Distribution Ratio Of Eu Research Articles

Extraction of Trivalent Europium and Americium from Nitric Acid Solution with Bisdiglycolamides

Two bisdiglycolamides (BisDGAs) of N,N,N′′′,N′′′-tetrabutyl-Nʹ,N′′-ethidene bisdiglycolamide (TBE-BisDGA) and N,N,N′′′,N′′′-tetrabutyl-Nʹ,N′′-m-xylylene bisdiglycolamide (TBX-BisDGA) were synthesized. Their extraction behaviors of Eu(III) and Am(III), as well as nitric acid were investigated from nitric acid medium by using n-octanol as diluent. Nitric acid is extracted as the form of HNO3·(BisDGAs)0.6 by BisDGAs and the conditional acid uptake constants of TBE-BisDGA and TBX-BisDGA were 0.26 and 0.10, respectively. The distribution ratios of Eu(III) and Am(III) increased with the increase of nitric acid and extractant concentration, whilst decreased with temperature rise. TBX-BisDGA had a stronger extraction power for Eu(III) and Am(III) than TBE-BisDGA. Both of the extractants displayed a higher affinity toward Eu(III) than Am(III). In the examination of the acidity range from 0.5 to 5.0 M, a maximum separation factor SFEu(III)/Am(III) can reach 8.0 at 3.0 M HNO3 for TBX-BisDGA; and 10 at 4.0 M HNO3 for TBE-BisDGA, respectively. Slope analyses showed that Eu(III) and Am(III) are extracted as di-solvated species by TBX-BisDGA or TBE-BisDGA. The extraction mechanism was described and the apparent extraction equilibrium constant as well as Gibbs free energy change, enthalpy change and entropy change were presented. In addition, their Eu(III) complexes were analyzed by using infrared spectra.

Study of the Interaction between HDEHP and CMPO and Its Effect on the Extraction of Selected Lanthanides

Separation of the trivalent actinides from the trivalent lanthanides relevant to used nuclear fuel reprocessing remains still a challenging task. One of the options currently being investigated is the combination of two extraction processes, TRUEX and TALSPEAK. However, the two extractants used in the individual processes, when combined, result in a system with complex extraction behavior. To better understand the interactions in this combined extraction system, FT-IR spectroscopy was used in combination with small-scale solvent extraction tests. The data indicate that in the presence of CMPO, HDEHP dimer cleaves and interacts with CMPO through hydrogen bonding between POH and phosphoryl group of CMPO. The formation of a new HDEHP-CMPO adduct (log β = 3.4) at [HDEHP] > [CMPO] significantly lowers the concentration of free CMPO available for complexation with metal. The distribution ratios of Eu(III) decrease significantly with increasing nitric acid concentration and point to the acidic properties of this mixed extractant. The data presented suggest that several species containing HDEHP-CMPO adduct, HDEHP, and nitrate are formed upon extraction of Eu(III) by the mixture of HDEHP and CMPO.

Ionic liquid extractants in molecular diluents: Extraction behavior of europium (III) in quarternary ammonium-based ionic liquids

The ionic liquids, tri-n-octylmethylammonium bis(2-ethylhexyl)phosphate ([A336]+[DEHP]−) and tri-n-octylmethylammonium bis(2-ethylhexyl)diglycolamate ([A336]+[DGA]−) were prepared and characterized by IR and NMR spectroscopy. The extraction behavior of europium (III) in the solution of these ionic liquids present in different molecular diluents was studied as a function of various parameters such as pH, nature of diluent, concentration of ionic liquid. The data obtained were compared with those obtained in a solution composed of the precursors of ionic liquid. The extraction of europium (III) in [A336]+[DEHP]− and [A336]+[DGA]− ionic liquids showed a strong dependence on the nature of molecular diluent used. The distribution ratio of Eu(III) increased with increase of pH; at pH>2, the distribution ratios obtained in ionic liquids were much higher than their precursors. The effect of diethylenetriaminepentaacetic acid (DTPA) on the extraction of Am(III) and Eu(III) at a fixed pH was studied to separate europium (III) from americium (III). Superior extraction of the target metals and excellent separation factors achieved with the use of these ionic liquids in conventional diluents indicates the feasibility of separating lanthanides from actinides.

Solvent extraction of europium from aqueous-organic solutions by solvating extractants

The partition of Eu(III) between benzene containing solvating extractants (TBP, TOPO, dioctylsulfoxide) and aqueous nitrate, perchlorate and thiocyanate solutions containing various organic solvents miscible with water (alcohols, acetone, acetonitrile, ethylene glycol, dimethyl sulfoxide and dimethylformamide) was investigated. Depending on the specific extraction system, the presence of organic solvents in the mixed phase showed various effects on the distribution ratio of Eu(III). These were discussed in terms of solute-solvent interactions. The results in the systems containing dimethylformamide and dimethyl sulfoxide indicated complexation of Eu(III) with these solvents in the polar phase.

Synergism in the sorption of europium on chromatographic supports impregnated with dicarbollide acid and bidentate phosphororganic extractant

Extraction chromatographic supports (XAD-7) impregnated with binary mixtures of cobalt dicarbollide and one of the two phosphororganic extractants (dibutyl-N,N-diethylcarbamoylmethyl phosphonate, DBDECMP, or octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide, (CMPO) were prepared using methanolic solutions of the extractants and subsequent evaporation of methanol at room temperature. The molar ratios (x) in isomolar series of the two extractants were 0, 0.25, 0.5, 0.75, and 1. The sorbents were used for investigating Eu capture from 0.1 and 1M HNO3 solutions under static conditions (24 hours shaking, 2 cm3 aqueous phase with 0.2 g sorbent, Eu initial concentrations 3·10−9, 0.0001, 0.001, 0.01 and 0.1M). The sorbents containing mixtures of extractants corresponding to the interpolated value x=0.45 (phosphororg./dicarb.) exhibited the highest values of the distribution ratios of Eu. A synergic effect of three orders of magnitude for low concentrations of Eu was observed. A tentative determination is given of the nature and the equilibrium constants of the chemical reactions assumed.

Comparative liquid-liquid extraction behaviour of europium (II) and europium (III)

The liquid-liquid extraction behaviour of Eu(II) into solutions of acidic phosphoric and phosphonic esters has been investigated both on a macro-scale and tracer-scale. The distribution ratio of Eu(II) was investigated as a function of extractant concentration in the organic phase and HCl concentration in the aqueous phase using β-active 13, 16 year 152, 154Eu. Advantage was taken of the large separation factors Pm(III)/Eu(II), Sm(III)/Eu(II), and Gd(III)/Eu(II) in effecting the mutual separation of 147Pm and 152, 154Eu, the high purification of 147Pm with respect to 152, 154Eu, and the enrichment, concentration and recovery in high yield of europium from a rare earth oxide containing 0·1 per cent Eu.