Electrochemical reduction of uranium and rhenium in hydrochloric acid system

Abstract The electrochemical reduction of U(VI) and Re(VII) ions on Pt and Mo metals are discussed. The electrochemical behavior of U(VI) and Re(VII) in hydrochloric acid media was investigated using various electrochemical techniques. By analyzing the cyclic voltammogram of U(VI) and Re(VII) recorded on Pt electrode, a series of electrochemical reactions associated with uranium and rhenium were recognized, indicating that U(VI) and Re(VII) undergoes a single-step electron and multistep electron process under experimental conditions, respectively. The reduction of U(VI) and Re(VII) was found to be controlled by charge transfer and diffusion in hydrochloric acid media. The diffusion coefficient of U(VI) and Re(VII)was determined to be 4.22–5.99 × 10 −6 cm 2 s −1 and 1.50–2.90 × 10 −5 cm 2 s −1 , respectively, and the activation energy for the diffusion are calculated to be 18.12 kJ mol −1 and 14.52 kJ mol −1 by cyclic voltammetry at different temperatures. The reduction process of U(VI) and Re(VII) at hydrochloric acid is further studied by potentiostatic electrolysis. It is feasible to realize the reduction of uranium and rhenium from aqueous solution by electrolysis.