Aluminum hydroxide is a white powder, insoluble in water, soluble in acid or alkali. It is a typical amphoteric hydroxide, aluminum hydroxide, with a melting point of 300 ℃, insoluble in water and alcohol, soluble in inorganic acid and alkali solutions. According to use, it is divided into two types: industrial grade and pharmaceutical grade.
Aluminum hydroxide has a wide range of uses. The specific applications and functions are as follows:
1. Chemical raw materials: Because aluminum hydroxide can be produced on a large scale, raw materials Sufficient, the product has high purity and is easily soluble in acid and alkali. Therefore, aluminum hydroxide is an important raw material for preparing aluminum salts, such as barium aluminate, aluminum sulfate, etc.
2. Flame retardant: It is understood that aluminum hydroxide powder has the functions of filling, flame retardant and smoke elimination and is non-toxic and harmless. It is usually regarded as plastic, unsaturated polyester and rubber. An ideal flame retardant filler for other organic polymers. Flame retardant mechanism of aluminum hydroxide: When the temperature exceeds 200°C, aluminum hydroxide begins to endothermically decompose and release three crystal waters. Its decomposition rate is maximum at around 250°C. That is to say: this reaction is a strong endothermic reaction, which inhibits the increase in polymer temperature, reduces its decomposition rate, and only produces water vapor, without generating toxic and harmful gases.
3. Ceramics: Aluminum hydroxide is roasted at high temperature to obtain alumina, which has high thermochemical stability, thermal strength, creep resistance, dielectric properties and low thermal expansion coefficient. , is an important material for synthetic ceramics. During the ceramic synthesis process, aluminum hydroxide activates and controls the crystallization process, thereby controlling the phase formation of the composite material.
4. Sewage treatment: Aluminum hydroxide is mainly Al(OH)4- in water. It can precipitate toxic heavy metals in sewage through co-precipitation and then filter it to achieve the effect of water purification. Aluminum hydroxide has a high specific surface area and can adsorb colloids, suspended solids, dyes, organic matter, etc. in sewage on the surface.
5. Medicine: Aluminum hydroxide can neutralize gastric acid and is non-toxic and harmless. It is a traditional medicine for treating stomach problems. Using aluminum hydroxide as an adjuvant can improve the immunogenicity of the vaccine. Its mechanism of action is to adsorb the antigen on the surface of aluminum hydroxide and allow it to be slowly released to prolong the efficacy of the vaccine.
6. Catalyst carrier: During the preparation process of aluminum hydroxide, target products with different specific surface areas, pore volumes, pore structures and crystal structures are prepared by controlling the temperature, concentration and pH of the reactants. It can be effectively used as a catalyst carrier for the hydrogenation of unsaturated carbonyl compounds, the preparation of fullerenes, etc.
7. Paper industry: Aluminum hydroxide has high whiteness, ultra-fine particle size, complete crystal form, and strong compatibility with whitening agents. Using it as an additive for coatings and resins can effectively improve the whiteness, opacity, smoothness and inkability of coated paper.
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