Tripolyphosphate and Pyrophosphate Hydrolysis in Sediments

Abstract

AbstractThe rate of hydrolysis of tripolyphosphate (TPP) and pyrophosphate (PP) in river, creek, and lake sediments was determined. Half‐lives for the hydrolysis of TPP and PP ranged from 1.6 to 2.6 and 6.7 to 27.4 days, respectively. The influence of temperature, biological activity, and pH on the rate of TPP and PP hydrolysis was investigated using Flat Branch Creek sediment. The rate of TPP and PP hydrolysis increased with increasing temperature. The activation energy was 5,415 cal/mole for TPP and 10,412 cal/mole for PP. TPP and PP hydrolyzed slower in sediment which had been autoclaved than in non‐sterilized sediment. The half‐life for TPP hydrolysis was 1.76 day at pH 5, 1.61 day at pH 7, and 2.16 day at pH 9. The rate of PP hydrolysis was increased as pH increased from 5 to 7 to 9 as indicated by half‐lives of 13.7, 10.0, and 7.3 days, respectively. When TPP was added to the sediment as a Ca5(P3O10)2 precipitate, the rate of hydrolysis was slower than when TPP was added as a solution.