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The liquid extraction of the 13 lanthanides with mixtures of 8-hydro­xyquinoline (HQ) and crown ethers (S) dibenzo-18-crown-6 (DB18C6) and di­benzo-24-crown-8 (DB24C8) in 1,2-dichloroethane as a diluent from chloride medium at constant ionic strength µ = 0.1 was investigated. The composition of the extracted species was established as LnQ3 with HQ alone and as LnQ3·S in the presence of a crown ether. The values of the equilibrium constants were calculated. The addition of DB18C6 to the metal chelate system improved the extraction efficiency, while a weak synergistic enhancement was found when the metals were extracted with mixtures of HQ-DB24C8. The parameters of the extraction process were determined and the separation factors between two adjacent lanthanides(III) were calculated.

Abstract: The solvent extraction of trivalent lanthanoids (without Pm) with mixtures of chelating extractant 1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedione (thenoyltrifluoroacetone, HTTA) or 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-on (HP) and 1-(2-pyridylazo)-2-naphthol (PAN, S) in C6H6 has been studied. It was found that in the presence of 1-(2-pyridylazo)-2-naphthol the lanthanoids have been extracted as Ln(TTA)3S and LnP3S. On the basis of the experimental data, the values of the equilibrium constants have been calculated. The addition of PAN to the chelating extractant produces synergistic effect which is larger for the heavier lanthanoids. The separation of the lanthanoids with synergistic mixtures was higher than those obtained with HTTA or HP alone. In the most cases an enhancement of the metal ions separation was observed upon the change of the chelating extractant HP with HTTA. [Copyright &y& Elsevier]

The solvent extraction of trivalent lanthanoids (without Pm) with thenoyltrifluoroacetone (HTTA) and dibenzo-18-crown-6 (DB18C6) or dibenzo-24-crown-8 (DB24C8) has been studied. It was found that in the presence of a crown ether (S) the lanthanoids have been extracted as Ln(TTA) 3 · S. On the basis of the experimental data, the values of the equilibrium constants have been calculated. It was established that the stability of the complexes involving DB24C8 is higher than those involving DB18C6. The influence of the synergistic agent on the extraction process has been discussed. The synergistic and separation factors have been determined too. [ABSTRACT FROM AUTHOR]