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A calculation model for liquid-liquid extraction of protactinium by 2,6-dimethyl-4-heptanol

100%
Knight A. W., Eitrheim E. S., Nelson A. W., Schultz M. K.
Nukleonika
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2015
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vol. 60
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issue 4
837-845
EN
Reprocessing of spent nuclear fuel usually employs the solvent extraction technique to recover fissile material, isolate other valuable radionuclides, recover precious metals, and remove contaminants. Efficient recovery of these species from highly radioactive solutions requires a detailed understanding of reaction conditions and metal speciation that leads to their isolation in pure forms. Due to the complex nature of these systems, identification of ideal reaction conditions for the efficient extraction of specific metals can be challenging. Thus, the development of experimental approaches that have the potential to reduce the number of experiments required to identify ideal conditions are desirable. In this study, a full-factorial experimental design was used to identify the main effects and variable interactions of three chemical parameters on the extraction of protactinium (Pa). Specifically we investigated the main effects of the anion concentration (NO3-, Cl-) extractant concentration, and solution acidity on the overall extraction of protactinium by 2,6-dimethyl-4-heptanol (diisobutylcarbinol; DIBC) from both HCl and HNO3 solutions. Our results indicate that in HCl, the extraction of protactinium was dominated by the solution acidity, while in nitric acid the extraction was strongly effected by the [DIBC]. Based on our results, a mathematical model was derived, that describes the relationship between concentrations of anions, extractant, and solution acidity and the expected values of Pa distribution coefficients in both HCl and HNO3. This study demonstrates the potential to predict the distribution coefficient values, based upon a mathematical model generated by a full-factorial experimental design.
2
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Characterization of solvents containing CyMe4-BTPhen in selected cyclohexanone-based diluents after irradiation by accelerated electrons

88%
Distler P., Kondé J., John J., Hájková Z., Švehla J., Grüner B.
Nukleonika
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2015
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vol. 60
|
issue 4
885-891
EN
Radiation stability of CyMe4-BTPhen was examined in systems with three selected cyclohexanone-based diluents. Accelerated electrons were used as a source of ionizing radiation. The CyMe4-BTPhen radiation degradation identification and characterization of the degradation products were performed by high performance liquid chromatography (HPLC) and mass spectrometry (MS) analyses. Residual concentrations of tested ligand were determined. Moreover, extraction properties of the solvents irradiated at two different doses were compared with the extraction properties of non-irradiated solvents to estimate the influence of the presence of degradation products in the organic phase.
3
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SACSESS – the EURATOM FP7 project on actinide separation from spent nuclear fuels

75%
Bourg S., Geist A., Narbutt J.
Nukleonika
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2015
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vol. 60
|
issue 4
809-814
EN
Recycling of actinides by their separation from spent nuclear fuel, followed by transmutation in fast neutron reactors of Generation IV, is considered the most promising strategy for nuclear waste management. Closing the fuel cycle and burning long-lived actinides allows optimizing the use of natural resources and minimizing the long-term hazard of high-level nuclear waste. Moreover, improving the safety and sustainability of nuclear power worldwide. This paper presents the activities striving to meet these challenges, carried out under the Euratom FP7 collaborative project SACSESS (Safety of Actinide Separation Processes). Emphasis is put on the safety issues of fuel reprocessing and waste storage. Two types of actinide separation processes, hydrometallurgical and pyrometallurgical, are considered, as well as related aspects of material studies, process modeling and the radiolytic stability of solvent extraction systems. Education and training of young researchers in nuclear chemistry is of particular importance for further development of this field.
4
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Determination of formation constants of uranyl(VI) complexes with a hydrophilic SO3-Ph-BTP ligand, using liquid-liquid extraction

75%
Steczek L., Narbutt J., Charbonnel M.-C., Moisy P.
Nukleonika
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2015
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vol. 60
|
issue 4
821-827
EN
Complex formation between uranyl ion, UO22+, and a hydrophilic anionic form of SO3-Ph-BTP4- ligand, L4-, in water was studied by liquid-liquid extraction experiments performed over a range of the ligand and HNO3 concentrations in the aqueous phase, at a constant concentration of nitrate anions at 25°C . The competition for UO22+ ions between the lipophilic TODGA extractant and the hydrophilic L4- ligand leads to the decrease in the uranyl distribution ratios, D, with an increasing L4- concentration. The model of the solvent extraction process used accounts - apart from uranyl complexation by TODGA and SO3-Ph-BTP4- - also for uranyl complexation by nitrates and for the decrease in the concentration of the free L4- ligand in the aqueous phase, due to its protonation, bonding in the uranyl complex and the distribution between the two liquid phases. The unusually strong dependence of the D values on the acidity, found in the experiment, could hardly be explained as due to L4- protonation merely. Three hypotheses were experimentally tested, striving to interpret the data in terms of additional extraction to the organic phase of ion associates of protonated TODGA cation with either partly protonated anionic L4- ligands or anionic UO22+ complexes with NO3 - or L4-. None of them has been confirmed. The analysis of the results, based on the formal correction of free ligand concentrations, points to the formation of 1 : 1 and 1 : 2 uranyl - SO3-Ph-BTP complexes in the aqueous phase. The conditional formation constant of the 1:1 complex has been determined, logßL,1 = 2.95 ± 0.15.
5
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Development of the Chalmers Grouped Actinide Extraction Process

75%
Halleröd J., Ekberg C., Löfström-Engdahl E., Aneheim E.
Nukleonika
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2015
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vol. 60
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issue 4
829-835
EN
Several solvents for Grouped ActiNide EXtraction (GANEX) processes have been investigated at Chalmers University of Technology in recent years. Four different GANEX solvents; cyclo-GANEX (CyMe4- -BTBP, 30 vol.% tri-butyl phosphate (TBP) and cyclohexanone), DEHBA-GANEX (CyMe4-BTBP, 20 vol.% N,N-di-2(ethylhexyl) butyramide (DEHBA) and cyclohexanone), hexanol-GANEX (CyMe4-BTBP, 30 vol.% TBP and hexanol) and FS-13-GANEX (CyMe4-BTBP, 30 vol.% TBP and phenyl trifluoromethyl sulfone (FS-13)) have been studied and the results are discussed and compared in this work. The cyclohexanone based solvents show fast and high extraction of the actinides but a somewhat poor diluent stability in contact with the acidic aqueous phase. FS-13-GANEX display high separation factors between the actinides and lanthanides and a good radiolytic and hydrolytic stability. However, the distribution ratios of the actinides are lower, compared to the cyclohexanone based solvents. The hexanol-GANEX is a cheap solvent system using a rather stable diluent but the actinide extraction is, however, comparatively low.
6
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Processes and Technologies for the Recycling of Spent Fluorescent Lamps

75%
Kujawski W., Pospiech B.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 3
80-85
EN
The growing industrial application of rare earth metals led to great interest in the new technologies for the recycling and recovery of REEs from diverse sources. This work reviews the various methods for the recycling of spent fluorescent lamps. The spent fluorescent lamps are potential source of important rare earth elements (REEs) such as: yttrium, terbium, europium, lanthanum and cerium. The characteristics of REEs properties and construction of typical fl uorescent lamps is described. The work compares also current technologies which can be utilized for an efficient recovery of REEs from phosphors powders coming from spent fluorescent lamps. The work is especially focused on the hydrometallurgical and pyrometallurgical processes. It was concluded that hydrometallurgical processes are especially useful for the recovery of REEs from spent fluorescent lamps. Moreover, the methods used for recycling of REEs are identical or very similar to those utilized for the raw ores processing.
7
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Selective recovery of cobalt(II) towards lithium(I) from chloride media by transport across polymer inclusion membrane with triisooctylamine

75%
Pospiech B.
Polish Journal of Chemical Technology
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2014
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vol. 16
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issue 1
15-20
EN
In this work the selective transport of cobalt(II) and lithium(I) ions from aqueous chloride solutions through polymer inclusion membranes (PIMs) is presented. Triisooctylamine (TIOA) has been applied as the ion carrier in membrane. The effects of various parameters on the transport of Co(II) and Li(I) were studied. The obtained results show that Co(II) ions were effectively removed from source phase through PIM containing 32 wt.% TIOA, 22 wt.% CTA (cellulose triacetate) and 46 wt.% ONPOE (o-nitrophenyl octyl ether) or ONPPE (o-nitrophenyl pentyl ether) into deionized water as the receiving phase. The results indicate that there is a possibility of polymer inclusion membranes application to recover Co(II) and Li(I) from aqueous chloride solutions
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