SODIUM TRIPOLYPHOSPHATE (STPP) -25 KG PACK

Description

Sodium triphosphate (STP), also sodium tripolyphosphate (STPP), or tripolyphosphate (TPP), is an inorganic compound with formula Na₅P₃O₁₀. It is the sodium salt of the polyphosphate penta-anion, which is the conjugate base of triphosphoric acid. It is produced on a large scale as a component of many domestic and industrial products, especially detergents. Environmental problems associated with eutrophication are attributed to its widespread use.

Preparation and properties

Sodium tripolyphosphate is produced by heating a stoichiometric mixture of disodium phosphate, Na₂HPO₄, and monosodium phosphate, NaH₂PO₄, under carefully controlled conditions.

2 Na₂HPO₄ + NaH₂PO₄ → Na₅P₃O₁₀ + 2 H₂O

In this way, approximately 2 million tons are produced annually.

STPP is a colourless salt, which exists both in anhydrous form and as the hexahydrate. The anion can be described as the pentanionic chain [O₃POP(O)₂OPO₃]⁵⁻. Many related di-, tri-, and polyphosphates are known including the cyclic triphosphate P₃O₉³⁻. It binds strongly to metal cations as both a bidentate and tridentate chelating agent.