Electrolytic Extraction of Lanthanides (Ln=Tb, Dy, Ho) and Thermodynamic Evaluation of Cu-Ln Intermetallic Compounds in LiCl-KCl Melts

Abstract

The electrochemical reductions of Ln (III) (Ln= Tb, Dy, Ho) were studied on W and Cu electrodes in LiCl-KCl melts by transient electrochemical methods. Compared with W electrode, the electrochemical results indicated a series of new reduction peaks appeared at less negative potential owing to the formation of different Cu-Ln intermetallics. Moreover, the thermodynamic properties of Cu-Ln intermetallic compounds were estimated by open circuit chronopotentiometry. Using linear polarization method, the exchange current densities (j 0) of Lns on Cu electrode were estimated, and the temperature dependence of j 0 was studied to estimate the activation energies. In addition, potentiostatic electrolysis was conducted to extract Lns on Cu electrode, and different Cu-Ln intermetallic compounds were identified by X-ray diffraction and scanning electron microscope and energy dispersive spectrometer. Meanwhile, the change of Ln (III) concentration was monitoring using inductively coupled plasma-atomic emission spectrometry, and the extraction efficiency was estimated. Acknowledgement The work was financially supported by the National Natural Science foundation of China (11675044, 21790373, 21876034 and 11875116), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation.