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Bagus PS, Nelin CJ, Rosso KM, Schacherl B, Vitova T. Electronic Structure of Actinyls: Orbital Properties. Inorg Chem 2024; 63:1793-1802. [PMID: 38232379 DOI: 10.1021/acs.inorgchem.3c03158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
A detailed analysis is presented for the covalent character of the orbitals in the actinyls: UO22+, NpO22+, and PuO22+. Both the initial, or ground state, GS, configuration and the excited configurations where a 3d electron is excited into the open valence, nominally the 5f shell, are considered. The orbitals are determined as fully relativistic, four component Dirac-Coulomb Hartree-Fock solutions. Several measures, which go beyond the commonly used population analyses, are used to characterize the covalent character of an orbital in order to obtain reliable estimates of the covalency. Although there are differences in the covalent character of the orbitals for the initial and excited configurations of the different actinyls, there is a surprising similarity in the covalent character for all of the states considered. This is true both between the initial and excited configurations as well as between the different actinyls. The analysis emphasizes the 5f covalent character in the closed shell bonding orbitals and the open shell antibonding orbitals since the focus is on characterizing orbitals needed in a many-body treatment of the actinyl wave functions. However, estimates are also made of the participation of the actinide 6d in the covalent bonding.
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Affiliation(s)
- Paul S Bagus
- Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, United States
| | | | - Kevin M Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Bianca Schacherl
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE), P.O. 3640, Karlsruhe, D-76021 Germany
| | - Tonya Vitova
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE), P.O. 3640, Karlsruhe, D-76021 Germany
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2
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Misael WA, Severo Pereira Gomes A. Core Excitations of Uranyl in Cs 2UO 2Cl 4 from Relativistic Embedded Damped Response Time-Dependent Density Functional Theory Calculations. Inorg Chem 2023; 62:11589-11601. [PMID: 37432868 DOI: 10.1021/acs.inorgchem.3c01302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2023]
Abstract
X-ray spectroscopies, by their high selectivity and sensitivity to the chemical environment around the atoms probed, provide significant insights into the electronic structures of molecules and materials. Interpreting experimental results requires reliable theoretical models, accounting for environmental, relativistic, electron correlation, and orbital relaxation effects in a balanced manner. In this work, we present a protocol for the simulation of core excited spectra with damped response time-dependent density functional theory based on the Dirac-Coulomb Hamiltonian (4c-DR-TD-DFT), in which environmental effects are accounted for through the frozen density embedding (FDE) method. We showcase this approach for the uranium M4- and L3-edges and oxygen K-edge of the uranyl tetrachloride (UO2Cl42-) unit as found in a host Cs2UO2Cl4 crystal. We have found that the 4c-DR-TD-DFT simulations yield excitation spectra that very closely match the experiment for the uranium M4-edge and the oxygen K-edge, with good agreement for the broad experimental spectra for the L3-edge. By decomposing the complex polarizability in terms of its components, we have been able to correlate our results with angle-resolved spectra. We have observed that for all edges, but in particular the uranium M4-edge, an embedded model in which the chloride ligands are replaced by an embedding potential reproduces rather well the spectral profile obtained for UO2Cl42-. Our results underscore the importance of the equatorial ligands to simulating core spectra at both uranium and oxygen edges.
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Affiliation(s)
- Wilken Aldair Misael
- Univ. Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules, F-59000 Lille, France
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Połomski D, DiBlasi NA, Dardenne K, Gaona X, Czerwinski K, Chotkowski M. Choline chloride-formic acid mixture as a medium for the reduction of pertechnetates - electrochemical and spectroscopic studies. Phys Chem Chem Phys 2023; 25:1819-1826. [PMID: 36601876 DOI: 10.1039/d2cp05398e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The physicochemical properties of a choline chloride (ChCl) and formic acid (FA) mixture (1 : 2 molar ratio) have been studied over a broad range of temperatures (-140 to 60 °C). Differential scanning calorimetry has shown that the examined system remains in the liquid state at very low temperatures - a glass transition is observed in the range of -125 °C to -90 °C. The kinematic viscosity, ionic conductivity and the width of the electrochemical window determined for this system revealed its beneficial electrochemical properties. This indicates the suitability of ChCl : FA electrolytes in electrochemical measurements. In this non-aqueous electrolyte, electrochemical reduction of Tc(VII) ions has been studied for the first time. Cyclic voltammetry and chronopotentiometry experiments revealed that the electroreduction of pertechnetates is a multi-path process which leads to the formation of a Tc(IV) ionic form. X-Ray absorption spectroscopy of the latter revealed its structure as a TcCl62- complex.
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Affiliation(s)
- Damian Połomski
- University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre, Żwirki i Wigury 101, 02-089, Warsaw, Poland.
| | - Nicole A DiBlasi
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Kathy Dardenne
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | - Xavier Gaona
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, 76344, Germany
| | | | - Maciej Chotkowski
- University of Warsaw, Faculty of Chemistry, Biological and Chemical Research Centre, Żwirki i Wigury 101, 02-089, Warsaw, Poland.
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Kiefer C, Neill T, Cevirim-Papaioannou N, Schild D, Gaona X, Vitova T, Dardenne K, Rothe J, Altmaier M, Geckeis H. Interlink between solubility, structure, surface and thermodynamics in the ThO2(s, hyd)–H2O(l) system. Front Chem 2022; 10:1042709. [DOI: 10.3389/fchem.2022.1042709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
The impact of temperature on a freshly precipitated ThO2(am, hyd) solid phase was investigated using a combination of undersaturation solubility experiments and a multi-method approach for the characterization of the solid phase. XRD and EXAFS confirm that ageing of ThO2(am, hyd) at T = 80°C promotes a significant increase of the particle size and crystallinity. TG-DTA and XPS support that the ageing process is accompanied by an important decrease in the number of hydration waters/hydroxide groups in the original amorphous Th(IV) hydrous oxide. However, while clear differences between the structure of freshly precipitated ThO2(am, hyd) and aged samples were observed, the characterization methods used in this work are unable to resolve clear differences between solid phases aged for different time periods or at different pH values. Solubility experiments conducted at T = 22°C with fresh and aged Th(IV) solid phases show a systematic decrease in the solubility of the solid phases aged at T = 80°C. In contrast to the observations gained by solid phase characterization, the ageing time and ageing pH significantly affect the solubility measured at T = 22°C. These observations can be consistently explained considering a solubility control by the outermost surface of the ThO2(s, hyd) solid, which cannot be properly probed by any of the techniques considered in this work. Solubility data are used to derive the thermodynamic properties (log *K°s,0, ΔfG°m) of the investigated solid phases, and discussed in terms of particle size using the Schindler equation. These results provide new insights on the interlink between solubility, structure, surface and thermodynamics in the ThO2(s, hyd)–H2O(l) system, with special emphasis on the transformation of the amorphous hydrous/hydroxide solid phases into the thermodynamically stable crystalline oxides.
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DiBlasi NA, Tasi AG, Trumm M, Schnurr A, Gaona X, Fellhauer D, Dardenne K, Rothe J, Reed DT, Hixon AE, Altmaier M. Pu(iii) and Cm(iii) in the presence of EDTA: aqueous speciation, redox behavior, and the impact of Ca(ii). RSC Adv 2022; 12:9478-9493. [PMID: 35424870 PMCID: PMC8985188 DOI: 10.1039/d1ra09010k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 03/14/2022] [Indexed: 11/21/2022] Open
Abstract
The impact of calcium on the solubility, redox behavior, and speciation of the An(iii)–EDTA (An = Pu or Cm) system under reducing, anoxic conditions was investigated through batch solubility experiments, X-ray absorption spectroscopy (XAS), density functional theory (DFT), and time-resolved laser fluorescence spectroscopy (TRLFS). Batch solubility experiments were conducted from undersaturation using Pu(OH)3(am) as the solid phase in contact with 0.1 M NaCl–NaOH–HCl–EDTA–CaCl2 solutions at [EDTA] = 1 mM, pHm = 7.5–9.5, and [CaCl2] ≤20 mM. Additional samples targeted brine systems represented by 3.5 M CaCl2 and WIPP simulated brine. Solubility data in the absence of calcium were well-described by Pu(iii)–EDTA thermodynamic models, thus supporting the stabilization of Pu(iii)–EDTA complexes in solution. Cm(iii)–EDTA TRLFS data suggested the stepwise hydrolysis of An(iii)-EDTA complexes with increasing pH, and current Pu(iii)-EDTA solubility models were reassessed to evaluate the possibility of including Pu(iii)–OH–EDTA complexes and to calculate preliminary formation constants. Solubility data in the presence of calcium exhibited nearly constant log m(Pu)tot, as limited by total ligand concentration, with increasing [CaCl2]tot, which supports the formation of calcium-stabilized Pu(iii)–EDTA complexes in solution. XAS spectra without calcium showed partial oxidation of Pu(iii) to Pu(iv) in the aqueous phase, while calcium-containing experiments exhibited only Pu(iii), suggesting that Ca–Pu(iii)–EDTA complexes may stabilize Pu(iii) over short timeframes (t ≤45 days). DFT calculations on the Ca–Pu(iii)–EDTA system and TRLFS studies on the analogous Ca–Cm(iii)–EDTA system show that calcium likely stabilizes An(iii)–EDTA complexes but can also potentially stabilize An(iii)–OH–EDTA species in solution. This hints towards the possible existence of four major complex types within Ca–An(iii)–EDTA systems: An(iii)–EDTA, An(iii)–OH–EDTA, Ca–An(iii)–EDTA, and Ca–An(iii)–OH–EDTA. While the exact stoichiometry and degree of ligand protonation within these complexes remain undefined, their formation must be accounted for to properly assess the fate and transport of plutonium under conditions relevant to nuclear waste disposal. Combined advanced spectroscopy and solubility studies provide evidence for the formation of novel calcium-containing and hydrolyzed (Cm,Pu)(iii)–EDTA complex(es).![]()
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Affiliation(s)
- Nicole A DiBlasi
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame 301 Stinson-Remick, Notre Dame IN 46556 USA .,Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Agost G Tasi
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Michael Trumm
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Andreas Schnurr
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Xavier Gaona
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - David Fellhauer
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Kathy Dardenne
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Jörg Rothe
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
| | - Donald T Reed
- Los Alamos National Laboratory 1400 University Dr. Carlsbad NM 88220 USA
| | - Amy E Hixon
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame 301 Stinson-Remick, Notre Dame IN 46556 USA
| | - Marcus Altmaier
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal P.O. Box 3640 Karlsruhe 76021 Germany
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Schacherl B, Prüssmann T, Dardenne K, Hardock K, Krepper V, Rothe J, Vitova T, Geckeis H. Implementation of cryogenic tender X-ray HR-XANES spectroscopy at the ACT station of the CAT-ACT beamline at the KIT Light Source. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:80-88. [PMID: 34985425 PMCID: PMC8733978 DOI: 10.1107/s1600577521012650] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 11/28/2021] [Indexed: 06/07/2023]
Abstract
The ACT experimental station of the CAT-ACT wiggler beamline at the Karlsruhe Institute of Technology (KIT) Light Source is dedicated to the investigation of radionuclide materials with radioactivities up to 1000000 times the exemption limit by various speciation techniques applying monochromatic X-rays. In this article, the latest technological developments at the ACT station that enable high-resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy for low radionuclide loading samples are highlighted - encompassing the investigation of actinide elements down to 1 p.p.m. concentration - combined with a cryogenic sample environment reducing beam-induced sample alterations. One important part of this development is a versatile gas tight plexiglass encasement ensuring that all beam paths in the five-analyzer-crystal Johann-type X-ray emission spectrometer run within He atmosphere. The setup enables the easy exchange between different experiments (conventional X-ray absorption fine structure, HR-XANES, high-energy or wide-angle X-ray scattering, tender to hard X-ray spectroscopy) and opens up the possibility for the investigation of environmental samples, such as specimens containing transuranium elements from contaminated land sites or samples from sorption and diffusion experiments to mimic the far field of a breached nuclear waste repository.
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Affiliation(s)
- Bianca Schacherl
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Tim Prüssmann
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kathy Dardenne
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Kirsten Hardock
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Volker Krepper
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Jörg Rothe
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Tonya Vitova
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Horst Geckeis
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
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Stagg O, Morris K, Lam A, Navrotsky A, Velázquez JM, Schacherl B, Vitova T, Rothe J, Galanzew J, Neumann A, Lythgoe P, Abrahamsen-Mills L, Shaw S. Fe(II) Induced Reduction of Incorporated U(VI) to U(V) in Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16445-16454. [PMID: 34882383 DOI: 10.1021/acs.est.1c06197] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Over 60 years of nuclear activities have resulted in a global legacy of radioactive wastes, with uranium considered a key radionuclide in both disposal and contaminated land scenarios. With the understanding that U has been incorporated into a range of iron (oxyhydr)oxides, these minerals may be considered a secondary barrier to the migration of radionuclides in the environment. However, the long-term stability of U-incorporated iron (oxyhydr)oxides is largely unknown, with the end-fate of incorporated species potentially impacted by biogeochemical processes. In particular, studies show that significant electron transfer may occur between stable iron (oxyhydr)oxides such as goethite and adsorbed Fe(II). These interactions can also induce varying degrees of iron (oxyhydr)oxide recrystallization (<4% to >90%). Here, the fate of U(VI)-incorporated goethite during exposure to Fe(II) was investigated using geochemical analysis and X-ray absorption spectroscopy (XAS). Analysis of XAS spectra revealed that incorporated U(VI) was reduced to U(V) as the reaction with Fe(II) progressed, with minimal recrystallization (approximately 2%) of the goethite phase. These results therefore indicate that U may remain incorporated within goethite as U(V) even under iron-reducing conditions. This develops the concept of iron (oxyhydr)oxides acting as a secondary barrier to radionuclide migration in the environment.
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Affiliation(s)
- Olwen Stagg
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Andy Lam
- Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California Davis, Davis, California 95616, United States
| | - Alexandra Navrotsky
- School of Molecular Sciences and Navrotsky Eyring Center for Materials of the Universe, Arizona State University, Tempe, Arizona 85287, United States
| | - Jesús M Velázquez
- Department of Chemistry, University of California─Davis, Davis, California 95616, United States
| | - Bianca Schacherl
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Tonya Vitova
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Jörg Rothe
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Jurij Galanzew
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Anke Neumann
- School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Paul Lythgoe
- Manchester Analytical Geochemistry Unit, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | | | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
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DiBlasi NA, Tasi AG, Gaona X, Fellhauer D, Dardenne K, Rothe J, Reed DT, Hixon AE, Altmaier M. Impact of Ca(II) on the aqueous speciation, redox behavior, and environmental mobility of Pu(IV) in the presence of EDTA. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 783:146993. [PMID: 33866175 DOI: 10.1016/j.scitotenv.2021.146993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/01/2021] [Accepted: 04/03/2021] [Indexed: 06/12/2023]
Abstract
The impact of calcium on the solubility and redox behavior of the Pu(IV)-EDTA system was investigated using a combination of undersaturation solubility studies and advanced spectroscopic techniques. Batch solubility experiments were conducted in 0.1 M NaCl-NaOH-HCl-EDTA-CaCl2 solutions at constant [EDTA] = 1∙10-3 M, 1 ≤ pHm ≤ 11, and 1∙10-3 M ≤ [CaCl2] ≤ 2∙10-2 M. Additional samples targeted brine systems represented by 3.5 M CaCl2 and WIPP simulated brine. Redox conditions were buffered with hydroquinone (pe + pH ≈ 9.5) with selected samples prepared in the absence of any redox buffer. All experiments were performed at T = 22 °C under Ar atmosphere. In-situ X-ray absorption spectroscopy indicated that PuO2(ncr,hyd) was the solubility-controlling phase during the lifetime of all experiments and that aqueous plutonium was present in the +IV oxidation state across all experimental conditions except at pHm ≈ 1, where a small fraction of Pu(III) was also identified. Current thermodynamic models overestimate Pu(IV)-EDTA solubility in the absence of calcium by approximately 1-1.5 log10-units and do not describe the nearly pH-independent, increased solubility observed with increased calcium concentrations. The ternary Pu(IV)-OH-EDTA system without calcium was reevaluated using solubility data obtained in this work and reported in the literature. An updated thermodynamic model including the complexes Pu(OH)(EDTA)-, Pu(OH)2(EDTA)2-, and Pu(OH)3(EDTA)3- was derived. Solubility data collected in the presence of calcium follows a pH-independent trend (log m(Pu)tot vs. pHm), which can only be explained by assuming the formation of a quaternary complex, tentatively defined as CaPu(OH)4(EDTA)2-, in solution. The significant enhancement of plutonium solubility observed in the investigated brine systems supports the formation of a quaternary complex that is not outcompeted by Ca(EDTA)2-, even in concentrated CaCl2 solutions. Although the exact stoichiometry of the complex may need to be revisited, this new quaternary complex has a pronounced impact on plutonium predominance diagrams over a broad range of pH, pe, and calcium concentrations that are relevant to nuclear waste disposal.
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Affiliation(s)
- Nicole A DiBlasi
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, 301 Stinson-Remick, Notre Dame, IN 46556, United States of America
| | - Agost G Tasi
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Xavier Gaona
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany.
| | - David Fellhauer
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Kathy Dardenne
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Jörg Rothe
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany
| | - Donald T Reed
- Los Alamos National Laboratory, 1400 University Dr., Carlsbad, NM 88220, United States of America
| | - Amy E Hixon
- Department of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, 301 Stinson-Remick, Notre Dame, IN 46556, United States of America.
| | - Marcus Altmaier
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal, P.O. Box 3640, 76021 Karlsruhe, Germany
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Townsend LT, Morris K, Harrison R, Schacherl B, Vitova T, Kovarik L, Pearce CI, Mosselmans JFW, Shaw S. Sulfidation of magnetite with incorporated uranium. CHEMOSPHERE 2021; 276:130117. [PMID: 34088087 DOI: 10.1016/j.chemosphere.2021.130117] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 02/03/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Uranium (U) is a radionuclide of key environmental interest due its abundance by mass within radioactive waste and presence in contaminated land scenarios. Ubiquitously present iron (oxyhydr)oxide mineral phases, such as (nano)magnetite, have been identified as candidates for immobilisation of U via incorporation into the mineral structure. Studies of how biogeochemical processes, such as sulfidation from the presence of sulfate-reducing bacteria, may affect iron (oxyhydr)oxides and impact radionuclide mobility are important in order to underpin geological disposal of radioactive waste and manage radioactively contaminated land. Here, this study utilised a highly controlled abiotic method for sulfidation of U(V) incorporated into nanomagnetite to determine the fate and speciation of U. Upon sulfidation, transient release of U into solution occurred (∼8.6% total U) for up to 3 days, despite the highly reducing conditions. As the system evolved, lepidocrocite was observed to form over a period of days to weeks. After 10 months, XAS and geochemical data showed all U was partitioned to the solid phase, as both nanoparticulate uraninite (U(IV)O2) and a percentage of retained U(V). Further EXAFS analysis showed incorporation of the residual U(V) fraction into an iron (oxyhydr)oxide mineral phase, likely nanomagnetite or lepidocrocite. Overall, these results provide new insights into the stability of U(V) incorporated iron (oxyhydr)oxides during sulfidation, confirming the longer term retention of U in the solid phase under complex, environmentally relevant conditions.
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Affiliation(s)
- Luke T Townsend
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, UK
| | - Robert Harrison
- School of Mechanical, Aerospace & Civil Engineering, University of Manchester, Manchester, M13 9PL, UK
| | - Bianca Schacherl
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (KIT-INE), P.O. Box 3640, D-76021, Karlsruhe, Germany
| | - Tonya Vitova
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (KIT-INE), P.O. Box 3640, D-76021, Karlsruhe, Germany
| | - Libor Kovarik
- Pacific Northwest National Laboratory, Richland, WA, 99352, United States
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory, Richland, WA, 99352, United States
| | - J Frederick W Mosselmans
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, UK
| | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, UK.
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Gerber E, Romanchuk AY, Weiss S, Bauters S, Schacherl B, Vitova T, Hübner R, Shams Aldin Azzam S, Detollenaere D, Banerjee D, Butorin SM, Kalmykov SN, Kvashnina KO. Insight into the structure–property relationship of UO 2 nanoparticles. Inorg Chem Front 2021. [DOI: 10.1039/d0qi01140a] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We show that the structural and electronic properties of UO2 NPs (2–3 nm) are similar to those of bulk UO2 under inert conditions, with U(iv) as the dominating oxidation state, though NPs oxidize with time and under the X-ray beam.
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11
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Boulanger N, Kuzenkova AS, Iakunkov A, Romanchuk AY, Trigub AL, Egorov AV, Bauters S, Amidani L, Retegan M, Kvashnina KO, Kalmykov SN, Talyzin AV. Enhanced Sorption of Radionuclides by Defect-Rich Graphene Oxide. ACS APPLIED MATERIALS & INTERFACES 2020; 12:45122-45135. [PMID: 32902246 PMCID: PMC7684581 DOI: 10.1021/acsami.0c11122] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Extremely defect graphene oxide (dGO) is proposed as an advanced sorbent for treatment of radioactive waste and contaminated natural waters. dGO prepared using a modified Hummers oxidation procedure, starting from reduced graphene oxide (rGO) as a precursor, shows significantly higher sorption of U(VI), Am(III), and Eu(III) than standard graphene oxides (GOs). Earlier studies revealed the mechanism of radionuclide sorption related to defects in GO sheets. Therefore, explosive thermal exfoliation of graphite oxide was used to prepare rGO with a large number of defects and holes. Defects and holes are additionally introduced by Hummers oxidation of rGO, thus providing an extremely defect-rich material. Analysis of characterization by XPS, TGA, and FTIR shows that dGO oxygen functionalization is predominantly related to defects, such as flake edges and edge atoms of holes, whereas standard GO exhibits oxygen functional groups mostly on the planar surface. The high abundance of defects in dGO results in a 15-fold increase in sorption capacity of U(VI) compared to that in standard Hummers GO. The improved sorption capacity of dGO is related to abundant carboxylic group attached hole edge atoms of GO flakes as revealed by synchrotron-based extended X-ray absorption fine structure (EXAFS) and high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy.
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Affiliation(s)
| | - Anastasiia S. Kuzenkova
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Artem Iakunkov
- Department
of Physics, Umeå University, S-90187 Umeå, Sweden
| | - Anna Yu. Romanchuk
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Alexander L. Trigub
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
- National
Research Centre “Kurchatov Institute”, Moscow 123098, Russia
| | - Alexander V. Egorov
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - Stephen Bauters
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Lucia Amidani
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Marius Retegan
- The
European
Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Kristina O. Kvashnina
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
- The
Rossendorf Beamline at ESRF − The
European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz
Zentrum Dresden-Rossendorf (HZDR), Institute
of Resource Ecology, P. O. Box 510119, 01314 Dresden, Germany
| | - Stepan N. Kalmykov
- Department
of Chemistry, Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
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12
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Bauters S, Scheinost AC, Schmeide K, Weiss S, Dardenne K, Rothe J, Mayordomo N, Steudtner R, Stumpf T, Abram U, Butorin SM, Kvashnina KO. Signatures of technetium oxidation states: a new approach. Chem Commun (Camb) 2020; 56:9608-9611. [DOI: 10.1039/d0cc03905e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A general strategy for the determination of Tc oxidation state by a new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3 edge is shown.
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13
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Pidchenko I, Bauters S, Sinenko I, Hempel S, Amidani L, Detollenaere D, Vinze L, Banerjee D, van Silfhout R, Kalmykov SN, Göttlicher J, Baker RJ, Kvashnina KO. A multi-technique study of altered granitic rock from the Krunkelbach Valley uranium deposit, Southern Germany. RSC Adv 2020; 10:25529-25539. [PMID: 35518608 PMCID: PMC9055283 DOI: 10.1039/d0ra03375h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/11/2020] [Indexed: 11/21/2022] Open
Abstract
Herein, a multi-technique study was performed to reveal the elemental speciation and microphase composition in altered granitic rock collected from the Krunkelbach Valley uranium (U) deposit area near an abandoned U mine, Black Forest, Southern Germany. The former Krunkelbach U mine with 1–2 km surrounding area represents a unique natural analogue site with the rich accumulation of secondary U minerals suitable for radionuclide migration studies from a spent nuclear fuel (SNF) repository. Based on a micro-technique analysis using several synchrotron-based techniques such as X-ray fluorescence analysis, X-ray absorption spectroscopy, powder X-ray diffraction and laboratory-based scanning electron microscopy and Raman spectroscopy, the complex mineral assemblage was identified. While on the surface of granite, heavily altered metazeunerite–metatorbernite (Cu(UO2)2(AsO4)2−x(PO4)x·8H2O) microcrystals were found together with diluted coatings similar to cuprosklodowskite (Cu(UO2)2(SiO3OH)2·6H2O), in the cavities of the rock predominantly well-preserved microcrystals close to metatorbernite (Cu(UO2)2(PO4)2·8H2O) were identified. The Cu(UO2)2(AsO4)2−x(PO4)x·8H2O species exhibit uneven morphology and varies in its elemental composition, depending on the microcrystal part ranging from well-preserved to heavily altered on a scale of ∼200 μm. The microcrystal phase alteration could be presumably attributed to the microcrystal morphology, variations in chemical composition, and geochemical conditions at the site. The occurrence of uranyl-arsenate-phosphate and uranyl-silicate mineralisation on the surface of the same rock indicates the signatures of different geochemical conditions that took place after the oxidative weathering of the primary U- and arsenic (As)-bearing ores. The relevance of uranyl minerals to SNF storage and the potential role of uranyl-arsenate mineral species in the mobilization of U and As into the environment is discussed. A multi-technique elemental and microphase analysis of altered granitic rock from the Krunkelbach Valley uranium deposit, Black Forest, Southern Germany.![]()
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