Complete Recovery of Actinides from UREX-like Raffinates using a Combination of Hard and Soft Donor Ligands

Studies have shown a much enhanced differentiation between trivalent actinides and trivalent lanthanides when substituted alkyl dithiophosphinic acids are utilized as the active phase transfer reagents. We present a study evaluating the use of a synergistic combination of bis(o-trifluoromethylphenyl)dithiophosphinic acid and trioctylphosphine oxide for the complete actinide recovery from UREX-like raffinates. A complete single-step separation of uranium, neptunium, plutonium, and americium from aqueous mixtures containing 0.5 M nitric acid and a total fission product content of 5.5 g/L (45 mM) has been demonstrated.