Sodium Meta
Bisulphite (Na2S2O5) is used as a preservative
in the starch and food industry to control melanosis (black spot) in shrimp;
for fermentation in the wine industry; as an antichlor in the chemical industry
and as a redox catalyst in the acrylic fibre industry.
The
product is also used as a reducing agent in the purification of aldehydes and
ketones; in the manufacture of sulphonated oil and resin; for detoxification of
cyanide in gold ore processing plants and in the manufacture of photographic
chemicals.
Sodium Metabisulphite's
acidic and preservative properties also make it an effective substitute for
sodium bisulfite, a chemical which is used in traditional darkroom photography.
Also, Sodium Metabisulphite
is used as a bleaching agent in pulp and textile manufacture, as well as a
reducing agent in pharmaceuticals. It is also a known preservative in cosmetics.
The chemical, in
concentrated form, has also been used in landscape gardening as a tree stump
remover, as it disintegrates the lignin -- chemicals in plant cell walls -- in
the tree stumps, making them easier to remove.