When winter weather hits, air travelers can jet off to warmer climates, thanks to these chemicals, which dissolve snow and ice and then keep the water from refreezing.
The pilot has just announced that the weather is going to hold and that your airplane is ready to push back from the gate. It looks like your flight won’t be canceled after all, despite the sleet and freezing rain that has fallen. You relax. But the plane isn’t moving. Now what? A technician appears in a lift over the wing and starts spraying something. A shroud of steam rises from the wing and you remember–deicer. Then you wonder, what’s that stuff?
Most people are familiar with solid chemical deicers and anti-icers that are used on sidewalks and roadways. Deicers work to break up snow or ice so that it can be removed more easily. The chemicals work by dissolving slowly on contact to create a brine, with the heat of solvation for some chemicals helping to melt the ice or snow. Anti-icers work to keep water from freezing or refreezing.
Chemical deicers/anti-icers typically are urea or various chloride salts: calcium, magnesium, potassium, or sodium. These five chemicals and combinations of them account for essentially all roadway deicers, with CaCl2 being the most effective and most popular.
However, chloride salts are prohibited for use on aircraft because they can be corrosive. So like automobile antifreeze, aircraft deicing fluids are aqueous solutions of a glycol, or mixture of glycols, along with proprietary additives. Depending on the formulation required, the additives might include a surfactant, polymer thickening agent, pH buffer, corrosion inhibitor, flame retardant, or dye.
Visit “What’s That Stuff?” to read more about aircraft de-icers.
Excerpted with permission, Chemical & Engineering News
Copyright © 2001 American Chemical Society