Reductive extraction of lanthanides (Ce,Sm) and its monitoring in LiCl KCl/Bi Li system

Abstract The reductive extraction behavior of Ln (Ce,Sm) and its on-line monitoring were explored in LiCl KCl/Bi Li system. According to calibration curve, the relationship of peak current and concentration of Ln (Ce,Sm) measured by square wave voltammetry, the calculated Ln (III) concentration is almost consistent with that analyzed by ICP-AES, and the relative average error is about 5.37%. The effects of Li content in Bi Li alloys, temperature and stirring speed on extraction rates, efficiencies and distribution ratios for Ce and Sm were determined, and found that the extraction rates, efficiencies and distribution ratios for Ce and Sm increase with the increasing the temperature, content of Li in Bi Li alloys and stirring speed. The extraction rates and efficiencies for Ln from LiCl KCl LnCl 3 molten salts are higher than those for Ln from LiCl KCl CeCl 3 SmCl 3 molten salts, and the ones for Ce are much larger than those for Sm due to the formation of Sm (II) checked using XPS and linear sweep voltammetry. The produced Sm (II) could consume some reduced Sm metal: 2 Sm(III) + Sm = 3 Sm(II) , resulting in the decrease of the extraction rate, efficiency and distribution ratios of Sm. The experimental results showed the feasibility of on-line monitoring of reductive extraction process of Ln in LiCL-KCl/Bi Li system by electrochemical technique.