Received: 26 June 2007 Revised: 9 August 2007 Accepted: 13 August 2007
Abstract: 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.