Direct Extraction of Uranium Oxides with N,N-Di(2-ethylhexyl)isobutyramide

The direct extraction of uranium from voloxidized nuclear fuel into an organic solvent offers several potential advantages over conventional hydrometallurgical reprocessing, including reducing the reprocessing plant footprint, providing an initial degree of decontamination from fission products, and minimizing the amount of secondary waste from nitric acid. In this work, the direct extraction of uranium oxides into 1.5 M N,N-di(2-ethylhexyl)isobutyramide (DEHiBA) in n-dodecane is examined. UV-vis spectra and distribution ratios of HNO₂ in 1.5 M DEHiBA as well as the equilibrium organic phase H₂O concentrations in HNO₃-loaded 1.5 M DEHiBA are also reported. Hypothesized reaction stoichiometries for the direct extraction of uranium from UO₂, α-U₃O₈, and ε-UO₃ are verified through analysis of organic-phase U, HNO₂, and HNO₃ concentrations after dissolution. Water generated by the dissolution results in the formation of a separate aqueous phase, which will need to be accounted for in future flowsheet design.