Sodium perborate

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Sodium perborate (PBS) is a white, odorless, water-soluble chemical compound with chemical formula Na B O₃. It crystallizes as monohydrate or tetrahydrate. Sodium perborate is manufactured by reaction of sodium tetraborate, hydrogen peroxide, and sodium hydroxide. It is a skin irritant.

Perborate dimer, peroxide bond shown in red, charges in blue

Unlike percarbonate and perphosphate, perborate is not just an addition compound of peroxide, but contains true peroxygen bonds. This makes the material more stable, safer for handling and storage. The monohydrate form dissolves better than the tetrahydrate and has higher heat stability; it is prepared by heating the tetrahydrate.

Sodium perborate undergoes hydrolysis in contact with water, producing hydrogen peroxide and borate. It serves as a source of active oxygen in many detergents, laundry detergents, cleaning products, and laundry bleaches. It is also present in some tooth bleaching formulas. It has antiseptic properties and can act as a disinfectant. It is also used as a "disappearing" preservative in some brands of eye drops. One eye drop manufacturer, Novartis, claims that it "turns into pure water and oxygen upon contact with your eye."^[1]

Sodium perborate is a less aggressive bleach than sodium hypochlorite, causing less degradation to dyes and textiles. Borates also have some non-oxidative bleaching properties.

Sodium perborate releases oxygen rapidly at temperatures over 60 °C. To make it active at lower temperatures (40-60 °C), it has to be mixed with a suitable activator, typically tetraacetylethylenediamine (TAED).