Study on Redox Equilibrium of UO₂²⁺/U₂⁺in Molten NaCl-2CsCl by UV-Vis Spectrophotometry

Abstract

In order to enhance the understanding of the redox equilibriums of uranyl ions in molten NaCl-2CsCl eutectic salt UV-Vis absorption spectrophotometry measurements were performed for UO2 2+ in molten NaCl-2CsCl at 923 K under simultaneous electrolytic control of their ratio. A prominent absorption band at 395 nm was assigned to UO2 +, and its molar absorptivity was determined to be 832±27 mol-1·l·cm-1. From the dependence of the rest potential of the melt on the spectrophotometrically determined ratio of [UO2 2+]/[UO2 +], the standard redox potential of the couple UO2 2+/UO2 + was determined to be −0.903±0.007 V vs. Cl2/Cl—.