Selective Electrodeposition of Europium and Samarium in Molten LiCl-KCl with Copper and Aluminum Electrodes

Separation of the adjacent lanthanide (Ln) pair such as Sm-Eu from each other using chemical methods is difficult due to their similar chemical features. In the present work, electrochemical separation of Eu and Sm from each other were studied in molten LiCl-KCl-1 wt% EuCl3-1 wt% SmCl3 at 500 °C. By using a Cu reactive electrode, Sm was selectively separated from the salt because of the formation of several Cu-Sm intermetallic compounds while Eu remained in the salt. The formation of Al-Eu compounds occurs at a more negative potential than that of the Al-Sm compounds on Al electrode. However, the formation rate of Al-Eu compound is much higher than that of Al-Sm compound. With an electrolysis time of 0.5 h and a potential at −2.225 V (vs Ag(I)/Ag), the deposit on the electrode is mainly made up of Al-Eu compound. This study reveals the influence of working electrode on Eu-Sm separation and provides a potential method for adjacent lanthanide pair separation.