Photochemical reduction of the uranyl ion with dialkyl sulfides

Abstract

The photochemical reduction of the uranyl ion by diethyl, di-n-propyl, and di-n-butyl sulfides has been investigated in acidified water-acetone medium by using radiations in the visible region (greater than or equal to 365 nm) from a medium-pressure mercury lamp. The photoreduction is independent of temperature. The quantum yield increases with an increase in dialkyl sulfide or hydrogen ion concentration. The plots of the reciprocal of the quantum yield vs. the reciprocal of initial dialkyl sulfide concentration are linear with intercepts on the ordinate axis. Stern-Volmer quenching constants have been calculated from luminescence measurements and indicated that physical and chemical quenching compete with each other. Electronic absorption spectra reveal that there is no ground-state interaction between the uranyl ion and the dialkyl sulfide. On the basis of product analysis, quantum yield of uranium(IV) formation, and Stern-Volmer quenching constants, a dynamic mechanism of oxygen atom transfer from the excited uranyl ion to dialkyl sulfide has been proposed. 33 references, 3 figures, 3 tables.