Adduct Formation Constants in the Synergistic Solvent Extraction of Several Lanthanoids with Two Chelating Extractants: β-Diketone and Bidentate Nitrogen Bases

Abstract

The synergistic solvent extraction of La(III), Nd(III), Eu(III), Ho(III), and Lu(III) with a chelating extractant 4-benzoyl-3-phenyl-5-isoxazolone (HPBI) or 2-thenoyltrifluoroacetone (HTTA) and neutral bidentate heterocyclic amines, such as 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy), in CHCl 3 was investigated. Synergism was found to be due to formation of the ternary complex, Ln(PBI) 3 • S or Ln(TTA) 3 • S, in the organic phase, where S denotes a neutral ligand. On the basis of the experimental data, the values of the equilibrium constants were calculated. The parameters of the extraction process were determined. The influence of the synergistic agent on the extraction process is discussed. The synergistic and separation factors were determined.

Synergistic Solvent Extraction of Lanthanides(III) with Mixtures of 4-Benzoyl-3-Methyl-1-Phenyl-5-Pyrazolone and Phosphoryl-Containing Podands

“…20 The data presented in Table 1 show that the values of β P,L as well as SC decrease from La(III) to Lu(III). A similar tendency was observed for the adduct formation of LnP 3 with trioctylphospine oxide, 13 phosphorus-containing calix [6]arene and dibutyl-(N,N-dibutylcarbamoylmethoxy) phosphine oxide. 25,20 On the other hand, an increase of the β values from La(III) to Lu(III) was observed by Atanassova and Dukov in the HP-1-(2-pyridylazo)-2-naphtol synergistic system.…”

“…Hence, one molecule of neutral donor compound III is involved in the formation of synergistic Ln(III) complexes. The same stoichiometry of the Ln(III) extracted complexes was observed at the extraction with mixtures of HP and phosphorus-containing calix [6] arene. 31 On the other hand, in the HP -trioctylphosphine oxide (TOPO) system, the formation of LnP 3 TOPO complexes at lower TOPO concentrations and LnP 3 (TOPO) 2 at higher TOPO concentrations was observed.…”

“…The equilibrium constant β P,L for the adducts formation in the organic phase can calculated using the expression: log β P,L = log K P,L -log K P (6) The values of K P for the lanthanides(III) extraction with HP alone in toluene were obtained in the previous work. 20 The values of the equilibrium constants K P,L and β P,L were calculated from the experimental data and are presented in Table 1.Note that these constants are concentration only because they were calculated on the assumption that the activity coefficients of the species involved do not change significantly under the experimental conditions of the present work.…”

“…and neutral donor extractants (e.g. nitrogen-containing compounds, [4][5][6] sulfoxides, 7,8 crown ethers, 3,[9][10][11] diglycolamides, 12 neutral mono-and polydentate organophosphorus compounds, [13][14][15][16][17][18][19][20] etc.) has been studied.…”

“…[21][22][23][24][25][26] The introduction of P(O) functional groups in the calixarene architecture leads to a significant increase in the extraction efficiency. 26 The addition of phosphorus-containing calix [6]arene to the chelating extractant, 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone, improves the Ln(III) extraction and produces very large synergistic effects (more than five orders of magnitude). 25 Recently, a great interest has arisen in the use of acyclic analogues of crown ethers (podands), as extractants.…”