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Winstanley EH, Morris K, Abrahamsen-Mills LG, Blackham R, Shaw S. U(VI) sorption during ferrihydrite formation: Underpinning radioactive effluent treatment. JOURNAL OF HAZARDOUS MATERIALS 2019; 366:98-104. [PMID: 30502577 DOI: 10.1016/j.jhazmat.2018.11.077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 10/06/2018] [Accepted: 11/19/2018] [Indexed: 05/22/2023]
Abstract
Iron (oxyhydr)oxide nanoparticles are known to sorb metals, including radionuclides, from solution in various environmental and industrial systems. Effluent treatment processes including the Enhanced Actinide Removal Plant (EARP) (Sellafield, UK) use a neutralisation process to induce the precipitation of iron (oxyhydr)oxides to remove radionuclides from solution. There is a paucity of information on mechanism(s) of U(VI) removal under conditions relevant to such industrial processes. Here, we investigated removal of U(VI) from simulated effluents containing 7.16 mM Fe(III) with 4.2 × 10-4-1.05 mM U(VI), during the base induced hydrolysis of Fe(III). The solid product was ferrihydrite under all conditions. Acid dissolutions, Fourier Transform infrared spectroscopy and thermodynamic modelling indicated that U(VI) was removed from solution by adsorption to the ferrihydrite. The sorption mechanism was supported by X-ray Absorption Spectroscopy which showed U(VI) was adsorbed to ferrihydrite via a bidentate edge-sharing inner-sphere species with carbonate forming a ternary surface complex. At concentrations ≤0.42 mM U(VI) was removed entirely via adsorption, however at 1.05 mM U(VI) there was also evidence for precipitation of a discrete U(VI) phase. Overall these results confirm that U(VI) sequestered via adsorption to ferrihydrite over a concentration range from 4.2 × 10-4-0.42 mM confirming a remarkably consistent removal mechanism in this industrially relevant system.
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Affiliation(s)
- Ellen H Winstanley
- Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences, The University of Manchester, M13 9PL, UK
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences, The University of Manchester, M13 9PL, UK
| | | | - Richard Blackham
- Sellafield Ltd., Hinton House, Birchwood Park Avenue, Risley, Warrington, Cheshire, WA3 6GR, UK
| | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences, The University of Manchester, M13 9PL, UK.
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Neill TS, Morris K, Pearce CI, Sherriff NK, Burke MG, Chater PA, Janssen A, Natrajan L, Shaw S. Stability, Composition, and Core-Shell Particle Structure of Uranium(IV)-Silicate Colloids. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:9118-9127. [PMID: 30001122 DOI: 10.1021/acs.est.8b01756] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Uranium is typically the most abundant radionuclide by mass in radioactive wastes and is a significant component of effluent streams at nuclear facilities. Actinide(IV) (An(IV)) colloids formed via various pathways, including corrosion of spent nuclear fuel, have the potential to greatly enhance the mobility of poorly soluble An(IV) forms, including uranium. This is particularly important in conditions relevant to decommissioning of nuclear facilities and the geological disposal of radioactive waste. Previous studies have suggested that silicate could stabilize U(IV) colloids. Here the formation, composition, and structure of U(IV)-silicate colloids under the alkaline conditions relevant to spent nuclear fuel storage and disposal were investigated using a range of state of the art techniques. The colloids are formed across a range of pH conditions (9-10.5) and silicate concentrations (2-4 mM) and have a primary particle size 1-10 nm, also forming suspended aggregates <220 nm. X-ray absorption spectroscopy, ultrafiltration, and scanning transmission electron microscopy confirm the particles are U(IV)-silicates. Additional evidence from X-ray diffraction and pair distribution function data suggests the primary particles are composed of a UO2-rich core and a U-silicate shell. U(IV)-silicate colloids formation correlates with the formation of U(OH)3(H3SiO4)32- complexes in solution indicating they are likely particle precursors. Finally, these colloids form under a range of conditions relevant to nuclear fuel storage and geological disposal of radioactive waste and represent a potential pathway for U mobility in these systems.
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Affiliation(s)
- Thomas S Neill
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Katherine Morris
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory, Richland , Washington 99354 , United States
| | - Nicholas K Sherriff
- National Nuclear Laboratory, Chadwick House, Warrington Road , Birchwood Park, Warrington WA3 6AE , U.K
| | - M Grace Burke
- Materials Performance Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Philip A Chater
- Diamond Light Source, Harwell Campus , Didcot , Oxfordshire OX11 0DE , U.K
| | - Arne Janssen
- Materials Performance Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
- Diamond Light Source, Harwell Campus , Didcot , Oxfordshire OX11 0DE , U.K
| | - Louise Natrajan
- School of Chemistry , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
| | - Samuel Shaw
- Research Centre for Radwaste and Disposal, Williamson Research Centre , The University of Manchester , Oxford Road , Manchester M13 9PL , U.K
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Hettiarachchi GM, Donner E, Doelsch E. Application of Synchrotron Radiation-based Methods for Environmental Biogeochemistry: Introduction to the Special Section. JOURNAL OF ENVIRONMENTAL QUALITY 2017; 46:1139-1145. [PMID: 29293855 DOI: 10.2134/jeq2017.09.0349] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
To understand the biogeochemistry of nutrients and contaminants in environmental media, their speciation and behavior under different conditions and at multiple scales must be determined. Synchrotron radiation-based X-ray techniques allow scientists to elucidate the underlying mechanisms responsible for nutrient and contaminant mobility, bioavailability, and behavior. The continuous improvement of synchrotron light sources and X-ray beamlines around the world has led to a profound transformation in the field of environmental biogeochemistry and, subsequently, to significant scientific breakthroughs. Following this introductory paper, this special collection includes 10 papers that either present targeted reviews of recent advancements in spectroscopic methods that are applicable to environmental biogeochemistry or describe original research studies conducted on complex environmental samples that have been significantly enhanced by incorporating synchrotron radiation-based X-ray technique(s). We believe that the current focus on improving the speciation of ultra-dilute elements in environmental media through the ongoing optimization of synchrotron technologies (e.g., brighter light sources, improved monochromators, more efficient detectors) will help to significantly push back the frontiers of environmental biogeochemistry research. As many of the relevant techniques produce extremely large datasets, we also identify ongoing improvements in data processing and analysis (e.g., software improvements and harmonization of analytical methods) as a significant requirement for environmental biogeochemists to maximize the information that can be gained using these powerful tools.
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Zhao P, Begg JD, Zavarin M, Tumey SJ, Williams R, Dai ZR, Kips R, Kersting AB. Plutonium(IV) and (V) Sorption to Goethite at Sub-Femtomolar to Micromolar Concentrations: Redox Transformations and Surface Precipitation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6948-56. [PMID: 27268262 DOI: 10.1021/acs.est.6b00605] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Pu(IV) and Pu(V) sorption to goethite was investigated over a concentration range of 10(-15)-10(-5) M at pH 8. Experiments with initial Pu concentrations of 10(-15) - 10(-8) M produced linear Pu sorption isotherms, demonstrating that Pu sorption to goethite is not concentration-dependent across this concentration range. Equivalent Pu(IV) and Pu(V) sorption Kd values obtained at 1 and 2-week sampling time points indicated that Pu(V) is rapidly reduced to Pu(IV) on the goethite surface. Further, it suggested that Pu surface redox transformations are sufficiently rapid to achieve an equilibrium state within 1 week, regardless of the initial Pu oxidation state. At initial concentrations >10(-8) M, both Pu oxidation states exhibited deviations from linear sorption behavior and less Pu was adsorbed than at lower concentrations. NanoSIMS and HRTEM analysis of samples with initial Pu concentrations of 10(-8) - 10(-6) M indicated that Pu surface and/or bulk precipitation was likely responsible for this deviation. In 10(-6) M Pu(IV) and Pu(V) samples, HRTEM analysis showed the formation of a body centered cubic (bcc) Pu4O7 structure on the goethite surface, confirming that reduction of Pu(V) had occurred on the mineral surface and that epitaxial distortion previously observed for Pu(IV) sorption occurs with Pu(V) as well.
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Affiliation(s)
- Pihong Zhao
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - James D Begg
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Mavrik Zavarin
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Scott J Tumey
- Center for Accelerator Mass Spectrometry, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Ross Williams
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Zurong R Dai
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Ruth Kips
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Annie B Kersting
- Glenn T. Seaborg Institute, Physical & Life Sciences, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
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Materlik G, Rayment T, Stuart DI. Diamond Light Source: status and perspectives. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2013.0161. [PMID: 25624517 PMCID: PMC4308985 DOI: 10.1098/rsta.2013.0161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Diamond Light Source, a third-generation synchrotron radiation (SR) facility in the UK, celebrated its 10th anniversary in 2012. A private limited company was set up in April 2002 to plan, construct and operate the new user-oriented SR facility, called in brief Diamond. It succeeded the Synchrotron Radiation Source in Daresbury, a second-generation synchrotron that opened in 1980 as the world's first dedicated X-ray-providing facility, closing finally in 2008, by which time Diamond's accelerators and first beamlines were operating and user experiments were under way. This theme issue of Philosophical Transactions of the Royal Society A gives some examples of the rich diversity of research done in the initial five years, with some glimpses of activity up to 2014. Speakers at the 10 year anniversary symposium were drawn from a small number of major thematic areas and each theme was elaborated by a few speakers whose contributions were placed into a broader context by a leading member of the UK academic community in the role of rapporteur. This introduction gives a summary of the design choices and strategic planning of Diamond as a coherent user facility, a snapshot of its present status and some consideration of future perspectives.
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Affiliation(s)
- Gerhard Materlik
- Diamond Light Source, University College London, 17-19 Gordon Street, London WC1H 0AH, UK London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Trevor Rayment
- Diamond Light Source, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - David I Stuart
- Diamond Light Source, University College London, 17-19 Gordon Street, London WC1H 0AH, UK Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK
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Catlow CRA. Synchrotron radiation techniques in materials and environmental science. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2013.0162. [PMID: 25624522 DOI: 10.1098/rsta.2013.0162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- C Richard A Catlow
- Department of Chemistry, University College London, 21 Gordon Street, London WC1H 0AJ, UK
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Marshall TA, Morris K, Law GTW, Mosselmans JFW, Bots P, Parry SA, Shaw S. Incorporation and retention of 99-Tc(IV) in magnetite under high pH conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11853-11862. [PMID: 25236360 DOI: 10.1021/es503438e] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Technetium incorporation into magnetite and its behavior during subsequent oxidation has been investigated at high pH to determine the technetium retention mechanism(s) on formation and oxidative perturbation of magnetite in systems relevant to radioactive waste disposal. Ferrihydrite was exposed to Tc(VII)(aq) containing cement leachates (pH 10.5-13.1), and crystallization of magnetite was induced via addition of Fe(II)aq. A combination of X-ray diffraction (XRD), chemical extraction, and X-ray absorption spectroscopy (XAS) techniques provided direct evidence that Tc(VII) was reduced and incorporated into the magnetite structure. Subsequent air oxidation of the magnetite particles for up to 152 days resulted in only limited remobilization of the incorporated Tc(IV). Analysis of both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data indicated that the Tc(IV) was predominantly incorporated into the magnetite octahedral site in all systems studied. On reoxidation in air, the incorporated Tc(IV) was recalcitrant to oxidative dissolution with less than 40% remobilization to solution despite significant oxidation of the magnetite to maghemite/goethite: All solid associated Tc remained as Tc(IV). The results of this study provide the first direct evidence for significant Tc(IV) incorporation into the magnetite structure and confirm that magnetite incorporated Tc(IV) is recalcitrant to oxidative dissolution. Immobilization of Tc(VII) by reduction and incorporation into magnetite at high pH and with significant stability upon reoxidation has clear and important implications for limiting technetium migration under conditions where magnetite is formed including in geological disposal of radioactive wastes.
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Affiliation(s)
- Timothy A Marshall
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences, The University of Manchester , Manchester, M13 9PL, United Kingdom
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