Silica gel: also known as silicone rubber, is a highly active adsorption material, is an amorphous substance, its chemical formula is mSiO2·nH2O. Insoluble in water and any solvent, non-toxic and tasteless, chemically stable, in addition to strong alkali, hydrofluoric acid does not react with any substance.

Silica gel according to its properties and components can be divided into organic silica gel and inorganic silica gel two categories.

1, organic silica gel is a kind of organic silicon compound. Silicone is mainly divided into silicone rubber, silicone resin, silicone oil, silane coupling agent four categories.

2, inorganic silica gel according to the size of its pore size is divided into: large pore silica gel, coarse pore silica gel, B type silica gel, fine pore silica gel.