Temperature-dependent photochemical reduction of UOUO22+-ions with sulfoxides in 5MH2SO4 solution

Photochemical reduction of uranyl ions with dimethylsulfoxide has been studied at a temperature exceeding 323 K in the solution of 5M H2SO4. The solutions have been irradiated with ultraviolet light of 2x1017 photon/sxcm2 intensity. The absorption spectra of the solutions have been studied in the process of irradiation. The bands at 18.000 and 15.660 cm-1 arising during irradiation are assigned to V4+. The rate of VO22+ reduction at 363 K is three times higher than at 323 K which corresponds to an effective activation energy of 25 kJoule/mole. The quantum yield of the reaction is 3x10-2. The proposed mechanism of the reduction which includes the stage of oxygen transfer from uranyl ions to sulfoxide has been considered