Electrochemical separation of fission element samarium on lead electrodes from KCl-LiCl molten salts and the kinetic research of the process

In order to improve the utilization of spent fuel, electrolysis is used to recover fissile elements from nuclear waste samarium. The electrochemical behaviors of Sm(III) and Pb(II) were examined by CV, SWV, and OCP techniques in LiCl-KCl molten salts at 773 K. The redox mechanism of Sm(III) ions on the liquid Pb thin film electrode was analyzed. The results demonstrate that Sm(III) electro-reduction at the inert W electrode only occurred in a soluble-soluble electrochemical transition Sm(III)/Sm(II). Additionally, the kinetic parameters of samarium and lead ions were computed. The activation energies of diffusion for Sm(III) and Pb(II) were 32.92 kJ mol^-1 and 35.21 kJ mol^-1, respectively. SmPb₃ and Sm₂Pb intermetallic compounds were derived using constant potential electrolysis and constant current electrolysis at the Pb electrode in a molten salt system. The cathodic deposition output was characterized by XRD and SEM-EDS. The ICP-AES results showed that the average extraction ratio of Sm on the Pb electrode was about 94.23%. (author)