Extraction of Rare Earth Elements(III) with Mixtures of Some New Tridentate Carbamoylmethylphosphine Oxides and 4-Benzoyl-3-methyl-1-phenyl-1 H -pyrazol-5(4 H )-one from Hydrochloric Acid Solutions

Extraction of rare earths(III) from hydrochloric acid solutions with mixtures of new tridentate carbamoylmethylphosphine oxides Ph2P(O)CH2CON(R)CH2CH2P(O)Ph2 (R = Me, Bu, Oct) and 4-benzoyl-3-methyl-1-phenyl-1H-pyrazol-5(4H)-one in organic solvents has been studied. The observed strong synergistic effect has been attributed to the formation of hydrophobic mixed-ligand rare earth complexes in the organic phase. Stoichiometry of the extractable complexes has been determined, and extraction constants have been calculated. The effect of organic solvent and composition of the aqueous phase on the extraction efficiency has been analyzed.