Sodium metabisulphite/ Sodium metadisulphite

Uses
Food additive
It is used as a preservative and antioxidant in food and is also known as E223.

Sodium metabisulfite is used for wine and beer making.

Other uses[edit]

It is also used to precipitate gold from auric acid (gold dissolved in aqua regia).
It is used in waste treatment to chemically reduce hexavalent chromium to trivalent chromium which can then be precipitated and removed from an aqueous waste stream.
It is used as a bleaching agent in the production of Coconut cream
It is used as a SO2 source (mixed with air or oxygen) for the destruction of cyanide in commercial gold cyanidation processes.

 

Chemical formula   Na2S2O5
EC NUMBER – 231-673-0
CAS NUMBER – 7681-57-4