Comparison of the spectroscopic characteristics of uranium status when U(III) in LiCl-KCl eutectic melt is leached out with water and ionic liquid

The physicochemical properties of U(III) in molten salt in contact with ionic liquid and water were investigated to obtain better understandable information on the long-term storage of waste salt remaining from pyrochemical processing. UCl3 in LiCl-KCl eutectic melt was added into appropriate room-temperature ionic liquid and water, and determination of the oxidation state of uranium (U) in LiCl-KCl eutectic melt was achieved using spectroscopic methods. The addition of UCl3 in LiCl-KCl eutectic melt into the ionic liquid provided the same absorption spectrum as that obtained from the solvation of UCl3 by LiCl-KCl eutectic melt at 450 °C except for much less absorption peak intensities. The room-temperature ionic liquid of 1-hexyl-3-methyl-imidazolium chloride (HMICl) used in this research did not cause any oxidation or reduction of the U(III), as the other reported ionic liquids did. The U(III) in LiCl-KCl eutectic melt was stable in an HMICl ionic liquid and unstable in water.