{ads}} versus χ {\displaystyle \chi } acts as a self-standard. Ultramicroporous, microporous, and mesoporous conditions may be analyzed using this technique. Typical standard deviations for full isotherm fits including porous samples are less than 2%. Notice that in this description of physical adsorption, the entropy of adsorption is consistent with the Dubinin thermodynamic criterion, that is the entropy of adsorption from the liquid state to the adsorbed state is approximately zero. == Adsorbents == === Characteristics and general requirements ===


id: adsorption-20260505-4
file: data/en.wikipedia.org/wiki/Adsorption-4.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
== Water adsorption == The adsorption of water at surfaces is of broad importance in chemical engineering, materials science, and catalysis. Also termed surface hydration, the presence of physically or chemically adsorbed water at the surfaces of solids plays an important role in governing interface properties, chemical reaction pathways, and catalytic performance in a wide range of systems. In the case of physically adsorbed water, surface hydration can be eliminated simply through drying at conditions of temperature and pressure allowing full vaporization of water. For chemically adsorbed water, hydration may be in the form of either dissociative adsorption, where H2O molecules are dissociated into surface adsorbed -H and -OH, or molecular adsorption (associative adsorption) where individual water molecules remain intact == Adsorption solar heating and storage == The low cost ($200/ton) and high cycle rate (2,000 ×) of synthetic zeolites such as Linde 13X with water adsorbate has garnered much academic and commercial interest recently for use for thermal energy storage (TES), specifically of low-grade solar and waste heat. Several pilot projects have been funded in the EU from 2000 to the present (2020). The basic concept is to store solar thermal energy as chemical latent energy in the zeolite.


id: adsorption-20260505-5
file: data/en.wikipedia.org/wiki/Adsorption-5.md
category: reference
title: Adsorption
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Adsorption
date_saved: 2026-05-05T10:45:47.677105+00:00
instance: kb-cron
parent: adsorption-20260505-0
summary:
== Adsorption spillover == In the case catalytic or adsorbent systems where a metal species is dispersed upon a support (or carrier) material (often quasi-inert oxides, such as alumina or silica), it is possible for an adsorptive species to indirectly adsorb to the support surface under conditions where such adsorption is thermodynamically unfavorable. The presence of the metal serves as a lower-energy pathway for gaseous species to first adsorb to the metal and then diffuse on the support surface. This is possible because the adsorbed species attains a lower energy state once it has adsorbed to the metal, thus lowering the activation barrier between the gas phase species and the support-adsorbed species. Hydrogen spillover is the most common example of an adsorptive spillover. In the case of hydrogen, adsorption is most often accompanied with dissociation of molecular hydrogen (H2) to atomic hydrogen (H), followed by spillover of the hydrogen atoms present. The spillover effect has been used to explain many observations in heterogeneous catalysis and adsorption. == Polymer adsorption == Adsorption of molecules onto polymer surfaces is central to a number of applications, including development of non-stick coatings and in various biomedical devices. Polymers may also be adsorbed to surfaces


id: aeration-20260505-0
file: data/en.wikipedia.org/wiki/Aeration-0.md
category: reference
title: Aeration
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aeration
date_saved: 2026-05-05T10:45:48.840057+00:00
instance: kb-cron
parent: aeration-20260505-0
summary:
Aeration (also called aerification or aeriation) is the process by which air is circulated through, mixed with or dissolved in a liquid or other substances that act as a fluid (such as soil). Aeration processes create additional surface area in the mixture, allowing greater chemical or suspension reactions. == Aeration of liquids == === Methods === Aeration of liquids (usually water) is achieved by: passing air through the liquid by means of the Venturi tube, aeration turbines or compressed air which can be combined with diffuser(s) air stone(s), as well as fine bubble diffusers, coarse bubble diffusers or linear aeration tubing. Ceramics are suitable for this purpose, often involving dispersion of fine air or gas bubbles through the porous ceramic into a liquid. The smaller the bubbles, the more gas is exposed to the liquid increasing the gas transfer efficiency. Diffusers or spargers can also be designed into the system to cause turbulence or mixing if desired. Porous ceramic diffusers are made by fusing aluminum oxide grains using porcelain bonds to form a strong, uniformly porous and homogeneous structure. The naturally hydrophilic material is easily wetted resulting in the production of fine, uniform bubbles. On a given volume of air


id: alkali-manufacture-20260505-0
file: data/en.wikipedia.org/wiki/Alkali_manufacture-0.md
category: reference
title: Alkali manufacture
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alkali_manufacture
date_saved: 2026-05-05T10:45:50.015803+00:00
instance: kb-cron
parent: alkali-manufacture-20260505-0
summary:
Alkali manufacture is the process by which an alkali is made. Typical alkalis, produced commercially, include sodium hydroxide, sodium carbonate, potassium hydroxide and potassium carbonate. == The lime process == Historically, sodium hydroxide was produced by treating sodium carbonate (usually from seaweed ash or "glasswort"-plant ash) with calcium hydroxide (aka lime) in a metathesis reaction. (Sodium hydroxide is soluble while calcium carbonate is not.) This process was called causticizing. Ca ( OH ) 2 ( aq ) + Na 2 CO 3 ( s ) ⟶ CaCO 3 ↓ + 2 NaOH ( aq ) {\displaystyle {\ce {Ca(OH)2(aq) + Na2CO3(s) -> CaCO3 v + 2 NaOH(aq)}}} == The Leblanc process == The Leblanc process, which was invented by Nicolas Leblanc around 1790, begins with the decomposition of sodium chloride by sulfuric acid, by which sodium sulfate and hydrochloric acid are produced. The sodium sulfate is afterwards fired with calcium carbonate and coal. Sodium carbonate can be extracted from this mixture by washing the mixture with water. Until the rise of the ammonia-soda process, which has better economics, the Leblanc process was used extensively making the United Kingdom the lead in alkali production. By the early 20th century, the UK's production


id: alkaline-water-electrolysis-20260505-0
file: data/en.wikipedia.org/wiki/Alkaline_water_electrolysis-0.md
category: reference
title: Alkaline water electrolysis
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alkaline_water_electrolysis
date_saved: 2026-05-05T10:45:51.241822+00:00
instance: kb-cron
parent: alkaline-water-electrolysis-20260505-0
summary:
Alkaline water electrolysis is a type of electrolysis that is characterized by having two electrodes operating in a liquid alkaline electrolyte. Commonly, a solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH) at 25-40 wt% is used. These electrodes are separated by a diaphragm, separating the product gases and transporting the hydroxide ions (OH−) from one electrode to the other. A recent comparison showed that state-of-the-art nickel based water electrolysers with alkaline electrolytes lead to competitive or even better efficiencies than acidic polymer electrolyte membrane water electrolysis with platinum group metal based electrocatalysts. The technology has a long history in the chemical industry. The first large-scale demand for hydrogen emerged in late 19th century for lighter-than-air aircraft, and before the advent of steam reforming in the 1930s, the technique was competitive. Hydrogen-based technologies have evolved significantly since the initial discovery of hydrogen and its early application as a buoyant gas approximately 250 years ago. In 1804, the Swiss inventor Francois Isaac de Rivaz secured a patent for the inaugural hydrogen-powered vehicle. This prototype, equipped with a four-wheel design, utilised an internal combustion engine (ICE) fuelled by a mixture of hydrogen and oxygen gases. The hydrogen fuel was stored in a


id: alkylation-20260505-0
file: data/en.wikipedia.org/wiki/Alkylation-0.md
category: reference
title: Alkylation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alkylation
date_saved: 2026-05-05T10:45:52.443136+00:00
instance: kb-cron
parent: alkylation-20260505-0
summary:
Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents. == Nucleophilic alkylating agents == Nucleophilic alkylating agents deliver the equivalent of an alkyl anion (carbanion). The formal "alkyl anion" attacks an electrophile, forming a new covalent bond between the alkyl group and the electrophile. The counterion, which is a cation such as lithium, can be removed and washed away in the work-up. Examples include the use of organometallic compounds such as Grignard (organomagnesium), organolithium, organocopper, and organosodium reagents. These compounds typically can add to an electron-deficient carbon atom such as at


id: alkylation-20260505-1
file: data/en.wikipedia.org/wiki/Alkylation-1.md
category: reference
title: Alkylation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Alkylation
date_saved: 2026-05-05T10:45:52.443136+00:00
instance: kb-cron
parent: alkylation-20260505-0
summary:
C 2 H 4 + CH 3 CO 2 H ⟶ CH 3 CO 2 C 2 H 5 {\displaystyle {\ce {C2H4 + CH3CO2H -> CH3CO2C2H5}}} == In biology == Alkylation in biology causes DNA damage. It is the transfer of alkyl groups to the nitrogenous bases. It is caused by alkylating agents such as EMS (Ethyl methanesulfonate). Bifunctional alkyl groups which have two alkyl groups in them cause cross linking in DNA. Alkylation damaged ring nitrogen bases are repaired via the base excision repair (BER) pathway. == Commodity chemicals == Several commodity chemicals are produced by alkylation. Included are several fundamental benzene-based feedstocks such as ethylbenzene (precursor to styrene), cumene (precursor to phenol and acetone), linear alkylbenzene sulfonates (for detergents). == Gasoline production == In a conventional oil refinery, isobutane is alkylated with low-molecular-weight alkenes (primarily a mixture of propene and butene) in the presence of a Brønsted acid catalyst, which can include solid acids (zeolites). The catalyst protonates the alkenes (propene, butene) to produce carbocations, which alkylate isobutane. The product, called "alkylate", is composed of a mixture of high-octane, branched-chain paraffinic hydrocarbons (mostly isoheptane and isooctane). Alkylate is a premium gasoline blending stock because it has exceptional antiknock


id: aludel-20260505-0
file: data/en.wikipedia.org/wiki/Aludel-0.md
category: reference
title: Aludel
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Aludel
date_saved: 2026-05-05T10:45:53.667093+00:00
instance: kb-cron
parent: aludel-20260505-0
summary:
An aludel (Arabic: ﺍﻟﻮﺛﻞ al-ūṯal from Greek αἰθαλίων aithaliōn, 'smoky, sooty, burnt-colored') is a subliming pot used in alchemy. The term refers to a range of earthen tubes, or pots without bottoms, fitted one over another, and diminishing as they advance towards the top. The lowest is adapted to a pot, placed in a furnace, wherein the matter to be sublimed is placed. At the top is a head to retain the flowers, or condensation, which ascends. An aludel was used as a condenser in the sublimation process and thus came to signify the end-stages of transformation and the symbol of creation. Also called the Hermetic Vase, the Philosopher's Egg, and the Vase of the Philosophy. == Description == The aludel is illustrated in a Pseudo-Geber treatise, in the Bibliotheca Chemica Curiosa of Jean-Jacques Manget, and in a Syriac alchemy manuscript conserved in the British Museum. It is mentioned in the "Mafātīḥ al-ʿUlūm" ("Key of Sciences") of al-Khwarazmi. == See also == Alembic == References == This article incorporates text from a publication now in the public domain: Chambers, Ephraim, ed. (1728). "Aludels". Cyclopædia, or an Universal Dictionary of Arts and Sciences. Vol. 1 (1st ed.). James and John Knapton,


id: ames-process-20260505-0
file: data/en.wikipedia.org/wiki/Ames_process-0.md
category: reference
title: Ames process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ames_process
date_saved: 2026-05-05T10:45:54.883880+00:00
instance: kb-cron
parent: ames-process-20260505-0
summary:
The Ames process is a process by which pure uranium metal is obtained. It can be achieved by mixing any of the uranium halides (commonly uranium tetrafluoride) with magnesium metal powder or aluminium metal powder. == History == The Ames process was used on August 3, 1942, by a group of chemists led by Frank Spedding and Harley Wilhelm at the Ames Laboratory as part of the Manhattan Project. It is a type of thermite-based purification, which was patented in 1895 by German chemist Hans Goldschmidt. Development of the Ames process came at a time of increased research into mass uranium-metal production. The desire for increased production was motivated by a fear of Nazi Germany's developing nuclear weapons before the Allies. The process originally involved mixing powdered uranium tetrafluoride and powdered magnesium together. This mixture was placed inside an iron pipe that was welded shut on one side and capped shut on another side. This container, called a "bomb" by Spedding, was placed into a furnace. When heated to a temperature of 1,500 °C (2,730 °F), the contents of the container reacted violently, leaving a 35-gram ingot of pure uranium metal. The process was quickly scaled up; by October 1942


id: amine-gas-treating-20260505-0
file: data/en.wikipedia.org/wiki/Amine_gas_treating-0.md
category: reference
title: Amine gas treating
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Amine_gas_treating
date_saved: 2026-05-05T10:45:56.042709+00:00
instance: kb-cron
parent: amine-gas-treating-20260505-0
summary:
Amine gas treating, also known as amine scrubbing, gas sweetening and acid gas removal, refers to a group of processes that use aqueous solutions of various alkylamines (commonly referred to simply as amines) to remove hydrogen sulfide (H2S) and carbon dioxide (CO2) from gases. It is a common unit process used in refineries, and is also used in petrochemical plants, natural gas processing plants and other industries. Processes within oil refineries or chemical processing plants that remove hydrogen sulfide are referred to as "sweetening" processes because the odor of the processed products is improved by the absence of "sour" hydrogen sulfide. An alternative to the use of amines involves membrane technology. However, membrane separation is less attractive due to the relatively high capital and operating costs as well as other technical factors. Many different amines are used in gas treating: Diethanolamine (DEA) Monoethanolamine (MEA) Methyldiethanolamine (MDEA) Diisopropanolamine (DIPA) Aminoethoxyethanol (Diglycolamine) (DGA) The most commonly used amines in industrial plants are the alkanolamines DEA, MEA, and MDEA. These amines are also used in many oil refineries to remove sour gases from liquid hydrocarbons such as liquified petroleum gas (LPG). == Description of a typical amine treater == Gases containing H2S or


id: amine-gas-treating-20260505-1
file: data/en.wikipedia.org/wiki/Amine_gas_treating-1.md
category: reference
title: Amine gas treating
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Amine_gas_treating
date_saved: 2026-05-05T10:45:56.042709+00:00
instance: kb-cron
parent: amine-gas-treating-20260505-0
summary:
Monoethanolamine: About 20 % for removing H2S and CO2, and about 30 % for removing only CO2, where the plant metallurgy is appropriate. Diethanolamine: About 25 to 35 % removing H2S and CO2 Methyldiethanolamine: About 30 to 55 % for removing H2S and CO2 Diglycolamine: About 40 to 50 % for removing H2S and CO2 The choice of amine concentration in the circulating aqueous solution depends upon several factors, involving the composition of the feed gas natural gas or petroleum refinery by-product gases that contain relatively low concentrations of both H2S and CO2 or whether the unit is treating gases with a high percentage of CO2 such as the offgas from the steam reforming process used in ammonia production or the flue gases from power plants. Both H2S and CO2 are acid gases and hence corrosive to unprotected carbon steel. Their corrosiveness are greatly enhanced in the presence of moisture. However, in an amine treating unit, CO2 is a stronger acid than H2S. Furthermore hydrogen sulfide can form a passivating film of iron sulfide that may act to protect the steel. When treating gases with a high percentage of CO2, control of the CO2 loading in the amine is important


id: amine-gas-treating-20260505-2
file: data/en.wikipedia.org/wiki/Amine_gas_treating-2.md
category: reference
title: Amine gas treating
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Amine_gas_treating
date_saved: 2026-05-05T10:45:56.042709+00:00
instance: kb-cron
parent: amine-gas-treating-20260505-0
summary:
Low pressure gas increases difficulty of transferring CO2 from the gas into amine Oxygen content of the gas can cause amine degradation and acid formation CO2 degradation of primary (and secondary) amines High energy consumption Very large facilities Finding a suitable location (enhanced oil recovery, deep saline aquifers, basaltic rocks...) to dispose of the removed CO2 The partial pressure is the driving force to transfer CO2 into the liquid phase. Under low pressure, this transfer is hard to achieve without increasing the reboilers' heat duty, which will result in higher costs. Primary and secondary amines, for example, MEA and DEA, will react with CO2 and form degradation products. O2 from the inlet gas will cause degradation as well. The degraded amine is no longer able to capture CO2, which decreases the overall carbon capture efficiency. Currently, a variety of amine mixtures are being synthesized and tested to achieve a more desirable set of overall properties for use in CO2 capture systems. One major focus is on lowering the energy required for solvent regeneration, which has a major impact on process costs. However, there are trade-offs to consider. For example, the energy required for regeneration is typically related to the driving


id: ammonia-production-20260505-0
file: data/en.wikipedia.org/wiki/Ammonia_production-0.md
category: reference
title: Ammonia production
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ammonia_production
date_saved: 2026-05-05T10:45:57.215847+00:00
instance: kb-cron
parent: ammonia-production-20260505-0
summary:
Ammonia production takes place worldwide, mostly in large-scale manufacturing plants that produce 240 million metric tonnes of ammonia (2023) annually. Based on the annual production in 2023 the major part (~70%) of the production facilities are based in China (29%), India (9.5%), USA (9.5%), Russia (9.5%), Indonesia (4%), Iran (2.9%), Egypt (2.7%), and middle Saudi Arabia (2.7%). 80% or more of ammonia is used as fertilizer. Ammonia is also used for the production of plastics, fibres, explosives, nitric acid (via the Ostwald process), and intermediates for dyes and pharmaceuticals. The industry contributes 1% to 2% of global CO2. Between 18–20 Mt of the gas is transported globally each year. == History == === Dry distillation === Before the start of World War I, most ammonia was obtained by the dry distillation of nitrogenous vegetable and animal products; by the reduction of nitrous acid and nitrites with hydrogen; and also by the decomposition of ammonium salts by alkaline hydroxides or by quicklime, the salt most generally used being the chloride (sal-ammoniac). === Frank–Caro process === Adolph Frank and Nikodem Caro found that Nitrogen could be fixed by using the same calcium carbide produced to make acetylene to form calcium-cyanamide, which could


id: ammonia-production-20260505-1
file: data/en.wikipedia.org/wiki/Ammonia_production-1.md
category: reference
title: Ammonia production
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ammonia_production
date_saved: 2026-05-05T10:45:57.215847+00:00
instance: kb-cron
parent: ammonia-production-20260505-0
summary:
=== Small-scale onsite plants === In April 2017, Japanese company Tsubame BHB implemented a method of ammonia synthesis that could allow economic production at scales 1-2 orders of magnitude below than ordinary plants with utilizing electrochemical catalyst. == Green ammonia == In 2024, the BBC announced numerous companies were attempting to reduce the 2% of global carbon dioxide emissions caused by the use/production of ammonia by producing the product in labs. The industry has become known as "green ammonia." When an existing blast furnace is modified to use biomass as its fuel, production of both green steel and green hydrogen/ammonia are feasible. == Byproducts and shortages due to shutdowns == One of the main industrial byproducts of ammonia production is CO2. In 2018, high oil prices resulted in an extended summer shutdown of European ammonia factories causing a commercial CO2 shortage, thus limiting production of CO2-based products such as beer and soft drinks. This situation repeated in September 2021 due to a 250-400% increase in the wholesale price of natural gas over the course of the year. == See also == Ammonia Amine gas treating Haber process Liquid nitrogen wash Hydrogen economy Methane pyrolysis == References == === Works cited


id: anodic-protection-20260505-0
file: data/en.wikipedia.org/wiki/Anodic_protection-0.md
category: reference
title: Anodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Anodic_protection
date_saved: 2026-05-05T10:45:58.383409+00:00
instance: kb-cron
parent: anodic-protection-20260505-0
summary:
Anodic protection (AP) otherwise referred to as Anodic Control is a technique to control the corrosion of a metal surface by making it the anode of an electrochemical cell and controlling the electrode potential in a zone where the metal is passive. Anodic protection is used to protect metals that exhibit passivation in environments whereby the current density in the freely corroding state is significantly higher than the current density in the passive state over a wide range of potentials. Anodic protection is used for carbon steel storage tanks containing extreme pH environments including concentrated sulfuric acid and 50 percent caustic soda where cathodic protection is not suitable due to very high current requirements. In anodic protection potentiostat is used to maintain a metal at constant potential with respect to reference electrode. Out of three terminals of the potentiostat one is connected to tank to be protected, another to an auxiliary cathode (platinum) and the third to reference electrode. Thus, a potentiostat maintains a constant potential between tank and reference electrode. An anodic protection system includes an external power supply connected to auxiliary cathodes and controlled by a feedback signal from one or more reference electrodes. Careful design and control


id: anthraquinone-process-20260505-0
file: data/en.wikipedia.org/wiki/Anthraquinone_process-0.md
category: reference
title: Anthraquinone process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Anthraquinone_process
date_saved: 2026-05-05T10:45:59.550481+00:00
instance: kb-cron
parent: anthraquinone-process-20260505-0
summary:
The anthraquinone process, also called the Riedl–Pfleiderer process, is a process for the production of hydrogen peroxide, which was developed by IG Farben in the 1940s. The industrial production of hydrogen peroxide is based on the reduction of oxygen, as in the direct synthesis from the elements. Instead of hydrogen itself, however, a 2-alkyl-anthrahydroquinone, which is generated before from the corresponding 2-alkyl-anthraquinone by catalytic hydrogenation with palladium is used. Oxygen and the organic phase react under formation of the anthraquinone and hydrogen peroxide. Among other alkyl groups (R) ethyl- and tert-butyl- are used, e.g., 2-ethylanthraquinone. The hydrogen peroxide is then extracted with water and in a second step separated by fractional distillation from the water. The hydrogen peroxide accumulates as sump product. The anthraquinone acts as a catalyst, the overall reaction equation is therefore: H2 + O2 → H2O2 If ozone is used instead of oxygen, dihydrogen trioxide can be produced by this method. == References == == External links == The manufacture of hydrogen peroxide Archived 2019-02-03 at the Wayback Machine


id: asymmetric-hydrogenation-20260505-0
file: data/en.wikipedia.org/wiki/Asymmetric_hydrogenation-0.md
category: reference
title: Asymmetric hydrogenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Asymmetric_hydrogenation
date_saved: 2026-05-05T10:46:00.770091+00:00
instance: kb-cron
parent: asymmetric-hydrogenation-20260505-0
summary:
Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity. Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction. This allows spatial information (what chemists refer to as chirality) to transfer from one molecule to the target, forming the product as a single enantiomer. The chiral information is most commonly contained in a catalyst and, in this case, the information in a single molecule of catalyst may be transferred to many substrate molecules, amplifying the amount of chiral information present. Similar processes occur in nature, where a chiral molecule like an enzyme can catalyse the introduction of a chiral centre to give a product as a single enantiomer, such as amino acids, that a cell needs to function. By imitating this process, chemists can generate many novel synthetic molecules that interact with biological systems in specific ways, leading to new pharmaceutical agents and agrochemicals. The importance of asymmetric hydrogenation in both academia and industry contributed to two of its pioneers — William Standish Knowles and Ryōji Noyori — being collectively awarded one half of the 2001 Nobel


id: asymmetric-hydrogenation-20260505-1
file: data/en.wikipedia.org/wiki/Asymmetric_hydrogenation-1.md
category: reference
title: Asymmetric hydrogenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Asymmetric_hydrogenation
date_saved: 2026-05-05T10:46:00.770091+00:00
instance: kb-cron
parent: asymmetric-hydrogenation-20260505-0
summary:
hydrides, which transfer to the unsaturated substrate diamines, which interact with substrate and with base activator by the second coordination sphere diphosphine, which confers asymmetry. The "Noyori-class" of catalysts are often referred to as bifunctional catalysts to emphasize the fact that both the metal and the (amine) ligand are functional. In the hydrogenation of C=O containing substrates, the mechanism was long assumed to operate by a six membered pericyclic transition state/intermediate whereby the hydrido ruthenium hydride center (HRu-NH) interacts with the carbonyl substrate R2C=O. More recent DFT and experimental studies have shown that this model is largely incorrect. Instead, the amine backbone interacts strongly with the base activator, which often is used in large excess. However in both cases, the substrate does not bond directly with the metal centre, thus making it a great example of an outer sphere mechanism. == Metals == Practical AH employ platinum metal-based catalysts. === Base metals === Iron is a popular research target for many catalytic processes, owing largely to its low cost and low toxicity relative to other transition metals. Asymmetric hydrogenation methods using iron have been realized, although in terms of rates and selectivity, they are inferior to catalysts based on precious


id: asymmetric-hydrogenation-20260505-2
file: data/en.wikipedia.org/wiki/Asymmetric_hydrogenation-2.md
category: reference
title: Asymmetric hydrogenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Asymmetric_hydrogenation
date_saved: 2026-05-05T10:46:00.770091+00:00
instance: kb-cron
parent: asymmetric-hydrogenation-20260505-0
summary:
Conversely to the case of olefins, asymmetric hydrogenation of enamines has favoured diphosphine-type ligands; excellent results have been achieved with both iridium- and rhodium-based systems. However, even the best systems often suffer from low ee's and a lack of generality. Certain pyrrolidine-derived enamines of aromatic ketones are amenable to asymmetrically hydrogenation with cationic rhodium(I) phosphonite systems, and I2 and acetic acid system with ee values usually above 90% and potentially as high as 99.9%. A similar system using iridium(I) and a very closely related phosphoramidite ligand is effective for the asymmetric hydrogenation of pyrrolidine-type enamines where the double bond was inside the ring: in other words, of dihydropyrroles. In both cases, the enantioselectivity dropped substantially when the ring size was increased from five to six. === Imines and ketones === Ketones and imines are related functional groups, and effective technologies for the asymmetric hydrogenation of each are also closely related. Early examples are Noyori's ruthenium-chiral diphosphine-diamine system. For carbonyl and imine substrates, end-on, η1 coordination can compete with η2 mode. For η1-bound substrates, the hydrogen-accepting carbon is removed from the catalyst and resists hydrogenation. Iridium/P,N ligand-based systems have been effective for some ketones and imines. For example, a consistent system


id: asymmetric-hydrogenation-20260505-3
file: data/en.wikipedia.org/wiki/Asymmetric_hydrogenation-3.md
category: reference
title: Asymmetric hydrogenation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Asymmetric_hydrogenation
date_saved: 2026-05-05T10:46:00.770091+00:00
instance: kb-cron
parent: asymmetric-hydrogenation-20260505-0
summary:
An alternative technique and one that allows more control over the structural and electronic properties of active catalytic sites is the immobilization of catalysts that have been developed for homogeneous catalysis on a heterogeneous support. Covalent bonding of the catalyst to a polymer or other solid support is perhaps most common, although immobilization of the catalyst may also be achieved by adsorption onto a surface, ion exchange, or even physical encapsulation. One drawback of this approach is the potential for the proximity of the support to change the behaviour of the catalyst, lowering the enantioselectivity of the reaction. To avoid this, the catalyst is often bound to the support by a long linker though cases are known where the proximity of the support can actually enhance the performance of the catalyst. The final approach involves the construction of MOFs that incorporate chiral reaction sites from a number of different components, potentially including chiral and achiral organic ligands, structural metal ions, catalytically active metal ions, and/or preassembled catalytically active organometallic cores. One of these involved ruthenium-based catalysts. As little as 0.005 mol% of such catalysts proved sufficient to achieve the asymmetric hydrogenation of aryl ketones, although the usual conditions featured 0.1


id: atomic-layer-etching-20260505-0
file: data/en.wikipedia.org/wiki/Atomic_layer_etching-0.md
category: reference
title: Atomic layer etching
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Atomic_layer_etching
date_saved: 2026-05-05T10:46:01.933848+00:00
instance: kb-cron
parent: atomic-layer-etching-20260505-0
summary:
Atomic layer etching (ALE) is an emerging technique in semiconductor manufacture, in which a sequence alternating between self-limiting chemical modification steps which affect only the top atomic layers of the wafer, and etching steps which remove only the chemically-modified areas, allows the removal of individual atomic layers. The standard example is etching of silicon by alternating reaction with chlorine and etching with argon ions. This is a better-controlled process than reactive ion etching, though the issue with commercial use of it has been throughput; sophisticated gas handling is required, and removal rates of one atomic layer per second are around the state of the art. The equivalent process for depositing material is atomic layer deposition (ALD). ALD is substantially more mature, having been used by Intel for high-κ dielectric layers since 2007 and in Finland in the fabrication of thin film electroluminescent devices since 1985. == See also == Single layer etching == References == == External links == ECS-JSS focus journal on atomic layer etch Overview of atomic layer etching in the semiconductor industry


id: atomic-vapor-laser-isotope-separation-20260505-0
file: data/en.wikipedia.org/wiki/Atomic_vapor_laser_isotope_separation-0.md
category: reference
title: Atomic vapor laser isotope separation
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Atomic_vapor_laser_isotope_separation
date_saved: 2026-05-05T10:46:03.097326+00:00
instance: kb-cron
parent: atomic-vapor-laser-isotope-separation-20260505-0
summary:
Atomic vapor laser isotope separation (AVLIS) is a method by which specially tuned lasers are used to separate isotopes of uranium using selective ionization of hyperfine transitions. A similar technology, using molecules instead of atoms, is molecular laser isotope separation (MLIS). Natural uranium consists of a large mass of 238U and a much smaller mass of fissile 235U. Traditionally, the 235U is separated from the mass by dissolving it in acid to produce uranium hexafluoride and then using gas centrifuges to separate the isotopes. Each trip through the centrifuge "enriches" the amount of 235U and leaves behind depleted uranium. In contrast, AVLIS produces much higher enrichment in a single step without the need to mix it with acid. The technology could, in principle, also be used for isotope separation of other elements, which is uneconomic outside specialist applications with current non-laser-based technologies for most elements. As the process does not require the feedstock to be chemically processed before enrichment, it is also suitable for use with used nuclear fuel from light water reactors and other nuclear waste. At present, extracting 235U from those sources is only economical up to a degree, leaving tons of 235U still contained in waste products.


id: ballotechnics-20260505-0
file: data/en.wikipedia.org/wiki/Ballotechnics-0.md
category: reference
title: Ballotechnics
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Ballotechnics
date_saved: 2026-05-05T10:46:04.284208+00:00
instance: kb-cron
parent: ballotechnics-20260505-0
summary:
In chemistry, ballotechnics are a class of materials that undergo a chemical reaction when quickly subjected to extreme pressures. These pressures are of the order of tens of thousands of atmospheres, and the chemical reactions are initiated by shock waves transmitted through the material. The reaction progresses with little change in volume, and are therefore not "explosive", i.e. the energy is released in the form of heat, rather than work. == Research == While most of the research performed on ballotechnics originates from Sandia National Laboratories, the researchers involved primarily focus on chemical and simulation research, not nuclear weapons research. Other research has been performed at the Georgia Institute of Technology. A critical reevaluation was written in 1995, concluding that shock compression data do not provide evidence for strong exothermic reactions, but this report was not publicly released by Sandia until 2017. == See also == Entropic explosion - The reverse of this, an explosion with a large change in volume but relatively little heat produced. == References ==


id: bayer-process-20260505-0
file: data/en.wikipedia.org/wiki/Bayer_process-0.md
category: reference
title: Bayer process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bayer_process
date_saved: 2026-05-05T10:46:05.458075+00:00
instance: kb-cron
parent: bayer-process-20260505-0
summary:
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer. Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al2O3), the rest being a mixture of silica, various iron oxides, and titanium dioxide. The aluminium oxide must be further purified before it can be refined into aluminium. The Bayer process is also the main source of gallium as a byproduct despite low extraction yields. == Process == Bauxite ore is a mixture of hydrated aluminium oxides and compounds of other elements such as iron. The aluminium compounds in the bauxite may be present as gibbsite (Al(OH)3), böhmite (γ-AlO(OH)) or diaspore (α-AlO(OH)); the different forms of the aluminium component and the impurities dictate the extraction conditions. Aluminium oxides and hydroxides are amphoteric, meaning that they are both acidic and basic. The solubility of Al(III) in water is very low but increases substantially at either high or low pH. In the Bayer process, bauxite ore is heated in a pressure vessel along with a sodium hydroxide solution (caustic soda) at a temperature of 150 to 200 °C (302 to 392 °F). At these temperatures, the aluminium


id: bayer-process-20260505-1
file: data/en.wikipedia.org/wiki/Bayer_process-1.md
category: reference
title: Bayer process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bayer_process
date_saved: 2026-05-05T10:46:05.458075+00:00
instance: kb-cron
parent: bayer-process-20260505-0
summary:
On October 4, 2010, the Ajka alumina plant in Hungary had an incident where the western dam of its red mud reservoir collapsed. The reservoir was filled with 700,000 cubic metres (25 million cubic feet) of a mixture of red mud and water with a pH of 12. The mixture was released into the valley of Torna river and flooded parts of the city of Devecser and the villages of Kolontár and Somlóvásárhely. The incident resulted in 10 deaths, more than a hundred injuries, and contamination in lakes and rivers. == History == In 1859, Henri Étienne Sainte-Claire Deville in France developed a method for making alumina by heating bauxite in sodium carbonate, Na2CO3, at 1,200 °C (2,190 °F), leaching the sodium aluminate formed with water, then precipitating aluminium hydroxide by carbon dioxide, CO2, which was then filtered and dried. This process is known as the Deville–Pechiney process. In 1886, the Hall–Héroult electrolytic aluminium process was invented, and the cyanidation process was invented in 1887. The Bayer process was invented in 1888 by Carl Josef Bayer. Working in Saint Petersburg, Russia to develop a method for supplying alumina to the textile industry (it was used as a mordant in dyeing


id: becher-process-20260505-0
file: data/en.wikipedia.org/wiki/Becher_process-0.md
category: reference
title: Becher process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Becher_process
date_saved: 2026-05-05T10:46:06.641562+00:00
instance: kb-cron
parent: becher-process-20260505-0
summary:
The Becher process is a process to produce rutile, a form of titanium dioxide, from the ore ilmenite. Although it is competitive with the chloride process and the sulfate process, the Becher process is not used on scale. With the idealized formula FeTiO3, ilmenite contains 55-65% titanium dioxide, the rest being iron oxide. The Becher process, like other beneficiation processes, aims to remove iron. The Becher process exploits the conversion of the ferrous iron (FeO) to ferric iron (Fe2O3). Ilmenite ores can be upgraded to synthetic rutile by increasing their TiO2 content to between 90 and 96 percent. == History == This technology was developed in the early 1960s in Western Australia by a joint initiative between industry and government. The process was named after Robert Gordon Becher, who while working at the Western Australian Government Chemical Laboratories (the precursor to ChemCentre) invented, developed and introduced the technique to the Western Australian Mineral Sands industry. The process was patented in 1961. == Process == The Becher process is suitable for weathered ilmenite that has low concentrations of chromium and magnesium. There are four steps involved in removing the iron portion of the ilmenite: Oxidation Reduction Aeration Leaching === Oxidation ===


id: biochemical-cascade-20260505-0
file: data/en.wikipedia.org/wiki/Biochemical_cascade-0.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
A biochemical cascade, also known as a signaling cascade or signaling pathway, is a series of chemical reactions that occur within a biological cell when initiated by a stimulus. This stimulus, known as a first messenger, acts on a receptor that is transduced to the cell interior through second messengers which amplify the signal and transfer it to effector molecules, causing the cell to respond to the initial stimulus. Most biochemical cascades are series of events, in which one event triggers the next, in a linear fashion. At each step of the signaling cascade, various controlling factors are involved to regulate cellular actions, in order to respond effectively to cues about their changing internal and external environments. An example would be the coagulation cascade of secondary hemostasis which leads to fibrin formation, and thus, the initiation of blood coagulation. Another example, sonic hedgehog signaling pathway, is one of the key regulators of embryonic development and is present in all bilaterians. Signaling proteins give cells information to make the embryo develop properly. When the pathway malfunctions, it can result in diseases like basal cell carcinoma. Recent studies point to the role of hedgehog signaling in regulating adult stem cells involved in


id: biochemical-cascade-20260505-1
file: data/en.wikipedia.org/wiki/Biochemical_cascade-1.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Examples of biochemical cascades === In biochemistry, several important enzymatic cascades and signal transduction cascades participate in metabolic pathways or signaling networks, in which enzymes are usually involved to catalyze the reactions. For example, the tissue factor pathway in the coagulation cascade of secondary hemostasis is the primary pathway leading to fibrin formation, and thus, the initiation of blood coagulation. The pathways are a series of reactions, in which a zymogen (inactive enzyme precursor) of a serine protease and its glycoprotein co-factors are activated to become active components that then catalyze the next reaction in the cascade, ultimately resulting in cross-linked fibrin. Another example, sonic hedgehog signaling pathway, is one of the key regulators of embryonic development and is present in all bilaterians. Different parts of the embryo have different concentrations of hedgehog signaling proteins, which give cells information to make the embryo develop properly and correctly into a head or a tail. When the pathway malfunctions, it can result in diseases like basal cell carcinoma. Recent studies point to the role of hedgehog signaling in regulating adult stem cells involved in maintenance and regeneration of adult tissues. The pathway has also been implicated in the development of some


id: biochemical-cascade-20260505-2
file: data/en.wikipedia.org/wiki/Biochemical_cascade-2.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Neurons === Purinergic signalling has an essential role at interactions between neurons and glia cells, allowing these to detect action potentials and modulate neuronal activity, contributing for intra and extracellular homeostasis regulation. Besides purinergic neurotransmitter, ATP acts as a trophic factor at cellular development and growth, being involved on microglia activation and migration, and also on axonal myelination by oligodendrocytes. There are two main types of purinergic receptors, P1 binding to adenosine, and P2 binding to ATP or ADP, presenting different signalling cascades. The Nrf2/ARE signalling pathway has a fundamental role at fighting against oxidative stress, to which neurons are especially vulnerable due to its high oxygen consumption and high lipid content. This neuroprotective pathway involves control of neuronal activity by perisynaptic astrocytes and neuronal glutamate release, with the establishment of tripartite synapses. The Nrf2/ARE activation leads to a higher expression of enzymes involved in glutathione syntheses and metabolism, that have a key role in antioxidant response. The LKB1/NUAK1 signalling pathway regulates terminal axon branching at cortical neurons, via local immobilized mitochondria capture. Besides NUAK1, LKB1 kinase acts under other effectors enzymes as SAD-A/B and MARK, therefore regulating neuronal polarization and axonal growth, respectively. These kinase cascades implicates also


id: biochemical-cascade-20260505-3
file: data/en.wikipedia.org/wiki/Biochemical_cascade-3.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Lymphocytes === The main goal of biochemical cascades in lymphocytes is the secretion of molecules that can suppress altered cells or eliminate pathogenic agents, through proliferation, differentiation and activation of these cells. Therefore, the antigenic receptors play a central role in signal transduction in lymphocytes, because when antigens interact with them lead to a cascade of signal events. These receptors, that recognize the antigen soluble (B cells) or linked to a molecule on Antigen Presenting Cells (T cells), do not have long cytoplasm tails, so they are anchored to signal proteins, which contain a long cytoplasmic tails with a motif that can be phosphorylated (ITAM – immunoreceptor tyrosine-based activation motif) and resulting in different signal pathways. The antigen receptor and signal protein form a stable complex, named BCR or TCR, in B or T cells, respectively. The family Src is essential for signal transduction in these cells, because it is responsible for phosphorylation of ITAMs. Therefore, Lyn and Lck, in lymphocytes B and T, respectively, phosphorylate immunoreceptor tyrosine-based activation motifs after the antigen recognition and the conformational change of the receptor, which leads to the binding of Syk/Zap-70 kinases to ITAM and its activation. Syk kinase is specific of


id: biochemical-cascade-20260505-4
file: data/en.wikipedia.org/wiki/Biochemical_cascade-4.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Stem cells === Self-renewal and differentiation abilities are exceptional properties of stem cells. These cells can be classified by their differentiation capacity, which progressively decrease with development, in totipotents, pluripotents, multipotents and unipotents. Self-renewal process is highly regulated from cell cycle and genetic transcription control. There are some signaling pathways, such as LIF/JAK/STAT3 (Leukemia inhibitory factor/Janus kinase/Signal transducer and activator of transcription 3) and BMP/SMADs/Id (Bone morphogenetic proteins/ Mothers against decapentaplegic/ Inhibitor of differentiation), mediated by transcription factors, epigenetic regulators and others components, and they are responsible for self-renewal genes expression and inhibition of differentiation genes expression, respectively. At cell cycle level there is an increase of complexity of the mechanisms in somatic stem cells. However, it is observed a decrease of self-renewal potential with age. These mechanisms are regulated by p16Ink4a-CDK4/6-Rb and p19Arf-p53-P21Cip1 signaling pathways. Embryonic stem cells have constitutive cyclin E-CDK2 activity, which hyperphosphorylates and inactivates Rb. This leads to a short G1 phase of the cell cycle with rapid G1-S transition and little dependence on mitogenic signals or D cyclins for S phase entry. In fetal stem cells, mitogens promote a relatively rapid G1-S transition through cooperative action of cyclin D-CDK4/6 and cyclin E-CDK2 to inactivate


id: biochemical-cascade-20260505-5
file: data/en.wikipedia.org/wiki/Biochemical_cascade-5.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Spermatozoon === Spermatozoon is the male gamete. After ejaculation this cell is not mature, so it can not fertilize the oocyte. To have the ability to fertilize the female gamete, this cell suffers capacitation and acrosome reaction in female reproductive tract. The signaling pathways best described for spermatozoon involve these processes. The cAMP/PKA signaling pathway leads to sperm cells capacitation; however, adenylyl cyclase in sperm cells is different from the somatic cells. Adenylyl cyclase in spermatozoon does not recognize G proteins, so it is stimulated by bicarbonate and Ca2+ ions. Then, it converts adenosine triphosphate into cyclic AMP, which activates Protein kinase A. PKA leads to protein tyrosine phosphorylation. Phospholipase C (PLC) is involved in acrosome reaction. ZP3 is a glycoprotein present in zona pelucida and it interacts with receptors in spermatozoon. So, ZP3 can activate G protein coupled receptors and tyrosine kinase receptors, that leads to production of PLC. PLC cleaves the phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) into diacyl glycerol (DAG) and inositol 1,4,5-trisphosphate. IP3 is released as a soluble structure into the cytosol and DAG remains bound to the membrane. IP3 binds to IP3 receptors, present in acrosome membrane. In addition, calcium and DAG together work to activate


id: biochemical-cascade-20260505-6
file: data/en.wikipedia.org/wiki/Biochemical_cascade-6.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
Legend: Y – Yes, N – No; BIND – Biomolecular Interaction Network Database, DIP – Database of Interacting Proteins, GNPV – Genome Network Platform Viewer, HPRD = Human Protein Reference Database, MINT – Molecular Interaction database, MIPS – Munich Information center for Protein Sequences, UNIHI – Unified Human Interactome, OPHID – Online Predicted Human Interaction Database, EcoCyc – Encyclopaedia of E. Coli Genes and Metabolism, MetaCyc – aMetabolic Pathway database, KEGG – Kyoto Encyclopedia of Genes and Genomes, PANTHER – Protein Analysis Through Evolutionary Relationship database, STKE – Signal Transduction Knowledge Environment, PID – The Pathway Interaction Database, BioPP – Biological Pathway Publisher. A comprehensive list of resources can be found at http://www.pathguide.org. == Pathway-related databases and tools == === KEGG === The increasing amount of genomic and molecular information is the basis for understanding higher-order biological systems, such as the cell and the organism, and their interactions with the environment, as well as for medical, industrial and other practical applications. The KEGG resource provides a reference knowledge base for linking genomes to biological systems, categorized as building blocks in the genomic space (KEGG GENES), the chemical space (KEGG LIGAND), wiring diagrams of interaction networks and reaction networks (KEGG PATHWAY),


id: biochemical-cascade-20260505-7
file: data/en.wikipedia.org/wiki/Biochemical_cascade-7.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
== Pathway-oriented approaches == In the post-genomic age, high-throughput sequencing and gene/protein profiling techniques have transformed biological research by enabling comprehensive monitoring of a biological system, yielding a list of differentially expressed genes or proteins, which is useful in identifying genes that may have roles in a given phenomenon or phenotype. With DNA microarrays and genome-wide gene engineering, it is possible to screen global gene expression profiles to contribute a wealth of genomic data to the public domain. With RNA interference, it is possible to distill the inferences contained in the experimental literature and primary databases into knowledge bases that consist of annotated representations of biological pathways. In this case, individual genes and proteins are known to be involved in biological processes, components, or structures, as well as how and where gene products interact with each other. Pathway-oriented approaches for analyzing microarray data, by grouping long lists of individual genes, proteins, and/or other biological molecules according to the pathways they are involved in into smaller sets of related genes or proteins, which reduces the complexity, have proven useful for connecting genomic data to specific biological processes and systems. Identifying active pathways that differ between two conditions can have more explanatory


id: biochemical-cascade-20260505-8
file: data/en.wikipedia.org/wiki/Biochemical_cascade-8.md
category: reference
title: Biochemical cascade
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Biochemical_cascade
date_saved: 2026-05-05T10:46:07.942614+00:00
instance: kb-cron
parent: biochemical-cascade-20260505-0
summary:
=== Alzheimer's disease (AD) === Synaptic degeneration and death of nerve cells are defining features of Alzheimer's disease (AD), the most prevalent age-related neurodegenerative disorders. In AD, neurons in the hippocampus and basal forebrain (brain regions that subserve learning and memory functions) are selectively vulnerable. Studies of postmortem brain tissue from AD people have provided evidence for increased levels of oxidative stress, mitochondrial dysfunction and impaired glucose uptake in vulnerable neuronal populations. Studies of animal and cell culture models of AD suggest that increased levels of oxidative stress (membrane lipid peroxidation, in particular) may disrupt neuronal energy metabolism and ion homeostasis, by impairing the function of membrane ion-motive ATPases, glucose and glutamate transporters. Such oxidative and metabolic compromise may thereby render neurons vulnerable to excitotoxicity and apoptosis. Recent studies suggest that AD can manifest systemic alterations in energy metabolism (e.g., increased insulin resistance and dysregulation of glucose metabolism). Emerging evidence that dietary restriction can forestall the development of AD is consistent with a major "metabolic" component to these disorders, and provides optimism that these devastating brain disorders of aging may be largely preventable. == References == == External links == KEGG resource DAVID tools Archived 16 September 2014 at the


id: bioconversion-20260505-0
file: data/en.wikipedia.org/wiki/Bioconversion-0.md
category: reference
title: Bioconversion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bioconversion
date_saved: 2026-05-05T10:46:09.109620+00:00
instance: kb-cron
parent: bioconversion-20260505-0
summary:
Bioconversion, also known as biotransformation, is the conversion of organic materials, such as plant or animal waste, into usable products or energy sources by biological processes or agents, such as certain microorganisms. One example is the industrial production of cortisone, which one step is the bioconversion of progesterone to 11-alpha-Hydroxyprogesterone by Rhizopus nigricans. Another example is the bioconversion of glycerol to 1,3-propanediol, which is part of scientific research for many decades. Another example of bioconversion is the conversion of organic materials, such as plant or animal waste, into usable products or energy sources by biological processes or agents, such as certain microorganisms, some detritivores or enzymes. In the US, the Bioconversion Science and Technology group performs multidisciplinary R&D for the Department of Energy's (DOE) relevant applications of bioprocessing, especially with biomass. Bioprocessing combines the disciplines of chemical engineering, microbiology and biochemistry. The Group 's primary role is investigation of the use of microorganism, microbial consortia and microbial enzymes in bioenergy research. New cellulosic ethanol conversion processes have enabled the variety and volume of feedstock that can be bioconverted to expand rapidly. Feedstock now includes materials derived from plant or animal waste such as paper, auto-fluff, tires, fabric, construction materials, municipal


id: birkeland-eyde-process-20260505-0
file: data/en.wikipedia.org/wiki/Birkeland–Eyde_process-0.md
category: reference
title: Birkeland–Eyde process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Birkeland–Eyde_process
date_saved: 2026-05-05T10:46:10.310451+00:00
instance: kb-cron
parent: birkeland-eyde-process-20260505-0
summary:
The Birkeland–Eyde process was one of the competing industrial processes in the beginning of nitrogen-based fertilizer production. It is a multi-step nitrogen fixation reaction that uses electrical arcs to react atmospheric nitrogen (N2) with oxygen (O2), ultimately producing nitric acid (HNO3) with water. The resultant nitric acid was then used as a source of nitrate (NO−3) in the reaction HNO3 + H2O → H3O+ + NO−3 which may take place in the presence of water or another proton acceptor. It was developed by Norwegian industrialist and scientist Kristian Birkeland along with his business partner Sam Eyde in 1903, based on a method used by Henry Cavendish in 1784. A factory based on the process was built in Rjukan and Notodden in Norway, combined with the building of large hydroelectric power facilities. The Birkeland–Eyde process is relatively inefficient in terms of energy consumption. Therefore, in the 1910s and 1920s, it was gradually replaced in Norway by a combination of the Haber process and the Ostwald process. The Haber process produces ammonia (NH3) from molecular nitrogen (N2) and hydrogen (H2), the latter usually but not necessarily produced by steam reforming methane (CH4) gas in current practice. The ammonia from the Haber process


id: bleaching-of-wood-pulp-20260505-0
file: data/en.wikipedia.org/wiki/Bleaching_of_wood_pulp-0.md
category: reference
title: Bleaching of wood pulp
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bleaching_of_wood_pulp
date_saved: 2026-05-05T10:46:11.463710+00:00
instance: kb-cron
parent: bleaching-of-wood-pulp-20260505-0
summary:
Bleaching of wood pulp is the chemical processing of wood pulp to lighten its color and whiten the pulp. The primary product of wood pulp is paper, for which whiteness (similar to, but distinct from brightness) is an important characteristic. These processes and chemistry are also applicable to the bleaching of non-wood pulps, such as those made from bamboo or kenaf. == Paper brightness == Brightness is the amount of incident light reflected from paper under specified conditions, usually reported as the percentage of light reflected, so a higher number means a brighter or whiter paper. In the US, the TAPPI T 452 or T 525 standards are used. The international community uses ISO standards. The table shows how the two systems rate high-brightness papers, but there is no simple way to convert between the two systems because the test methods are so different. The ISO rating is higher and can be over 100. This is because contemporary white paper incorporates fluorescent whitening agents (FWA). Because the ISO standard only measures a narrow range of blue light, it is not directly comparable to human vision of whiteness or brightness. Newsprint ranges from 55 to 75 ISO brightness. Writing and printer


id: bleaching-of-wood-pulp-20260505-1
file: data/en.wikipedia.org/wiki/Bleaching_of_wood_pulp-1.md
category: reference
title: Bleaching of wood pulp
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bleaching_of_wood_pulp
date_saved: 2026-05-05T10:46:11.463710+00:00
instance: kb-cron
parent: bleaching-of-wood-pulp-20260505-0
summary:
Cl2 + H2O ⇌ H+ + Cl− + HClO At pH > 8 the dominant species is hypochlorite, ClO−, which is also useful for lignin removal. Sodium hypochlorite can be purchased or generated in situ by reacting chlorine with sodium hydroxide: 2 NaOH + Cl2 ⇌ NaOCl + NaCl + H2O The main objection to the use of chlorine for bleaching pulp is the large amounts of soluble organochlorine compounds produced and released into the environment. === Chlorine dioxide === Chlorine dioxide, ClO2 is an unstable gas with moderate solubility in water. It is usually generated in an aqueous solution and used immediately because it decomposes and is explosive in higher concentrations. It is produced by reacting sodium chlorate with a reducing agent like sulfur dioxide: 2 NaClO3 + H2SO4 + SO2 → 2 ClO2 + 2 NaHSO4 Chlorine dioxide is sometimes used in combination with chlorine, but it is used alone in ECF (elemental-chlorine-free) bleaching sequences. It is used at moderately acidic pH (3.5 to 6). The use of chlorine dioxide minimizes the amount of organochlorine compounds produced. Chlorine dioxide (ECF technology) currently is the most important bleaching method worldwide. About 95% of all bleached kraft pulp is made


id: bleaching-of-wood-pulp-20260505-2
file: data/en.wikipedia.org/wiki/Bleaching_of_wood_pulp-2.md
category: reference
title: Bleaching of wood pulp
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bleaching_of_wood_pulp
date_saved: 2026-05-05T10:46:11.463710+00:00
instance: kb-cron
parent: bleaching-of-wood-pulp-20260505-0
summary:
The bleaching of chemical pulps has the potential to cause significant environmental damage, primarily through the release of organic materials into waterways. Pulp mills are almost always located near large bodies of water because they require substantial quantities of water for their processes. An increased public awareness of environmental issues from the 1970s and 1980s, as evidenced by the formation of organizations like Greenpeace, influenced the pulping industry and governments to address the release of these materials into the environment. Conventional bleaching using elemental chlorine produces and releases into the environment large amounts of chlorinated organic compounds, including chlorinated dioxins. Dioxins are recognized as a persistent environmental pollutant, regulated internationally by the Stockholm Convention on Persistent Organic Pollutants. Dioxins are highly toxic, and health effects on humans include reproductive, developmental, immune and hormonal problems. They are known to be carcinogenic. Over 90% of human exposure is through food, primarily meat, dairy, fish and shellfish, as dioxins accumulate in the food chain in the fatty tissue of animals. As a result, from the 1990s onwards, the use of elemental chlorine in the delignification process was substantially reduced and replaced with ECF (elemental chlorine free) and TCF (totally chlorine free) bleaching processes.


id: bma-process-20260505-0
file: data/en.wikipedia.org/wiki/BMA_process-0.md
category: reference
title: BMA process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/BMA_process
date_saved: 2026-05-05T10:46:12.608080+00:00
instance: kb-cron
parent: bma-process-20260505-0
summary:
The BMA process or Degussa process is a chemical process developed by the German chemical company Degussa for the production of hydrogen cyanide from methane and ammonia in presence of a platinum catalyst. Hydrogen cyanide is used in the chemical industry for the production of intermediate chemicals like acrylonitrile, methyl methacrylate, and adiponitrile. The name is abbreviated from Blausäure (hydrogen cyanide) from Methan (methane) and Ammoniak (ammonia) in German. The reaction equation is analog to the steam methane reforming (SMR) reaction of methane and water: CH4 + NH3 → HCN + 3 H2, ΔHR = 251 kJ / mol The reaction is extremely endothermic. The reactants react in a Platinum-covered pipe at approximately 1400 °C. The reaction mixture contains around 23 Vol.-% HCN and 72 Vol.-% H2 as well as minor quantities of ammonia, nitrogen, and unreacted methane. The gaseous mixture is introduced in a scrubber and treated with an ammonia solution (producing ammonium cyanide) allowing the other gaseous components: H2, CH4, and N2 to pass through. In a second step the HCN is released by acidification of the solution, followed by a final distillation of the hydrogen cyanide. Because of the highly endothermic reaction, the BMA process is of


id: boiler-blowdown-20260505-0
file: data/en.wikipedia.org/wiki/Boiler_blowdown-0.md
category: reference
title: Boiler blowdown
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Boiler_blowdown
date_saved: 2026-05-05T10:46:13.787359+00:00
instance: kb-cron
parent: boiler-blowdown-20260505-0
summary:
Boiler blowdown is water intentionally wasted from a boiler to avoid concentration of impurities during continuing evaporation of steam. The water is blown out of the boiler with some force by steam pressure within the boiler. Bottom blowdown used with early boilers caused abrupt downward adjustment of boiler water level and was customarily expelled downward to avoid the safety hazard of showering hot water on nearby individuals. == Background == A steam boiler evaporates liquid water to form steam, or gaseous water, and requires frequent replenishment of boiler feedwater for the continuous production of steam required by most boiler applications. Water is a capable solvent, and will dissolve small amounts of solids from piping and containers including the boiler. Continuing evaporation of steam concentrates dissolved impurities until they reach levels potentially damaging to steam production within the boiler. Without blowdown, impurities would reach saturation levels and begin to precipitate within the boiler. Impurity concentrations are highest where steam is being produced near heat exchange surfaces. Precipitation would be expected to occur in the form of scale deposits on those heat exchange surfaces. Scale deposits thermally insulate heat exchange surfaces initially decreasing the rate of steam generation, and potentially causing boiler


id: borax-method-20260505-0
file: data/en.wikipedia.org/wiki/Borax_method-0.md
category: reference
title: Borax method
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Borax_method
date_saved: 2026-05-05T10:46:14.970192+00:00
instance: kb-cron
parent: borax-method-20260505-0
summary:
The borax method is a technique of artisanal gold mining, which uses borax as a flux to purify gold concentrates. By using borax, no mercury flour is produced, hence gold recovery increases. == History == The borax method of gold extraction has been used by artisanal gold miners in the Benguet area north of Manila in the Philippines for more than 30 years. Some believe it was in practice as early as the 1900s. The method is increasingly being seen as a safe alternative to the widespread use of toxic mercury in artisanal gold mining today. About 30% of the world's mercury emissions comes from small scale mining. Efforts are being made to revive the method and spread its use. As of 2012, around 15,000 artisanal gold miners in a small area of Luzon, the main island in the northern portion of the Philippines, use this method exclusively. The mineral is inexpensive and easily available, and the miners have reportedly found that more gold is recovered through its use. == Chemistry == In contrast to the use of mercury (which relies on amalgamation of the gold to coalesce it and separate it from impurities) this method relies on borax's ability


id: bosch-meiser-process-20260505-0
file: data/en.wikipedia.org/wiki/Bosch–Meiser_process-0.md
category: reference
title: Bosch–Meiser process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Bosch–Meiser_process
date_saved: 2026-05-05T10:46:16.158874+00:00
instance: kb-cron
parent: bosch-meiser-process-20260505-0
summary:
The Bosch–Meiser process is an industrial process for the large-scale manufacturing of urea, a valuable nitrogenous chemical. It was patented in 1922 and named after its discoverers, the German chemists Carl Bosch and Wilhelm Meiser. The whole process consists of two main equilibrium reactions, with incomplete conversion of the reactants. The first, called carbamate formation: the fast exothermic reaction of liquid ammonia with gaseous carbon dioxide (CO2) at high temperature and pressure to form ammonium carbamate ([NH4]+[NH2COO]−): 2 NH3 + CO2 ⇌ [NH4]+[NH2COO]− (ΔH = −117 kJ/mol at 110 atm and 160 °C) The second, called urea conversion: the slower endothermic decomposition of ammonium carbamate into urea and water: [NH4]+[NH2COO]− ⇌ CO(NH2)2 + H2O (ΔH = +15.5 kJ/mol at 160–180 °C) The overall conversion of NH3 and CO2 to urea is exothermic, with the reaction heat from the first reaction driving the second. The conditions that favor urea formation (high temperature) have an unfavorable effect on the carbamate formation equilibrium. The process conditions are a compromise: the ill-effect on the first reaction of the high temperature (around 190 °C) needed for the second is compensated for by conducting the process under high pressure (140–175 bar), which favors the first reaction.


id: brin-process-20260505-0
file: data/en.wikipedia.org/wiki/Brin_process-0.md
category: reference
title: Brin process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Brin_process
date_saved: 2026-05-05T10:46:17.336792+00:00
instance: kb-cron
parent: brin-process-20260505-0
summary:
Brin process is a now-obsolete industrial scale production process for oxygen. In this process barium oxide reacts at 500–600 °C with air to form barium peroxide which decomposes at above 800 °C by releasing oxygen. 2 BaO + O2 ⇌ 2 BaO2 The reaction was discovered by Joseph-Louis Gay-Lussac and Louis-Jacques Thenard in 1811 and Jean-Baptiste Boussingault tried to use this reaction to establish a process to produce oxygen in 1852. The process worked only for a few cycles and then became inefficient. Two students of Boussingault, Quentin and Arthur Leon Brin, discovered that traces of carbon dioxide formed barium carbonate. Removing the carbon dioxide with sodium hydroxide solved this problem. In 1884 they opened a factory producing oxygen by their improved process. In the commercial process, oxygen capture and release was controlled by pressure rather than temperature, with oxygen being captured at high pressure and released at low pressure. This allowed a faster change between the capture and release phases, which would last one to two hours. The company was first named Brins Oxygen Company after the two brothers. In 1906 it was renamed as the British Oxygen Company. One major application of the oxygen was the use for


id: burton-process-20260505-0
file: data/en.wikipedia.org/wiki/Burton_process-0.md
category: reference
title: Burton process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Burton_process
date_saved: 2026-05-05T10:46:18.510217+00:00
instance: kb-cron
parent: burton-process-20260505-0
summary:
The Burton process is a thermal cracking process invented by William Merriam Burton and Robert E. Humphreys, both of whom held a PhD in chemistry from Johns Hopkins University. The process they developed is commonly referred to as the Burton process. However, it should be recognized as the Burton-Humphreys process, as both individuals played pivotal roles in its development. The legal dispute surrounding this matter was eventually settled, although the decision primarily recognized Burton's contributions. The process involves the destructive distillation of crude oil, which is heated under pressure in a still. The innovative design of this still allows various products to emerge from a bubble tower at different temperatures and pressures. One crucial aspect of the process is that it significantly increased gasoline production from various types of oil, more than doubling the output. The first large-scale implementation of these towers occurred when Standard Oil of Indiana made the decision to construct 120 stills using an authorized budget of $709,000 in 1911. Notably, this decision coincided with the US Supreme Court's ruling to dissolve the Standard Oil Trust. This thermal cracking process was patented on January 7, 1913 (Patent No. 1,049,667). The first thermal cracking method, the Shukhov cracking


id: calcination-20260505-0
file: data/en.wikipedia.org/wiki/Calcination-0.md
category: reference
title: Calcination
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcination
date_saved: 2026-05-05T10:46:19.682635+00:00
instance: kb-cron
parent: calcination-20260505-0
summary:
Calcination is thermal treatment of a solid chemical compound (e.g. mixed carbonate ores) whereby the compound is raised to high temperature without melting with a restricted supply of oxygen (i.e. gaseous O2 fraction of air), generally for the purpose of removing impurities or volatile substances and/or to induce thermal decomposition. The root of the word calcination refers to its most prominent use, which is to remove carbon and oxygen from limestone (calcium carbonate) through applying heat to yield calcium oxide (quicklime). This calcination reaction (which is endothermic) is CaCO3(s) → CaO(s) + CO2(g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in smelting. Industrial calcination generally emits carbon dioxide (CO2). A calciner is a steel cylinder that rotates inside a heated furnace and performs indirect high-temperature processing (550–1150 °C, or 1000–2100 °F) within a controlled atmosphere. == Etymology == The process of calcination derives its name from the Latin calcinare 'to burn lime' due to its most common application, the decomposition of calcium carbonate (limestone) to calcium oxide (lime) and carbon dioxide, in order to create cement. The product of calcination is usually referred to in general as "calcine", regardless of


id: calcium-looping-20260505-0
file: data/en.wikipedia.org/wiki/Calcium_looping-0.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
Calcium looping (CaL), or the regenerative calcium cycle (RCC), is a second-generation carbon capture technology. It is the most developed form of carbonate looping, where a metal (M) is reversibly reacted between its carbonate form (MCO3) and its oxide form (MO) to separate carbon dioxide from other gases coming from either power generation or an industrial plant. For this reason, calcium looping is also known as carbonate looping. In the calcium looping process, the two species are calcium carbonate (CaCO3) and calcium oxide (CaO). The captured carbon dioxide can then be transported to a storage site, used in enhanced oil recovery or used as a chemical feedstock. Calcium oxide is often referred to as the sorbent. Calcium looping is being developed as it is a more efficient, less toxic alternative to current post-combustion capture processes such as amine scrubbing. It also has interesting potential for integration with the cement industry, as well as waste incineration and waste-to-energy plants. == Basic concept == There are two main steps in CaL: Calcination: Solid calcium carbonate is fed into a calciner, where it is heated to 850-950 °C to cause it to thermally decompose into gaseous carbon dioxide and solid calcium oxide (CaO).


id: calcium-looping-20260505-1
file: data/en.wikipedia.org/wiki/Calcium_looping-1.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
Combustion of fuel in an external chamber and conduction of energy in to the vessel Combustion of fuel in an external chamber and use of a heat transfer medium. Indirect methods are generally less efficient but do not require the provision of oxygen for combustion within the calciner to prevent dilution. The flue gas from the combustion of fuel in the indirect method could be mixed with the flue gas from the process that the CaL plant is attached to and passed through the carbonator to capture the CO2. One efficient way of transferring heat into the calciner is by means of heat pipes. The indirectly heated calcium looping (IHCaL) using heat pipes has high potential to decarbonize the lime and cement industry. The deployment of this technology with refuse-derived fuels would allow to achieve net negative CO2 emissions. == Recovery of energy from the carbonator == Although the heat from the carbonator is not at a high enough temperature to be used in the calciner, the high temperatures involved (>600 °C) mean that a relatively efficient Rankine cycle for generating electricity can be operated. Note that the waste heat from the market-leading amine scrubbing CO2 capture process is emitted


id: calcium-looping-20260505-2
file: data/en.wikipedia.org/wiki/Calcium_looping-2.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
=== Sintering === CaO is also prone to sintering, or change in pore shape, shrinkage and grain growth during heating. Ionic compounds such as CaO mostly sinter because of volume diffusion or lattice diffusion mechanics. As described by sintering theory, vacancies generated by temperature sensitive defects direct void sites from smaller to larger ones, explaining the observed growth of large pores and the shrinkage of small pores in cycled limestone. It was found that sintering of CaO increases at higher temperatures and longer calcination durations, whereas carbonation time has minimal effect on particle sintering. A sharp increase in sintering of particles is observed at temperatures above 1173 K, causing a reduction in reactive surface area and a corresponding decrease in reactivity. Solutions: Several options to reduce sorbent deactivation are currently being researched. An ideal sorbent would be mechanically strong, maintain its reactive surface through repeated cycles, and be reasonably inexpensive. Using thermally pre-activated particles or reactivating spent sorbents through hydration are two promising options. Thermally pre-activated particles have been found to retain activity for up to a thousand cycles. Similarly, particles reactivated by hydration show improved long term (after~20 cycles) conversions. Additionally, an optimized make-up strategy can maintain sufficient levels


id: calcium-looping-20260505-3
file: data/en.wikipedia.org/wiki/Calcium_looping-3.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
=== Cost per metric ton for CO2 captured === Firstly, Ca-looping offers greater cost advantage compared to conventional amine-scrubbing technologies. The cost/metric ton for CO2 captured through Ca-looping is ~$23.70 whereas that for CO2 captured through amine scrubbing is about $35–$96. This can be attributed to the high availability and low cost of the CaO sorbent (derived from limestone) as compared to MEA. Also, Ca-looping imposes a lower energy penalty than amine scrubbing, resulting in lower energy costs. The amine scrubbing process is energy intensive, with approximately 67% of the operating costs going into steam requirements for solvent regeneration. A more detailed comparison of Ca-looping and amine scrubbing is shown below. === Cost of CO2 emissions avoided through Ca-looping === In addition, the cost of CO2 emissions avoided through Ca-looping is lower than the cost of emissions avoided via an oxyfuel combustion process (~US$23.8/t). This can be explained by the fact that, despite the capital costs incurred in constructing the carbonator for Ca-looping, CO2 will not only be captured from the oxy-fired combustion, but also from the main combustor (before the carbonator). The oxygen required in the calciners is only 1/3 that required for an oxyfuel process, lowering air separation


id: calcium-looping-20260505-4
file: data/en.wikipedia.org/wiki/Calcium_looping-4.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
=== Political implications === Though many recent scientific reports (e.g.: the seven-wedge stabilization plan by Pacala and Socolow) convey an urgent need to deploy CCS, this urgency has not spread to the political establishment, mainly due to the high costs and energy penalty of CCS The economics of calcium looping are integral to its political viability. One economic and political advantage is the ability for Ca-looping to be retrofitted onto existing power plants, rather than requiring new plants to be built. The IEA sees power plants as an important target for carbon capture, and has set the goal to have all fossil fuel based power plants deploy CCS systems by 2040. However, power plants are expensive to build, and long lived. Retrofitting of post-combustion capture systems, such as Ca-looping, seems to be the only politically and economically viable way to achieve the IEA's goal. A further political advantage is the potential synergy between calcium looping and cement production. An IEA report concludes that to meet emission reduction goals, there should be 450 CCS projects in India and China by 2050. However, this could be politically difficult, especially with these nations' numerous other development goals. After all, for a politician to


id: calcium-looping-20260505-5
file: data/en.wikipedia.org/wiki/Calcium_looping-5.md
category: reference
title: Calcium looping
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Calcium_looping
date_saved: 2026-05-05T10:46:20.922266+00:00
instance: kb-cron
parent: calcium-looping-20260505-0
summary:
== Benefits of calcium looping compared with other post-combustion capture processes == Calcium looping compares favorably with several post-combustion capture technologies. Amine scrubbing is the capture technology closest to being market-ready, and calcium looping has several marked benefits over it. When modeled on a 580 MW coal-fired power plant, Calcium looping experienced not only a smaller efficiency penalty (6.7-7.9% points compared to 9.5% for monoethanolamine and 9% for chilled ammonia) but also a less complex retrofitting process. Both technologies would require the plant to be retrofitted for adoption, but the calcium looping retrofitting process would result in twice the net power output of the scrubbing technology. Furthermore, this advantage can be compounded by introducing technology such as cryogenic O2 separation systems. This ups the efficiency of the calcium looping technology by increasing the energy density by 57.4%, making the already low energy penalties even less of an issue. Calcium looping already has an energy advantage over amine scrubbing, but the main problem is that amine scrubbing is the more market-ready technology. However, the accompanying infrastructure for amine scrubbing include large solvent scrubbing towers, the likes of which have never been used on an industrial scale. The accompanying infrastructure for calcium


id: carbon-dioxide-reforming-20260505-0
file: data/en.wikipedia.org/wiki/Carbon_dioxide_reforming-0.md
category: reference
title: Carbon dioxide reforming
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carbon_dioxide_reforming
date_saved: 2026-05-05T10:46:22.090561+00:00
instance: kb-cron
parent: carbon-dioxide-reforming-20260505-0
summary:
Carbon dioxide reforming (also known as dry reforming) is a method of producing synthesis gas (mixtures of hydrogen and carbon monoxide) from the reaction of carbon dioxide with hydrocarbons such as methane with the aid of metal catalysts (typically Ni or Ni alloys). Synthesis gas is conventionally produced via the steam reforming reaction or coal gasification. In recent years, increased concerns on the contribution of greenhouse gases to global warming have increased interest in the replacement of steam as reactant with carbon dioxide. The dry reforming reaction may be represented by: CH 4 + CO 2 ⇌ 975 o C 2 CO + 2 H 2 {\displaystyle {\ce {CH4 + CO2 <=>[975^oC] 2CO + 2H2}}} Thus, two greenhouse gases are consumed and useful chemical building blocks, hydrogen and carbon monoxide, are produced. A challenge to the commercialization of this process is that the hydrogen that is produced tends to react with carbon dioxide. For example, the following reaction typically proceeds with lower activation energy than the dry reforming reaction itself: CO + H 2 O ⇌ 600 o C CO 2 + H 2 {\displaystyle {\ce {CO + H2O <=>[600^oC] CO2 + H2}}} Another issue with dry reforming is situated


id: carbonization-20260505-0
file: data/en.wikipedia.org/wiki/Carbonization-0.md
category: reference
title: Carbonization
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carbonization
date_saved: 2026-05-05T10:46:23.312060+00:00
instance: kb-cron
parent: carbonization-20260505-0
summary:
Carbonization or carbonisation is the conversion of organic matters like plants and dead animal remains into carbon through destructive distillation. == Complexity in carbonization == Carbonization is a pyrolytic reaction, therefore, is considered a complex process in which many reactions take place concurrently such as dehydrogenation, condensation, hydrogen transfer and isomerization. Carbonization differs from coalification in that it occurs much faster. For the final pyrolysis temperature, the amount of heat applied controls the degree of carbonization and the residual content of foreign elements. For example, at T ~ 1,200 K (930 °C; 1,700 °F) the carbon content of the residue exceeds a mass fraction of 90 wt.%, whereas at T ~ 1,600 K (1,330 °C; 2,420 °F) more than 99 wt.% carbon is found. Carbonization is often exothermic, which means that it could in principle be made self-sustaining and be used as a source of energy that does not produce carbon dioxide. In the case of glucose, the reaction releases about 237 calories per gram. When biomaterial is exposed to sudden searing heat (as in the case of a nuclear explosion or pyroclastic flow from a volcano, for instance), it can be carbonized extremely quickly, turning it into solid carbon.


id: carbonyl-metallurgy-20260505-0
file: data/en.wikipedia.org/wiki/Carbonyl_metallurgy-0.md
category: reference
title: Carbonyl metallurgy
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Carbonyl_metallurgy
date_saved: 2026-05-05T10:46:24.518564+00:00
instance: kb-cron
parent: carbonyl-metallurgy-20260505-0
summary:
Carbonyl metallurgy is used to manufacture products of iron, nickel, steel, and other metals. Coatings are produced by vapor plating using metal carbonyl vapors. These are metal-ligand complexes where carbon monoxide is bonded to individual atoms of metals . Iron carbonyl is stable as iron pentacarbonyl, where five carbon monoxide molecules are pendently bonded to the iron atom, while nickel carbonyl is stable as nickel tetracarbonyl, which has four carbon monoxide molecules pendantly bonded to the nickel atom. Both can be formed by the exposure of the powdered metal to carbon monoxide gas at temperatures of around 75 degrees Celsius. Both the metal carbonyls decompose near 175 °C, resulting in a vapor plated metallic coating. The thickness of the vapor plated deposit can be increased to desired thicknesses by controlling the amount of metal carbonyl used and the duration of the plating process. Vale Inco produces over 100 million pounds (ca. 45000 tonnes) of nickel metal annually by the carbonyl process. The carbonyl process has been used to produce molds in custom shapes for industry. Such molds have been used in plastic molding and other manufacturing techniques. William Jenkin developed many of the techniques and procedures used in carbonyl metallurgy.


id: castner-process-20260505-0
file: data/en.wikipedia.org/wiki/Castner_process-0.md
category: reference
title: Castner process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Castner_process
date_saved: 2026-05-05T10:46:25.678559+00:00
instance: kb-cron
parent: castner-process-20260505-0
summary:
The Castner process is a process for manufacturing sodium metal by electrolysis of molten sodium hydroxide at approximately 330 °C. Below that temperature, the melt would solidify; above that temperature, the molten sodium would start to dissolve in the melt. == History == The Castner process for production of sodium metal was introduced in 1888 by Hamilton Castner. At that time (prior to the introduction in the same year of the Hall-Héroult process) the primary use for sodium metal was as a reducing agent to produce aluminium from its purified ores. The Castner process reduced the cost of producing sodium in comparison to the old method of reducing sodium carbonate at high temperature using carbon. This in turn reduced the cost of producing aluminium, although the reduction-by-sodium method still could not compete with Hall-Héroult. The Castner process continued nevertheless due to Castner's finding new markets for sodium. In 1926, the Downs cell replaced the Castner process. == Process details == The diagram shows a ceramic crucible with a steel cylinder suspended within. Both cathode (C) and anode (A) are made of iron or nickel. The temperature is cooler at the bottom and hotter at the top so that the sodium


id: castner-kellner-process-20260505-0
file: data/en.wikipedia.org/wiki/Castner–Kellner_process-0.md
category: reference
title: Castner–Kellner process
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Castner–Kellner_process
date_saved: 2026-05-05T10:46:26.853544+00:00
instance: kb-cron
parent: castner-kellner-process-20260505-0
summary:
The Castner–Kellner process is a method of electrolysis on an aqueous alkali chloride solution (usually sodium chloride solution) to produce the corresponding alkali hydroxide, invented by American Hamilton Castner and Austrian Carl Kellner in the 1890s. It is a type of chloralkali process, but in this role it is gradually being replaced by membrane electrolysis which has lower energy cost and fewer environmental concerns. == History == The first patent for electrolyzing brine was granted in England in 1851 to Charles Watt. His process was not an economically feasible method for producing sodium hydroxide though because it could not prevent the chlorine that formed in the brine solution from reacting with its other constituents. American chemist and engineer, Hamilton Castner, solved the mixing problem with the invention of the mercury cell and was granted a U.S. patent in 1894. Austrian chemist, Carl Kellner arrived at a similar solution at about the same time. In order to avoid a legal battle they became partners in 1895, founding the Castner-Kellner Alkali Company, which built plants employing the process throughout Europe. The mercury cell process continues in use to this day. Current-day mercury cell plant operations are criticized for environmental release of mercury


id: catalytic-chain-transfer-20260505-0
file: data/en.wikipedia.org/wiki/Catalytic_chain_transfer-0.md
category: reference
title: Catalytic chain transfer
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_chain_transfer
date_saved: 2026-05-05T10:46:28.072666+00:00
instance: kb-cron
parent: catalytic-chain-transfer-20260505-0
summary:
Catalytic chain transfer (CCT) is a process that can be incorporated into radical polymerization to obtain greater control over the resulting products. == Introduction == Radical polymerization of vinyl monomers, such as methyl (metha)acrylate or vinyl acetate is a common (industrial) method to prepare polymeric materials. One of the problems associated with this method is, however, that the radical polymerisation reaction rate is so high that even at short reaction times the polymeric chains are exceedingly long. This has several practical disadvantages, especially for polymer processing (e.g. melt-processing). A solution to this problem is catalytic chain transfer, which is a way to make shorter polymer chains in radical polymerisation processes. The method involves adding a catalytic chain transfer agent to the reaction mixture of the monomer and the radical initiator. == Historical background == Boris Smirnov and Alexander Marchenko (USSR) discovered in 1975 that cobalt porphyrins are able to reduce the molecular weight of PMMA formed during radical polymerization of methacrylates. Later investigations showed that the cobalt dimethylglyoxime complexes were as effective as the porphyrin catalysts and also less oxygen sensitive. Due to their lower oxygen sensitivity these catalysts have been investigated much more thoroughly than the porphyrin catalysts and


id: catalytic-combustion-20260505-0
file: data/en.wikipedia.org/wiki/Catalytic_combustion-0.md
category: reference
title: Catalytic combustion
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_combustion
date_saved: 2026-05-05T10:46:29.243349+00:00
instance: kb-cron
parent: catalytic-combustion-20260505-0
summary:
Catalytic combustion is a chemical process which uses a catalyst to speed desired oxidation reactions of fuel and so reduce the formation of undesired products, especially pollutant nitrogen oxide gases (NOx) far below what can be achieved without catalysts. The process was discovered in the 1950s by Catalytic Combustion LLC. == Chemical process == Catalysts may be used to control combustion reactions in the following ways: fuel preparation, such as splitting long molecules into shorter ones; fuel oxidation to release heat energy; the destruction of pollutant gases in the exhaust. == Technology == Catalytic combustion was developed by Norb Ruff in the 1950s. He founded Catalytic Combustion LLC in the 1950s where he created and patented the first metal catalyst. Other early work was carried out by researchers at Acurex, Westinghouse, NASA and the United States Air Force. The technique was revisited in the 1990s, leading to two types of catalytic system: Catalytica's fuel-lean approach, and Precision Combustion's fuel-rich approach. == See also == Gas chromatography: Detectors Lanny D. Schmidt == References ==


id: catalytic-reforming-20260505-0
file: data/en.wikipedia.org/wiki/Catalytic_reforming-0.md
category: reference
title: Catalytic reforming
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_reforming
date_saved: 2026-05-05T10:46:30.409156+00:00
instance: kb-cron
parent: catalytic-reforming-20260505-0
summary:
Catalytic reforming is a chemical process used to convert naphthas from crude oil into liquid products called reformates, which are premium "blending stocks" for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking and hydrodesulfurization. A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes. In addition to a gasoline blending stock, reformate is the main source of aromatic bulk chemicals such as benzene, toluene, xylene and ethylbenzene, which have diverse uses, most importantly as raw materials for conversion into plastics. However, the benzene content of reformate makes it carcinogenic, which has led to governmental regulations effectively requiring further processing to reduce its benzene content. Catalytic reforming is quite different from and not to be confused with the catalytic steam reforming process used industrially to produce products such as hydrogen, ammonia, and methanol from natural gas, naphtha or other petroleum-derived feedstocks. Nor is this process to be confused with various other catalytic reforming processes


id: catalytic-reforming-20260505-1
file: data/en.wikipedia.org/wiki/Catalytic_reforming-1.md
category: reference
title: Catalytic reforming
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_reforming
date_saved: 2026-05-05T10:46:30.409156+00:00
instance: kb-cron
parent: catalytic-reforming-20260505-0
summary:
== Reactions == Many chemical reactions occur in the catalytic reforming process. All require the presence of a catalyst, almost always platinum-containing, and a high partial pressure of hydrogen. Depending upon the type or version of catalytic reforming used as well as the desired reaction severity, the reaction conditions range from temperatures of about 495 to 525 °C (923 to 977 °F) and from pressures of about 5 to 45 standard atmospheres (510 to 4,560 kPa). The four major catalytic reforming reactions are: The dehydrogenation of naphthenes to convert them into aromatics as exemplified in the conversion methylcyclohexane (a naphthene) to toluene (an aromatic): The isomerization of normal paraffins to isoparaffins as exemplified in the conversion of normal octane to 2,5-dimethylhexane (an "isoparaffin"): The dehydrogenation and aromatization of paraffins to aromatics (commonly called dehydrocyclization) as exemplified in the conversion of normal heptane to toluene: The hydrocracking of paraffins into smaller molecules as exemplified by the cracking of normal heptane into isopentane and ethane: During the reforming reactions, the carbon number of the reactants remains unchanged, except for hydrocracking reactions which break down the hydrocarbons. The hydrocracking of paraffins is the only one of the above four major reforming reactions that


id: catalytic-reforming-20260505-2
file: data/en.wikipedia.org/wiki/Catalytic_reforming-2.md
category: reference
title: Catalytic reforming
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_reforming
date_saved: 2026-05-05T10:46:30.409156+00:00
instance: kb-cron
parent: catalytic-reforming-20260505-0
summary:
The liquid feed (at the bottom left in the diagram) is pumped up to the reaction pressure (5–45 standard atmospheres [510–4,560 kPa]) 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 mixture is then totally vaporized and heated to the reaction temperature (495–520 °C [923–968 °F]) before the vaporized reactants enter the first reactor. As the vaporized reactants flow through the fixed bed of catalyst in the reactor, the major reaction is the dehydrogenation of naphthenes to aromatics (as described earlier herein) which is highly endothermic and results in a large temperature decrease between the inlet and outlet of the reactor. To maintain the required reaction temperature and the rate of reaction, the vaporized stream is reheated in the second fired heater before it flows through the second reactor. The temperature again decreases across the second reactor and the vaporized stream must again be reheated in the third fired heater before it flows through the third reactor. As the vaporized stream proceeds through the three reactors, the reaction rates decrease and the reactors therefore become larger. At the same time, the amount of reheat


id: catalytic-reforming-20260505-3
file: data/en.wikipedia.org/wiki/Catalytic_reforming-3.md
category: reference
title: Catalytic reforming
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_reforming
date_saved: 2026-05-05T10:46:30.409156+00:00
instance: kb-cron
parent: catalytic-reforming-20260505-0
summary:
== Weaknesses and competition == The sensitivity of catalytic reforming to contamination by sulfur and nitrogen requires hydrotreating the naphtha before it enters the reformer, adding to the cost and complexity of the process. Dehydrogenation, an important component of reforming, is a strongly endothermic reaction, and as such, requires the reactor vessel to be externally heated. This contributes both to costs and the emissions of the process. Catalytic reforming has a limited ability to process naphthas with a high content of normal paraffins, e.g. naphthas from the gas-to-liquids (GTL) units. The reformate has a much higher content of benzene than is permissible by the current regulations in many countries. This means that the reformate should either be further processed in an aromatics extraction unit, or blended with appropriate hydrocarbon streams with low content of aromatics. Catalytic reforming requires a whole range of other processing units at the refinery (apart from the distillation tower, a naphtha hydrotreater, usually an isomerization unit to process light naphtha, an aromatics extraction unit, etc.) which puts it out of reach for smaller (micro-)refineries. Main licensors of catalytic reforming processes, UOP and Axens, constantly work on improving the catalysts, but the rate of improvement seems to


id: catalytic-resonance-theory-20260505-0
file: data/en.wikipedia.org/wiki/Catalytic_resonance_theory-0.md
category: reference
title: Catalytic resonance theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_resonance_theory
date_saved: 2026-05-05T10:46:31.645312+00:00
instance: kb-cron
parent: catalytic-resonance-theory-20260505-0
summary:
In chemistry, catalytic resonance theory was developed to describe the kinetics of reaction acceleration using dynamic catalyst surfaces. Catalytic reactions occur on surfaces that undergo variation in surface binding energy and/or entropy, exhibiting overall increase in reaction rate when the surface binding energy frequencies are comparable to the natural frequencies of the surface reaction, adsorption, and desorption. == History == Catalytic resonance theory is constructed on the Sabatier principle of catalysis developed by French chemist Paul Sabatier. In the limit of maximum catalytic performance, the surface of a catalyst is neither too strong nor too weak. Strong binding results in an overall catalytic reaction rate limitation due to product desorption, while weak binding catalysts are limited in the rate of surface chemistry. Optimal catalyst performance is depicted as a 'volcano' peak using a descriptor of the chemical reaction defining different catalytic materials. Experimental evidence of the Sabatier principle was first demonstrated by Balandin in 1960. The concept of catalytic resonance was proposed on dynamic interpretation of the Sabatier volcano reaction plot. As described, extension of either side of the volcano plot above the peak defines the timescales of the two rate-limiting phenomena such as surface reaction(s) or desorption. For binding


id: catalytic-resonance-theory-20260505-1
file: data/en.wikipedia.org/wiki/Catalytic_resonance_theory-1.md
category: reference
title: Catalytic resonance theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_resonance_theory
date_saved: 2026-05-05T10:46:31.645312+00:00
instance: kb-cron
parent: catalytic-resonance-theory-20260505-0
summary:
Surface binding energy oscillation also occurs to different extent with the various chemical surface species as defined by the γi-j parameter. For any non-unity γi-j system, the asymmetry in the surface energy profile results in conducting work to bias the reaction to a steady state away from equilibrium. Similar to the controlled directionality of molecular machines, the resulting ratchet (device) energy mechanism selectively moves molecules through a catalytic reaction against a free energy gradient. Application of dynamic binding energy to a surface with multiple catalytic reactions exhibits complex behavior derived from the differences in the natural frequencies of each chemistry; these frequencies are identified by the inverse of the adsorption, desorption, and surface kinetic rate parameters. Considering a system of two parallel elementary reactions of A-to-B and A-to-C that only occur on a surface, the performance of the catalyst under dynamic conditions will result in varying capability for selecting either reaction product (B or C). For the depicted system, both reactions have the same overall thermodynamics and will produce B and C in equal amounts (50% selectivity) at chemical equilibrium. Under normal static catalyst operation, only product B can be produced at selectivities greater than 50% and product C is


id: catalytic-resonance-theory-20260505-2
file: data/en.wikipedia.org/wiki/Catalytic_resonance_theory-2.md
category: reference
title: Catalytic resonance theory
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Catalytic_resonance_theory
date_saved: 2026-05-05T10:46:31.645312+00:00
instance: kb-cron
parent: catalytic-resonance-theory-20260505-0
summary:
== Characteristics of Dynamic Surface Reactions == Catalytic reactions on surfaces exhibit an energy ratchet that biases the reaction away from equilibrium. In the simplest form, the catalyst oscillates between two states of stronger or weaker binding, which in this example is referred to as 'green' or 'blue,' respectively. For a single elementary reaction on a catalyst oscillating between two states (green & blue), there exists four rate coefficients in total, one forward (k1) and one reverse (k−1) in each catalyst state. The catalyst switches between catalyst states (j of blue or green) with a frequency, f, with the time in each catalyst state, τj, such that the duty cycle, Dj is defined for catalyst state, j, as the fraction of the time the catalyst exists in state j. For the catalyst in the 'blue' state: D B = τ B τ t o t a l {\displaystyle D_{B}={\frac {\tau _{B}}{\tau _{total}}}} The bias of a catalytic ratchet under dynamic conditions can be predicted via a ratchet directionality metric, λ, that can be calculated from the rate coefficients, ki, and the time constants of the oscillation, τi (or the duty cycle). For a catalyst oscillating between two catalyst states (blue


id: cathodic-modification-20260505-0
file: data/en.wikipedia.org/wiki/Cathodic_modification-0.md
category: reference
title: Cathodic modification
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_modification
date_saved: 2026-05-05T10:46:33.903492+00:00
instance: kb-cron
parent: cathodic-modification-20260505-0
summary:
Cathodic modification within chemistry is the retardation of anodic reaction as the result of an increase in the ability of an alloy to be passivated by the introduction of an active cathode into the alloy e.g. the alloying of stainless steel and titanium with platinum group metals (1). This is one way in which corrosion resistant alloys can be produced and the resistance of alloy against electrochemical attack increased. == See also == Cathodic protection == References == 1. Potgieter J. H., Heyns A.M., Skinner W. 1990. Cathodic modification as a means of improving the corrosion resistance of alloys. Journal of Applied Electrochemistry, 20: 711 - 715.


id: cathodic-protection-20260505-0
file: data/en.wikipedia.org/wiki/Cathodic_protection-0.md
category: reference
title: Cathodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_protection
date_saved: 2026-05-05T10:46:35.089302+00:00
instance: kb-cron
parent: cathodic-protection-20260505-0
summary:
Cathodic protection (CP; ) is a technique used to control the corrosion of a metal surface by making it the cathode of an electrochemical cell. A simple method of protection connects the metal to be protected to a more easily corroded "sacrificial metal" to act as the anode. The sacrificial metal then corrodes instead of the protected metal. For structures such as long pipelines, where passive galvanic cathodic protection is not adequate, an external DC electrical power source is used to provide sufficient current. Cathodic protection systems protect a wide range of metallic structures in various environments. Common applications are: steel water or fuel pipelines and steel storage tanks such as home water heaters; steel pier piles; ship and boat hulls; offshore oil platforms and onshore oil well casings; offshore wind farm foundations and metal reinforcement bars in concrete buildings and structures. Another common application is in galvanized steel, in which a sacrificial coating of zinc on steel parts protects them from rust. Cathodic protection can, in some cases, prevent stress corrosion cracking. == History == Cathodic protection was first described by Sir Humphry Davy in a series of papers presented to the Royal Society in London in 1824. The


id: cathodic-protection-20260505-1
file: data/en.wikipedia.org/wiki/Cathodic_protection-1.md
category: reference
title: Cathodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_protection
date_saved: 2026-05-05T10:46:35.089302+00:00
instance: kb-cron
parent: cathodic-protection-20260505-0
summary:
In some cases, impressed current cathodic protection (ICCP) systems are used. These consist of anodes connected to a DC power source, often a transformer-rectifier connected to AC power. In the absence of an AC supply, alternative power sources may be used, such as solar panels, wind power or gas powered thermoelectric generators. Anodes for ICCP systems are available in a variety of shapes and sizes. Common anodes are tubular and solid rod shapes or continuous ribbons of various materials. These include high silicon, cast iron, graphite, mixed metal oxide (MMO), platinum and niobium coated wire and other materials. For pipelines, anodes are arranged in groundbeds either distributed or in a deep vertical hole depending on several design and field condition factors including current distribution requirements. Cathodic protection transformer-rectifier units are often custom manufactured and equipped with a variety of features, including remote monitoring and control, integral current interrupters and various type of electrical enclosures. The output DC negative terminal is connected to the structure to be protected by the cathodic protection system. The rectifier output DC positive cable is connected to the anodes. The AC power cable is connected to the rectifier input terminals. The output of the ICCP system


id: cathodic-protection-20260505-2
file: data/en.wikipedia.org/wiki/Cathodic_protection-2.md
category: reference
title: Cathodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_protection
date_saved: 2026-05-05T10:46:35.089302+00:00
instance: kb-cron
parent: cathodic-protection-20260505-0
summary:
Cathodic protection on ships is often implemented by galvanic anodes attached to the hull and ICCP for larger vessels. Since ships are regularly removed from the water for inspections and maintenance, it is a simple task to replace the galvanic anodes. Galvanic anodes are generally shaped to reduced drag in the water and fitted flush to the hull to also try to minimize drag. Smaller vessels, with non-metallic hulls, such as yachts, are equipped with galvanic anodes to protect areas such as outboard motors. As with all galvanic cathodic protection, this application relies on a solid electrical connection between the anode and the item to be protected. For ICCP on ships, the anodes are usually constructed of a relatively inert material such as platinized titanium. A DC power supply is provided within the ship and the anodes mounted on the outside of the hull. The anode cables are introduced into the ship via a compression seal fitting and routed to the DC power source. The negative cable from the power supply is simply attached to the hull to complete the circuit. Ship ICCP anodes are flush-mounted, minimizing the effects of drag on the ship, and located a minimum 5 ft


id: cathodic-protection-20260505-3
file: data/en.wikipedia.org/wiki/Cathodic_protection-3.md
category: reference
title: Cathodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_protection
date_saved: 2026-05-05T10:46:35.089302+00:00
instance: kb-cron
parent: cathodic-protection-20260505-0
summary:
=== Automobiles === Several companies market electronic devices claiming to mitigate corrosion for automobiles and trucks. Corrosion control professionals find they do not work. There is no peer reviewed scientific testing and validation supporting the use of the devices. In 1996 the FTC ordered David McCready, a person that sold devices claiming to protect cars from corrosion, to pay restitution and banned the names "Rust Buster" and "Rust Evader." Under section 74.01(1) (b) of the Competition Act Canada, no performance claims about a product or its effectiveness can be done unless it can be proven that they are based on adequate and proper tests. The Competition Bureau Canada proceeded to investigate several companies selling electronic corrosion devices in Canada. Some were forced to withdraw their product from the market as they could not support their claims scientifically. == Testing == Electrode potential is measured with reference electrodes. Copper–copper sulphate electrodes are used for structures in contact with soil or fresh water. Silver/silver chloride/seawater electrodes or pure zinc electrodes are used for seawater applications. The methods are described in EN 13509:2003 and NACE TM0497 along with the sources of error in the voltage that appears on the display of the meter.


id: cathodic-protection-20260505-4
file: data/en.wikipedia.org/wiki/Cathodic_protection-4.md
category: reference
title: Cathodic protection
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Cathodic_protection
date_saved: 2026-05-05T10:46:35.089302+00:00
instance: kb-cron
parent: cathodic-protection-20260505-0
summary:
==== UK ==== Institute of Corrosion (ICorr), Corrosion Prevention Association (CPA), and TWI offer a Cathodic Protection, Training, Assessment, and Certification Scheme that evaluates the competence levels of cathodic protection personnel. ==== US ==== AMPP is the main certification body. Moreover, AMPP is highly active and known in the Middle East. == Standards == 49 CFR 192.451 - Requirements for Corrosion Control - Transportation of natural and other gas by pipeline: US minimum federal safety standards 49 CFR 195.551 - Requirements for Corrosion Control - Transportation of hazardous liquids by pipelines: US minimum federal safety standards AS 2832 - Australian Standards for Cathodic Protection ASME B31Q 0001-0191 ASTM G 8, G 42 - Evaluating Cathodic Disbondment resistance of coatings DNV-RP-B401 - Cathodic Protection Design - Det Norske Veritas EN 12068:1999 - Cathodic protection. External organic coatings for the corrosion protection of buried or immersed steel pipelines used in conjunction with cathodic protection. Tapes and shrinkable materials EN 12473:2000 - General principles of cathodic protection in sea water EN 12474:2001 - Cathodic protection for submarine pipelines EN 12495:2000 - Cathodic protection for fixed steel offshore structures EN 12499:2003 - Internal cathodic protection of metallic structures EN 12696:2012 - Cathodic protection of


id: charring-20260505-0
file: data/en.wikipedia.org/wiki/Charring-0.md
category: reference
title: Charring
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Charring
date_saved: 2026-05-05T10:46:36.280959+00:00
instance: kb-cron
parent: charring-20260505-0
summary:
Charring is a chemical process of incomplete combustion of certain solids when subjected to high heat. Heat distillation removes water vapour and volatile organic compounds (syngas) from the matrix. The residual black carbon material is char, as distinguished from the lighter colored ash. By the action of heat, charring removes hydrogen and oxygen from the solid, so that the remaining char is composed primarily of carbon. Most solid organic compounds, like wood or biological tissue, and thermoset polymers exhibit charring behaviour. In non-scientific terms, charring means partially burning so as to blacken the surface. Charring can result from naturally occurring processes like fire; it is also a deliberate and controlled reaction used in the manufacturing of certain products. The mechanism of charring is part of the normal burning of certain solid fuels like wood. During normal combustion, the volatile compounds created by charring are consumed at the flames within the fire or released to the atmosphere, while combustion of char can be seen as glowing red coals or embers which burn without the presence of flames. == Production of char == Coke and charcoal are both produced by charring, whether on an industrial scale or through normal combustion of coal


id: chemical-milling-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_milling-0.md
category: reference
title: Chemical milling
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_milling
date_saved: 2026-05-05T10:46:37.502171+00:00
instance: kb-cron
parent: chemical-milling-20260505-0
summary:
Chemical milling or industrial etching is the subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. Other names for chemical etching include photo etching, chemical etching, photo chemical etching and photochemical machining. It is mostly used on metals, though other materials are increasingly important. It was developed from armor-decorating and printing etching processes developed during the Renaissance as alternatives to engraving on metal. The process essentially involves bathing the cutting areas in a corrosive chemical known as an etchant, which reacts with the material in the area to be cut and causes the solid material to be dissolved; inert substances known as maskants are used to protect specific areas of the material as resists. == History == Organic chemicals such as lactic acid and citric acid have been used to etch metals and create products as early as 400 BCE, when vinegar was used to corrode lead and create the pigment ceruse, also known as white lead. Most modern chemical milling methods involve alkaline etchants; these may have been used as early as the first century CE. Armor etching, using strong mineral acids, was not developed until the


id: chemical-milling-20260505-1
file: data/en.wikipedia.org/wiki/Chemical_milling-1.md
category: reference
title: Chemical milling
tags: science, encyclopedia
source_url: https://en.wikipedia.org/wiki/Chemical_milling
date_saved: 2026-05-05T10:46:37.502171+00:00
instance: kb-cron
parent: chemical-milling-20260505-0
summary:
=== Scribing === Scribing is the removal of maskant on the areas to be etched. For decorative applications, this is often done by hand through the use of a scribing knife, etching needle or similar tool; modern industrial applications may involve an operator scribing with the aid of a template or use computer numerical control to automate the process. For parts involving multiple stages of etching, complex templates using colour codes and similar devices may be used. === Etching === Etching is the immersion of the part into the chemical bath, and the action of the chemical on the part to be milled. The time spent immersed in the chemical bath determines the depth of the resulting etch; this time is calculated via the formula: E = s t {\displaystyle E={\frac {s}{t}}} where E is the rate of etching (usually abbreviated to etch rate), s is the depth of the cut required, and t is the total immersion time. Etch rate varies based on factors such as the concentration and composition of the etchant, the material to be etched, and temperature conditions. Due to its inconstant nature, etch rate is often determined experimentally immediately prior to the etching process. A


id: chemical-vapor-deposition-20260505-0
file: data/en.wikipedia.org/wiki/Chemical_vapor_deposition-0.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:
Chemical vapor deposition (CVD) is a thin film deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce electrically conductive layers in the range of a few 100 nm up to a few μm. In typical CVD, the wafer (substrate) is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface, in order to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber. Microfabrication processes widely use CVD to deposit materials in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial. These materials include: silicon (dioxide, carbide, nitride, oxynitride), carbon (fiber, nanofibers, nanotubes, diamond and graphene), fluorocarbons, filaments, tungsten, titanium nitride and various high-κ dielectrics. The term chemical vapour deposition was coined in 1960 by John M. Blocher, Jr. who intended to differentiate chemical from physical vapour deposition (PVD). == Types == CVD is practiced in a variety of formats. These processes generally differ in the means by which chemical reactions are initiated. Classified by operating conditions: Atmospheric pressure CVD (APCVD) – CVD at atmospheric pressure. Low-pressure CVD (LPCVD) – CVD at sub-atmospheric pressures.


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 ==


