Silicagel

Silicagel, commonly called silica gel, is a granular, porous form of silicon dioxide (SiO2) designed to absorb moisture. It is produced by forming a silica network in a gel and drying it to create a solid with a high internal surface area.

The porous structure consists of micro- and mesopores, giving silica gel a large adsorption capacity relative to mass. This makes it a widely used desiccant in packaging and storage. It is chemically inert with many substances and remains stable under typical use conditions. Some forms include moisture-indicator beads that change color as humidity rises, providing a visual dryness cue.

Production commonly involves hydrolysis and polycondensation of silicate solutions, or sol-gel processing of silicon alkoxides, followed by aging and drying. Drying yields xerogels; supercritical drying yields aerogels. Silica gel is typically available as beads, granules, or sachets, and may be offered with or without a moisture indicator.

Regeneration is achieved by heating to drive off adsorbed water, commonly in the range of about 110–180°C, after which the material can be reused. It can absorb several times its weight in water, depending on relative humidity and temperature.

In addition to desiccation, silica gel serves as a support in catalysis and as a drying agent in laboratories and industrial processes. It is used in chromatography and in moisture-control applications in electronics, pharmaceuticals, foods, and consumer products.

Safety: silica gel is non-toxic in small quantities but should not be ingested; silica dust can irritate the respiratory tract if inhaled. Some moisture-indicator formulations may introduce additional hazards.