Caustic soda can be divided into flake soda, granular soda and solid soda according to its form. The use of caustic soda involves many fields, the following is a detailed introduction for you:
1. Refined petroleum.
After being washed with sulfuric acid, petroleum products still contain some acidic substances, which must be washed with sodium hydroxide solution and then washed with water to obtain refined products.
2.printing and dyeing
Mainly used in indigo dyes and quinone dyes. In the dyeing process of vat dyes, caustic soda solution and sodium hydrosulfite should be used to reduce them to leuco acid, and then oxidized to the original insoluble state with oxidants after dyeing.
After the cotton fabric is treated with caustic soda solution, the wax, grease, starch and other substances covered on the cotton fabric can be removed, and at the same time, the mercerized luster of the fabric can be increased to make the dyeing more uniform.
3. Textile fiber
1).Textile
Cotton and linen fabrics are treated with concentrated sodium hydroxide (caustic soda) solution to improve fiber properties. Man-made fibers such as rayon, rayon, rayon, etc., are mostly viscose fibers. They are made of cellulose (such as pulp), sodium hydroxide, and carbon disulfide (CS2) as raw materials to make viscose liquid, which is sprayed, made by condensation.
2). Viscose fiber
First, use 18-20% caustic soda solution to impregnate the cellulose to make it into alkali cellulose, then dry and crush the alkali cellulose, add carbon disulfide, and finally dissolve the sulfonate with dilute lye to obtain viscose . After filtering and vacuuming (removing air bubbles), it can be used for spinning.
4. Paper making
The raw materials for papermaking are wood or grass plants, which contain a considerable amount of non-cellulose (lignin, gum, etc.) in addition to cellulose. Sodium hydroxide is used for delignification, and only when the lignin in the wood is removed can fibers be obtained. The non-cellulose components can be dissolved and separated by adding dilute sodium hydroxide solution, so that pulp with cellulose as the main component can be obtained.
5. Improve the soil with lime.
In soils, the weathering of minerals may also produce acids due to the formation of organic acids as organic matter decomposes. In addition, the use of inorganic fertilizers such as ammonium sulfate and ammonium chloride will also make the soil acidic. Applying an appropriate amount of lime can neutralize the acidic substances in the soil, making the soil suitable for crop growth and promoting the reproduction of microorganisms. The increase of Ca2+ in the soil can promote the coagulation of soil colloids, which is conducive to the formation of aggregates, and at the same time can supply the calcium needed for plant growth.
6. Chemical industry and chemical reagents.
In the chemical industry, caustic soda is used for making sodium metal and electrolyzing water. Caustic soda or soda ash is used in the production of many inorganic salts, especially in the preparation of some sodium salts (such as borax, sodium silicate, sodium phosphate, sodium dichromate, sodium sulfite, etc.). Caustic soda or soda ash is also used in the synthesis of dyes, drugs and organic intermediates.
7. rubber, leather
1). Precipitated silica
First: make water glass (Na2O.mSO2) by reacting sodium hydroxide with quartz ore (SiO2)
Second: react water glass with sulfuric acid, hydrochloric acid, and carbon dioxide to produce precipitated white carbon black (silicon dioxide)
The silica mentioned here is the best reinforcing agent for natural rubber and synthetic rubber
2). Recycling of old rubber
In the recycling of old rubber, the rubber powder is pretreated with sodium hydroxide solution, and then processed
3). Leather
Tannery: a recycling process of tannery waste ash liquid, on the one hand, between the two steps of sodium sulfide aqueous solution soaking treatment and adding lime powder soaking treatment in the existing expansion process, the use of tare weight is increased by 0.3-0.5% The 30% sodium hydroxide solution treatment step makes the leather fiber fully expand, meets the process requirements, and improves the quality of the semi-finished product.
8. metallurgy, electroplating
In the metallurgical industry, it is often necessary to convert the active ingredients in the ore into soluble sodium salts in order to remove the insoluble impurities. Therefore, it is often necessary to add soda ash (it is also a flux), and sometimes caustic soda is also used.
9.other aspects of the role
1). There are two functions of ceramic caustic soda in the manufacture of ceramics. First, caustic soda is used as a diluent in the firing process of ceramics. Second, the surface of fired ceramics will be scratched or very rough. Clean it with caustic soda solution Finally, make the ceramic surface more smooth.
2). In the instrument industry, it is used as acid neutralizer, decolorizer and deodorizer. Adhesive industry is used as starch gelatinizer and neutralizer. It can be used as peeling agent, decolorizing agent and deodorizing agent of citrus, peach, etc.
Post time: Feb-16-2023