Hydrolysis of an organophosphate ester by manganese dioxide

La Trobe University Faculty of Science, Technology and Engineering Murray Darling Freshwater Research Centre

MDFRC item.

Amorphous manganese dioxide facilitates the hydrolysisof p-nitrophenyl phosphate to p-nitrophenol and orthophosphatedespite insignificant adsorption of p-nitrophenylphosphate or p-nitrophenol to the manganese dioxide. AtpH 8, the orthophosphate product is released into solution;at pH 4 and pH 6, some remains adsorbed. The rate ofhydrolysis is an order of magnitude more rapid than thesame reaction facilitated by iron oxides. Because manganesedioxides are ubiquitous components of soils and sediments,this suggests the possibility of significant abiotic pathwaysfor the formation of bioavailable orthophosphate fromphosphate ester precursors.