Electrochemical monitoring of lanthanum ion concentration in high-temperature molten salt

Online monitoring of lanthanide fission product concentrations has been a great challenge in the pyrochemical reprocessing of spent nuclear fuels. Electrochemical techniques, with the advantages of accuracy and timeliness, provide a feasible strategy. In this work, the relationship between lanthanum ion (La(III)) concentration and reaction current was investigated by various electrochemical methods in LiCl–KCl eutectic salt. Tafel test results show that there is a linear relationship between the exchange current density (i₀) and ion concentration (i₀ = 0.06618x + 0.04409). In addition, according to the comparative analysis of electrochemical test results, it is found that anodic stripping voltammetry is a potential ion concentration detection technology. The peak current (i_pc) and ion concentration satisfy the relationship: i_pc = 0.08503x − 0.02245. According to the equation, the calculated La(III) concentration is almost consistent with that analyzed by inductively coupled plasma atomic spectrometer (ICP-AES), which provides a plausible way for ion concentration monitoring in high-temperature molten salt.