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Silica gel desiccant is a kind of highly active adsorption material, which is usually made by reaction of sodium sulfate and sulfuric acid, and after a series of aging, acid bubble and other processes. Silicic acid belongs to amorphous substance, its chemical molecular formula MSI02, NH20. Insoluble in water and any solvent, non-toxic, tasteless, chemical property stable. Different types of silica gel form different microporous structures because of their different manufacturing methods. Because of its chemical structure and physical structure, silica gel has many characteristics that can not be replaced by other similar materials, such as good adsorption, chemical property stability and high mechanical strength.