Silica gel is a processed form of silicon dioxide. Its porous, crystalline structure gives this material an enormous interior surface area, equivalent to over 800 square meters per gram of the material, according to GeeJay Chemicals Ltd. This internal structure allows silica gel to hold a large amount of water. Silica gel is used as a dessicant, in chemical processing and in cat litter.
Silica gel's main use is as a drying agent, or dessicant. SorbentSystems says silica gel can hold up to 40 per cent of its weight in water. That means one pound of silica gel can hold up to 6.4 fluid ounces of water. Silica gel starts losing its ability to hold water at temperatures over 25 degrees Celsius, which means you can reuse the gel by heating it until all the water has been driven out, and then using it again.
Used in Packaging
Silica gel is non-toxic and chemically inert under normal atmospheric conditions. For this reason, silica gel is approved by the U.S. government to be used for protection against moisture damage when packaging foods and medicines, says SorbentSystems. It is also used for packaging electronics, optical goods and any other product that might be harmed by exposure to moisture while in storage. Silica gel is typically found in porous packets included in the product container.
Silica gel is used in chemical processing as a solid adsorbent in column chromatography, a purification technique in which solvents are used to isolate desired compounds from a mixture. The University of Colorado's organic chemistry website says the silica gel adsorbent is chemically "sticky" and holds solvent molecules on its exterior and interior surface area. This property of silica gel serves to control the flow of the solvents through the chromatography column.
Cat Litter Ingredient
Silica gel is an ingredient in cat litter, states the Fresh Step kitty litter company, because its porous nature and affinity for water absorbs cat urine and urine odour on contact. It's inert and non-toxic, and so is safe around pets. Silica gel isn't used alone, however; it is mixed with scoopable clay-based litter and odour-controlling carbon compounds.
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