Silica gel (Silica gel; Silica) alias: Silica gel is a highly active adsorption material, an amorphous substance, its chemical formula is mSiO2·nH2O; it does not react with any substance except strong alkali and hydrofluoric acid. It is insoluble in water and any solvent, non-toxic, tasteless, and chemically stable. Various types of silica gel form different microporous structures due to different manufacturing methods. The chemical composition and physical structure of silica gel determine that it has many other similar materials that are difficult to replace: high adsorption performance, good thermal stability, stable chemical properties, and high mechanical strength. According to its pore size, silica gel is divided into: macroporous silica gel, coarse pore silica gel, B-type silica gel, fine pore silica gel, etc.
Silica gel use:
Silica gel can be used as a desiccant and can be reused. Silica gel is a porous material with different particle sizes formed by proper dehydration of silicic acid gel mSiO2·nH2O. It has an open porous structure with a large specific surface (surface area per unit mass) and can adsorb many substances. It is a good desiccant, adsorbent and catalyst carrier. The adsorption of silica gel is mainly physical adsorption, which can be regenerated and used repeatedly. Add acid to the alkali metal silicate (such as sodium silicate) solution to make it acidify, and then add a certain amount of electrolyte to stir to form a silicic acid gel; or add acid or Ammonium salts can also generate silica gel. Let the silicic acid gel stand for a few hours to age it, then wash it with hot water to remove the soluble salts, dry it at 60-70℃ and activate it at about 300℃ to obtain silica gel. The silicic acid gel is soaked in the cobalt chloride solution and then dried and activated to obtain the color-changing silica gel. When it is used as a desiccant, it is blue before absorbing water, and turns red after absorbing water. From the change of color, we can see the degree of water absorption and whether it needs regeneration treatment. Silica gel is also widely used in steam recovery, petroleum refining, and catalyst preparation.