Views:325 Author:Site Editor Publish Time: 2020-03-24 Origin:Site
The alias of silica gel is a silicic acid gel, which is a highly active adsorption material, which is an amorphous substance. The main component of silica gel is silicon dioxide, which is chemically stable and does not burn. Generally speaking, silica gel can be divided into two categories: organic silica gel and inorganic silica gel according to its properties and components.
Inorganic silica gel is a highly active adsorption material, which is usually made by reacting sodium silicate and sulfuric acid and undergoing a series of post-treatment processes such as aging and acid foaming. Silica gel is an amorphous substance, and its chemical molecular formula is mSiO2. nH2O. It is insoluble in water and any solvents, non-toxic and tasteless, and stable in chemical properties. It does not react with any substance except strong alkali and hydrofluoric acid. Various types of silica gel have different microporous structures due to their 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, high mechanical strength and so on. It is used as a desiccant, humidity regulators, deodorants in households. In industrial, it is used as decolorants, catalyst carriers, pressure swing adsorbents. It can also be used as separation and purification agents for fine chemicals, beer stabilizers, coating thickeners, toothpaste friction agents, matting agents, etc.
Inorganic silica gel can also be divided into beer silica gel, PSA silica gel, medical silica gel, color-changing silica gel, silica gel desiccant, silica gel opening agent, silica gel for toothpaste and so on.
Silica gel can be used as a desiccant and can be reused. Silica gel is a porous substance with different particle sizes, which is formed by appropriately dehydrating a silicic acid gel mSiO2 · nH2O. It has an open porous structure, has a large specific surface (surface area per unit mass), can absorb many substances, and is a good desiccant, adsorbent and catalyst support. The adsorption of silica gel is mainly physical adsorption, which can be regenerated and reused. Add an acid to an alkali metal silicate (such as sodium silicate) solution to acidify it, and then add a certain amount of electrolyte to stir to form a silicic acid gel, or add an acid or Ammonium salts can also form silicic acid gels. The silicic acid gel is left to stand for several hours to age, and then the soluble salts are washed with hot water, dried at 60 to 70 ° C and activated at about 300 ° C to obtain silica gel. The silica gel can be obtained by soaking the silicic acid gel with a cobalt chloride solution and then drying and activating it. When using it as a desiccant, it is blue before absorbing water and turns red after absorbing water. The degree of water absorption can be seen from the change in color, and whether regeneration treatment is required. Silica gel is also widely used in steam recovery, petroleum refining and catalyst preparation. Silicone can also be used as a mobile phone case, which has extremely high drop resistance.
Organic silica gel is an organic silicon compound, which refers to compounds containing Si-C bonds, and at least one organic group is directly connected to the silicon atom. It is customary to use organic compounds such as oxygen, sulfur, nitrogen, etc. Atomically linked compounds are also treated as organosilicon compounds. Among them, polysiloxanes with a silicon-oxygen bond (-Si-O-Si-) as the skeleton are among the most organosilicon compounds, the most researched and widely used, accounting for more than 90% of the total amount .
Organic silicon is mainly divided into four categories: silicone kitchen utensil set, silicone resin, silicone oil, and silane coupling agent. Silicone products can be divided into three major categories according to different molding processes: molded silicone products, such as various silicone mold, extruded silicone products and liquid silicone products.
Because silicone has these excellent properties, its application range is very wide. It is not only used as a special material in aviation, cutting-edge technology, and military technology sectors, but also in various sectors of the national economy. Its application scope has been expanded to: construction, electronic and electrical, textile, automotive, machinery, leather paper, chemical light industry, Metals and paints, medicine and medical.
In addition, silica gel can also be divided into: large-pore silica gel, coarse-pore silica gel, B-type silica gel, and fine-pore silica gel. Due to the different pore structures, their adsorption properties are different. Coarse-pored silica gel has a higher adsorption capacity under high relative humidity conditions, while fine-pored silica gel has a higher adsorption capacity than coarse-pored silica gel with lower relative humidity, while type B silica gel has a coarser and finer pore structure. Between pores, its adsorption capacity is also between coarse and fine pores.
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