Journal of Nuclear Fuel Cycle and Waste Technology

A spectroelectrochemical method has been applied to investigate the electrochemical behaviors and identify the kinds of samarium ions dissolved in high temperature molten LiCl-KCl eutectic. An optically transparent electrode (OTE) fabricated with a tungsten gauze as a working electrode has been used to conduct cyclic voltammetry and potential step chronoabsorptometry. Based on the reversibility of the redox reaction of Sm3+/Sm2+ , which was determined from the cyclic voltammograms, the formal potential and the diffusion coefficient were calculated to be -1.99 V vs. Cl2/Cl- and 2.53 × 10-6 cm2·s-1, respectively. From the chronoabsorptometry results at the applied potential of -1.5 V vs. Ag/AgCl (1wt%), the characteristic peaks of absorption for samarium ions were determined to be 408.08 nm for Sm3+ and 545.62 nm for Sm2+. Potential step chronoabsorptometry was conducted using the anodic and the cathodic peak potentials from the voltammograms. Absorbance analysis at 545.63 nm shows that the diffusion coefficient of Sm3+ is 2.15 × 10-6 cm2·s-1, which is comparable to the value determined by cyclic voltammetry at the same temperature.

Keywords

Samarium,Molten LiCl-KCl eutectic,Spectroelectrochemical,Cyclic voltametry,Potential step chronoabsometry