Determination of the rate of tripoly and pyro-phosphate hydrolysis in sediments
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Abstract
The rate of hydrolysis of tripolyphosphate (TPP) and pyrophosphate (PP) in sediments was determined. The sediments used were collected from Cape Fair, Thomas Hill Lake, Flat Branch Creek, and Maries River. The rate of hydrolysis of TPP and PP was similar to that predicted from first order kinetics. Half lives for the hydrolysis of TPP and PP were found to be 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 5415 cal/mole for TPP and 10,412 cal/mole for PP. TPP and PP were hydrolyzed faster in non-sterile sediment than in sediment which had been sterilized, possibly due to the destruction of phosphatase and pyrophosphatase enzyme systems during sterilization. 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. PP hydrolysis was increased as pH was 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 (1/2life= 2.79 day) than when TPP was added as a solution (1/2life = 1.68 day).
This material is based upon work supported by the U.S. Geological Survey and the Missouri Water Center under the Grant/Cooperative Agreement.
The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey or Missouri Water Center. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey or Missouri Water Center.
This material is based upon work supported by the U.S. Geological Survey and the Missouri Water Center under the Grant/Cooperative Agreement.
The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Geological Survey or Missouri Water Center. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Geological Survey or Missouri Water Center.