Sodium dithionite is also called sodium hydrosulfite, sodium hydrosulphite, sodium sulfoxylate, and sulfoxylate. Sodium dithionite is not stable under physiological conditions, with the rate of decomposition increasing with increasing acidity. Upon contact with moisture, it is oxidized to hydrogen sulfite (HSO3-), sulfite (SO32-) and hydrogen sulfate (HSO4-). Under strongly acidic conditions it may liberate sulfur dioxide. Under anaerobic conditions (such as in the lower gastrointestinal tract), hydrogen sulfite (HSO3-) and thiosulfate (S2O32-) may be formed. Hydrogen sulfite (HSO3-) can be absorbed after ingestion. It is efficiently metabolized and the major part rapidly is excreted as sulfate into the urine.
Sodium dithionite is widely used in industry owing to its reducing properties and ability to react with oxygen. It is used in textile industry for dyeing, in the pulp and paper industry as a reducing bleach to remove yellow discoloration from cellulose based products, as an oxygen scavenger in boilers, in conservation to remove iron stains on cultural artifacts, and in water treatment for controlling iron flash on white fabrics in bleaching environments. It is also used in photographic film, clay, wine, leather goods, foods and beverages, polymers, cleaners, gas purification, environmental remediation, metal recovery, and chemical processing.
