Electrochemical separation of La from LiCl-KCl fused salt by forming La-Pb alloys

Abstract To separate La from LiCl-KCl fused salt by forming La-Pb alloy, the electrochemical codeposition of Pb(II) and La(III) on inert W electrode and electroreduction of La(III) on liquid Pb were explored, respectively, using a group of electrochemical measurement methods. The formation mechanism reduction peak potentials of La-Pb intermetallics were obtained from the results of cycle voltammetry (CV), square wave voltammetry (SWV) and anodic stripping voltammetry (ASV). The kinetic data of La(III)/La (in Pb) couple on liquid Pb cathode, for instance, exchange current density, transfer coefficient, charge transfer resistance and activation energy, were studied by linear polarization and Tafel techniques. Moreover, constant potentials electrolysis (CPE) and constant current electrolysis (CCE) were conducted onliquid Pb cathode to recover La from fused salt. The electrolytic products checked by SEM-EDS and XRD were composed of LaPb3 phases.The maximum separation efficiency of La could reach 92.03% after CCE (0.15 A) for 7 h, which confirmed the feasibility of separating La from LiCl-KCl fused salt.