Sodium metabisulfite is a sterilizer and antioxidant, it has the chemical formula Na₂S₂O₅, and is also known as disodium salt. It is a food additive, and is commonly used in homebrewing preparations for the sterilization of equipment. It is also used as a cleaning agent for potable water reverse osmosis membranes in desalination systems. It can be purchased in powdered form, and is also the primary ingredient in campden tablets. In solid form it ranges in colour from white to slightly yellow.

Sodium metabisulfite releases sulfur dioxide when mixed with water, a foul-smelling gas that can also cause breathing difficulties in some people. For this reason, sodium metabisulfite has lost favour in recent times, with agents such as hydrogen peroxide becoming more popular for effective and odorless sterlisation of equipment.

Sodium metabisulfite is also used to remove chlorine from drinking water after treatment, as well as many industrial uses.

It is also known as sodium metabisulphite.

External Links

• BASF AG's Chemical factsheet on Sodium Metabisulfite (http://www.basf.de/en/produkte/chemikalien/anorganika/schwefel/natriumdi_sorten.htm?id=V00-6NnIm5_Tabsf2zn)