Silica gel alias: Silicic acid gel. It is a highly active adsorbent material and an amorphous material. The main component of silica gel is silica, which is chemically stable and does not burn. It has an open porous structure with strong adsorption and can absorb a variety of materials. When dilute sulfuric acid (or hydrochloric acid) is added to the aqueous solution of water glass, it will become hydrous silicic acid gel and become solid. The dissolved electrolyte Na+ and SO4 2-(Cl-) ions are removed by water washing. Silica gel can be obtained after drying.
Generally speaking, chemical composition of silica gel can be divided into organic silica gel and inorganic silica gel according to its properties and components.
Inorganic silica gel is a kind of highly active adsorption material, which is usually prepared by the reaction of sodium silicate and sulfuric acid and a series of post-treatment processes such as aging and submerge in acid. Silica gel is an amorphous substance. Its chemical formula is mSiO2. nH2O. It is insoluble in water and any solvent, non-toxic, odorless, stable in chemical properties, and does not react with any substances except strong alkali and hydrofluoric acid. Different types of silica gel have different micropore structure due to different manufacturing methods.
The chemical composition of silica gel determine that it has many other characteristics which are difficult to be replaced by other similar materials: high adsorption performance, good thermal stability, stable chemical properties, high mechanical strength, etc. It is used by families as desiccant, humidity regulator, deodorant, etc., by industry as oil hydrocarbon decolorizing agent, catalyst carrier, variable pressure adsorbent, etc., and by fine chemical industry as separation purifier, beer stabilizer, paint thickener, toothpaste friction agent, polish remover, etc.
Organic silica gel is an organosilicon compound that contains Si-C bonds, and at least one organic base is directly connected to the silicon atom. Traditionally, those compounds that connect the organic base to the silicon atom via oxygen, sulfur, nitrogen, etc., are also considered as organosilicon compounds. Moulded silica gel is a little more complex with irregular shapes, including silica gel bowl, silica gel ice lattice, silica gel cake mold and so on.