Silica gel, also known as precipitated silica, amorphous silica, and spherical silica, is a white, amorphous solid with the chemical formula SiO₂. It appears as a granular, white solid with no odor, and is practically insoluble in water and alcohol.

The three-dimensional arrangement of silica gel at the atomic level creates gaps in its structure that can be filled with water molecules. Its structure and its ability to attract water into those gaps explains silica gel’s widespread use a desiccant, appearing in small, porous pouches packed with various consumer items such as shoes and electronics to keep them moisture free in transit. In some uses, the silica gel will change color when water has been absorbed.

In chemistry and industry, silica gel is used as the stationary phase in chromatography, and is also used in filtration. It can be used as a food additive and is regarded as Generally Recognized as Safe (GRAS) by the FDA. In that context, silica gel can be used as an anti-caking agent (to keep solids and powders free-flowing), and for defoaming, emulsifying, and preventing settling.

It can also help to extend the shelf-life of foods and medicines.

Common Uses of Silica Gel

• Desiccant
• Catalyst supports
• Stationary phase in chromatography
• HPLC packing
• Resin filler

Industries that use Silica Gel

• Chromatography
• Packaging
• Food
• Pharmaceutical