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Zhang D, Zhao X, Zu G, Chen K, Gao G, Fan Y, Jin Q, Chen Z, Guo Z. Elemental and particle size fractionation during the transport of Eu(III)-silicate colloids in water-saturated porous media. JOURNAL OF HAZARDOUS MATERIALS 2024; 477:135300. [PMID: 39088955 DOI: 10.1016/j.jhazmat.2024.135300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 07/04/2024] [Accepted: 07/21/2024] [Indexed: 08/03/2024]
Abstract
Actinides (An)-bearing colloids could facilitate An migration in the environment. However, little is known about the transport behavior of An(III)-silicate colloids, which are readily formed by the reaction of An3+ with silicic acid under environmental conditions. Column experiments were conducted to investigate the transport of Eu(III)-silicate colloids (chemical analog of An(III)-silicate colloids) in water-saturated porous media as a function of pH, ionic strength (IS) and the presence of fulvic acid (FA). The results showed that colloid transport was more favorable at relatively low IS (≤ 50 mM) and high pH levels (pH ≥ 7). The presence of FA (5-10 mg/L) significantly enhanced the colloid transport. Under high IS (≥ 100 mM), the transport feature of colloids was turned from blocking to ripening due to the on-going aggregation of colloids. Additionally, an interesting elemental fractionation, i.e., a discrepancy in the breakthrough curves (BTCs) with respect to the C/C0 values of Si and Eu, was observed in the IS of 100-500 mM. A detailed investigation indicated that the elemental fractionation could be attributed to the partial Si dissolution of the colloids, the heterogeneity of the colloid size and element composition, and particle size fractionation during colloid transport. Extended Derjaguin-Landau-Verwey-Overbeek interaction energy calculations and convective-dispersive equation modeling were performed to illustrate variations in the colloid transport profiles. These findings illustrate the importance of Si dissolution in the migration of metal-silicate colloids and highlight the significant influence of the heterogeneity of colloid size and composition on the transport/migration behavior of colloids in the environment.
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Affiliation(s)
- Daming Zhang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Xin Zhao
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Ganlin Zu
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Kang Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Guangjie Gao
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Ye Fan
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Qiang Jin
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
| | - Zongyuan Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China
| | - Zhijun Guo
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; MOE Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
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2
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Shang C, Gaona X, Oher H, Polly R, Skerencak-Frech A, Duckworth S, Altmaier M. Experimental and computational evidence of U(VI)-OH-Si(OH) 4 complexes under alkaline conditions: Implications for cement systems. CHEMOSPHERE 2024; 350:141048. [PMID: 38182084 DOI: 10.1016/j.chemosphere.2023.141048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/07/2024]
Abstract
The complexation of uranyl hydroxides with orthosilicic acid was investigated by experimental and theoretical methods. Spectroluminescence titration was performed in a glovebox under argon atmosphere at pH 9.2, 10.5 and 11.5, with [U(VI)] = 10-6 and 5 × 10-6 mol kgw-1. The polymerization effects of silicic acid were minimized by ruling out samples with less than 90 % monomeric silicic acid present, identified via UV-Vis spectrometry using the molybdate blue method. Linear regression analysis based on time-resolved laser-induced fluorescence spectroscopy (TRLFS) results yielded the conditional stepwise formation constants of U(VI)-OH-Si(OH)4 complexes at 0.05 mol kgw-1 NaNO3. The main spectroscopic features - characteristic peak positions and decay-time - are reported for the first time for the UO2(OH)2SiO(OH)3- species observed at pH 9.2 and 10.5 and UO2(OH)2SiO2(OH)22- predominant at pH 11.5. Quantum chemical calculations successfully computed the theoretical luminescence spectrum of the complex UO2(OH)2SiO(OH)3- species, thus underpinning the proposed chemical model for weakly alkaline systems. The conditional stability constants were extrapolated to infinite dilution using the Davies equation, resulting in log10β°(UO2(OH)2SiO(OH)3-) and log10β°(UO2(OH)2SiO2(OH)22-). Implications for U(VI) speciation in the presence and absence of competing carbonate are discussed for silicate-rich environments expected in certain repository concepts for nuclear waste disposal.
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Affiliation(s)
- Chengming Shang
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany.
| | - Xavier Gaona
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany.
| | - Hanna Oher
- Laboratoire de Physique des 2 Infinis Irène Juliot-Curie (IJCLab), CNRS/IN2P3, Université Paris-Saclay, 91405 Orsay, France
| | - Robert Polly
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Andrej Skerencak-Frech
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Sarah Duckworth
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
| | - Marcus Altmaier
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany
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Zhang D, Diao X, Wang Y, Xu K, Jin Q, Chen Z, Guo Z. Effect of Si content, pH, electrolyte and fulvic acid on the stability of Th(IV)-silicate colloids. J Radioanal Nucl Chem 2022. [DOI: 10.1007/s10967-022-08703-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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4
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Zhang D, Wang Y, Heng J, Diao X, Zu G, Jin Q, Chen Z, Guo Z. Stability of Eu(III)-silicate colloids: Effect of Eu content, pH, electrolyte and fulvic acid. JOURNAL OF HAZARDOUS MATERIALS 2022; 438:129363. [PMID: 35777145 DOI: 10.1016/j.jhazmat.2022.129363] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/30/2022] [Accepted: 06/09/2022] [Indexed: 06/15/2023]
Abstract
Dissolved silicic acid in the environment has strong affinity for actinides (An), but An(III)-silicate colloids have been scarcely investigated. In this study, Eu(III)-silicate colloids, an analogue to An(III)-silicate, were prepared and the aggregation kinetics of the colloids was investigated as a function of Eu content (Si/Eu molar ratio), pH, background electrolyte (NaCl, NaNO3, NaClO4, KCl and CsCl) and fulvic acid (FA). Results indicated that the colloids with higher Si/Eu molar ratio exhibited higher stability under the same conditions. The stability of the colloids increased with increasing aqueous pH (7.1-9.4) and decreasing ionic strength, and the inhibition effect of monovalent electrolytes on the colloid stability followed the order of Na+ < K+ < Cs+ and Cl- < NO3- < ClO4-. In addition, the presence of FA significantly increased the stability of the colloids. The dependence of the stability on the chemical conditions in all cases could be illustrated by DLVO theory. Disaggregation kinetics showed that the aggregation process of the colloids was not fully reversible, because a time-dependent size memory effect led to a bigger mean size of disaggregated colloids as compared to the initial ones. The present work provides detailed insight in the formation and stability of An(III)-silicate colloids under the alkaline conditions relevant to geological disposal of radioactive waste, which is critical for understanding the behavior of this type of colloids in the environment.
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Affiliation(s)
- Daming Zhang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Yuxiong Wang
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Jiaxi Heng
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Xinya Diao
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Ganlin Zu
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China
| | - Qiang Jin
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
| | - Zongyuan Chen
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China
| | - Zhijun Guo
- Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, 730000 Lanzhou, China; Frontiers Science Center for Rare Isotopes, Lanzhou University, 730000 Lanzhou, China.
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Montoya V, Noseck U, Mattick F, Britz S, Blechschmidt I, Schäfer T. Radionuclide geochemistry evolution in the Long-term In-situ Test (LIT) at Grimsel Test Site (Switzerland). JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127733. [PMID: 34848070 DOI: 10.1016/j.jhazmat.2021.127733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
The Long-term In-situ Test (LIT) of the Colloid Formation and Migration project (CFM) at the Grimsel Test Site, investigates the generation of bentonite colloids and, hence, radionuclide mobilization within a well-defined and controlled shear zone in a crystalline rock. In this context, the determination of radionuclide aqueous speciation is essential to understand whether radionuclides are easily transported or immobilized by precipitation or uptake processes in the bentonite barrier included in a repository concept for nuclear waste, and mimic in the LIT experiment. The objective of this work is to determine the aqueous speciation of seven radionuclides (i.e. 75Se(VI), 99Tc(VII),233U(VI), 237Np(V), 241Am(III), Th(IV) and 242Pu(IV)) by thermodynamic calculations in different water compositions representing the geochemical evolution through the LIT. A comparison of the results obtained from two different modelling groups allows the identification of the geochemical key parameters affecting radionuclide mobility in this context and the corresponding numerical and conceptual uncertainties. Particularly, silicate complexes of trivalent actinides and uranium(VI) carbonato complexes (i.e. CanUO2(CO3)3(4-2n) n = 1 or 2) seem to be crucial in these environments, even at reducing conditions. Conceptual uncertainties like inclusion/exclusion of tetravalent actinide-bearing colloids formation and polyselenides have clearly been identified.
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Affiliation(s)
- Vanessa Montoya
- Department of Environmental Informatics - Helmholtz Centre for Environmental Research (UFZ), 04318 Leipzig, Germany; Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
| | - Ulrich Noseck
- Gesellschaft für Anlagen, und Reaktorsicherheit (GRS), 38122 Braunschweig, Germany
| | - Felix Mattick
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany
| | - Susan Britz
- Gesellschaft für Anlagen, und Reaktorsicherheit (GRS), 38122 Braunschweig, Germany
| | - Ingo Blechschmidt
- Nagra (National Cooperative for the Disposal of Radioactive Waste), 5430 Wettingen, Switzerland
| | - Thorsten Schäfer
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany; Friedrich-Schiller-University Jena (FSU), Institute of Geosciences - Applied Geology, 07749 Jena, Germany
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6
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Neumann J, Brinkmann H, Britz S, Lützenkirchen J, Bok F, Stockmann M, Brendler V, Stumpf T, Schmidt M. A comprehensive study of the sorption mechanism and thermodynamics of f-element sorption onto K-feldspar. J Colloid Interface Sci 2020; 591:490-499. [PMID: 33279214 DOI: 10.1016/j.jcis.2020.11.041] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/22/2020] [Accepted: 11/09/2020] [Indexed: 10/23/2022]
Abstract
The mobility of heavy metal contaminants and radionuclides in the environment is directly controlled by their interactions with charged mineral surfaces, hence an assessment of their potential toxicity, e.g. in the context of radioactive waste disposal sites, requires understanding of sorption processes on the molecular level. Here, we investigate the sorption of a variety of rare earth elements (REE) and trivalent actinides (Am, Cm) on K-feldspar using batch sorption, time-resolved laser-induced fluorescence spectroscopy (TRLFS), and a surface complexation model. Initially, a reliable pKa for K-feldspar's surface deprotonation reaction was determined as 2.5 ± 0.02 by column titration experiments, in excellent agreement with a measured pHIEP of 2.8. Batch sorption experiments over a broad range of experimental conditions in terms of mineral grain size, pH, [M3+], ionic radius, solid/liquid ratio, ionic strength, and equilibration procedures were carried out to quantify macroscopic retention. The trivalent d-block element Y, early, mid, and late lanthanides (La, Eu, Nd, Lu), as well as two minor actinides (Am, Cm) were used for batch sorption experiments and showed similar pH dependent uptake behavior, underlining their chemical analogy. In parallel, spectroscopic investigations provided insight into surface speciation. Cm TRLFS spectra indicate the formation of three inner-sphere sorption complexes with increasing hydrolysis. Additionally, a ternary K-feldspar/Cm/silicate complex was found for pH > 10, and batch and spectroscopic data at low pH (<4) point to small amounts of outer sphere sorption complexes. Based on TRLFS data, batch sorption, and titration data, a generic geochemical sorption model was developed, that describes sorption edges for all investigated M3+/K-feldspar systems satisfactorily. The derived stability constants for the binary sorption complexes (logK1-4 = -3.6, -7.7, -11.5, and -17.4, respectively) could successfully be used to reproduce literature data. The stability constants obtained for the surface complexes were included into the database for the Smart Kd-concept, which will further improve the safety assessment of potential repositories for radioactive waste.
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Affiliation(s)
- J Neumann
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - H Brinkmann
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - S Britz
- Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH, Theodor-Heuss-Straße 4, 38122 Braunschweig, Germany.
| | - J Lützenkirchen
- Karlsruher Institut für Technologie (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
| | - F Bok
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - M Stockmann
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - V Brendler
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - T Stumpf
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
| | - M Schmidt
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Bautzner Landstraße 400, 01328 Dresden, Germany.
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7
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Evaluation of sorption capability and aqueous stability of Ba2TiSi2O8 (BTS). J Radioanal Nucl Chem 2017. [DOI: 10.1007/s10967-016-5066-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Zänker H, Weiss S, Hennig C, Brendler V, Ikeda‐Ohno A. Oxyhydroxy Silicate Colloids: A New Type of Waterborne Actinide(IV) Colloids. ChemistryOpen 2016; 5:174-182. [PMID: 27957406 PMCID: PMC5130165 DOI: 10.1002/open.201500207] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/26/2016] [Indexed: 11/10/2022] Open
Abstract
At the near-neutral and reducing aquatic conditions expected in undisturbed ore deposits or in closed nuclear waste repositories, the actinides Th, U, Np, and Pu are primarily tetravalent. These tetravalent actinides (AnIV) are sparingly soluble in aquatic systems and, hence, are often assumed to be immobile. However, AnIV could become mobile if they occur as colloids. This review focuses on a new type of AnIV colloids, oxyhydroxy silicate colloids. We herein discuss the chemical characteristics of these colloids and the potential implication for their environmental behavior. The binary oxyhydroxy silicate colloids of AnIV could be potentially more mobile as a waterborne species than the well-known mono-component oxyhydroxide colloids.
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Affiliation(s)
- Harald Zänker
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Stephan Weiss
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Christoph Hennig
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Vinzenz Brendler
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
| | - Atsushi Ikeda‐Ohno
- Institute of Resource EcologyHelmholtz-Zentrum Dresden-RossendorfP.O. Box 51 01 1901314DresdenGermany
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9
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Husar R, Weiss S, Hennig C, Hübner R, Ikeda-Ohno A, Zänker H. Formation of neptunium(IV)-silica colloids at near-neutral and slightly alkaline pH. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:665-671. [PMID: 25401282 DOI: 10.1021/es503877b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The reducing conditions in a nuclear waste repository render neptunium tetravalent. Thus, Np is often assumed to be immobile in the subsurface. However, tetravalent actinides can also become mobile if they occur as colloids. We show that Np(IV) is able to form silica-rich colloids in solutions containing silicic acid at concentrations of both the regions above and below the "mononuclear wall" of silicic acid at 2 × 10(-3) M (where silicic acid is expected to start polymerization). These Np(IV)-silica colloids have a size of only very few nanometers and can reach significantly higher concentrations than Np(IV) oxyhydroxide colloids. They can be stable in the waterborne form over longer spans of time. In the Np(IV)-silica colloids, the actinide--oxygen--actinide bonds are increasingly replaced by actinide--oxygen--silicon bonds due to structural incorporation of Si. Possible implications of the formation of such colloids for environmental scenarios are discussed.
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Affiliation(s)
- Richard Husar
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf , Bautzner Landstrasse 400, 01328 Dresden, Germany
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Zänker H, Hennig C. Colloid-borne forms of tetravalent actinides: a brief review. JOURNAL OF CONTAMINANT HYDROLOGY 2014; 157:87-105. [PMID: 24365396 DOI: 10.1016/j.jconhyd.2013.11.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 11/08/2013] [Accepted: 11/26/2013] [Indexed: 06/03/2023]
Abstract
Tetravalent actinides, An(IV), are usually assumed to be little mobile in near-neutral environmental waters because of their low solubility. However, there are certain geochemical scenarios during which mobilization of An(IV) in a colloid-borne (waterborne) form cannot be ruled out. A compilation of colloid-borne forms of tetravalent actinides described so far for laboratory experiments together with several examples of An(IV) colloids observed in field experiments and real-world scenarios are given. They are intended to be a knowledge base and a tool for those who have to interpret actinide behavior under environmental conditions. Synthetic colloids containing structural An(IV) and synthetic colloids carrying adsorbed An(IV) are considered. Their behavior is compared with the behavior of An(IV) colloids observed after the intentional or unintentional release of actinides into the environment. A list of knowledge gaps as to the behavior of An(IV) colloids is provided and items which need further research are highlighted.
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Affiliation(s)
- Harald Zänker
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden, Germany.
| | - Christoph Hennig
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 51 01 19, D-01314 Dresden, Germany
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11
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Spezia R, Vuilleumier R. p of silicic acid in presence of La3+using single sweep method coupled to DFT-based molecular dynamics. Mol Phys 2013. [DOI: 10.1080/00268976.2013.848300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Altmaier M, Gaona X, Fanghänel T. Recent advances in aqueous actinide chemistry and thermodynamics. Chem Rev 2013; 113:901-43. [PMID: 23369090 DOI: 10.1021/cr300379w] [Citation(s) in RCA: 145] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marcus Altmaier
- Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany.
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13
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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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14
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Kar AS, Kumar S, Tomar BS. U(VI) sorption by silica: Effect of complexing anions. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2011.12.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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15
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Moll H, Brendler V, Bernhard G. Aqueous curium(III) phosphate species characterized by time-resolved laser-induced fluorescence spectroscopy. RADIOCHIM ACTA 2011. [DOI: 10.1524/ract.2011.1878] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
The formation of aqueous Cm(III) phosphate complexes was studied at room temperature by time-resolved laser-induced fluorescence spectroscopy (TRLFS) in 0.1 M NaClO4 solutions. The experiments were perfomed at a fixed total Cm(III) concentration of 3 × 107 or 2 × 108 M by varying the phosphoric acid concentration (3 × 105–0.1 M) and the pH (1.4–6.0). The red shift of the excitation and emission spectra, as well as the increase of luminescence lifetimes clearly showed the influence of phosphate on the aqueous Cm(III) speciation. In acidic phosphate solutions ([H3PO4] ≤0.1 M, pH 1.4–2.6) an increase in luminescence intensity was detected due to complexation with H2PO4
−. At [H3PO4] ≥4 × 104 M and between pH 4.0 and 6.0 in general a decrease in luminescence intensity affiliates the complexation with HPO4
2−. Two Cm(III)-phosphate complexes could be identified from the emission data, CmH2PO4
2+ and CmHPO4
+, having peak maxima at 599.6 and 600.8 nm, respectively. TRLFS in combination with ultra-filtration (1 kD) showed that the formation of CmHPO4
+ is accompanied by the generation of Cm(III)-phosphate colloids especially at [H3PO4] ≥0.002 M and pH ≥ 5. Cm(III)-phosphate colloids formed at pH 5 and 6 are characterized by an emission maximum at 603.1 nm. Based on the factor analysis of the emission data the stability constants of the two complexes were calculated to be log β
121 = 20.23 ± 0.13 and log β
111 = 16.54 ± 0.80 at an ionic strength of 0.1 M (NaClO4).
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Affiliation(s)
| | - V. Brendler
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiochemistry, Dresden, Deutschland
| | - Gert Bernhard
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiochemistry, Dresden, Deutschland
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16
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Kar A, Tomar B, Godbole S, Manchanda V. Time resolved fluorescence spectroscopy and modeling of Eu(III) sorption by silica in presence and absence of alpha hydroxy isobutyric acid. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.01.039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Pathak PN, Choppin GR. Effect of complexing anions on europium sorption on suspended silica: a TRLFS study for ternary complex formation. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2007.95.5.267] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The sorption of europium, Eu(III), on suspended silica was studied in perchlorate media under varying concentrations of Eu(III) and silica, at pH 4 to 8, and ionic strength from 0.20 to 1.40 M NaClO4at 298 K. The complexing anions, carbonate, acetate, citrate, oxalate, phosphate and EDTA, affected the sorption of Eu(III). A synergistic enhancement in the sorption of Eu(III) was observed for oxalate and phosphate ligands. Other anions suppressed the sorption in the order: acetate < carbonate < citrate < EDTA. The results of TRLFS studies were consistent with ternary Eu/silica/ligand complexation for oxalate and phosphate anions.
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Pathak P, Choppin GR. Sorption behavior of curium(III) on hydrous silica: a kinetic and thermodynamic study. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.2007.95.3.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Sorption of tracer curium, Cm3+, on SiO2· H2O (silica gel) was investigated under different experimental conditions such as time of equilibration, concentration of Sm3+, pcH, and temperature. Sm3+was used as a carrier for Cm3+ions in this study. From the sorption kinetics data, the diffusion coefficient of Cm3+ion was calculated to be 1.20(±0.05)×10-11m2s-1under particle diffusion-controlled conditions. The sorption rate was determined to be 3.47(±0.19)×10-3s-1at 298 K, pcH 5.25(±0.03) in 0.20 M (NaClO4). The sorption data were fitted in Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherms. A synergistic enhancement in the sorption of Cm3+(Sm3+)-ligand (e.g., CO32-, F-, H2PO4-and C2O42-) complexes on silica gel was observed. The presence of these anions increase the sorption of Cm3+(Sm3+) in the following order: CO32-< F-< C2O42-< H2PO4-. Temperature variation experiments gave enhanced sorption with increased temperature for Cm3+indicating an endothermic enthalpy.
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Cao Z, Balasubramanian K, Calvert MG, Nitsche H. Solvation Effects on Isomeric Preferences of Curium(III) Complexes with Multidentate phosphonopropionic Acid Ligands: CmH2PPA2+ and CmHPPA+ Complexes. Inorg Chem 2009; 48:9700-14. [DOI: 10.1021/ic901054h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhiji Cao
- College of Science, California State University, East Bay, Hayward, California 94542
| | - K. Balasubramanian
- College of Science, California State University, East Bay, Hayward, California 94542
- Chemistry and Material Science Directorate Lawrence Livermore National Laboratory Livermore, California 94550
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Michael G. Calvert
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Department of Chemistry, University of California, Berkeley, California 94720
| | - Heino Nitsche
- Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
- Department of Chemistry, University of California, Berkeley, California 94720
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Kunze P, Seher H, Hauser W, Panak PJ, Geckeis H, Fanghänel T, Schäfer T. The influence of colloid formation in a granite groundwater bentonite porewater mixing zone on radionuclide speciation. JOURNAL OF CONTAMINANT HYDROLOGY 2008; 102:263-272. [PMID: 18992961 DOI: 10.1016/j.jconhyd.2008.09.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 08/08/2008] [Accepted: 09/29/2008] [Indexed: 05/27/2023]
Abstract
In the context of deep geological storage of high level nuclear waste the repository will be designed as multiple barrier system including bentonite as buffer/backfill material and the host rock formation as geological barrier. The engineered barrier (bentonite) will be in contact with the host rock formation and consequently it can be expected that bentonite porewater will mix with formation groundwater. We simulate in this study the mixing of Grimsel groundwater (glacial melt water) with synthetic Febex porewater (assuming already saturated state) in a batch-type study and investigate the formation of colloids by laser-induced breakdown detection (LIBD) and SEM-EDX as well as the changes in radionuclide (U, Th, Eu) speciation via ultrafiltration or via time-resolved laser fluorescence spectroscopy (TRLFS) analysis in the case of Cm(III). Based on PHREEQC saturation index (SI) calculations a precipitation of calcite might be expected at low Febex porewater (FPW) content (<20%), fluorite precipitation at FPW contents <60% and gibbsite precipitation at FPW contents above 10%. The colloids generated in the mixing zone aggregate when the synthetic FPW content exceeds 10%. LIBD analysis of the time-dependent colloid generation/aggregation revealed a low concentration of colloids to be stable with an estimated plateau value around 100-200 ppt and an average colloid diameter around 30 nm after 140 days reaction time at FPW admixture >10%. SEM/EDX mostly identifies Al/Si containing colloidal phases and some sulfates could be found under certain admixture ratios. TRLFS studies show that the Cm speciation is strongly influenced by colloid formation in all solutions. In the Febex pore water/GGW mixing zone with high groundwater contents (>80%) colloids are newly formed and Cm is almost quantitatively associated with most likely polysilicilic acid colloids.
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Affiliation(s)
- P Kunze
- University of Applied Science (FH), Faculty of Mechanical Engineering, P.O. Box 1455, D-02754 Zittau/Görlitz, Germany
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Stumpf S, Stumpf T, Lützenkirchen J, Walther C, Fanghänel T. Immobilization of trivalent actinides by sorption onto quartz and incorporation into siliceous bulk: Investigations by TRLFS. J Colloid Interface Sci 2008; 318:5-14. [DOI: 10.1016/j.jcis.2007.09.080] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 09/24/2007] [Accepted: 09/28/2007] [Indexed: 11/25/2022]
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Polymerization study of o-Si(OH)4 and complexation with Am(III), Eu(III) and Cm(III). Inorganica Chim Acta 2007. [DOI: 10.1016/j.ica.2007.04.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Sorption of Am3+ cations on suspended silicate: Effects of pH, ionic strength, complexing anions, humic acid and metal ions. J Radioanal Nucl Chem 2007. [DOI: 10.1007/s10967-006-6942-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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