Sodium tripolyphosphate

Sodium Tripolyphosphate or STPP is an inorganic compound produced by heating a stoichiometric mixture of monosodium phosphate, NaH2PO4, and disodium phosphate, Na2HPO4, under carefully controlled conditions.
2Na2HPO4 + NaH2PO4 → Na5P3O10 + 2 H2O


Chemical name: Sodium Tripolyphosphate

CAS No.: 7758-29-4

Molecular formula: Na5P3O10

Standard executed: GB/T9983-2004

Packaging: in 25KG/50KG/1000KG/1250KG PP Woven bag with PE liner


Technical specification

Items Standards
Purity (Na5P3O10 ), %
Phosphorus pentoxide (P2O5) content, %
Ferric (Fe) content, %
Water insoluble matter content
pH value (10g/L solution)
Whiteness(W10), %
Phase 1 content, %
Particle size (through 35 mesh), %
Particle size (through 100 mesh), %
Bulk density, g/cm³
Inorganic compound, Builder
Molecular mass
367.864 g/mol in standard state (25 ℃[77 °F], 100 kPa)
Melting point
622 °C (1,152 °F; 895 K)
Solubility in water
14.5 g/100 mL (25 °C)
Dry, tight-closed, in low to moderate temperatures and humidity
Shelf life/Retest
24 months
White powder or granular


The majority of STPP is consumed as a component in various types of commercial detergents. Sodium tripolyphosphate (STPP) is a builder agent and a provider of a wide range of benefits in detergent formulations. Its role consists of sequestration of calcium and magnesium, provision of alkalinity, transition metal ion complexation, metal oxide colloid stabilization, and provision of substantial surface charge for peptization and suspension of other soils. Modern builders are usually less multifunctional than STPP, as their role is primarily focused on binding and neutralizing the calcium and magnesium ions—the culprits of hardness in water. 

Calcium and magnesium ions insolubilize anionic surfactants by forming soap curd, LAS, and AS. They also bind to stains and prevent their removal. Hardness ions can also flocculate soil presenting in the wash solution, leading to its deposition on fabrics. STPP is a colorless salt, found either in anhydrous form or as the hexahydrate. As a chelating agent, both a bidentate and tridentate, STPP binds strongly to metal cations, preventing them from interfering with the sulfonate detergent.

Builders like STPP have a substantial role in detergents, including improving the removal of various stain classes and levels (particulates, blood, grass, beverages), together with enhanced whiteness maintenance.

Builders can neutralize hardness via a variety of mechanisms. Sequestering builders like STPP form soluble complexes with the hardness ions. Precipitating builders like fatty acids are soluble materials that form insoluble Ca/Mg salts. Finally, ion exchange builders like zeolites are insoluble materials that can bind hardness ions by ion exchange.

STPP provides fast and effective binding of both Ca2+ and Mg2+ ions. Additionally, it presents an excellent dispersion/suspension agent for insoluble soils. However, its use is banned or limited in some countries based on concerns about its role in the eutrophication of surface water.

Stability/Shelf life

More stable than the higher (ie, meta-) phosphates, but less stable than tetrasodium pyrophosphate. With prolonged heating of sodium tripolyphosphate solution, it tends to revert to the orthophosphate. 

Recommended storage: Dry, tight-closed, ideally in its original packaging, in low to moderate temperatures and low to moderate humidity environment.


Molecular dehydration of mono- and disodium phosphates, or controlled calcination of sodium orthophosphate mixture from sodium carbonate and phosphoric acid.

Industry use

Bleaching agents, corrosion inhibitors and anti-scaling agents, detergents, dyes, plating agents and surface treating agents, solids separation agents, solvents for cleaning and degreasing, surface-active agents, emulsifier, water softener, industrial cleaners.

Consumer use

Cleaning and furnishing care products, fabric, textile, leather care products, laundry and dishwashing products, and water treatment products.

STPP is one of the most effective widely used builders in heavy-duty fabric washing compositions. Its high sequestration power enables extensive application in automatic dishwashing detergents. Due to its ability to form stable hydrates, the STPP aids in manufacturing crisp spray-dried laundry powders.


Soluble in water. Insoluble in ethanol.

Common synonyms

  • Sodium Tripolyphosphate
  • Pentasodium Triphosphate
  • Sodium Triphosphate
  • STPP

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STPP Group’s subsidiary Liuzhou Jiaji Chemicals Co., Ltd has been manufacturing STPP for years.

No, STPP Group manufactures only Industrial grade STPP and 90%+ of the STPP we manufacture are consumed in detergents. The rest are used for ceramics and water treatment.

Our MOQ for STPP is 1*20’’GP (25MT/26MT/27MT).

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STPP-Elie Li

Elie Li

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