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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Deicing | 2/2 | https://en.wikipedia.org/wiki/Deicing | reference | science, encyclopedia | 2026-05-05T10:47:10.308341+00:00 | kb-cron |
==== 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, the freezing point of pure water (freezing point depression). Sometimes, there is an exothermic dissolution reaction that allows for an even stronger melting power. The following lists contains the most-commonly used de-icing chemicals and their typical chemical formula.
=== Salts === Sodium chloride (NaCl or table salt; the most common de-icing chemical) Magnesium chloride (MgCl2, often added to salt to lower its working temperature) Calcium chloride (CaCl2, often added to salt to lower its working temperature, attacks concrete) Potassium chloride (KCl) Calcium magnesium acetate (CaMg2(CH3COO)6) Potassium acetate (CH3COOK) Potassium formate (CHO2K) Sodium formate (HCOONa) Calcium formate (Ca(HCOO)2)
=== Organics === Urea (CO(NH2)2), a common fertilizer Agricultural by-products, generally used as additives to sodium chloride Methanol (CH4O), scarcely used on roads Ethylene glycol (C2H6O2), scarcely used on roads Propylene glycol (C3H8O2), scarcely used on roads Glycerol (C3H8O3), scarcely used on roads
== Environmental impact and mitigation ==
De-icing agents pose significant environmental threat at airports. The benzotriazole- and tolyltriazole-based deicers are of particular interest. Even routine salts such as sodium chloride or calcium chloride leach into natural waters, affecting their salinity. Ethylene glycol and propylene glycol exert high levels of biochemical oxygen demand (BOD) during degradation in surface waters. This process can adversely affect aquatic life by consuming oxygen needed by aquatic organisms for survival. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol.
=== Recycling === Some airports recycle used de-icing fluid, separating water and solid contaminants, enabling reuse of the fluid in other applications. Other airports have an on-site wastewater treatment facility, and/or send collected fluid to a municipal sewage treatment plant or a commercial wastewater treatment facility.
=== Road salt === The use of road salt (sodium chloride) has caused a variety of environmental and infrastructure damage. Road salt has cost the US up to $5 billion annually in repair costs across the country due to salt corrosion. Environmental concerns primarily include the contamination of waterways, endangerment of wildlife, and soil salinization. Road salt can wash into sewer systems, waterways, and eventually large bodies of water, which can lead to water salinization. This results in a variety of environmental damages, including decreasing biodiversity for various species that are not salt-tolerant, and providing a survival advantage for other species that are. Salt can accumulate in plants by the road, which decreases plant growth and may even lead to death. In Beijing (spring of 2005), use of de-icing salt resulted in the deaths of 11,000 pavement trees, 1.5 million shrubs, and 200 square kilometres (49,000 acres) of lawn grass. Salt-rich roadside pools attract wildlife and increase the likelihood of vehicle and mammal (such as moose) collisions by nearly 80%. Birds may also consume road salt, leading to salt poisoning and potential overdose.
== See also == Atmospheric icing Pollution Winter service vehicle
== References ==
== External links == Media related to De-icing of aircraft at Wikimedia Commons