Synergistic Solvent Extraction of Trivalent Lanthanoids with Mixtures of 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone and Crown Ethers

Department of General and Inorganic Chemistry, University of Chemical Technology and Metallurgy, 8 Kliment Okhridski blvd, 1756 Sofia, Bulgaria, dukov@uctm.edu

Absrtract
The synergistic solvent extraction of 14 trivalent lanthanoids (except Pm) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone(HP) and dibenzo-18-crown-6 (DB18C6) or dibenzo-24-crown-8(DB24C8) in 1, 2-dichloroethane has been studied. It was found that in the presence of HP alone the lanthanoids have been extracted as LnP₃∙HP and in the presence of mixtures of HP and crown ethers (S) − as LnP₃∙S. On the basis of the experimental data, the values of the equilibrium constants as well as the values of the synergistic coefficients and the separation factors have been calculated. The addition of crown ethers to the system Ln³⁺ − HP improves both the extraction efficiency and the selectivity among the lanthanoid(III) ions.

Keywords: Synergistic solvent extraction; 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone; Dibenzo-18-crown-6; Dibenzo-24-crown-8; Lanthanoids; Separation factors.