Photochemical reduction of the uranyl ion by phosphorus acid amides in aqueous solutions

The authors investigate the photochemical reduction of the uranyl ion by hexamethyphosphoric triamide and hexaethylphosphoric triamide molecules in aqueous sulfuric acid solutions, upon irradiation with light of wavelength 313 nm. The quantum yield of the photoreduction has been determined at various HMPA concentrations. It has been shown that a maximum quantum yield is reached at equal concentrations of uranyl ion and HMPA. The relation between the quantum yield and the temperature has been found. A reaction mechanism which includes a transfer of an oxygen atom from the uranyl ion to the HMPA is proposed for the photo reduction of the uranyl ion by HMPA molecules