Trisodium Phosphate

About This Product

Trisodium phosphate has the formula Na3PO4 and CAS number 7601-54-9, supplied anhydrous or as the dodecahydrate in white crystals or granules. It is the end point of neutralising phosphoric acid with sodium hydroxide, with all three protons replaced, and it dissolves to give a strongly alkaline solution around pH 12. That alkalinity is the working property. A strongly alkaline solution saponifies fats and oils, converting them into soluble soaps that rinse away, which is why TSP cuts through heavy greasy soil that a neutral detergent cannot shift. The same alkalinity etches and degreases painted surfaces, giving a clean, slightly roughened key, which is why it became the standard preparation before repainting. It also acts as a water softener, precipitating calcium and magnesium as insoluble phosphates so they cannot interfere with a detergent. The strength that makes it effective also makes it corrosive to skin and eyes and damaging to aluminium and to some finishes, and phosphate discharge is restricted in many jurisdictions on eutrophication grounds, so phosphate-free substitutes are common in consumer products. It is used in heavy-duty cleaners and degreasers, paint preparation, water softening, metal treatment and as a pH adjuster. Bio Green Chem supplies trisodium phosphate to specification on assay, alkalinity, insoluble matter, chlorides, sulphates and heavy metals.