Abstract
This study was undertaken to define the role of polyphosphate builders in detergent , systems. Radiochemical methods were employed to trace polyphosphate and calcium reactions with cotton at various calcium to polyphosphate ratios. Cotton does not adsorb polyphosphate in the absence of polyvalent metal ions. The amount of calcium and polyphosphate adsorbed by, or deposited on, cotton during a 10-min. wash in hard water is dependent on the calcium-polyphosphate phase present. A heterogeneous (pre cipitate) phase results in considerable deposition of a calcium-polyphosphate salt, while little deposition or adsorption occurs in a homogeneous (solution) phase. Deposition of clay soil onto cotton is not influenced by the presence of insoluble calcium-polyphos phate salts. However, there appears to be a direct relationship between soil deposition and number of unsequestered or unprecipitated calcium ions remaining in the wash solu tion. Tetrasodium pyrophosphate is relatively more efficient in achieving minimum soil deposition than sodium tripolyphosphate.
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