Production method of sodium hydroxide:
Sodium hydroxide is mainly produced by electrolytic sodium chloride solution electrolysis (see chlor-alkali production process). It can also be prepared by reacting lime milk with soda ash (Na2CO3) aqueous solution through chemical method (causticizing method). The chemical formula of sodium hydroxide is NaOH, commonly known as caustic soda, caustic soda, and caustic soda. It is a strong alkali with strong corrosivity. It is generally in the form of flakes or lumps. Alkaline solution is also deliquescent. It is easy to absorb water vapor (deliquescent) and carbon dioxide (deterioration) in the air. Hydrochloric acid can be added to check for deterioration. Sewage treatment tablets are widely used as neutralizers in the alkaline water treatment industry. They are widely used in the chemical industry to produce various sodium salts, soaps, paper, cotton, silk, viscose fibers, rubber products, metal cleaning, and electroplating. , Bleach, etc. Protopine is highly corrosive and has special requirements for the safety protection of protopine.
The caustic soda produced by the chemical method has low purity and poor economic benefits. Currently, it is only produced in a small number of countries. Pycnogenine is sodium hydroxide, a white translucent flake solid. It is a basic chemical raw material. It is widely used in the light textile industry such as papermaking, synthetic detergents and soaps, viscose fibers, rayon and cotton, pesticides, dyes, In the rubber and chemical industries, petroleum drilling, the petroleum industry refining petroleum oils and tars, as well as the defense industry, machinery industry, wood processing, metallurgical industry, pharmaceutical industry and urban construction. The 50% or 73% sodium hydroxide solution produced by various methods is directly heated in a falling film transpiration device with a 450 ° C molten heat carrier, and participates in reducing agents such as sucrose to remove chlorate impurities and can be further concentrated. It can also be heated by direct fire in a nickel-containing (Ni) cast iron pot, and evaporated and concentrated to become molten anhydrous sodium hydroxide. When using a cast iron pot to boil alkali, participate in a small amount of ammonia nitrogen (Nitric acid) sodium to oxidize impurities, and add appropriate sulfur toning. The molten sodium hydroxide can directly participate in the iron barrel to condense into a whole solid alkali, or it can be made into flakes or beads and granular solid alkali through a tableting machine or a granulating tower. There are two kinds of products, solid and liquid, referred to as solid alkali and liquid alkali. The latter has standards of 73%, 50%, 45%, 42% and 30%. Due to different production processes and different application requirements, industrial products are divided into standard grade and rayon grade. Standard grade has high salt content. The 50% liquid alkali produced by the separation method contains NaCl 1.0% ~ 1.1% for general use. The rayon grade contains less salt and other impurities. The mercury method 50% liquid alkali contains NaCl at 50ppm. In the following, the requirements for the production of rayon and recycled ion exchange resins are suitable.