Questions regarding industrial salt??
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Recently, there have been severe snow disasters in the south, and salt is being spread on roads to remove the snow. I’m curious about how this process works. Also, I wonder if the salt, once it melts and enters the water system, could cause secondary pollution
Generally speaking, when this salt is spread on snow, it lowers the freezing point of water, ensuring that it remains in a liquid state even at temperatures of minus three to four degrees Celsius without freezing. Conversely, the use of salt allows ice and snow to melt into liquid water at lower temperatures, thereby preventing the roads from freezing and becoming slippery, which could lead to accidents. The salts commonly used are ordinary sodium chloride and calcium chloride; these substances are inexpensive, practical, and do not cause environmental pollution. This is also why seawater does not freeze as easily as fresh water. Last edited by bingyu252 on 2008-2-1 13:21
The analysis on the 2nd floor is very accurate; I agree with its viewpoint—that the purpose of adding salt is to create a mixed water solution, thereby lowering the freezing point of water； Another method is to add salt to the ice surface; as the salt dissolves, it releases heat, which in turn melts the ice and snow. The presence of salt in the melted ice and snow disrupts its freezing point, allowing it to reach a solid-liquid equilibrium at lower temperatures.
The analysis on the 2nd floor is quite accurate; typically, sodium chloride and calcium chloride are mixed together to use as de-icing agents.
It affects plants such as boxwood and holly on both sides of the road; anyway, they need to be replaced regularly.
Then why can’t industrial salt be used for eating? If what you say is true, it’s not poisonous, right?
Current environmental considerations lead to the use of the more expensive calcium acetate, as sodium chloride and calcium chloride cause severe salt corrosion of road surfaces
Chemical plants commonly use brine as a coolant, namely aqueous solutions of sodium chloride or calcium chloride. Sodium chloride-based brine can reach temperatures below minus 20 degrees Celsius, while calcium chloride-based brine can reach temperatures below minus 30 degrees Celsius. The addition of salt results in brine with a low freezing point. After salt is spread as required, the saline water on the road surface must be sent to the wastewater (or sewage) treatment facility, as salt can corrode the road surface and damage vegetation; long-term use of soil bags can also lead to salinization.
The testing standards for table salt and industrial salt are different; one is of food grade while the other is of industrial grade. The so-called toxicity is relative; after industrial salt is dissolved in water, substances that might be toxic in small quantities can have their concentration reduced to an extremely low level due to the dilution by large amounts of water. Additionally, the water body’s self-purification mechanism is capable of removing any potential toxins, thus preventing harm to the water. Moreover, the amounts of these supposed toxic substances in industrial salt are already very low. So, it’s not a question of whether to eat it or not — just like monosodium glutamate, which is a chemical product, and chemical products are generally toxic; therefore monosodium glutamate might also be toxic. Then why do people still consume it?