What are the industrial uses of sodium metabisulfite?

Sodium metabisulfite, also known as sodium metabisulfite and sodium metabisulfite, is an inorganic compound, a white crystalline powder, soluble in water, glycerin, slightly soluble in ethanol, and the aqueous solution is acidic. Contact with strong acid releases sulfur dioxide and generates corresponding salts. Sodium metabisulfite is divided into industrial grade and food grade. So what are the industrial uses of sodium metabisulfite?

Industrial uses of sodium metabisulfite:
1. Used in the chemical industry to produce hydroxyvanillin, hydroxylamine hydrochloride, etc.
2. Used as chromatographic analysis reagent.
3. Used as bleaching agent in paper industry.
4. Used as coagulant in rubber industry.
5. Used as a fixing agent ingredient in the photographic industry.
6. Used in the fragrance industry to produce vanillin.
7. In the printing and dyeing industry, it is used as a dechlorination agent and cotton scouring agent after bleaching cotton.
8. Used in the production of insurance powder, sulfamethazine, caprolactam, etc.
9. Used in the tanning industry to treat leather, making the leather soft, plump, tough, waterproof, anti-bending, and wear-resistant.
10. Used as an anti-fat oxidant and preservative in cosmetics and skin care products to prevent and delay product deterioration caused by oxidation reactions.
11. Used as reducing agent in water treatment. Sodium metabisulfite and sodium sulfide are used for electroplating wastewater treatment. For example, when treating wastewater containing hexavalent chromium, sodium metabisulfite can be added first. After sufficient reduction reaction, the alkali is adjusted and polyaluminum chloride or polymeric ferric sulfate flocculant is added. Finally, sodium sulfide is added to remove unfinished precipitation of heavy metals.
12. Mine beneficiation agent. Sodium metabisulfite is an agent that reduces the floatability of minerals. It can form a hydrophilic film on the surface of mineral particles and form a colloidal adsorption film, thereby preventing the collector from interacting with the mineral surface.
13. Used in the construction industry to make concrete water-reducing agents, which play an early strength role in concrete, but the dosage should not exceed 0.1%-0.3%. If too much is added, the later strength of the concrete will be affected.
14. Used as preservatives, bleaching agents, leavening agents, antioxidants, preservatives and color protectants in the food industry. (1) Antiseptic fungicide. Adding it to juice, preserves, and canned food can extend the shelf life of food and effectively sterilize it. (2) Bleach. It is used to bleach flour used in making pastries and other foods. (3) Leavening agent. It can loosen the structure of foods such as bread and biscuits and make them crispier in texture. (4) Antioxidant preservative. It has good antioxidant and preservation effects on seafood, fruits and vegetables. (5) Color protectant. During the processing and preservation of light-colored vegetables, such as mushrooms, lotus roots, water chestnuts, bamboo shoots, yams and other products, sodium metabisulfite solution is often used to protect the color.
15. Used as a feed additive as a preservative and antifungal agent.