Synergistic Solvent Extraction of Lanthanides(III) with Mixtures of 4-benzoyl-3-methyl-1-phenylpyrazol-5-one and Some Novel Carbamoyl- and Phosphorylmethoxymethylphosphine Oxides

Abstract

The solvent extraction of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y from weak acidic hydrochloric acid solutions into an organic phase containing 4-benzoyl-3-methyl-1-phenylpyrazol-5-one (HP) and neutral tridentate organophosphorus ligands R₂P(O)CH₂OCH₂C(O)NBu₂ R = Bu (I), R = Ph (II) and R₂P(O)CH₂OCH₂P(O)R¹₂ R = R¹ = Bu (III); R = Bu, R¹ = Ph (IV); R = R¹ = Ph(V) has been studied. A considerable synergistic effect was observed in the presence of HP in the organic phase containing tetraoctyldiglycolamide (TODGA) and neutral organophosphorus ligands I - V. A successive replacement of C(O)NAlk₂ groups in the diglycolamide extractant molecule by P(O)Ph₂ groups leads to an increase in the extraction efficiency of Ln(III) ions when toluene was used as diluent. Phosphoryl-containing podand I possess a higher extraction efficiency towards Ln(III) ions than TODGA. The extraction equilibrium was investigated and the equilibrium constants were calculated. It was found that the lanthanide(III) ions are extracted as LnLP₃ and LnL₂P₃ complexes with mixtures of HP and I in toluene from weak acidic solutions.

Keywords:

• lanthanides(III)
• synergistic extraction
• 4-benzoyl-3-methyl-1-phenylpyrazol-5-one
• TODGA
• neutral tridentate organophosphorus ligands