Extraction of Rare-Earth Elements from Hydrochloric Acid by Carbamoyl Methyl Phosphine Oxides in the Presence of Ionic Liquids

Abstract

The distribution of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y between aqueous HCl solutions and solutions of carbamoyl methyl phosphine oxides (CMPOs) has been studied in the presence of the 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid (IL). The efficiency and selectivity of REE(III) extraction by CMPO solutions increase considerably in the presence of the ionic liquid in the organic phase. The stoichiometry of the extractable complexes has been determined; the effects of the IL cation, organic solvent, CMPO structure, and aqueous HCl concentration on the efficiency of REE(III) recovery into the organic phase has been considered.