Caustic soda liquid

1. Sodium hydroxide, also known as caustic soda, caustic soda, caustic soda, caustic soda tablet, is an inorganic compound with the chemical formula NaOH and a relative molecular weight of 39.9970. Sodium hydroxide has a strong alkaline, extremely corrosive, can be used as acid neutralizer, with masking agent, precipitating agent, precipitation masking agent, color development agent, saponification agent, peeling agent, detergent, etc., the use is very wide.

nature
Pure sodium hydroxide is a white solid, readily soluble in water, and its aqueous solution is astringent and slippery. Sodium hydroxide is easy to absorb water when exposed to air, and the surface is wet and gradually dissolved, which is called delixing. Its relative density is 2.130. Melting point 318.4℃. Boiling point 1390℃. There are two kinds of caustic soda on the market: solid caustic soda is white, block, flake, rod, granular, brittle; Pure liquid caustic soda is colorless transparent liquid. Solid caustic soda has strong hygroscopicity. Easy to dissolve in water, heat release when dissolved, the aqueous solution is alkaline, there is a slippery sense; Soluble in ethanol and glycerol; Insoluble in acetone and ether. Extremely corrosive, corrosive to fiber, skin, glass, ceramics and so on. React with aluminum and zinc, non-metallic boron and silicon to release hydrogen; Disproportionation with halogens such as chlorine, bromine and iodine; Neutralize with acids to form salt and water.

preparation
There are two methods of industrial production of caustic soda: causticization and electrolysis. Causticizing method is divided into soda ash causticizing method and trona causticizing method according to different raw materials. Electrolysis can be divided into membrane electrolysis and ion exchange membrane method.
Soda ash causticization method: soda ash and lime are made into soda ash solution by alkali, lime milk is made from ash, causticization reaction is carried out at 99 ~ 101℃, and the causticization solution is clarified, evaporated and concentrated to more than 40% to obtain liquid caustic soda. The concentrated liquid was further boiled and solidified to produce the finished solid caustic soda. The causticized mud is washed with water, which is used for alkali conversion.
Trona causticization method: trona is pulverized, dissolved (or alkaline halide), clarified and added to lime milk for causticization at 95 ~ 100 ° C, the causticization liquid is clarified, evaporated and concentrated to about 46% NaOH concentration, the clear liquid is cooled, and the salt is further enriched to produce solid caustic soda products. The causticized mud is washed with water, which is used to dissolve trona.
Diaphragm electrolysis method: The original salinized salt is added to soda ash, caustic soda, barium chloride fine preparation to remove impurities such as calcium, magnesium, sulfate ions, etc., and then sodium polyacrylate or causticized bran is added to the clarifying tank to accelerate precipitation, and hydrochloric acid is added to neutralize after sand filtration. The brine is preheated and sent for electrolysis, and the electrolyte is preheated, evaporated, salted and cooled to obtain liquid caustic soda, which is further enriched to obtain solid caustic soda. The salt mud wash water is used to melt the salt.

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