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Abstract  

Previously it was found that in the extraction separation on lanthanides and americium from acidic nitrate solutions of nuclear fission products, benzyldimethyldodecylammonium nitrate gives high values of separation coefficients. The change in the extraction capacity of this agent and its solutions in benzene in the extraction of Eu(III) and Am(III) was investigated as a function of the adsorbed dose of ionizing radiation. The slight reduction in the extraction of both metals is caused mainly by the radiolysis products of nitric acid in the organic phase that enter into secondary reactions with both the solvent and the extractant. Comparison of the radiation stability of benzyldimethyldodecylammonium nitrate systems with tertiary amines show that the changes in distribution coefficients in the range of investigated absorbed doses are significantly lower in the former case. The investigated system may be characterized as radiation stable up to about 100 kGy even in the presence of nitric acid.

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Abstract  

The selective transport of Am across a supported liquid membrane (SLM) has been investigated by using bis (2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) as a mobile carrier. This extractant containing soft donor atoms exhibits strong affinity for actinoids, giving a large separation factor between trivalent Am and Eu. Separation of Am from Eu was achieved by an SLM containing highly purified Cyanex 301. Americium was preferentially transported across the SLM and concentrated in the product solution, while most of Eu remained in the feed solution.

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Summary  

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 C m=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 X m=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 (ΔH diff) have been evaluated and discussed.

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Abstract  

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.

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Abstract  

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 determined.

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Abstract  

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.

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Abstract  

The absorption effect of 5% w/w non-proliferative cell suspensions of Mycobacterium smegmatis on labelled solutions of Eu3+ ions, both alone and in admixtures with Am3+, Co2+ and Cs+, was studied at pH 1.0 as a function of time and cationic concentration. For 10 M concentrations of Eu, Co and Cs, selective adsorption of the trivalent lanthanide and actinide ions was practically quantitative after 90 min; no significant adsorption was observed for cobalt and cesium ions. Column adsorption measurements with the mycobacterial biomass showed that desorption of the M3+ ions did not occur at less than 2M HCl and remained incomplete even at higher acidities.

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Abstract  

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.

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Abstract  

The adsorption of Eu(III) on multiwalled carbon nanotubes (MWCNTs) as a function of pH, ionic strength and solid contents are studied by batch technique. The results indicate that the adsorption of Eu(III) on MWCNTs is strongly dependent on pH values, dependent on ionic strength at low pH values and independent of ionic strength at high pH values. Strong surface complexation and ion exchange contribute to the adsorption of Eu(III) on MWCNTs at low pH values, whereas surface complexation and surface precipitation are the main adsorption mechanism of Eu(III) on MWCNTs. The desorption of adsorbed Eu(III) from MWCNTs by adding HCl is also studied and the recycling use of MWCNTs in the removal of Eu(III) is investigated after the desorption of Eu(III) at low pH values. The results indicate that adsorbed Eu(III) can be easily desorbed from MWCNTs at low pH values, and MWCNTs can be repeatedly used to remove Eu(III) from aqueous solutions. MWCNTs are suitable material in the preconcentration and solidification of radionuclides from large volumes of aqueous solutions in nuclear waste management.

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Abstract  

The complex formation of Eu(III) by bicarbonate/carbonate ions has been studied at 0.1 M ionic strength and 25°C using synergistic solvent extraction system of 1-nitroso-2-naphthol and 1,10-phenanthroline in chloroform. Concentrations of bicarbonate (5·10–3 to 1·10–1 M) and carbonate (5·10–4 to 1·10–2 M) ions in the aqueous phase have been varied in the pH range of 8.0 to 9.1 to simulate ground and natural water compositions. Under these conditions, the following species have been identified: Eu(HCO3)2+, Eu(HCO3)2 +, Eu(CO3)+ and Eu(CO3)2 . Their conditional formation constants (log ) have been calculated as 4.77, 6.74, 6.92 and 10.42, respectively. These values suggest that the carbonate complexes of Eu(III) are highly stable.

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