Physics helps to get rid of snow and ice in the winter, writes Deike Hatscher ̶ but chemistry will be more efficient. Removing the snow and applying sand-like grit will, of course, prevent the snow from densifying to a glassy and slippery surface. But as soon as fresh snow falls, the effect is ruined, she writes. So chemistry might be the better choice.
De-icing salt like sodium chloride dissolves in the liquid surface layer and lowers the melting point. How large the impact is, depends only on the concentration of the deicing substance, not on its kind. Therefore, sugars are also suitable for deicing ̶ but more expensive.
At very windy and chilly locations, for example on motorway bridges, automatic facilities spray sodium or calcium chloride solutions on the road when sensors detect ice formation. On airfields noncorrosive sodium formate is used which however necessitates cleaning the waste water of airport fields in special treatment plants.
What if the airplane itself has been attacked by Jack Frost? Then solutions of different ethylene glycol derivates are sprayed on. Only in Oslo, Norway, and in Newark, USA, the airport staff uses infrared light for this purpose.
Ethanol keeps the windscreen wiper water in your car flowing, and ethylene glycol keeps the cooling fluid running. The latter compound has double effects: it not only prevents the liquid from freezing when it is getting cold but also protects it from overheating in the engine compartment.
- Freud und Leid des Winters,
Deike Hatscher
Chem.Uns. Zeit 2010, 44, 436.
DOI: 10.1002/ciuz.201000101
