Piidioksidigeelejän

Piidioksidigeelejän, more commonly known as silica gel, is a granular form of silicon dioxide (SiO2) that is made synthetically from sodium silicate. It is an amorphous and porous material with a high surface area. Silica gel is well-known for its ability to absorb moisture from the air, making it a common desiccant. Its porous structure allows it to hold significant amounts of water or other liquids through adsorption.

The manufacturing process typically involves reacting sodium silicate with a mineral acid, followed by a series of washing, drying, and activation steps. The resulting beads or granules can vary in pore size, which influences their adsorption capacity and rate. For instance, finer pores are better for adsorbing smaller molecules like water vapor, while larger pores can hold larger liquid molecules.

Silica gel is widely used in packaging to protect goods from moisture damage during storage and transport. It is found in small packets in products like electronics, leather goods, and food items. Beyond its desiccant properties, silica gel also finds applications as a catalyst support, a chromatographic stationary phase, and in certain types of cat litter due to its absorbent nature. It is generally considered safe and non-toxic, though it should not be ingested. Its effectiveness can be monitored; some types change color when saturated with moisture, indicating they need to be replaced or regenerated by heating.