Sodium metabisulfite (Na2S2O5), is an inorganic compound, white or yellow crystals, with a strong pungent odor, soluble in water, acidic in aqueous solution, and released when in contact with strong acidsSulfur dioxideand generate corresponding salts. If left in the air for a long time, it will oxidize to sodium sulfate, so sodium metabisulfite cannot be stored for a long time. It is used in the production of insurance powders, sulfadimethylpyrimidine, analin, and caprolactam etc.; Used for chloroform, phenylpropylsulfone and benzaldehydePurification. The photographic industry is used as a fixing agent; The fragrance industry is used in the production of vanillin; used as a preservative in the brewing industry; rubber coagulant and cotton bleaching dechlorinator; organic intermediates; used for printing and dyeing, tanning; Used as a reducing agent; It is used as a wastewater treatment agent in the electroplating industry, oilfield, and mineral processing agent in mines. It is used as a preservative, bleaching agent, and loosening agent in food processing.