Electrochemical Behavior and Extraction of Yttrium on Cu Electrode in LiCl-KCl Eutectic

Abstract

The electrochemical behaviors of Y(III) were investigated on inert W and reactive Cu electrodes in LiCl-KCl eutectic by electrochemical technique at 773K. On an inert W electrode, the apparent standard potential of Y(III)/Y(0) couple was studied at different concentration of Y(III) ions using cyclic voltammetry. The result shows the apparent standard potential of Y(III)/Y(0) couple has a dependent on the concentration of Y(III) ions. On a reactive Cu electrode, cyclic voltammetry, stripping voltammetry and square wave voltammetry experiment results indicated that the deposition potential of Y (III) shift toward more positive values than that on W electrode because of the formation of Cu-Y intermetallic compound. Five Cu-Y intermetallic compounds, Cu6Y, Cu4Y, Cu7Y2, Cu2Y and CuY, were found to be formed by transient and steady electrochemical methods. Based on open circuit chronopotentiogram, the intermetallic compounds of Cu7Y2 is easier to form and more stable than the others because its platform is longer. Potentiostatic and galvanostatic electrolysis was conducted on Cu electrode to extract metallic yttrium. Furthermore, the cyclic voltammetry curves showed that the redox signals observed before electrolysis almost disappeared after electrolysis. In addition, the concentration of Y(III) ions in LiCl-KCl melts were detected by inductive coupled plasma atomic emission spectrometer before and after electrolysis, and the current efficiency for the electroextraction of Y was estimated. The results showed that Y(III) ions could be effectively extracted using reactive Cu electrode. Finally, the electrolysis products were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results showed that yttrium and copper can form Cu-Y intermetallic compounds during electrolysis and the thickness of alloy layer is about 50 mm. Acknowledgement The work was financially supported by the National Natural Science foundation of China (11675044, 11575047, 21790373, 21271054 and 21173060), the Major Research plan of the National Natural Science Foundation of China (91326113 and 91226201), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation. Figure 1