XSiO2 ·yH2O. Transparent or milky white granular solid. It has an open porous structure, strong adsorbability and can absorb a variety of substances. Dilute sulfuric acid (or hydrochloric acid) is added to the aqueous solution of sodium silicate and left to stand. The electrolyte Na+ and SO4 2-(Cl-) ions dissolved in it are washed with water, and silica gel can be obtained after drying. Such as moisture absorption, some silica gel moisture absorption of about 40%, even 300%. Used for gas drying, gas absorption, liquid dehydration, chromatographic analysis, etc. Also used as catalyst. If cobalt chloride is added, it is blue when dry and red after absorbing water. It can be recycled and used repeatedly.
The main component of silica gel is silica, which is stable in chemical properties and does not burn. Silica gel is a kind of amorphous silica, the dust content in the workshop should be controlled not more than 10 mg/m3, it needs to be strengthened for ventilation, and masks should be worn during operation.
Silica gel has a strong adsorption ability, can produce dry effect on the human skin, therefore, when operating should wear work clothes. If silicone enters the eye, flush with plenty of water and seek medical attention as soon as possible.
Blue silica gel contains a small amount of cobalt chloride, potentially toxic, should avoid contact with food and inhalation mouth, in case of poisoning incidents should immediately seek medical treatment.
Silica gel can be reused after regeneration due to its adsorption of water vapor or other organic substances in the medium during use.
Safety term: S22 Do not breathe dust.