Extraction of Uranium from Aqueous Solutions by Using Ionic Liquid and Supercritical Carbon Dioxide in Conjunction

Super powers! Uranium(VI) ions can be extracted from aqueous solutions into supercritical CO2 (sc‐CO2) via an ionic liquid phase that contained tri‐n‐butyl phosphate (TBP) as a complexing agent (see figure). This process has potential applications in the nuclear industry for removing actinides from nuclear waste. magnified image Uranyl ions [UO2]2+ in aqueous nitric acid can be extracted into supercritical CO2 (sc‐CO2) by using an imidazolium‐based ionic liquid with tri‐n‐butyl phosphate (TBP) as a complexing agent. The transfer of uranium from the ionic liquid to the supercritical fluid phase was monitored by UV/Vis spectroscopy using a high‐pressure fiber‐optic cell. The form of the uranyl complex extracted into the sc‐CO2 phase was identified to be [UO2(NO3)2(TBP)2]. The extraction results were confirmed by fluorescence spectroscopy and by neutron activation analysis. This technique has potential applications in the field of nuclear waste management for extracting other actinides.