What is Deicing agent?
Deicing agents, as the name implies, are substances used to melt snow and ice and lower the freezing point of water. They are primarily used for de-icing and snow melting on urban roads, highways, airports, bridges, and other facilities. Some deicing agents can also be used as rapid-melting agents and antifreeze additives for winter construction projects. Ideally, deicing agents should not cause damage to roads, concrete structures, bridge facilities.
Deicing agents can be broadly categorized into two types. One type is organic deicing agents primarily composed of potassium acetate.These agents have good snow melting effects,cause minimal corrosion damage, but they tend to be more expensive and are generally used in important locations such as airports, bridges, and golf courses.
The other type is inorganic deicing agents primarily based on “chloride salts,” including sodium chloride, calcium chloride, magnesium chloride, potassium chloride, collectively referred to as “ice-melting salts.”The advantage of these agents is their lower cost, typically about one-tenth the price of organic deicing agents. However, they can cause significant corrosion to large public infrastructure. The deicing agents commonly seen belong to this category, with sodium chloride (industrial salt) being the most widely used.
How Does Deicing Agent Work?
Whenever it snows, we often see vehicles spreading salt or spraying solutions on the roads. While many understand that this is for snow melting and de-icing, most people are not familiar with the specific principles behind these substances. This article aims to explain the principles of snowmelt and de-icing agents.
The fundamental principle of snowmelt and de-icing agents is to lower the melting temperature of ice and snow, to decrease the freezing point of ice and snow for effective melting. When different types of snowmelt and de-icing agents dissolve in water. They form corresponding aqueous solutions, with their freezing points reaching below zero degrees Celsius. For example, when sodium chloride deicing agent dissolves in water. Its freezing point becomes around -10°C;calcium chloride solution is around -20°C;acetic acid solution can reach around -30°C. Generally, the lower the freezing point, the faster the snow melting and de-icing speed.
During the process of snow melting and de-icing, deicing agents not only absorb heat, but also lower the freezing point of the aqueous solution. This makes it difficult for the dissolved snow to re-freeze. Additionally, when deicing agents dissolve in water, the ion concentration in the water increases. Reducing the vapor pressure of the liquid phase in the water.However, the vapor pressure of the solid phase ice remains unchanged. When the vapor pressures of the ice-water mixture are the same, the ice melts.
The melting point of ice is also influenced by the pressure it experiences. Water, as we know, is a unique substance; its density decreases upon freezing. As a result, higher pressure leads to a lower melting point for ice. This is why ice and snow that have been compressed by vehicle wheels tend to melt more easily. After deicing agents are spread on snowy road surfaces, the subsequent vehicle compression accelerates snow melting.
