Calcium chloride is a "physical adsorption agent" in dehumidification scenarios due to its strong hygroscopicity. Its crystal structure easily combines with water molecules to form hydrates (such as CaCl₂・6H₂O). In an environment with a humidity of more than 60%, each kilogram of calcium chloride can absorb about 1.5 kilograms of water. It is often used for moisture-proof dehumidification in wardrobes, basements, and storage logistics. Compared with silica gel desiccant, it has higher dehumidification efficiency in high humidity environments and lower costs; however, it is easy to deliquesce into liquid after absorbing moisture, and needs to be matched with sealed containers or replaced regularly. Some scenarios can be reused by heating and regeneration (such as in industrial dehumidification equipment).
As a de-icing agent, the core advantage of calcium chloride lies in its "freezing point suppression power" - the freezing point of its aqueous solution can be as low as - 55℃, and after spreading, it can quickly destroy the ice and snow lattice structure and melt the accumulated snow into water. Compared with sodium chloride, it is still effective below - 20℃, and its corrosion to road concrete and steel bars is relatively weak (but the dosage still needs to be controlled). Calcium chloride is often used in combination with other salts in airports, highways and other scenarios, which not only improves snow melting efficiency but also reduces environmental impact (such as reducing salt damage to soil and vegetation). It is an "emergency weapon" for winter transportation security.
Chemical and refrigeration: As a refrigerant, calcium chloride aqueous solution is used for temperature control of cold storage and chemical reactors due to its low freezing point and stable chemical properties. It can be recycled to reduce costs; in the production of molecular sieves, it is used as an additive to adjust the pore structure and improve adsorption performance.
Construction and materials: Adding 2%-5% calcium chloride to concrete can accelerate cement hydration reaction, shorten the solidification time of winter construction, and enhance early strength; but the dosage must be strictly controlled to avoid late strength attenuation and steel corrosion.
Food and agriculture: Food-grade calcium chloride is used as a coagulant for soy products (such as tofu making) and a calcium fortifier for beverages; in agriculture, it is used as a foliar fertilizer to supplement calcium elements, enhance the ability of crops to resist lodging, and can also be used to preserve fruits and vegetables (inhibit microbial reproduction).
From daily moisture-proofing to large-scale industrial production, calcium chloride, with its triple properties of "hygroscopicity - freezing point lowering - chemical stability", can accurately solve humidity, temperature and process problems in different fields, making it a rare "all-rounder" among chemical materials. Its versatility essentially stems from the in-depth development of the physical and chemical properties of calcium ions and scene adaptation.
