Extraction of Lanthanides(III) from Nitric Acid Solutions by Selected Polyfunctional Monoacidic Organophosphorus Compounds

Abstract

The extraction of microquantities of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from HNO3 solutions by bis(diphenylphosphinylmethyl)‐phosphinic acid (II), bis[2‐(diphenylphosphinyl)phenoxymethyl]phosphinic acid (III) and bis[2‐(diphenylphosphinyl‐methyl)phenoxymethyl]phosphinic acid (IV) in organic diluents has been studied. The effect of HNO3 concentration in the aqueous phase and that of the extractant concentration in the organic phase on the extraction of metal ions is considered. The stoichiometry of the extracted complexes has been determined. The replacement of phenyl radical in the P(O)OH fragment of (diphenylphosphinylmethyl)phenylphosphinic acid (I) by a Ph2P(O)CH2‐ group, i.e., an increase in the number of phosphoryl groups in the extractant II molecule, leads to an increase of Ln(III) extraction from HNO3 solutions by compound II in polar organic diluents. Compound III possesses a lesser extraction efficiency towards Ln(III) than II, but it exhibits a higher Lu/La selectivity. The difference in the ability of extractant II and bis(dioctylphosphinylmethyl)phosphinic acid (V) to extract Ln(III) lessens as the atomic number of Ln(III) increases or when HNO3 concentration in the aqueous phase increases.