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Payne TE, Waite TD. Uranium adsorption – a review of progress from qualitative understanding to advanced model development. RADIOCHIM ACTA 2022. [DOI: 10.1515/ract-2022-0003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Surface adsorption has a major influence on the environmental mobility of radionuclides, including uranium. Six decades ago, the description of the sorption process relied predominantly on simple descriptive parameters of solid–liquid partitioning (such as Kd values). There have since been numerous systematic investigations of the processes controlling U adsorption, including the affinity of U for different types of geologic materials, the influence of factors such as pH, the effects of complexing ligands, and the role of microorganisms. Mathematical descriptions of sorption processes have adopted various models – including sorption isotherms, surface complexation models and other types of modelling approaches, aided by advances in computational and analytical techniques. In recent years, mechanistic models have incorporated structural insights gained from spectroscopic techniques (such as EXAFS and TRLFS). Throughout the period, the nuclear waste community has sought to develop models for U sorption in complex systems associated with radioactive waste disposal, involving a range of mineral surfaces and incorporating numerous interactions and processes. To some extent, the ongoing questions concerning U adsorption can be considered as being common to many environmental metal contaminants. However, uranium is a unique and significant case, particularly for the radiochemical community, where the long-term behaviour of actinides is a central issue.
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Affiliation(s)
- Timothy E. Payne
- Australian Nuclear Science and Technology Organisation , Locked Bag 2001 , Kirrawee DC , NSW 2232 , Australia
| | - T. David Waite
- School of Civil and Environmental Engineering, University of New South Wales , Sydney , NSW 2052 , Australia
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Surface Coverage- and Excitation Laser Wavelength-Dependent Luminescence Properties of U(VI) Species Adsorbed on Amorphous SiO2. MINERALS 2022. [DOI: 10.3390/min12020230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Time-resolved luminescence spectroscopy is usefully used to identify U(VI) surface species adsorbed on SiO2. However, the cause of the inconsistent luminescence lifetimes and spectral shapes reported previously remains undetermined. In this study, the U(VI) surface coverage (Γ) and excitation laser wavelength (λex) were examined as the predominant factors governing the luminescence properties of U(VI) surface species. At neutral pH, the luminescence lifetimes of U(VI) surface species increased with decreasing Γ. In the low-Γ region, where a relatively large number of adjacent surface sites are involved in the formation of multidentate surface complexes, the displacement of more number of coordinated water molecules in the equatorial plane of U(VI) results in a longer lifetime. The pH-dependent luminescence lifetimes of U(VI) surface species at the same U(VI) to SiO2 concentration ratio in the pH range of 4.5–7.5 also explain the effect of the surface binding sites on the luminescence lifetime. The time-resolved luminescence properties of the U(VI) surface species were also investigated at different excitation wavelengths. Continued irradiation of the SiO2 surface with a UV laser beam at λex = 266 nm considerably reduced the luminescence intensities of the U(VI) surface species. The higher the laser pulse energy, the greater the decrease in luminescence intensity. Laser-induced thermal desorption (LITD) of U(VI) surface species is suggested to be the origin of the decrease in luminescence intensity. LITD effects were not observed at λex = 355 and 422 nm, even at high laser pulse energies.
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Comarmond MJ, Steudtner R, Stockmann M, Heim K, Müller K, Brendler V, Payne TE, Foerstendorf H. The Sorption Processes of U(VI) onto SiO 2 in the Presence of Phosphate: from Binary Surface Species to Precipitation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11610-11618. [PMID: 27754663 DOI: 10.1021/acs.est.6b02075] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The ternary system containing aqueous U(VI), aqueous phosphate and solid SiO2 was comprehensively investigated using a batch sorption technique, in situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopy, time-resolved luminescence spectroscopy (TRLS), and surface complexation modeling (SCM). The batch sorption studies on silica gel (10 g/L) in the pH range 2.5 to 5 showed no significant increase in U(VI) uptake in the presence of phosphate at equimolar concentration of 20 μM, but significant increase in U(VI) uptake was observed for higher phosphate concentrations. In situ infrared and luminescence spectroscopic studies evidence the formation of two binary U(VI) surface species in the absence of phosphate, whereas after prolonged sorption in the presence of phosphate, the formation of a surface precipitate, most likely an autunite-like phase, is strongly suggested. From SCM, excellent fitting results were obtained exclusively considering two binary uranyl surface species and the formation of a solid uranyl phosphate phase. Ternary surface complexes were not needed to explain the data. The results of this study indicate that the sorption of U(VI) on SiO2 in the presence of inorganic phosphate initially involves binary surface-sorption species and evolves toward surface precipitation.
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Affiliation(s)
- M Josick Comarmond
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Robin Steudtner
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
| | - Madlen Stockmann
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
| | - Karsten Heim
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
| | - Katharina Müller
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
| | - Vinzenz Brendler
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Harald Foerstendorf
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , Bautzner Landstr. 400, D-01328 Dresden, Germany
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Uribe EC, Mason HE, Shusterman JA, Bruchet A, Nitsche H. Probing the interaction of U(vi) with phosphonate-functionalized mesoporous silica using solid-state NMR spectroscopy. Dalton Trans 2016; 45:10447-58. [DOI: 10.1039/c6dt01200k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Solid-state NMR techniques combined with batch contact experiments elucidate how U(vi) binds to phosphonate-functionalized mesoporous silica.
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Affiliation(s)
- Eva C. Uribe
- Department of Chemistry
- University of California
- Berkeley
- Berkeley
- USA
| | - Harris E. Mason
- Glenn T. Seaborg Institute
- Physical and Life Sciences Directorate
- Lawrence Livermore National Laboratory
- Livermore
- USA
| | | | - Anthony Bruchet
- Department of Chemistry
- University of California
- Berkeley
- Berkeley
- USA
| | - Heino Nitsche
- Department of Chemistry
- University of California
- Berkeley
- Berkeley
- USA
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Wang H, Chai Z, Wang D. Adsorption of uranyl on hydroxylated α-SiO2(001): a first-principle study. Dalton Trans 2015; 44:1646-54. [DOI: 10.1039/c4dt02872d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effects of pH, CO2, aqua solution and anionic ligands on the adsorption of uranyl on α-SiO2(001) were investigated.
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Affiliation(s)
- Hui Wang
- CAS Key Laboratory of Nuclear Radiation and Nuclear Energy Techniques
- and Multidisciplinary Initiative Center
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing
| | - Zhifang Chai
- CAS Key Laboratory of Nuclear Radiation and Nuclear Energy Techniques
- and Multidisciplinary Initiative Center
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing
| | - Dongqi Wang
- CAS Key Laboratory of Nuclear Radiation and Nuclear Energy Techniques
- and Multidisciplinary Initiative Center
- Institute of High Energy Physics
- Chinese Academy of Sciences
- Beijing
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Macé N, Wieland E, Dähn R, Tits J, Scheinost AC. EXAFS investigation on U(VI) immobilization in hardened cement paste: influence of experimental conditions on speciation. RADIOCHIM ACTA 2013. [DOI: 10.1524/ract.2013.2024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to investigate the coordination environment of U(VI) in cementitious materials. The EXAFS measurements were carried out on U(VI)-doped samples prepared under varying conditions, such as samples from sorption, hydration and diffusion experiments, and using different cementitious materials, such as crushed hydrated hardened cement paste (HCP) and calcium silicate hydrates (C-S-H). The samples had U(VI) loadings ranging from 1700 μg/g to 45000 μg/g. Applying principal component analysis (PCA) on 13 EXAFS spectra (each spectra corresponding to aminimum of five different scans) of the low loading samples, one single species is obtained indicating a similar U(VI) coordination environment for both HCP and C-S-H samples. This result confirms that C-S-H phases control the uptake of U(VI) in the complex cement matrix. The coordination environment structure of this species is similar to a U(VI) surface complex or to U(VI) in uranyl silicate minerals (two axial O atoms at 1.82 ± 0.02 Å; four equatorial O atoms at 2.25 ± 0.01 Å; one Si atom at 3.10 ± 0.03 Å). At high U(VI) loading, PCA revealed a second U(VI) species, with a coordination environment similar to that of U(VI) in calcium uranate (two axial O atoms at 1.94 ± 0.04 Å; five equatorial O atoms at 2.26 ± 0.01 Å; four Ca atoms at 3.69 ± 0.05 Å and five U atoms at 3.85 ± 0.04 Å).
This study suggest that, at low U(VI) loading, U(VI) is bound to C-S-H phases in HCP while at high U(VI) loading, the immobilization of U(VI) in cementitious materials is mainly controlled by the precipitation of a calcium uranate-type phase.
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Geckeis H, Lützenkirchen J, Polly R, Rabung T, Schmidt M. Mineral–Water Interface Reactions of Actinides. Chem Rev 2013; 113:1016-62. [DOI: 10.1021/cr300370h] [Citation(s) in RCA: 223] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Horst Geckeis
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal
(INE), Karlsruhe, P.O.Box 3640, D-76021 Karlsruhe, Germany
| | - Johannes Lützenkirchen
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal
(INE), Karlsruhe, P.O.Box 3640, D-76021 Karlsruhe, Germany
| | - Robert Polly
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal
(INE), Karlsruhe, P.O.Box 3640, D-76021 Karlsruhe, Germany
| | - Thomas Rabung
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal
(INE), Karlsruhe, P.O.Box 3640, D-76021 Karlsruhe, Germany
| | - Moritz Schmidt
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal
(INE), Karlsruhe, P.O.Box 3640, D-76021 Karlsruhe, Germany
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Affiliation(s)
- Kate Maher
- Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, United States
| | | | - Gordon E. Brown
- Department of Geological & Environmental Sciences, Stanford University, Stanford, California 94305-2115, United States
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Ilton ES, Wang Z, Boily JF, Qafoku O, Rosso KM, Smith SC. The effect of pH and time on the extractability and speciation of uranium(VI) sorbed to SiO2. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:6604-6611. [PMID: 22616921 DOI: 10.1021/es300501v] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The effect of pH and contact time on uranium extractability from quartz surfaces was investigated using either acidic or carbonate (CARB) extraction solutions, time-delayed spikes of different U isotopes ((238)U and (233)U), and liquid helium temperature time-resolved laser-induced fluorescence spectroscopy (TRLFS). Quartz powders were reacted with (238)U(VI) bearing solutions equilibrated with atmospheric CO(2) at pH 6, 7, and 8. After 42 days, the suspensions were spiked with (233)U(VI) and reacted for an additional 7 days. Sorbed U was then extracted with either dilute nitric acid or CARB. For the CARB, but not the acid, extraction there was a systematic decrease in extraction efficiency for both isotopes from pH 6 to 8, which was mimicked by less desorption of (238)U, after the (233)U spike, from pH 6 to 8. The efficiency of (233)U extraction was consistently greater than that of (238)U, indicating a strong temporal component to the strength of U association with the surface that was accentuated with increasing pH. TRLFS revealed a strong correlation between CARB extraction efficiency and sorbed U speciation as a function of pH and time. Collectively, the observations show that aging and pH are critical factors in determining the form and strength of uranium-silica interactions.
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Affiliation(s)
- Eugene S Ilton
- Pacific Northwest National Laboratory , 902 Battelle Blvd., MSIN: K8-96, Richland, Washington 99352, USA.
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Sylwester ER, Hudson EA, Allen PG. Surface Interactions of Actinide Ions with Geologic Materials Studied by XAFS. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-590-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTWe have investigated the interaction of the actinyl ion, , with silica, alumina, and montmorillonite surfaces under ambient atmosphere and aqueous conditions using x-ray Absorption Fine Structure (XAFS) Spectroscopy. In acid solution (pH ∼ 3.5), the uranyl ion shows a strong interaction with the silica and alumina surfaces, and a relatively weak association with the montmorillonite surface. The extent of direct surface interaction is determined by comparing structural distortions in the equatorial bonding environment of the uranyl ion relative to the structure of a “free” uranyl aquo complex. Based on this formalism, surface complexation on silica and alumina occurs through an inner-sphere mechanism with surface oxygen atoms binding directly to the equatorial region of the uranyl ion. In contrast, sorption on montmorillonite occurs by an outer sphere mechanism in which the uranyl ion retains the simple aquo complex structure and binds to the surface via ion-exchange. In near-neutral solutions (pH ∼ 6), sorption on all of the materials is dominated by an inner-sphere mechanism. The formation of surface oligomeric species is also observed on silica and alumina.
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11
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Boily JF, Rosso KM. Crystallographic controls on uranyl binding at the quartz/water interface. Phys Chem Chem Phys 2011; 13:7845-51. [DOI: 10.1039/c0cp01406k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Sorption speciation of lanthanides/actinides on minerals by TRLFS, EXAFS and DFT studies: a review. Molecules 2010; 15:8431-68. [PMID: 21085087 PMCID: PMC6259111 DOI: 10.3390/molecules15118431] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 11/09/2010] [Accepted: 11/15/2010] [Indexed: 11/17/2022] Open
Abstract
Lanthanides/actinides sorption speciation on minerals and oxides by means of time resolved laser fluorescence spectroscopy (TRLFS), extended X-ray absorption fine structure spectroscopy (EXAFS) and density functional theory (DFT) is reviewed in the field of nuclear disposal safety research. The theoretical aspects of the methods are concisely presented. Examples of recent research results of lanthanide/actinide speciation and local atomic structures using TRLFS, EXAFS and DFT are discussed. The interaction of lanthanides/actinides with oxides and minerals as well as their uptake are also of common interest in radionuclide chemistry. Especially the sorption and inclusion of radionuclides into several minerals lead to an improvement in knowledge of minor components in solids. In the solid-liquid interface, the speciation and local atomic structures of Eu(III), Cm(III), U(VI), and Np(IV/VI) in several natural and synthetic minerals and oxides are also reviewed and discussed. The review is important to understand the physicochemical behavior of lanthanides/actinides at a molecular level in the natural environment.
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Merroun M, Hennig C, Rossberg A, Reich T, Selenska-Pobell S. Characterization of U(VI)-Acidithiobacillus ferrooxidans complexes using EXAFS, transmission electron microscopy, and energy-dispersive X-ray analysis. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.91.10.583.22477] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Summary
We used a combination of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray (EDX) analysis to conduct molecular scale studies on U(VI) interaction with three recently described eco-types of Acidithiobacillus ferrooxidans. On the basis of the information obtained by using these methods, we concluded that uranyl phosphate complexes were formed by the cells of the three eco-types studied. The uranium accumulated by A. ferrooxidans cells was located mainly within the extracellular polysaccharides, and on the cell wall. Smaller amounts were also observed in the cytoplasm.
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Abstract
Sorption of uranyl ion, UO22+, on SiO2·xH2O (silica gel) has been investigated as a function of time, amount of silica gel (0.10–0.60g), uranium concentration (5.00×10−5–1.00×−3M), ionic strength (0.20–1.40M NaClO4), pH (∼2.0–6.0), and temperature (283–333K). Based on kinetic data, the diffusion coefficient of UO22+ion was calculated to be 6.83(±0.22)×10−12m2s−1under particle diffusion-controlled conditions. The rate of sorption of uranyl ion on silica gel was determined to be 8.56(±0.50)×10−2min−1at 298K, pH 1.82±0.05 and 0.20M NaClO4. The uranyl sorption data on silica gel followed the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms. Uranyl sorption (11.48±0.03 (0.20M NaClO4) to 34.81±0.20 (1.40M NaClO4) at pH 2.79±0.03 using 0.10g silica gel. The sorption decreased in the presence of 1.00×10−3M fluoride and oxalate ions; while the presence of carbonate anion showed negligible change in uranyl sorption profile in the pH range of 2 to 6 at 0.20M NaClO4. Temperature variation experiments showed that the sorption of uranium on silica gel had an endothermic enthalpy, which became more spontaneous at elevated temperatures.
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Hennig C, Reich T, Dähn R, Scheidegger AM. Structure of uranium sorption complexes at montmorillonite edge sites. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2002.90.9-11_2002.653] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SummaryExtended X-ray absorption fine structure (EXAFS) spectroscopy at the uranium LIII-edge was used for determining the structural environment of aqueous uranyl sorbed onto montmorillonite. The study reveals that uranyl uptake at pH ∼5-∼7 and at an initial uranyl concentration of 5×10−5M takes place at amphoteric surface hydroxyl sites as inner-sphere complex. The measured bond distances between uranium and the equatorial oxygen atoms are in the range of 2.34 Å and 2.37 Å indicating an inner-sphere coordination. At ∼3.4 Å the presence of a U-Al backscattering pair was determined. This backscattering pair indicates that the binding of the uranyl unit to amphoteric surface hydroxyl sites occurs preferred as a bidentate inner-sphere complex on aluminol groups.
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García-Rosales G, Drot R, Mercier-Bion F, Lagarde G, Simoni E. Interaction between U(VI) and SrTiO3 surfaces versus temperature. J Colloid Interface Sci 2009; 333:104-13. [DOI: 10.1016/j.jcis.2009.01.049] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Revised: 01/22/2009] [Accepted: 01/26/2009] [Indexed: 11/25/2022]
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Kremleva A, Krüger S, Rösch N. Density functional model studies of uranyl adsorption on (001) surfaces of kaolinite. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:9515-9524. [PMID: 18681466 DOI: 10.1021/la801278j] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The adsorption of uranyl on two types of neutral (001) surfaces of kaolinite, tetrahedral Si(t) and octahedral Al(o), was studied by means of density functional periodic slab model calculations. Various types of model surface complexes, adsorbed at different sites, were optimized and adsorption energies were estimated. As expected, the Si(t) surface was found to be less reactive than the Al(o) surface. At the neutral Al(o) surface, only adsorption at protonated sites is calculated to be exothermic for inner- as well as outer-sphere adsorption complexes, with monodentate coordination being preferred. Adsorption energies as well as structural features of the adsorption complexes are mainly determined by the number of deprotonated surface hydroxyl groups involved. Outer-sphere complexes on both surfaces exhibit a shorter U-O bond to the aqua ligand of uranyl that is in direct contact with the surface than to the other aqua ligands. This splitting of the shell of equatorial U-O bonds is at variance with common expectations for outer-sphere surface complexes of uranyl.
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Affiliation(s)
- Alena Kremleva
- Department Chemie, Theoretische Chemie, Technische Universität München, 85747 Garching, Germany
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Structural characterization of U(VI) surface complexes on kaolinite in the presence of humic acid using EXAFS spectroscopy. J Colloid Interface Sci 2008; 319:40-7. [DOI: 10.1016/j.jcis.2007.11.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 11/06/2007] [Accepted: 11/06/2007] [Indexed: 11/22/2022]
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Pavel CC, Walter M, Popa K. Improvement of retention capacity of ETS-10 for uranyl ions by porosity modification and their immobilization into a titanosilicate matrix. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b805049j] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Harfouche M, Wieland E, Dähn R, Fujita T, Tits J, Kunz D, Tsukamoto M. EXAFS study of U(VI) uptake by calcium silicate hydrates. J Colloid Interface Sci 2006; 303:195-204. [PMID: 16920135 DOI: 10.1016/j.jcis.2006.07.019] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 07/10/2006] [Accepted: 07/10/2006] [Indexed: 10/24/2022]
Abstract
Among the different cement minerals, calcium silicate hydrates (C-S-H) are the prime candidates for heavy metal binding because of their abundance and appropriate structure. Immobilization processes of heavy metals by cementitious materials, and in particular C-S-H phases, thus play an important role in multibarrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. In this study, the uptake of U(VI) by C-S-H has been investigated using X-ray absorption fine structure (XAFS) spectroscopy. C-S-H phases were synthesized using two different procedures: One is based on the mixing of CaO and SiO2 solids ("direct reaction" method); for the other one starting solutions of Ca and Si are used ("solution reaction" method). XAFS investigations were carried out on samples doped with U(VI). U(VI) was either sorbed onto previously precipitated C-S-H phases (sorption samples) or added during C-S-H synthesis (coprecipitation samples). The coordination environment of U(VI) in the sorption samples was found to be independent of the procedure used for C-S-H synthesis. A split equatorial oxygen shell (Oeq1: R=2.23-2.27 A; Oeq2: R=2.36-2.45 A), neighboring silicon atoms at short (R=3.07-3.11 A) and long (R=3.71-3.77 A) distances, and neighboring Ca atoms (R=3.77-3.81 and 4.15-4.29 A) were observed for all the samples. The structural parameters resemble those reported for uranophane. The coordination environment of U(VI) in the coprecipitation samples depends on the method used for C-S-H synthesis, and further, the spectra differ from those determined for the sorption samples. UU backscattering contributions were observed in the samples prepared using the direct reaction method, whereas no split equatorial shell appeared in the samples prepared using the solution reaction method.
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Affiliation(s)
- M Harfouche
- Paul Scherrer Institute, Nuclear Energy and Safety Research Department, Laboratory for Waste Management, 5232 Villigen PSI, Switzerland
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Moskaleva LV, Nasluzov VA, Rösch N. Modeling adsorption of the uranyl dication on the hydroxylated alpha-Al2O3(0001) surface in an aqueous medium. Density functional study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2006; 22:2141-5. [PMID: 16489800 DOI: 10.1021/la052973o] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
As a first step toward modeling the interaction of dissolved actinide contaminants with mineral surfaces, we studied low-coverage adsorption of aqueous uranyl, UO2(2+), on the hydroxylated alpha-Al2O3(0001) surface. We carried out density functional periodic slab model calculations and modeled solvation effects by explicit aqua ligands. We explored the formation of both inner- and outer-sphere complexes and estimated the corresponding adsorption energies. Effects of solvation were accounted for by explicit consideration of the first hydration shell of uranyl and by means of a posteriori corrections for long-range solvent effect. With energetics described at the GGA-PW91 level and under the assumption of a fully protonated ideal surface, we predict a weakly bound outer-sphere adsorption complex.
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Affiliation(s)
- Lyudmila V Moskaleva
- Department Chemie, Theoretische Chemie, Technische Universität München, 85747 Garching, Germany
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Walter M, Arnold T, Geipel G, Scheinost A, Bernhard G. An EXAFS and TRLFS investigation on uranium(VI) sorption to pristine and leached albite surfaces. J Colloid Interface Sci 2005; 282:293-305. [PMID: 15589533 DOI: 10.1016/j.jcis.2004.08.133] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 08/18/2004] [Indexed: 11/17/2022]
Abstract
Uranium(VI) was sorbed to freshly ground and leached albite in batch and flow-through systems in the pH range 5.0-6.4. The uranium(VI) surface complexes were studied by extended X-ray absorption fine structure (EXAFS) spectroscopy and time-resolved laser-induced fluorescence spectroscopy (TRLFS). The EXAFS analysis of uranium(VI) sorbed on albite at pH 5.8 and 5 x 10(-6) M U(VI) showed one silicon atom at a USi distance of 3.09 A, which is indicative of the formation of an inner-sphere, mononuclear, bidentate uranium(VI) surface complex, Si(O)2UO2, on the silicate tetrahedra of albite. Two additional uranium(VI) sorption complexes were detected by TRLFS at higher initial aqueous U(VI) concentrations. However, the structure of these surface complexes could not be derived from EXAFS, since the measured EXAFS spectra represent the average of two surface complex structures. In order to simulate U(VI) sorption onto weathered feldspar surfaces, albite was leached with 0.01 M HClO4, resulting in surface material similar to amorphous silica gel. EXAFS showed that the equatorial oxygen shell of uranium(VI) sorbed on this material at pH 5.0 and 5.8 was split in two distances of 2.23 and 2.44 A. This indicates the formation of an inner-sphere surface complex.
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Affiliation(s)
- Marcus Walter
- Forschungszentrum Rossendorf e.V., Institut für Radiochemie, P.O. Box 510119, D-01314 Dresden, Germany
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Greathouse JA, Cygan RT. Molecular dynamics simulation of uranyl(vi) adsorption equilibria onto an external montmorillonite surface. Phys Chem Chem Phys 2005; 7:3580-6. [PMID: 16294234 DOI: 10.1039/b509307d] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We used molecular dynamics simulations to study the adsorption of aqueous uranyl species (UO(2)(2+)) onto clay mineral surfaces in the presence of sodium counterions and carbonato ligands. The large system size (10,000 atoms) and long simulation times (10 ns) allowed us to investigate the thermodynamics of ion adsorption, and the atomistic detail provided clues for the observed adsorption behavior. The model system consisted of the basal surface of a low-charge Na-montmorillonite clay in contact with aqueous uranyl carbonate solutions with concentrations of 0.027 M, 0.081 M, and 0.162 M. Periodic boundary conditions were used in the simulations to better represent an aqueous solution interacting with an external clay surface. Uranyl adsorption tendency was found to decrease as the aqueous uranyl carbonate concentration was increased, while sodium adsorption remained constant. The observed behavior is explained by physical and chemical effects. As the ionic strength of the aqueous solution was increased, electrostatic factors prevented further uranyl adsorption once the surface charge had been neutralized. Additionally, the formation of aqueous uranyl carbonate complexes, including uranyl carbonato oligomers, contributed to the decreased uranyl adsorption tendency.
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Affiliation(s)
- Jeffery A Greathouse
- Geochemistry Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-0754, USA.
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Kowal-Fouchard A, Drot R, Simoni E, Ehrhardt JJ. Use of spectroscopic techniques for uranium(VI)/montmorillonite interaction modeling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:1399-1407. [PMID: 15046340 DOI: 10.1021/es0348344] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
To experimentally identify both clay sorption sites and sorption equilibria and to understand the retention mechanisms at a molecular level, we have characterized the structure of hexavalent uranium surface complexes resulting from the interaction between the uranyl ions and the surface retention groups of a montmorillonite clay. We have performed laser-induced fluorescence spectroscopy (LIFS) and X-ray photoelectron spectroscopy (XPS) on uranyl ion loaded montmorillonite. These structural results were then compared to those obtained from the study of uranyl ions sorbed onto an alumina and also from U(VI) sorbed on an amorphous silica. This experimental approach allowed for a clear determination of the reactive surface sites of montmorillonite for U(VI) sorption. The lifetime values and the U4f XPS spectra of uranium(VI) sorbed on montmorillonite have shown that this ion is sorbed on both exchange and edge sites. The comparison of U(VI)/clay and U(VI)/oxide systems has determined that the interaction between uranyl ions and montmorillonite edge sites occurs via both [triple bond]AlOH and [triple bond]SiOH surface groups and involves three distinct surface complexes. The surface complexation modeling of the U(VI)/montmorillonite sorption edges was determined using the constant capacitance model and the above experimental constraints. The following equilibria were found to account for the uranyl sorption mechanisms onto montmorillonite for metal concentrations ranged from 10(-6) to 10(-3) M and two ionic strengths (0.1 and 0.5 M): 2[triple bond]XNa + UO2(2+) <==> ([triple bond]X)2UO2 + 2Na+, log K0(exch) = 3.0; [triple bond]Al(OH)2 + UO2(2+) <==> [triple bond]Al(OH)2UO2(2+), log K0(Al) = 14.9; [triple bond]Si(OH)2 + UO2(2+) <==> [triple bond]SiO2UO2 + 2H+, log K0(Si1) = -3.8; and [triple bond]Si(OH)2 + 3UO2(2+) + 5H2O <==> [triple bond]SiO2(UO2)3(OH)5- + 7H+, log K0(Si2) = -20.0.
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Affiliation(s)
- A Kowal-Fouchard
- Institut de Physique Nucléaire, Groupe de Radiochimie, Université Paris XI, 91406 Orsay, France
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25
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Froideval A, Del Nero M, Barillon R, Hommet J, Mignot G. pH dependence of uranyl retention in a quartz/solution system: an XPS study. J Colloid Interface Sci 2003; 266:221-35. [PMID: 14527444 DOI: 10.1016/s0021-9797(03)00528-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have investigated the pH dependence of U(VI) retention in quartz/10(-4) M uranyl solution systems, under conditions favoring formation of polynuclear aqueous species and of colloids of amorphous schoepite as U(VI) solubility-limiting phases. X-ray photoelectron spectroscopy was used to gain insights into the coordination environments of sorbed/precipitated uranyl ions in the centrifuged quartz samples. The U4f XPS spectra made it possible to identify unambiguously the presence of two uranyl components. A high binding energy component, whose relative proportion increases with pH, exhibits the U4f lines characteristic of a reference synthetic metaschoepite. Such a high binding energy component is interpreted as a component having a U(VI) oxide hydrate character, either as polynuclear surface oligomers and/or as amorphous schoepite-like (surface) precipitates. Its pH dependence suggests that a binding of polynuclear species at quartz surfaces and/or a formation of amorphous schoepite-like (surface) precipitates is favored when the proportion of aqueous polynuclear species increases. A second surface component exhibits binding energies for the U4f core levels at values significantly lower (DeltaE(b)=1.2 eV) than for metaschoepite, evidencing uranyl ions in a distinct coordination environment. Such a low binding energy component may be attributed to monomeric uranyl surface complexes on the basis of published EXAFS data. Such a hypothesis is supported by a major contribution of the low binding energy component to the U4f XPS spectra of reference samples for uranyl sorbed on quartz from very acidic 10(-3) M uranyl solutions where UO(2)(2+) ions predominate.
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Affiliation(s)
- A Froideval
- Institut de Recherches Subatomiques, ULP/CNRS/IN2P3, UMR 7500, 67037 Cedex 2, Strasbourg, France.
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26
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Lomenech C, Simoni E, Drot R, Ehrhardt JJ, Mielczarski J. Sorption of uranium (VI) species on zircon: structural investigation of the solid/solution interface. J Colloid Interface Sci 2003; 261:221-32. [PMID: 16256526 DOI: 10.1016/s0021-9797(03)00101-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2002] [Accepted: 01/23/2003] [Indexed: 11/22/2022]
Abstract
This work is an investigation of the mechanisms of interaction between uranium (VI) ions and zirconium silicate. The speciation of uranium (VI) sorbed on zircon was studied using four complementary techniques as probes of the local structure around the uranium atom: laser spectrofluorimetry, X-ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier-transformed (DRIFT) spectroscopy, and EXAFS spectroscopy. The sorption of uranyl on zirconium oxide was also studied to allow structural comparisons. Spectrofluorimetry and XPS results allowed an identification of the silicate sorption sites on the solid. These methods associated with spectrofluorimetry and DRIFT led to a characterization of the sorbed surface complexes, taking into account the influence of the nature of the background salt and of the pH on the structure of the U(VI) surface species. EXAFS measurements, either on air-dried samples or in situ, were then carried out on well-characterized samples and allowed identification of the sorption mechanism on zircon as the formation of an inner-sphere polydentate surface complex.
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Affiliation(s)
- C Lomenech
- Université Paris XI, Institut de Physique Nucléaire d'Orsay, Groupe de Radiochimie, Bât. 100, 91406 Orsay, France
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Wheaton V, Majumdar D, Balasubramanian K, Chauffe L, Allen P. A comparative theoretical study of uranyl silicate complexes. Chem Phys Lett 2003. [DOI: 10.1016/s0009-2614(03)00237-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Greathouse JA, O'Brien RJ, Bemis G, Pabalan RT. Molecular Dynamics Study of Aqueous Uranyl Interactions with Quartz (010). J Phys Chem B 2002. [DOI: 10.1021/jp013250q] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jeffery A. Greathouse
- Department of Chemistry, St. Lawrence University, Canton, New York 13617, and Center for Nuclear Waste Regulatory Analysis, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238
| | - Robert J. O'Brien
- Department of Chemistry, St. Lawrence University, Canton, New York 13617, and Center for Nuclear Waste Regulatory Analysis, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238
| | - Gregory Bemis
- Department of Chemistry, St. Lawrence University, Canton, New York 13617, and Center for Nuclear Waste Regulatory Analysis, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238
| | - Roberto T. Pabalan
- Department of Chemistry, St. Lawrence University, Canton, New York 13617, and Center for Nuclear Waste Regulatory Analysis, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas 78238
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29
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Gabriel U, Charlet L, Schläpfer CW, Vial JC, Brachmann A, Geipel G. Uranyl Surface Speciation on Silica Particles Studied by Time-Resolved Laser-Induced Fluorescence Spectroscopy. J Colloid Interface Sci 2001; 239:358-368. [PMID: 11426999 DOI: 10.1006/jcis.2001.7602] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sorption of uranyl ions onto amorphous silica has been studied in the presence of atmospheric CO(2) by laser-induced time-resolved fluorescence spectroscopy at trace concentrations (1.0 and 0.1 &mgr;M). Two fluorescent uranyl surface complexes have been identified in the pH range 4 to 9. Both complexes could be differentiated by lifetimes (170+/-25 &mgr;s at low pH and 360+/-50 &mgr;s at high pH) and fluorescence emission spectra. Within the constant capacitance model framework they are described by mononuclear (1 : 1) complexes with release of two and three protons, respectively. When fluorescence data were compared to wet chemistry sorption data, a third "silent" ternary uranyl-silica-carbonate surface complex had to be postulated to account partly for adsorption between pH 8.0 and 9.0. Three independent data sets led therefore to the identification of three surface complexes, postulated as &tbond;SiO(2)UO(2) degrees,&tbond;SiO(2)UO(2)OH(-), and &tbond;SiO(2)UO(2)OHCO(3)(3-). Copyright 2001 Academic Press.
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Affiliation(s)
- U. Gabriel
- Laboratoire de Géophysique Interne et Tectonophysique, UJF-CNRS (UMR 5559) Grenoble, France
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30
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Clark DL, Conradson SD, Donohoe RJ, Keogh DW, Morris DE, Palmer PD, Rogers RD, Tait CD. Chemical Speciation of the Uranyl Ion under Highly Alkaline Conditions. Synthesis, Structures, and Oxo Ligand Exchange Dynamics. Inorg Chem 1999. [DOI: 10.1021/ic981137h] [Citation(s) in RCA: 247] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- David L. Clark
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - Steven D. Conradson
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - Robert J. Donohoe
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - D. Webster Keogh
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - David E. Morris
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - Phillip D. Palmer
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - Robin D. Rogers
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
| | - C. Drew Tait
- Chemical Science and Technology Division, Nuclear Materials Technology Division, Materials Science and Technology Division, and the G. T. Seaborg Institute for Transactinium Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
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