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5. Composition and structure of polynuclear chromium(III) hydroxo complexes

Author

Torapava, Natallia, Radkevich, Artsiom, Davydov, Dmitri, Titov, Andrei, and Persson, Ingmar

Subjects
Sodium hydroxide -- Chemical properties, Sodium hydroxide -- Structure, Chromium compounds -- Chemical properties, Chromium compounds -- Structure, Hydrolysis -- Analysis, Hydroxides -- Chemical properties, Hydroxides -- Structure, Polycyclic aromatic compounds -- Chemical properties, Polycyclic aromatic compounds -- Structure, Chemistry
Published
2009

8. SKIN: Slow Processes in Close-to-equilibrium Conditions for Radionuclides in Water/solid Systems of Relevance to Nuclear Waste Management

Author

Suzuki-Muresan, Tomo, Grambow, Bernd, Hedström, Hanna, Torapava, Natallia, Bosbach, Dirk, Brandt, Felix, Klinkenberg, Martina, Stumpf, Thorsten, Evans, Nick, Hinchliff, John, Curti, Enzo, Kulik, Dmitrii, Montavon, Gilles, Thien, Bruno, Cui, Daqing, Spahiu, Kastriot, Liu, Chunli, Prieto, Manolo, Ribet, Solange, Borre, Johan van den, Duro, Lara, Grive, Mireia, Valls, Alba, Colas, Eli, and Ekberg, Christian

Published
2014

9. Slow Processes in Close-to-equilibrium Conditions for Radionuclides in Water/solid Systems of Relevance to Nuclear Waste Management

Author

Suzuki-Muresan, Tomo, Grambow, Bernd, Montavon, Gilles, ribet, solange, Vandenborre, Johan, Duro, Lara, grivé, mireia, colas, eli, valls, alba, ekberg, christian, hedström, hanna, torapava, natallia, Brandt, Felix, Bosbach, Dirk, klinkenberg, martina, Stumpf, Thorsten, Evans, Nick, hinchliff, john, Curti, Enzo, Kulik, Dmitrii, thien, bruno, cui, daqing, spahiu, kastriot, chunli, liu, prieto, manolo, Suzuki-Muresan, Tomo, Slow processes in close-to-equilibrium conditions for radionuclides in water/solid systems of relevance to nuclear waste management - SKIN - - EC:FP7:Fission2011-01-01 - 2013-12-31 - 269688 - VALID, Laboratoire SUBATECH Nantes (SUBATECH), Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AMPHOS, XXI Consulting, Chalmers University of Technology [Göteborg], Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology (KIT), Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Department of Chemistry, Loughborough University, Laboratory for Waste Management, Paul Scherrer Institute (PSI), Stockholm University, Svensk Kärnbränslehantering AB (SKB), Peking University [Beijing], University of Oviedo, European Project: 269688,EC:FP7:Fission,FP7-Fission-2010,SKIN(2011), and Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes)

Subjects
[CHIM.RADIO] Chemical Sciences/Radiochemistry, [CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2013

10. Slow processes in close-to-equilibrium conditions for radionuclides in water/solid systems of relevance to nuclear waste management – SKIN

Author

Suzuki-Muresan, Tomo, Grambow, Bernd, Montavon, Gilles, Ribet, Solange, Vandenborre, Johan, Duro, Lara, Grivé, Mireia, Colas, Eli, Ekberg, Christian, Hedström, Hanna, Torapava, Natallia, Bosbach, Dirk, Brandt, Felix, Klinkenberg, Martina, Stumpf, Thorsten, Evans, Nick, Hinchliff, John, Curti, Enzo, Kulik, Dmitrii, Thien, Bruno, Cui, Daqing, Spahiu, Kastriot, Chunli, Liu, Laboratoire SUBATECH Nantes (SUBATECH), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Nantes (UN)-Mines Nantes (Mines Nantes), AMPHOS, XXI Consulting, Chalmers University of Technology [Göteborg], Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology (KIT), Institut für Nukleare Entsorgung (INE), Karlsruher Institut für Technologie (KIT), Department of Chemistry, Loughborough University, Laboratory for Waste Management, Paul Scherrer Institute (PSI), Stockholm University, Svensk Kärnbränslehantering AB (SKB), Peking University [Beijing], European Project: 269688,EC:FP7:Fission,FP7-Fission-2010,SKIN(2011), and Mines Nantes (Mines Nantes)-Université de Nantes (UN)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.RADIO]Chemical Sciences/Radiochemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2012

11. Hydration, solvation and hydrolysis of multicharged metal ions

Author

Torapava, Natallia

Subjects
Inorganic Chemistry
Abstract

Structures of hydrated, solvated and hydrolyzed multicharged metal ions are determined by EXAFS and LAXS in solution, and by X-ray crystallography and EXAFS in the solid state. During hydrolysis, the nine-coordinate hydrated thorium(IV) ion is first transformed to a dimer, [Th₂(μ²-OH)₂(H₂O)₁₂]⁶⁺, then to a tetramer, [Th₄(μ²-OH)₈(H₂O)₁₆]⁸⁺, and finally to a hexamer, [Th₆(μ³-O₈)(H₂O)n]⁸⁺ with increasing pH and thorium(IV) concentration in an aqueous solution. Coordinated water looses the protons in two steps, first with the formation of the dimer and tetramer, and finally with the formation of the hexamer. Together thorium(IV) and iron(III) form a stable and highly soluble heteronuclear hydrolysis complex, [Th₂Fe₂(μ²-OH)₈(H₂O)₁₂]⁶⁺, in the pH range 2.9 - 4.8 and metal concentrations 0.02 – 0.4 mol·dm⁻³. In the same solutions at pH < 2.9 two- or six-line ferrihydrite precipitates with time, while thorium(IV) remains in solution. Palladium(II) and platinum(II) hydrolyze very slowly in acidic aqueous solution and after 25 years of storage tiny oxide-like particles are formed at pH = 0.7. The particle size has been estimated from the number of M···M distances in the formed particles and in the corresponding solid oxides from EXAFS studies. The palladium(II) and platinum(II) oxide particles grow along a or b axies and reach a size of 1 - 1.5 nm³. These results have been supported by SAXS studies. During hydrolysis, the six-coordinate hydrated chromium(III) ion is first transformed to a dimer, then to a tetramer, [Cr₄(μ²-OH)₂(μ-OH)₄(OH)n(H₂O)₁₂-n](6-n)+ with increasing pH from 0 to 3.7 at chromium concentration of ca. 1 mol·dm⁻³. At pH  15, soluble [Cr(μ²-OH)₂(OH)₂]nn-, n  3, complex is formed, which at pH < 15 slowly precipitates as an amorphous solid with a structure similar to α-CrOOH. Dimethylsulfoxide (DMSO) solvated thorium(IV) is nine-coordinate both in solution and solid state. N,N’-Dimethylpropyleneurea (DMPU) solvated thorium(IV) is eight-coordinate in solution. The lower coordination number is due to the space-demanding properties of the DMPU molecules upon coordination.

Published
2011

13. Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water.

Author

Svengren, Henrik, Jansson, Kjell, Grins, Jekabs, Wan, Wei, Torapava, Natallia, and Johnsson, Mats

Subjects
OXIDATION of water, CATALYST synthesis, CARBON fibers, ELECTROCATALYSIS, CATALYTIC oxidation, ELECTRODES
Abstract

Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co3Sb4O6F6 and the new compound CoSbO4. The compounds express large differences in their morphology: CoSbO4 grows as thin needles whereas Co3Sb4O6F6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co3Sb4O6F6 was used it gave a low increase of +0.028 mV h−1 at an overpotential of η=472 mV after 10 h and a stability of +0.48 mV h−1 at an overpotential of η=488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at % Co and approximately 0.02 at % Sb were detected in the electrolyte. [ABSTRACT FROM AUTHOR]

Published
2017
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20. Recrystallization of Ra with barium sulfate.

Author

Torapava, Natallia, Ramebäck, Henrik, Curti, Enzo, Lagerkvist, Petra, and Ekberg, Christian

Subjects
RADIOACTIVE wastes, RECRYSTALLIZATION (Metallurgy), BARIUM sulfate, CHEMICAL kinetics, SOLUBILITY, BARITE
Abstract

In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm sodium sulfate solution using Ra and Ba tracers at very low total radium concentration, i.e. less than 10 mol dm. It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of Ra and Ba in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate-a mineral present in the deep underground repository. [ABSTRACT FROM AUTHOR]

Published
2014
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21. Direct Synthesis of Two Inorganic Catalysts on Carbon Fibres for the Electrocatalytic Oxidation of Water.

Author

Svengren H, Jansson K, Grins J, Wan W, Torapava N, and Johnsson M

Abstract

Two electrodes for anodic water oxidation made by direct synthesis of inorganic catalysts onto conductive carbon fibre sheets are evaluated. As catalysts two Co- and Sb-containing phases were tested, that is, Co 3 Sb 4 O 6 F 6 and the new compound CoSbO 4 . The compounds express large differences in their morphology: CoSbO 4 grows as thin needles whereas Co 3 Sb 4 O 6 F 6 grows as larger facetted crystals. Despite the smaller surface area the latter compound shows a better catalytic performance. When the compound Co 3 Sb 4 O 6 F 6 was used it gave a low increase of +0.028 mV h -1 at an overpotential of η=472 mV after 10 h and a stability of +0.48 mV h -1 at an overpotential of η=488 mV after 60 h. The leakages of Co and Sb were negligible and only <0.001 at % Co and approximately 0.02 at % Sb were detected in the electrolyte., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Published
2017
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