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Sodium tripolyphosphate as a food additive
- Aug 21, 2018 -


White powder, melting point 622 °C, soluble in water, has significant chelating ability to metal ions such as calcium and magnesium, can soften hard water, make suspension into solution, weakly alkaline, non-corrosive, is an inorganic substance Surfactant, has strong emulsification effect on lubricating oil and fat. The bulk density is usually divided into low density of 0.35-0.5g/cm 3 , medium density of 0.51-0.65g/cm 3 and high density of 0.66-0.9g/cm 3 ; Sodium tripolyphosphate has two crystal forms of type I (high temperature type) and type II (low temperature type), the two of which have the same chemical properties, the difference being that the thermal stability and hygroscopicity type I are higher than type II, and the solubility of both, The heat of hydration is different when dissolved.


According to the structure and shape, it is divided into white powder anhydrate (Na5P3O10) and right-angled parallelepiped crystal hexahydrate (Na5P3O10·6H2O). Anhydrates are classified as type I and type II. Industrial sodium tripolyphosphate is actually a mixture of Type I and Type II. Type I dissolves quickly, and when hydrated to form hexahydrate, the thermal effect is large, and it is easy to absorb moisture and agglomerate in the atmosphere. Type II absorbs moisture slowly and is not easy to agglomerate. Therefore, the content of type I in detergent sodium tripolyphosphate should not be too high, generally controlled at 10 to 30%.


Sodium tripolyphosphate is an indispensable and excellent auxiliaries in detergents, and the content of most detergents is 10 to 50%. Its main role can be summarized as follows.

1 Chelation of metal ions: In daily washing water, it usually contains hard metal ions (mainly Ca2+, Mg2+). During the washing process, they will form insoluble metal salts with the actives in the soap or detergent, thus not only increasing the consumption of the detergent, but also imparting an unpleasant dark gray to the washed fabric. Sodium tripolyphosphate has excellent properties for chelation of hard metal ions, thereby eliminating the adverse effects of these metal ions.

2 improve the role of peptization, emulsification and dispersion: dirt often contains human secretions (mainly protein and fat substances), but also contains sand, dust and other from the outside. The sodium tripolyphosphate has a swelling and solubilizing effect on the protein and acts as a peptizing solution; it can promote the emulsification of the fatty substance; and disperse and suspend the solid particles.

3 Buffering effect: Sodium tripolyphosphate has a large alkaline buffering effect, so that the pH value of the washing solution is maintained at about 9.4, which is beneficial to the removal of acidic soil.

4 to prevent the role of agglomeration: powdered synthetic detergent is hygroscopic, such as stored in a place with high humidity, agglomeration will occur. The agglomerated detergent is extremely inconvenient to use. The hexahydrate formed by the absorption of sodium tripolyphosphate has a dry characteristic. When there is a large amount of sodium tripolyphosphate in the detergent formulation, it can prevent the agglomeration caused by moisture absorption and keep the dry detergent of the synthetic detergent.


Used as a detergent additive, it can also be used in petroleum, metallurgy, mining, paper making, water treatment, etc. Mainly used as an auxiliary agent for synthetic detergents, used in soap synergists and to prevent the precipitation and blooming of bar soap oil. It has a strong emulsification effect on lubricating oil and fat and can be used to adjust the pH of the buffer soap. A softener for industrial water. Tanning - agent. Dyeing aids. In the paint, kaolin, magnesia, calcium carbonate and other industries, when used in suspension, it is used as a dispersing agent. Drilling mud dispersant. The paper industry is used as an anti-oil agent. In the food industry, it is used as a quality improver for cans, juice drinks, dairy products, soymilk, etc. It is mainly used for tenderizing ham, canned beans in canned beans, and can also be used as softeners and thickeners.