Selectivity of extraction of U(VI), Th(IV), and REE(III) from perchloric acid solutions with bidentate phosphoryl-substituted butyl phenylphosphinates

Abstract

Extraction of microamounts of U(VI), Th(IV), and REE(III) from HClO4 solutions with solutions of bidentate phosphoryl-substituted butyl phenylphosphinates R2P(O)CH2P(O)Ph(OBu) [R = phenyl (I), octyl (II)] in dichloroethane was studied. The effect of substituents at the phosphorus atom in the phosphine oxide moiety of these compounds on their extraction ability and selectivity was examined, and the stoichiometry of the extractable complexes was determined. In going from nitric to perchloric acid solutions, the efficiency of the extraction of U(VI) and REE(III) considerably increases, the U/REE separation factors increase, but the Th/U separation factors decrease.