Extraction of U(VI), Th(IV), and Lanthanides(III) from Nitric Acid Solutions with Mixtures of Diphenyl-N,N-dioctylcarbamoylmethylphosphine Oxide and Lithium Bis[(trifluoromethyl)sulfonyl]imide

The extraction of U(VI), Th(IV), and lanthanide(III) ions with mixtures of diphenyl-N,N-dioctylcarbamoylmethylphosphine oxide (Ph(2)Oct(2)) and lithium bis[(trifluoromethyl)sulfonyl]imide (LiTf2N) in dodecane containing 10% octanol was studied. A synergistic effect was discovered during the extraction of metal ions with such mixtures. When extracting Ln(III) from solutions of 3 M HNO3, the DLn values in the system with Ph(2)Oct(2)-LiTf2N are more than three orders of magnitude higher than when extracting with a solution of Ph(2)Oct(2). The stoichiometry of the extracted complexes was determined, and the effect of HNO3 concentration on the extraction of metal ions was studied. It has been established that actinide and lanthanide(III) ions are extracted with a mixture of Ph(2)Oct(2) and LiTf2N from nitric acid solutions via a cation-exchange mechanism.