Electrochemical separation of Gadolinium from variable valence europium in molten LiCl-KCl via liquid LBE alloy electrode

The highly effective separation of two adjacent rare earth is significant to the rare earth and nuclear industries. This paper investigates the highly effective separation of Gd over Eu using liquid lead–bismuth eutectic (LBE) alloy cathode in molten LiCl-KCl-EuCl3-GdCl3 by pulse potential electrolysis (PPE). Underpotential deposition of Eu and Gd is observed on the LBE alloy, with a depolarization value far greater than that of the liquid Pb electrode. Furthermore, the higher exchange current density and the lower activation energy of the electrode reaction indicate that the LBE alloy cathode has higher kinetic performance than the liquid Pb. Then, the practical electro-separation in LiCl-KCl-EuCl3-GdCl3 systems is carried out by applying different electrolysis technology. The effects of varying electrolysis methods and parameters on separation factor (SF), extraction efficiency, cathode product morphology, and crystal size are studied and compared. The results show that both the extraction efficiency and the separation factor obtained by the PPE are the largest. The calculated extraction efficiency of Gd and the actual separation factor SFGd/Eu of Gd/Eu could be up to 99.1 % and 759, respectively.