Effect of ionic liquid on the extraction of actinides and lanthanides with 1,2,3-triazole-modified carbamoylmethylphosphine oxide from nitric acid solutions

Solvent extraction of U(VI), Th(IV), Am(III) and lanthanides(III) from aqueous nitric acid solutions with 1,2,3-triazole-modified carbamoylmethylphosphine oxide (L) and [C(4)mim][Tf2N] ionic liquid dissolved in 1,2-dichloroethane was studied. A considerable synergistic effect in this system was observed. This effect is associated with the high hydrophobicity of the IL anions which participate in the formation of metal extracted ion species. The influence of aqueous and organic phases on the extraction efficiency was elucidated and stoichiometry of the complexes extracted was determined. The synergistic effect for metal ion extraction from aqueous nitric acid solutions with compound L and [C(4)mim][Tf2N] in 1,2-dichloroethane becomes weaker when the acidity of the aqueous phase increases. The partition of Tf2N- anions between the organic and aqueous phases is the major factor governing the extractability of metal ions in the L-IL synergistic system. The interaction of L with HTf2N and HNO3 also substantially affects the efficiency of metal ion extraction.