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Lan JH, Chai ZF, Shi WQ. A combined DFT and molecular dynamics study of U(VI)/calcite interaction in aqueous solution. Sci Bull (Beijing) 2017; 62:1064-1073. [PMID: 36659333 DOI: 10.1016/j.scib.2017.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 06/28/2017] [Accepted: 07/04/2017] [Indexed: 01/21/2023]
Abstract
Here we present a combined DFT and molecular dynamics study of uranyl (U(VI)) interaction mechanisms with the calcite (104) surface in aqueous solution. The roles of three anion ligands (CO32-, HCO3-, OH-) and solvation effect in U(VI) interaction with calcite have been evaluated. According to our calculations, water adsorbed on the calcite (104) surface prefers to exist in molecular state rather than dissociative state. Energy analysis indicate that the positively charged uranyl species prefers to form surface complexes on the surface, while neutral uranyl species may bind with the surface via both surface complexing and ion exchange reactions of U(VI)→Ca(II). In contrast, the negatively charged uranyl species prefer to interact with the surface via ion exchange reactions of U(VI)→Ca(II), and the one with UO2(CO3)2(H2O)2- as the reactant becomes the most favorable one in energy. We also found that uranyl adsorption increases the hydrophilicability of the (104) surface to different extents, where the UO2(CO3)3Ca2 species contributes to the largest degree of energy changes (-53kcal/mol). Our calculations proved that the (104) surface also has the ability to immobilize U(VI) via either surface complexing or ion exchange mechanisms under different pH values.
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Affiliation(s)
- Jian-Hui Lan
- Laboratory of Nuclear Energy Chemistry, and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
| | - Zhi-Fang Chai
- Laboratory of Nuclear Energy Chemistry, and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Radiological and Interdisciplinary Sciences (RAD-X) and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou 215123, China
| | - Wei-Qun Shi
- Laboratory of Nuclear Energy Chemistry, and Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
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Reinoso-Maset E, Ly J. Study of uranium(VI) and radium(II) sorption at trace level on kaolinite using a multisite ion exchange model. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 157:136-148. [PMID: 27077702 DOI: 10.1016/j.jenvrad.2016.03.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Revised: 03/17/2016] [Accepted: 03/18/2016] [Indexed: 06/05/2023]
Abstract
Uranium and the long-lived decay product radium-226 are abundantly present in mine wastes produced during uranium extraction activities. In the case of release to the surrounding environment, these radionuclides are at trace level compared to groundwater solutes, and the presence, content and properties of clay minerals in the host environment influence the extent of radionuclide sorption and, in turn, migration. Since clays are known to have the distinctive property of retaining ions, the aim of this work was to study the sorption of trace U(VI) and Ra(II) on a common phyllosilicate mineral, kaolinite, in the presence of excess K, a common groundwater cation, in order to obtain a thermodynamic database that describes the ion exchange equilibria occurring at the mineral-solution interface. Following a detailed experimental protocol using chemical and radiochemical analytical techniques, batch experiments over a wide pH range (from 2 to 11) and fixed concentration (ca. 10(-9) M), and additional adsorption isotherms at two different solution pH (6.2 and 10.4) over a concentration range (10(-10) to 10(-4) M) were carried out to measure the distribution coefficient (Kd) of U(VI) and Ra(II) sorption on kaolinite. The experimental sorption data was processed according to a general multisite sorbent/multispecies sorbate ion exchange model, which allowed deducing the charge of adsorbed species and the stoichiometry of the associated adsorption equilibria on kaolinite's surface sites. Aqueous speciation calculations predicted Ra(II) as Ra(2+) over the working pH range, and its adsorption curves and isotherms were explained using three sorption sites. Adsorption of U(VI) occurred on four sorption sites and was governed by its solution speciation, with positively charged hydroxylated (UO2(2+) and UO2(OH)(+)) and silicate (UO2(H3SiO4)(+)) species being adsorbed between pH 2 and 6, whereas its negatively charged forms (UO2(OH)3(-) and UO2(OH)4(2-)) dominated U(VI) sorption at pH > 7. Nonlinear fitting of the experimental data using the ion exchange model provided the associated equilibrium constants as corrected selectivity coefficients.
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Affiliation(s)
- Estela Reinoso-Maset
- DEN-Service d'Étude du Comportement des Radionucléides (SECR), CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
| | - Jacques Ly
- DEN-Service d'Étude du Comportement des Radionucléides (SECR), CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
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Tirler AO, Hofer TS. The structural influence of Ca(2+) counter-ions on uranyl(VI) tricarbonate in aqueous solution. Dalton Trans 2016; 45:4983-8. [PMID: 26932659 DOI: 10.1039/c5dt04718h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The presented study elucidates the influence of calcium(II) counter-ions on the structure of the environmentally relevant uranyl tricarbonates using hybrid quantum mechanical/molecular mechanical (QM/MM) MD simulations. Since experimental investigations may be subject to limitations in detecting the presence of counter-ions in solution, the present study is of importance to obtain a profound understanding of the effects counter-ions may have on coordination complexes. It can be concluded from the obtained simulation data that two calcium(II) ions are essential for stabilizing the experimentally observed uranyl tricarbonate complex in aqueous solution. Including only one calcium(II) ion in the coordination sphere was found to be insufficient to form a six-fold equatorial coordination of carbonates, but a five-fold coordination is adopted similar to the counter-ion free case in aqueous solution reported in a previous study.
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Affiliation(s)
- Andreas O Tirler
- Theoretical Chemistry Division Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
| | - Thomas S Hofer
- Theoretical Chemistry Division Institute of General, Inorganic and Theoretical Chemistry University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria.
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Tirler AO, Hofer TS. Structure and Dynamics of the Uranyl Tricarbonate Complex in Aqueous Solution: Insights from Quantum Mechanical Charge Field Molecular Dynamics. J Phys Chem B 2014; 118:12938-51. [DOI: 10.1021/jp503171g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Andreas O. Tirler
- Theoretical
Chemistry Division,
Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Thomas S. Hofer
- Theoretical
Chemistry Division,
Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
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Kerisit S, Liu C. Molecular dynamics simulations of uranyl and uranyl carbonate adsorption at aluminosilicate surfaces. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:3899-3907. [PMID: 24580048 DOI: 10.1021/es405387c] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(VI) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(VI) adsorption onto two neutral aluminosilicate surfaces, namely, the orthoclase (001) surface and the octahedral aluminum sheet of the kaolinite (001) surface. Although uranyl preferentially adsorbs as a bidentate inner-sphere complex on both surfaces, the free energy of adsorption on the orthoclase surface (-15 kcal mol(-1)) is significantly more favorable than that at the kaolinite surface (-3 kcal mol(-1)), which is attributed to differences in surface functional groups and the ability of the orthoclase surface to release a surface potassium ion upon uranyl adsorption. The structures of the adsorbed complexes compare favorably with X-ray absorption spectroscopy results. Simulations of the adsorption of uranyl complexes with up to three carbonate ligands revealed that uranyl complexes coordinated to up to two carbonate ions are stable on the orthoclase surface whereas uranyl carbonate surface complexes are unfavored at the kaolinite surface. Combining the MD-derived equilibrium adsorption constants for orthoclase with aqueous equilibrium constants for uranyl carbonate species indicates the presence of adsorbed uranium complexes with one or two carbonates under alkaline conditions, in support of current uranium(VI) surface complexation models.
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Affiliation(s)
- Sebastien Kerisit
- Physical Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
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Kerisit S, Liu C. Structure, Kinetics, and Thermodynamics of the Aqueous Uranyl(VI) Cation. J Phys Chem A 2013; 117:6421-32. [DOI: 10.1021/jp404594p] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Sebastien Kerisit
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
99352, United States
| | - Chongxuan Liu
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
99352, United States
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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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Odoh SO, Pan QJ, Shamov GA, Wang F, Fayek M, Schreckenbach G. Theoretical Study of the Reduction of Uranium(VI) Aquo Complexes on Titania Particles and by Alcohols. Chemistry 2012; 18:7117-27. [DOI: 10.1002/chem.201101197] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 12/20/2011] [Indexed: 11/06/2022]
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Kremleva A, Martorell B, Krüger S, Rösch N. Uranyl adsorption on solvated edge surfaces of pyrophyllite: a DFT model study. Phys Chem Chem Phys 2012; 14:5815-23. [DOI: 10.1039/c2cp23886a] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Alena Kremleva
- Department Chemie & Catalysis Research Center, Technische Universität München, 85747 Garching, Germany
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Abstract
The U-O(yl) triple bonds in the UO(2)(2+) aquo ion are known to be weakened by replacing the first shell water with organic or inorganic ligands. Weakening of the U-O(yl) bond may enhance the reactivity of "yl" oxygens and uranyl(VI) cation-cation interactions. Density functional theory calculations as well as previously published vibrational spectroscopic data have been used to study the origin of the U-O(yl) bond weakening in uranyl(VI) coordination complexes. Natural population analyses (NPA) revealed that the electron localization on the O(yl) 2p orbital is a direct measure of the U-O(yl) bond weakening, indicating that the bond weakening is correlated to the weakening of the U-O(yl) covalent bond and not that of the ionic bond. The Mulliken analysis gives poor results for uranium to ligand electron partitioning and is thus unreliable. Further analyses of molecular orbitals near the highest occupied molecular orbital (HOMO) show that both the σ and π donating abilities of the ligands may account for the U-O(yl) bond weakening. The mechanism of the bond weakening varies with coordinating ligand so that each case needs to be examined independently.
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Affiliation(s)
- Satoru Tsushima
- Institut für Radiochemie, Helmholtz Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstrasse 400, 01328, Dresden, Germany.
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