Technical index and application of sodium tripolyphosphate

Sodium tripolyphosphate (STPP)

[Structural formula]

[Physical and chemical properties] Sodium tripolyphosphate is also known as pentasodium phosphate , sodium triphosphate , pentasodium, and sodium pyrometaphosphate, with the molecular formula Na ₅ P ₃ O ₁₀

[Preparation]

(1) Thermal phosphoric acid method

Put the phosphoric acid (50%～60%) solution into the stainless steel neutralization tank after measuring, increase the temperature and start the mixer, slowly add soda ash under stirring for neutralization reaction, and maintain disodium hydrogen phosphate and diphosphate in the neutralization tank.

The reaction equation is as follows:

(2) Wet-process phosphoric acid method

The phosphate rock powder is reacted with sulfuric acid to obtain the extracted phosphoric acid.

(3) Caustic soda replaces soda ash

Add phosphoric acid to the neutralization tank, then add caustic soda to neutralize, prepare a mother liquor with a neutralization degree ( molar ratio of sodium oxide to phosphorus pentoxide ) of 1.

5NaOH+4H ₄ PO ₄ +nH ₂ O→2Na ₂ HPO ₄ +NaH ₂ PO ₄ +(n+5)H ₂ O

[Technical index] GB/T9983-2004 industrial sodium tripolyphosphate

[Application] Sodium tripolyphosphate is an inorganic builder with excellent performance.

Polyphosphate is one of the earliest, most widely used and most economical cooling water corrosion inhibitors.

Sodium tripolyphosphate has certain requirements for the flow rate of water.