Sodium Tripolyphosphate STPP - Pentasodium Triphosphate


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Pentasodium Triphosphate

Technical grade

Sodium tripolyphosphate (STPP) with formula Na5P3O10, is the sodium salt of triphosphoric acid. It is a water soluble, white, odourless powder or granules material. STPP is most commonly used as a builder in detergent and cleaning formulations as it enhances their cleaning power. It also acts as a water softener. It acts as a Sequestrant for alkaline metals, scale control, corrosion control, softening, lead control, red and black water control.

It is commonly used in detergents and cleaning products, water treatment, and in ceramics and textiles for its dispersing and emulsifying properties.


Uses for sodium tripolyphosphate

It is used as a builder in soaps and detergents, improving their cleansing ability.

STPP is a solid inorganic compound used in a large variety of household cleaning products, mainly as a builder, but also in industrial cleaning processes and ceramics manufacture. STPP is widely used in regular and compact laundry detergents and automatic dishwashing detergents (in powder, liquid, gel and/or tablet form), toilet cleaners, surface cleaners, and coffee urn cleaners. It also provides a number of chemical functions including: sequestration of "water hardness", enabling surfactants to function effectively; pH buffering; dirt emulsification and prevention of deposition; hydrolysis of grease; and dissolving-dispersing dirt particles. (see below further information on how to use sodium tripolyphosphate in Dishwasher and Laundry formulations)

Properties of sodium tripolyphosphate: 

  • CAS No: 7758-29-4
  • EINECS No: 231-838-7
  • Other Names: Sodium tripolyphosphate; STPP; STP; sodium triphosphate; TPP; Pentasodium triphosphate;
  • Appearance: White powder
  • Formula: Na5P3O10
  • Density: 2.52 g/cm3
  • Molar Mass: 367.86 g mol/1
  • Melting point: 622 oC
  • Solubility: soluble in water 145 g/L @25C
  • pH: 9.5 - 10.3 (10% solution)

Health & Safety

R-phrase(s): R36/37/38 Irritating to eyes, respiratory system and skin.

S-phrase(s): S26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36 Wear suitable protective clothing

PLEASE NOTE: This product is not for human or animal consumption.

Click here to view MSDS


Using Sodium Tripolyphosphate in Dishwasher and Laundry Formulations:

Sodium tripolyphosphate (STPP) is a common ingredient in dishwasher and laundry detergents, valued for its ability to soften water, enhance cleaning efficiency, and prevent the re-deposition of dirt on fabrics and surfaces. The typical levels of STPP used in these products can vary, but general guidelines are as follows:

Dishwasher Detergents:

  • Typical Concentration: In dishwasher detergents, sodium tripolyphosphate is often used at concentrations ranging from 20% to 50% by weight.
  • Function: STPP acts as a water softener and detergent booster. It helps to sequester metal ions (such as calcium and magnesium) in hard water, improving the effectiveness of surfactants and preventing scale formation on dishes and inside the dishwasher.

Laundry Detergents:

  • Typical Concentration: In laundry detergents, the concentration of sodium tripolyphosphate typically ranges from 15% to 35% by weight.
  • Function: STPP serves multiple roles in laundry detergents. It softens water, enhances the performance of surfactants, helps to suspend dirt and soils in the wash water, and prevents them from redepositing onto fabrics.

Factors Influencing Concentration Levels:

  1. Water Hardness: Higher concentrations of STPP may be used in areas with very hard water to ensure effective water softening and cleaning performance.
  2. Formulation Strategy: The specific formulation of the detergent, including the presence of other water softening and cleaning agents, will affect the amount of STPP used.
  3. Regulatory Restrictions: Due to environmental concerns about the contribution of phosphates to eutrophication in water bodies, many regions have regulations limiting or banning the use of phosphates in household detergents. In such cases, alternative chelating agents or reduced phosphate formulations may be used.