Electrochemical redox mechanism of uranium in acidic perchlorate solutions

Summary The reduction and oxidation processes of uranium(VI), (V), (IV) and (III), in aqueous perchlorate solutions have been studied using the dropping mercury electrode, the hanging mercury drop electrode and the thin-layer technique. The experiments were performed in acidic media (0 −1 . The data obtained show that under certain conditions, the reduction process of uranium(V) is influenced by the chemical reaction of uranium(V) with uranium(III), resulting in the formation of uranium(IV). In the presence of this reaction the character of the polarographic and chronovoltammetric curves is changed. The disappearance of the uranium(III) oxidation peak on the chronovoltammetric curves obtained with the hanging mercury drop electrode can also be explained by this reaction. The kinetic parameters of the reduction of uranium(V) to (IV) were determined as k f,h 0 =(4.0±0.4)×10 −8 cm s −1 , and α=0.46±0.01. A detailed mechanism of the reduction of uranium(V) is proposed.