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What Are The Functions of STPP In Detergent

Sodium tripolyphosphate has a wide range of applications in our daily life, and one of the most important uses is it can be used as a detergent additive. To know the functions of stpp in detergent, we first need to know some of the physical and chemical properties of sodium tripolyphosphate.

>>> STPP Properties

  • Hydration performance. Sodium tripolyphosphate can be divided into high temperature type and low temperature type due to the different formation temperature. Both the two types can generate hexahydrate Na5P3O10.6H2O.
  • Hydrolysis performance. Sodium tripolyphosphate can undergo hydrolysis reaction to produce sodium pyrophosphate, disodium hydrogen phosphate and sodium dihydrogen phosphate.
  • Chelating ability to metal ions. STPP chemical has complexing effect with metal ions such as Ca2+, Mg2+, Fe3+ dissolved in water to form a soluble complex.
  • Buffering effect. The aqueous solution of sodium tripolyphosphate is weakly alkaline, and it will form a suspension in water with the PH value of 4.3-14, that is dispersing effect. It can also make the liquid and solid particles better dissolve in the liquid medium, making the solution completely transparent, just like a real solution, this is called solubilization effect.

>>> Functions of STPP In Detergent

  • STPP is quite stable at room temperature, and will undergo hydrosis slowly in humid air, finally form sodium orthophosphate. The high-temperature type has faster hydration and high heat generation, and is prone to agglomeration when dissolved in water, while the low-temperature type generated hexahydrate at a very slow rate in water. So pay attention to the ratio of these two types of stpp in detergent.
  • Chelation of Metal Ions. Daily washing water generally contains hardening. With excellent properties of chelating hard metal ions, stpp can eliminate the adverse effects of these metal ions on washing.
  • The dirt on clothing often contains human secretions, mainly protein and fat, as well as sand and dust from the outside world. The swelling and solubilization effect of sodium tripolyphopshate on protein can have a peptizing effect. It can promote emulsification for fatty substances, disperse and suspend solid particles. These properties can make dirt more effectively removed, while also preventing the redeposition of dirt.
  • Its alkaline buffering effect can help the removal of acidic dirt.
  • The hexahydrate formed by stpp absorbing water has dry characteristics. Used in powdery synthetic detergent to prevent caking.


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