Solvent extraction of lanthanides(iii) with mixtures of 1,3,5-tris(2-diphenylphosphoryl-4-ethylphenoxymethyl)benzene and 4-benzoyl-5-methyl-2-phenyl-3-pyrazolone

1,3,5-Tris(2-diphenylphosphoryl-4-ethylphenoxymethyl)benzene (L′), a phosphorylcontaining tripodand, was synthesized for the first time in order to find extraction systems for efficient recovery of lanthanides. The main regularities of extraction of lanthanide(III) ions with mixtures of L′ and 4-benzoyl-5-methyl-2-phenyl-3-pyrazolone (HL) into CHCl3, 1,2-dichloroethane, toluene, and carbon tetrachloride from chloride solutions were elucidated. A significant synergistic effect, associated with the formation of hydrophobic mixed-ligand complexes of lanthanides(III), was found. The stoichiometry of the extracted complexes was determined by the equilibrium shift method. The equilibrium constants and values of the synergistic effect in the LnIII—L′—HL—dichloroethane system were calculated. The influence of the nature of the organic solvent and the composition of the aqueous phase on the efficiency of lanthanide(III) ion extraction into the organic phase was considered.