Behavior of mixed systems based on para-substituted 4-aroyl-5-pyrazolones in the presence of phosphorus containing calix[4]arene towards lanthanoids: Synergistic solvent extraction and separation

Synergistic solvent extraction of selected trivalent lanthanoids (La, Nd, Eu, Ho and Lu) with mixtures of a chelating extractants (HL), either 4-(4-fluorobenzoyl)-3-methyl-1-phenyl-pyrazol-5-one (HPMFBP) or 3-methyl-4-(4-methylbenzoyl)-1-phenyl-pyrazol-5-one (HPMMBP) and 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis-(dimethylphosphinoylmethoxy)calix[4]arene (S) in CHCl3 from chloride medium has been studied. The interaction between the extractants in deuterochloroform has been examined by 1H, 13C and 31P NMR spectra. The composition of the extracted species has been established as LnL3·HL (HL and L− represent either HPMFBP or HPMMBP and their anions, respectively). It has found that, in the presence of the phosphorus-containing calix[4]arene, the lanthanoids were extracted as LnL3·S. On the basis of the experimental data, the values of the equilibrium constants have been calculated. The influence of the para-substituted 4-aroyl-3-methyl-1-phenyl-pyrazol-5-ones on the extraction process has been discussed. The synergistic enhancement and separation factors between metals have been evaluated.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Five lanthanoid ions were synergistically extracted. ► 4-Acylpyrazolones and phosphorous-containing calix[4]arene were used. ► The composition of the extracted species was established as LnL3·S. ► The interaction between extractants in the organic phase was evaluated. ► The used systems offer high synergistic enhancements and good selectivity.