Extraction Properties of Diphenyl{[N-(2-diphenylphosphinylethyl)-N-alkyl]carbamoylmethyl}phosphine Oxides in Nitric Acid Solutions

Abstract

Extraction of micro amounts of U(VI), Th(IV), and REE(III) from HNO3 solutions with solutions of diphenyl{[N-(2-diphenylphosphinylethyl)-N-alkyl]carbamoylmethyl}phosphine oxides in organic solvents has been studied. Extracted complexes stoichiometry has been determined, effect of extractant structure, organic solvent nature, and aqueous phase composition on the efficiency of U(VI), Th(IV), and REE(III) recovery into organic phase have been considered. It has been shown that the modification of diphenyl(dialkylcarbamoylmethyl)phosphine oxide by the introduction of additional phosphoryl group into the amide moiety leads to increase in extraction ability toward Th(IV) and slight change in the recovery degree of U(VI) from nitric acid solutions. The efficiency of U(VI), Th(IV), and REE(III) recovery into organic phase increases considerably in the presence of ionic liquid: 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide.