Sodium bisulfite |sodium hydrogen sulfite) supplier Distributor Manufacturer in Kolkata West Bengal india

Sodium bisulfite (or sodium bisulphite, sodium hydrogen sulfite) is a chemical compound with the chemical formula NaHSO3. Sodium bisulfite is a food additive with E number E222. This salt of bisulfite can be prepared by bubbling sulfur dioxide in a solution of sodium carbonate in water. Sodium bisulfite in contact with chlorine bleach (aqueous solution of sodium hypochlorite) will generate heat and form sodium bisulfate and sodium chloride.

Uses in food 

While the related compound, sodium metabisulfite, is used in almost all commercial wines to prevent oxidation and preserve flavor, sodium bisulfite is sold by some home winemaking suppliers for the same purpose. In fruit canning, sodium bisulfite is used to prevent browning (caused by oxidation) and to kill microbes.

In the case of wine making, sodium bisulfite releases sulfur dioxide gas when added to water or products containing water. The sulfur dioxide kills yeasts, fungi, and bacteria in the grape juice before fermentation. When the sulfur dioxide levels have subsided (about 24 hours), fresh yeast is added for fermentation.

It is later added to bottled wine to prevent the formation of vinegar if bacteria are present, and to protect the color, aroma and flavor of the wine from oxidation, which causes browning and other chemical changes. The sulfur dioxide quickly reacts with oxidation by-products and prevents them from causing further deterioration.

Sodium bisulfite is also added to leafy green vegetables in salad bars and elsewhere, to preserve apparent freshness, under names like LeafGreen. The concentration is sometimes high enough to cause allergic reactions.

Industrial uses

Sodium bisulfite is a common reducing agent in the chemical industry, as it readily reacts with dissolved oxygen:

2 NaHSO3 + O2 → 2 NaHSO4
It is usually added to large piping systems to prevent oxidative corrosion. In biochemical engineering applications, it is helpful to maintain anaerobic conditions within a reactor. Sodium bisulfite should not be confused with sodium bisulfate which is used as a pH lowering chemical for swimming pools.

In drinking water treatment, sodium bisulfite is often added after super chlorination, to reduce the residual chlorine before discharging to the service reservoir.

In wastewater treatment, sodium bisulfite is often added following disinfection with chlorine prior to discharging the effluent to the receiving water. Residual chlorine can have a negative impact on aquatic life.