Extraction of Rare-Earth Elements from Nitric Acid Solutions with Bidentate Neutral Organophosphorus Compounds in the Presence of 1-Butyl-3-methylimidazolium Hexafluorophosphate

The distribution of microamounts of La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO3 solutions and solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoyhnethyflphosphine oxide, and dibutyl(diethylcarbamoylmethyflphosphine oxide in organic solvents in the presence of 1-buty1-3-methylimidazolium hexafluorophosphate (BMImPF(6)) was studied. The stoichiometry of the extractable complexes was determined. The influence of the HNO3 concentration and the nature of the extractant and organic solvent on the synergistic effect observed in the REE extraction in the presence of BMImPF(6) in the organic phase was analyzed. The possibility of using a macroporous polymeric sorbent impregnated with a mixture of tetraphenylmethylenediphosphine dioxide and BMImPF(6) for the recovery of REE(III), U(VI), and Th(IV) from HNO3 solution was demonstrated.