Authors:M. M. Saeed, M. M. Saeed, R. Ahmed, and R. Ahmed
The sorption of Eu(III) ions onto PAN loaded PUF has been optimized and investigated under the influence of various temperatures,
i.e., 303, 313 and 323 K. Maximum retention (>96%) of Eu(III) ions (1.79. 10-5M) onto PAN loaded PUF (7.75 mg. ml-1) was achieved after 30-minute equilibration time from pH 7 buffer solution. The variation of sorption with temperature yields
the thermodynamic parameters ΔH=79±2 kJ. mol-1, ΔS=276±7 kJ. mol-1. K-1and ΔG=-1.4±0.1 kJ. mol-1at 298 K. The positive value of enthalpy and negative free energy show endothermic and spontaneous nature of sorption, respectively.
The sorption data followed Freundlich, Dubinin-Radushkevich (D-R) and Langmuir isotherms at all the three given temperatures.
The Freundlich constant 1/n=0.70, 0.62 and 0.55 and sorption capacities Cm=10.8 mmol. g-1, 6.1 mmol. g-1and 4.4 mmol. g-1, respectively, decreased with increasing temperature. Similarly, the sorption capacities of D-R isotherm Xm=197.6 µmol. g-1, 201.2 µmol. g-1and 137.4 µmol. g-1, also decreased with temperature. However, the sorption free energy E=10.2 kJ. mol-1, 11.2 kJ. mol-1and 12.7 kJ. mol-1, increased with temperature. The monolayer coverage (Q) computed from Langmuir isotherm was 11.1±0.6 µmol. g-1and remains constant at all the three temperatures investigated. However, the binding energy constant bincreased with temperature. The relationship of bwith temperature and differential heat of adsorption (ΔHdiff) have been evaluated and discussed.
Authors:S. Khalifa, N. Zakareia, H. Aly, and A. Abdel-Rassoul
The extraction of Nd3+ and Eu3+ from aqueous media containing selected diamine ligands by HDEHP solution in benzene has been investigated. It is found that
the presence of the diamine in the aqueous phase enhances the extraction of both Nd3+ and Eu3 in the organic phase. The possible explanation for this behaviour is presented and a mechanism based on extraction of an
adduct of the type MH3(DEHP)6. B is found to be the most probable.
The solubility isotherm of the system Eu2O3-SeO2-H2O was studied at 100C. Certain amounts of the obtained selenites (normal and acid) were subjected to thermal analysis. The
intermediate phases were isolated and chemical and X-ray phase analysis was made. The scheme of thermal decomposition was
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 extraction of Eu3+ from perchloric acid by ethyl hydrogen benzyl phosphonate (HEBP) dissolved in a series of organic diluents, has been studied at different temperatures. From the variation of the distribution ratio with temperature, the thermodynamic functions H, S and G have been determined. The meaning of the experimentally obtained thermodynamic quantities is discussed.
Various chrysolite-asbestos from Canada and Russia, asbestos plate and, dry as well as wet manufactured asbestos, were analyzed for Hg, Fe, Eu, La and K by the neutron activation method. Following concentration values were found: Hg 0.01–0.46 ppm, Fe 4818–32738 ppm, Eu 0.02–0.125 ppm, La 0.061–0.874 ppm, K 14.829–358.5 ppm. Statistically significant differences /t=0.05/ in Hg, Fe, Eu, La and K contents were found in the different asbestos samples. The concentration of Hg, Fe, Eu in Italian asbestos were considerably higher than in Canadian chrysolite. High Concentration of La, K were found in Austrian asbestos plate.
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.