Definition of caustic soda
The scientific name of caustic soda is sodium hydroxide, the chemical formula is NaOH, commonly known as caustic soda. It is a kind of strong caustic soda with strong corrosivity. It is white crystal at normal temperature, and it is easy to dissolve in water (release heat when dissolved in water) and form alkaline solution. It is also deliquescent, easy to absorb water vapor in the air to deliquescence, and absorb carbon dioxide to deteriorate. Caustic soda is the basic chemical raw material of the national economy, and
As one of the two alkalis in the "three acids and two alkalis", there are mainly liquid and solid alkalis in the form of existence, which are widely used in alumina, printing and dyeing, chemical fiber, Water Treatment, metal smelting
Refining, cotton fabric finishing, purification of coal tar products, food processing and wood processing, machinery industry and chemical industry.
Classification and use
classification
Caustic soda is generally divided into liquid caustic soda and solid caustic soda according to its existence form. According to the different mass fraction of sodium hydroxide, it can be divided into 30% liquid alkali, 32% liquid alkali, 45% liquid alkali, 50% liquid alkali, 73% solid alkali, 95% solid alkali, 96% solid alkali, 99% solid alkali, 99.5% solid alkali and other series products. Solid caustic soda can be divided into barreled solid caustic soda, flake caustic soda and granular caustic soda in terms of its shape. The domestic solid caustic soda market is dominated by flake caustic soda. The main reason is that flake caustic soda has the advantages of simple production process, low production cost, multiple use scenarios and large market demand.
purpose
As an important basic chemical raw material, caustic soda is widely used in chemical industry, pulp production and papermaking, printing and dyeing, chemical fiber, metallurgy, soap and Detergent, environmental protection and other industries of the national economy.
In the field of chemical industry, caustic soda is an indispensable and important substance in a large number of chemical reactions. It is also one of the important raw materials for the production of polycarbonate, super absorbent polymer, Zeolite, epoxy Resin, sodium phosphate, sodium sulfite and a large amount of sodium salt.
In the pulp and paper industry, caustic soda, as an auxiliary agent, can remove non-cellulose such as lignin, carbohydrate and resin in the pulp, neutralize the organic ACID in it, and produce pulp with cellulose as the main component to improve the paper quality.
In the fields of printing and dyeing and chemical fiber industry, caustic soda is also widely used. In the printing and dyeing industry, caustic soda can be used as a water softener to improve the dyeing rate and uniformity of the printing and dyeing process, and improve the dyeing speed. In the chemical fiber industry, caustic soda can be used as a desizing agent to remove inorganic salt impurities from cotton fibers; It can also be used as a cooking agent to remove most of the natural impurities; It can also be used as a mercerizing agent to refine and purify cellulose, improve the appearance of the fabric and improve the moisture absorption of the fabric.
In the field of metallurgical industry, caustic soda can transform the effective components in the ore into soluble sodium salts to remove the insoluble impurities. For example, heating the caustic soda solution can dissolve the aluminum oxide in the bauxite to obtain the sodium aluminate solution. After the solution is separated from the residue (red mud), the temperature is reduced, and aluminum hydroxide is added as crystal seed. After stirring for a long time, the sodium aluminate decomposes and precipitates aluminum hydroxide, which is washed, and calcined at 950~1200 ℃ to obtain the finished aluminum oxide. For example, when smelting tungsten, the concentrate and caustic soda are first calcined into soluble sodium tungstate, and then the powdered tungsten is prepared through acid precipitation, dehydration, reduction and other processes.
In the field of daily washing industry, soap, soap and other kinds of washing products have a large demand for caustic soda. Soap is a sodium salt of higher fatty acids, which is generally prepared by saponification of oil under the action of slightly excessive caustic soda. Caustic soda is also used to produce various detergents, detergent, etc.
In the field of environmental protection, caustic soda is mainly used in the water treatment industry to reduce the hardness of water and adjust the PH value of water through neutralization reaction; It can neutralize with the acidic substances in the wastewater to produce harmless salt and water, and can also remove heavy metal ions in the water through adsorption and precipitation
