Sodium Bicarbonate( Food Grade) (CAS: 7758-29-4)

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.

Chelation of a metal cation by triphosphate.

Uses

In detergents

The majority of STPP is consumed as a component of commercial detergents. It serves as a “builder,” industrial jargon for a water softener. In hard water (water that contains high concentrations of Mg2+ and Ca2+), detergents are deactivated. Being a highly charged chelating agent, TPP5- binds to dications tightly and prevents them from interfering with the sulfonate detergent.

Food applications

STPP is a preservative for seafood, meats, poultry, and animal feeds. It is common in food production as E number E451. In foods, STPP is used as an emulsifier and to retain moisture. Many governments regulate the quantities allowed in foods, as it can substantially increase the sale weight of seafood in particular. The United States Food and Drug Administration lists STPP as “generally recognized as safe.”.

Other uses

Other uses (hundreds of thousands of tons/year) include “ceramics, leather tanning (as masking agent and synthetic tanning agent – SYNTAN), anticaking, setting retarders, flame retardants, paper, anticorrosion pigments, textiles, rubber manufacture, fermentation, antifreeze.” TPP is used as a polyanion crosslinker in polysaccharide based drug delivery.