The extraction of Eu3+ and Am3+ by a mixture of CMPO and dicarbollide in nitrobenzene has been studied. The synergetic effect of dicarbollide is pronounced at low acidities but still lower than for previously studied DBDECMP. Separation properties towards Am/Eu pair are small.
The thermal behavior of[Eu2(BA)6(dmbpy)2] (BA=C7H5O
, benzoate; dmbpy=C12H12N2, 4,4-dimethyl-2,2-bipyridine) and its kinetics were studied under the non-isothermal condition in a static air atmosphere by TG-DTG, IR and SEM methods. Thermal decomposition of [Eu2(BA)6(dmbpy)2] occurred in four consecutive stages at TP 232, 360, 455 and 495°C. The kinetic parameters were obtained from analysis of the TG-DTG curves by Achar and Madhusudanan—Krishnan—Ninan (MKN) methods. The most probable mechanisms for the first stage was suggested by comparing the kinetics parameters.
The extraction of Na3+, Eu3+ and Tm3+ by di-(2-ethylhexyl)phosphoric acid, HDEHP has been studied from various aqueous acidic solutions. The extraction of these elements is inversely proportional to the third power of the hydrogen ion concentration. Antagonistic effects were observed when the extraction was studied by mixtures of HDEHP and tributyl phosphate, TBP, or trioctylphosphine oxide, TOPO. The presence of water-miscible alcohols and acetone generally increases the extraction of these three elements from HCl solutions. Reaction mechanisms have been suggested and discussed in the light of the data obtained.
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.
Authors:Y. Takahashi, T. Kimura, Y. Kato, Y. Minai, and T. Tominaga
Luminescence lifetime of Eu(III) in polyacrylate and polymaleate complexes has been measured to evaluate the number of water molecules bound to the ion. The number of residual water molecules hydrated to Eu(III) in the polyacrylate and polymaleate complexes ranged from 3.5 to 4.5 when the supporting electrolyte concentration was 0.01. The residual hydration number decreased with the addition of supporting electrolyte. These results indicate that Eu(III) is surrounded by polymolecular ligands in these complexes.
The distribution of 137Cs, 152Eu, 238U, and 85Sr in a solid/aqueous system (poly(methyl acrylate)/phosphate/composite in contact with groundwater, was investigated using
γ-Spectrometry and flourometry. The results were compared with earlier results with mineral phosphate in the solid phase.
The effect of contact time, pH and the concentration of concurrent element were studied. The ability of the prepared polymer
composites to keep the studied radioisotopes in the solid phase is much higher than mineral phosphate. The used polymer composites
have been prepared consisting of natural phosphate powder and the monomer methyl acrylate using gamma irradiation. The yield
of polymerization was followed up with respect to the irradiation dose using thermogravimetric analyzer (TGA). A thermomechanical
analyzer (TMA) was used to locate the area of the glass transition temperatures (Tg) using the mode with alternative variable force; the mode with constant force was used to determine the Tg of the pure polymer and the polymer composite prepared at the same irradiation dose. The Tg of the pure poly(methyl acrylate) is 13 ± 3 °C, and the Tg of poly(methyl acrylate)/phosphate/composites is 8 ± 3 °C. The Tg were also determined using the DSC technique, and similar values were found.
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.
Authors:M. Abdel Raouf, K. Farah, M. Nofal, and A. Alian
Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.
The octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO), loaded as stationary phase on silica, has been used for the sorption of Eu and actinides from acidic aqueous solution. Different commerical solid support were investigated and, finally SiO2 was chosen. Experiments were performed to obtain basic data on actinide removal. Distribution coefficients, kinetics, sorption isotherms (three adsorption model correlations were tested) and the acidic concentration effect were studied.
Authors:Y. Takahashi, Y. Minai, T. Kimura, and T. Tominaga
Distribution of trace amount of Eu(III), or Am(III), in the aqueous/solid system containing humic acid and kaolinite, or montmorillonite,
was studied by batch experiments. Humic acid was also adsorbed on the clay minerals and its adsorption isotherm can be regarded
as a Langmuir type. It is shown that Eu(III), or Am(III), exists as humate complex either in the aqueous or on solid phase
in the system including kaolinite, or montmorillonite. These results suggest that the organic-inorganic complex like clay
minerals coated with humic substances is important as metal reservoir in the environment.