The role of sodium tripolyphosphate as an additive
Nov 26,2025
When using sodium tripolyphosphate, have you ever wondered about its role as an additive? As a manufacturer of sodium tripolyphosphate from Weifang, let me take you on a brief exploration of this topic!
1. Buffering Effect: Sodium tripolyphosphate has a strong alkaline buffering effect, maintaining the pH of the washing solution at around 9.4, thereby facilitating the removal of acidic dirt.
II. Function of Preventing Caking: Powdered synthetic detergents are hygroscopic; if stored in a humid environment, they tend to cake. Caked detergents are inconvenient to use. However, sodium tripolyphosphate, after absorbing water, forms a hexahydrate that exhibits a dry and crisp texture. When a detergent formulation contains a large amount of sodium tripolyphosphate, it effectively prevents caking caused by moisture absorption, thereby maintaining the synthetic detergent’s dry, granular consistency.
3. Chelating Action on Metal Ions: Household washing water typically contains hardness-causing metal ions—primarily Ca²⁺ and Mg²⁺. During the washing process, these ions react with the active ingredients in soaps or detergents to form insoluble metal salts. As a result, not only does the consumption of detergent increase, but the washed fabrics also acquire an unpleasant dark-gray hue. Sodium tripolyphosphate exhibits excellent chelating properties for hardness-causing metal ions, thereby effectively neutralizing the adverse effects of these ions.
4. Enhancing the effects of gel dissolution, emulsification, and dispersion: Dirt often contains human secretions (primarily proteins and fatty substances) as well as external contaminants such as sand, soil, and dust. Sodium tripolyphosphate exhibits a swelling and solubilizing effect on proteins, thereby achieving gel dissolution; it promotes emulsification of fatty substances; and it helps disperse and suspend solid particles.
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