Effect of ionic liquids on the extraction of rare-earth elements by bidentate neutral organophosphorus compounds from chloride solutions

The partition of microamounts of lanthanide chlorides (Ln = La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) between aqueous HCl and organic solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide was studied in the presence of ionic liquids (ILs): 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The stoichiometry of extracted complexes was determined. The effect of the aqueous HCl concentration, the nature of the extractant, and the organic diluent on the efficiency of lanthanide extraction was studied.