Silica gel (Silicon dioxide) is a highly active adsorbent material. It belongs to the amorphous material. Its chemical formula is mSiO2. NH2O, and it is dried and dehydrated by silicic acid gel. The main component is not SiO2. It is insoluble in water and any solvent, non-toxic and tasteless, chemical property is stable, has no reaction with any substance except for strong alkali, hydrofluoric acid and . Silica gel is not silicone rubber, and silicone rubber is a kind of synthetic rubber.
Solubility: It is insoluble in water. It can be impregnated with hydrochloric acid, sulfuric acid and nitric acid, soluble in hydrofluoric acid and strong alkali solution. With larger surface area and stronger mechanical strength, it is a polar adsorbent.
Storage: It should be stored in a sealed container and placed in a cool, dry place to avoid contact with moisture and water.
Silicon dioxide‘s adsorption capacity decreases because it adsorbs water vapor or other organic substances in the medium, but it can be reused after regeneration. After the silica gel adsorbed water, the water can be removed by thermal desorption. There are many ways of heating, such as electric heating furnace, flue heat and hot air drying. The temperature control of desorption heating is suitable for 120--180 C. For blue gel indicator, discoloration silica gel and DL type blue silica gel, temperature should be controlled at 100--120 C.
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