AUTOXIDATION OF URANIUM(V) - CATALYSIS AND INHIBITION BY COPPER IONS

The autoxidation of UO2+ in acidic aqueous solutions yields UO22+ and H2O2 as products. The initial step occurs with a rate constant k(U) = 31.4 M(-1) s(-1). The reaction is catalyzed by aquacopper(II) ions, owing to the reaction between Cu2+ and UO2+ (k = 915 M(-1) s(-1)) yielding Cu+, which is rapidly reoxidized by O-2. Cu2+ also reacts with an intermediate produced in the direct reaction of UO2+ and O-2, and the combined effects of Cu2+ aS catalyst and scavenger lead to an unusual dependence of the observed rate constant on [Cu2+]. The role of superoxouranium(VI) and HO2. as reaction intermediates is discussed.