Effect of crown ethers on the solvent extraction and separation of lanthanide(III) ions with 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one

Synergistic solvent extraction of 14 lanthanides with mixtures of 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and the crown ethers (S), 18-crown-6, benzo-18-crown-6 or dibenzo-18-crown-6 from an aqueous chloride medium with the constant ionic strength of 0.1 mol dm⁻³ was investigated using benzene as a diluent. The composition of the species extracted was determined as LnP3 · S. The addition of a crown ether to the chelating extractant produced rather significant synergistic effects. On basis of experimental data, values of equilibrium constants, synergistic coefficients, and separation factors were calculated.