De-icer, as the name implies, is used to melt snow and ice, primarily replacing salt for snow and ice removal on city roads, highways, airports, ports, bridges, and other facilities. Some de-icers can also be used as rapid-melting agents and anti-freezing admixtures for winter construction projects. It must not cause damage to roads, concrete structures, or bridge facilities, nor should it harm plants, trees, crops, animals, or people.
Basic Types
De-icers primarily composed of potassium acetate offer effective snow melting with minimal corrosion damage, but their high cost typically restricts their use to airports and other critical locations.
Another category of deicing agents consists of inorganic products primarily composed of "chlorides," such as sodium chloride, calcium chloride, magnesium chloride, potassium chloride, etc., commonly referred to as "ice melt." Their advantage lies in their low cost, which is only 1/10 of that of traditional deicing agents, but they are highly corrosive to large public infrastructures. The deicing agents we commonly use fall into this category, with sodium chloride (also known as industrial salt) being the most widely used.
Basic Principles
"Salt-based de-icers, such as those containing "chlorides," dissolve in water (or snow) and lower the freezing point below zero. For instance, sodium chloride (the main component of table salt) lowers the freezing point to about -10°C, calcium chloride to around -20°C, and acetates to about -30°C. The freezing point of the saltwater is lower than that of pure water, making it difficult for ice to form once salt is dissolved in the snow. Moreover, when de-icers dissolve in water, the ion concentration in the water increases, reducing the vapor pressure of the liquid phase but leaving the vapor pressure of the solid ice unchanged. To achieve a state where the vapor pressures of the solid and liquid phases in the ice-water mixture are equal, the ice melts. This principle also explains why saltwater is less likely to freeze. In simpler terms, de-icers lower the melting point of snow, making it easier to melt.
