Kinetic Properties and Electrochemical Separation of Uranium on Liquid Bismuth Electrode in LiCl–KCl Melt

Abstract

Electrochemical studies of UCl3 and LnCl3 (Ln: La, Ce, Pr, Nd) in LiCl–KCl melt were performed on inert tungsten and reactive bismuth electrodes. Galvanostatic pulse (GP) and electrochemical impedance spectroscopy (EIS) were carried out to investigate the exchange current density j0 of UCl3/U on liquid Bi electrode at the temperature range of 723–873 K. The impedance data were well fitted with the equivalent circuit. The relationship between j0 and the temperature was determined to model the electrowinning by using liquid Bi electrode. In addition, the electrochemical separation in low concentration uranium from multi-component lanthanide chlorides was demonstrated on liquid Bi electrode. Three electrochemical techniques, including coulometric titration, galvanostatic electrolysis and potentiostatic electrolysis, were applied for the separation of uranium. In which, the coulometric titration showed good separation results. The separation of uranium from lanthanides in terms of mole ratio (U/Ln) was determined, and the different values were discussed in detail. In general, the data from this work can provide theoretical reference for the separation process of various metals by electrochemistry.