Extraction of Am(III) and Eu(III) from nitrate media with Cyanex®-301 and neutral “N” donor ligands: A thermodynamic study

Abstract

Studies on the effect of temperature on the liquid-liquid extraction behaviour of a trivalent actinide ion, Am 3+ and a trivalent lanthanide ion, Eu 3+ using a "S"-donor soft ligand, bis (2,4,4-trimethylpentyl) dithiophosphinic acid (Cyanex ® -301) were carried out. The temperature effect on the enhancement in extraction as well as the selectivity which occurred in the presence of neutral soft donor auxiliary ligands with "N" donor atoms viz., bipyridyl (bipy) and 1,10-phenanthroline (phen) was also investigated. Thermodynamic parameters like the changes in the extraction enthalpy (∆H • ), entropy (∆S • ) and free energies (∆G • ) for both the binary as well as ternary extraction systems were obtained. These thermodynamic parameters could explain the nature of the species extracted with both Am(III) and Eu(III).

A Novel Solvent System Involving Terpyridine and Cyanex-301 for Am(III) and Eu(III) Separation from Weakly Acidic Feeds

“…Unlike the synergistic extraction of Am 3+ and Eu 3+ using a ternary mixture of Cyanex-301 and bipy/o-phen, reported by us previously (25), where the Am 3+ extraction was found to be more exothermic as compared to the Eu 3+ extraction, the H values for the extraction of Am 3+ -(60±3 kJ/mol) and Eu 3+ -(70±10 kJ/mol) here are found to be comparable. The S values, calculated for Am 3+ and Eu 3+ , were found to be -(191±11) and -(276±34) J/deg/mol, respectively.…”

“…Insight into the extraction mechanism can be made by measuring the thermodynamic parameters. In case of studies involving liquid-liquid extraction, distribution ratio values obtained at varying temperatures can help in evaluating the thermodynamic parameters (24,25). K ex was calculated at different temperatures by measuring the D values at those temperatures using Eq.…”

Hard-and-soft phosphinoxide receptors for f-element binding: structure and photophysical properties of europium(iii) complexes

“…Growing research efforts in the field of rare earth element (REE) complexes with bipyridine-type ligands are associated with their outstanding potential from the viewpoint of their fundamental and practical applications. [1][2][3][4][5][6][7][8][9][10][11][12][13] Extended variation capabilities of supramolecular structures, as well as modification of peripheral positions of heterocycles, allow fine tuning of the molecular properties required for high technology applications. The high coordination numbers of lanthanide ions provide alternative methods for the modification of the properties of complexes by varying the counter-ion coordinated to the metal centre.…”

Liquid–liquid extraction of Np4+ and Pu4+ using several tetra-alkyl substituted diglycolamides

“…On the other hand, the inner-sphere water molecules need not be replaced if outer-sphere complexation is preferred which mainly involve H-bonded interactions. These finer details of the complexation resulting in metal ion extraction can be understood by carrying out thermodynamics studies [23,24]. The extraction of Np 4+ and Pu 4+ was carried out as a function of temperature and the results have indicated lower metal ion extraction at higher temperature.…”