Comparing extraction, synergism and separation of lanthanoids using acidic and neutral compounds in chloroform and one ionic liquid: is the latter always “better”?

Maria Atanassova (1) , Vanya Kurteva (2) , Lubomir Lubenov (2) , Isabelle Billard (1)

1 LEPMI - Laboratoire d'Electrochimie et de Physico-chimie des Matériaux et des Interfaces
2 Institute of Organic Chemistry with Centre of Phytochemistry - IOCCP (Sofia, Bulgaria)

The complexation properties of a pyrazolone derivative, 3-methyl-1-phenyl-4-(4-trifluoromethylbenzoyl)-pyrazol-5-one (HL), in chloroform were examined and it was found that it possesses improved complexation ability in comparison with 4-benzoyl, 4-(4-methylbenzoyl) and 4-(4-fluorobenzoyl) derivatives. Mixed ligand chelate extractions of trivalent lanthanoids (La, Nd, Eu, Ho and Lu) with HL and 5,11,17,23-tetra-tert-butyl-25,26,27-tris(dimethylphosphinoylpropoxy)-28-hydroxy-calix[4]arene (S1) or 5,11,17,23-tetra-tert-butyl-25,27-bis(dimethylphosphinoylpropoxy)-26,28-dihydroxy-calix[4]arene (S2) as synergistic agents were also carried out in chloride medium at constant ionic strength m ¼ 0.1 and CHCl 3 as organic phase. The interactions between the extractants in deuterochloroform were studied by 1 H, 13 C, and 31 P NMR. The composition of the extracted species was established as LnL 3 $HL (L À represents HL anion) with HL as a single extractant, and as LnL 3 $S in the presence of the phosphorus-containing calix[4]arene. On the basis of the experimental data, the values of the equilibrium constants were calculated. The influence of the number of P]O groups of tert-butyl-calix[4]arene on the extraction process was discussed. The synergistic enhancement and separation factors between metals were evaluated. Finally, the extraction of La(III) and Eu(III) ions was performed by using an ionic liquid, 1-butyl-3-methylimidazolium-bis(trifluoromethanesulfonyl)imide, as a solvent and varying the type of ligands. By comparison to CHCl 3 , the ionic liquid offers increased distribution ratios, at the expense of a levelling off of the separation factors. Reasons for such a phenomenon are discussed.

Domaines: Génie chimique; Radiochimie

Maria Atanassova, Vanya Kurteva, Lubomir Lubenov, Isabelle Billard. Comparing extraction, synergism and separation of lanthanoids using acidic and neutral compounds in chloroform and one ionic liquid: is the latter always “better”?. RSC Advances, 2014, 4 (73), pp.38820-38829. ⟨10.1039/c4ra04302b⟩. ⟨hal-02271606⟩