Sodium hydroxide (NaOH) is extremely versatile. Used in the production of paper, soap, dyes, rayon, smelting metals, petroleum refining, cotton finishing, coal tar product purification, as well as food processing, wood processing and mechanical industry.

Sodium hydroxide is widely used in the national economy, many industrial sectors need sodium hydroxide. Sodium hydroxide is used most of the sectors is the manufacture of chemicals, followed by paper, aluminum, tungsten, rayon, rayon and soap manufacturing.

In addition, in the production of dyes, plastics, pharmaceuticals and organic intermediates, the regeneration of old rubber, the system of sodium metal, water electrolysis and the production of inorganic salts, the production of borax, chromium salts, manganate, phosphate, etc., but also to use a lot of caustic soda.

At the same time, sodium hydroxide is one of the important raw materials for the production of polycarbonate, super-absorbent polymers, zeolites, epoxy resins, sodium phosphate, sodium sulfite and a large number of sodium salts.

Sodium hydroxide is white translucent crystalline solid. Its aqueous solution has an astringent odor and slippery feeling.

1, water absorption (deliquescence): sodium hydroxide is easily deliquesced in the air, so solid sodium hydroxide is often used as a desiccant. But liquid sodium hydroxide has no water absorption.

2, solubility: very soluble in water, when dissolved, release a lot of heat. Easily soluble in ethanol, glycerol.

Expanded Information:

Industrial method:

1, causticization method

Soda ash, lime were made into soda ash solution, lime made of lime milk, causticizing reaction at 99 ~ 101 ℃, causticizing solution by clarification, evaporation and concentration to more than 40%, the system of liquid caustic soda. The concentrated solution is further boiled and solidified to produce solid caustic soda. The causticized mud is washed with water, and the washed water is used for chemical alkali.

2, diaphragm electrolysis method

The original salt salt, add soda ash, caustic soda, barium chloride refined to remove calcium, magnesium, sulfate ions and other impurities, and then in the clarification tank to add sodium polyacrylate or caustic soda bran in order to accelerate the precipitation, sand filtration and addition of hydrochloric acid neutralization.

The brine is sent to electrolysis after preheating, and the electrolyte is preheated, evaporated, salted and cooled to produce liquid caustic soda, which is further boiled and thickened to produce solid caustic soda. Salt mud wash water is used for chemical salt.

3, ion exchange membrane method

The raw salt saltification according to the traditional method of brine refining, the primary brine by microporous sintered carbon tubular filters for filtration, and then by the stinger ion exchange resin tower for the second refining, so that the brine calcium, magnesium content down to below 0.002%.

The electrolysis of the secondary refined brine generates chlorine gas in the anode chamber, Na+ in the brine in the anode chamber enters into the cathode chamber through the ionic membrane and generates sodium hydroxide with OH in the cathode chamber, and H+ discharges directly on the cathode to generate hydrogen gas.

An appropriate amount of high-purity hydrochloric acid is added to the anode chamber during electrolysis to neutralize the returning OH-, and the required pure water should be added to the cathode chamber. The concentration of high purity caustic soda generated in the cathode chamber is 30% to 32% (by mass), which can be directly used as a liquid caustic soda product or further boiled and thickened to produce a solid caustic soda finished product.

References:

Baidu Encyclopedia - Sodium Hydroxide