1
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Barron A, Jamieson J, Colombani N, Bostick BC, Ortega-Tong P, Sbarbati C, Barbieri M, Petitta M, Prommer H. Model-Based Analysis of Arsenic Retention by Stimulated Iron Mineral Transformation under Coastal Aquifer Conditions. ACS ES&T WATER 2024; 4:2944-2956. [PMID: 39005241 PMCID: PMC11242918 DOI: 10.1021/acsestwater.4c00134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
A multitude of geochemical processes control the aqueous concentration and transport properties of trace metal contaminants such as arsenic (As) in groundwater environments. Effective As remediation, especially under reducing conditions, has remained a significant challenge. Fe(II) nitrate treatments are a promising option for As immobilization but require optimization to be most effective. Here, we develop a process-based numerical modeling framework to provide an in-depth understanding of the geochemical mechanisms controlling the response of As-contaminated sediments to Fe(II) nitrate treatment. The analyzed data sets included time series from two batch experiments (control vs treatment) and effluent concentrations from a flow-through column experiment. The reaction network incorporates a mixture of homogeneous and heterogeneous reactions affecting Fe redox chemistry. Modeling revealed that the precipitation of the Fe treatment caused a rapid pH decline, which then triggered multiple heterogeneous buffering processes. The model quantifies key processes for effective remediation, including the transfer of aqueous As to adsorbed As and the transformation of Fe minerals, which act as sorption hosts, from amorphous to more stable phases. The developed model provides the basis for predictions of the remedial benefits of Fe(II) nitrate treatments under varying geochemical and hydrogeological conditions, particularly in high-As coastal environments.
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Affiliation(s)
- Alyssa Barron
- School of Earth Sciences, University of Western Australia, Crawley 6009 WA, Australia
| | | | | | - Benjamin C Bostick
- Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, United States
| | - Pablo Ortega-Tong
- School of Earth Sciences, University of Western Australia, Crawley 6009 WA, Australia; Intera Inc., Perth 6000 WA, Australia
| | - Chiara Sbarbati
- Dept. of Ecological and Biological Sciences, University of Tuscia, Viterbo 01100, Italy
| | - Maurizio Barbieri
- Dept. of Earth Sciences, "Sapienza" University of Roma, Roma 00185, Italy
| | - Marco Petitta
- Dept. of Earth Sciences, "Sapienza" University of Roma, Roma 00185, Italy
| | - Henning Prommer
- School of Earth Sciences, University of Western Australia, Crawley 6009 WA, Australia; Ekion Pty Ltd., Swanbourne 6010 WA, Australia
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2
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Ledingham GJ, Fang Y, Catalano JG. Irreversible Trace Metal Binding to Goethite Controlled by the Ion Size. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2007-2016. [PMID: 38232091 DOI: 10.1021/acs.est.3c06516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
The dynamics of trace metals at mineral surfaces influence their fate and bioaccessibility in the environment. Trace metals on iron (oxyhydr)oxide surfaces display adsorption-desorption hysteresis, suggesting entrapment after aging. However, desorption experiments may perturb the coordination environment of adsorbed metals, the distribution of labile Fe(III), and mineral aggregation properties, influencing the interpretation of labile metal fractions. In this study, we investigated irreversible binding of nickel, zinc, and cadmium to goethite after aging times of 2-120 days using isotope exchange. Dissolved and adsorbed metal pools exchange rapidly, with half times <90 min, but all metals display a solid-associated fraction inaccessible to isotope exchange. The size of this nonlabile pool is the largest for nickel, with the smallest ionic radius, and the smallest for cadmium, with the largest ionic radius. Spectroscopy and extractions suggest that the irreversibly bound metals are incorporated in the goethite structure. Rapid exchange of labile solid-associated metals with solution demonstrates that adsorbed metals can sustain the dissolved pool in response to biological uptake or fluid flow. Trace metal fractions that irreversibly bind following adsorption provide a contaminant sequestration pathway, limit the availability of micronutrients, and record metal isotope signatures of environmental processes.
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Affiliation(s)
- Greg J Ledingham
- Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Yihang Fang
- Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Jeffrey G Catalano
- Department of Earth, Environmental, and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States
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3
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Schwab L, Gallati N, Reiter SM, Kimber RL, Kumar N, McLagan DS, Biester H, Kraemer SM, Wiederhold JG. Mercury Isotope Fractionation during Dark Abiotic Reduction of Hg(II) by Dissolved, Surface-Bound, and Structural Fe(II). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15243-15254. [PMID: 37748105 PMCID: PMC10569049 DOI: 10.1021/acs.est.3c03703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 09/27/2023]
Abstract
Stable mercury (Hg) isotope ratios are an emerging tracer for biogeochemical transformations in environmental systems, but their application requires knowledge of isotopic enrichment factors for individual processes. We investigated Hg isotope fractionation during dark, abiotic reduction of Hg(II) by dissolved iron(Fe)(II), magnetite, and Fe(II) sorbed to boehmite or goethite by analyzing both the reactants and products of laboratory experiments. For homogeneous reduction of Hg(II) by dissolved Fe(II) in continuously purged reactors, the results followed a Rayleigh distillation model with enrichment factors of -2.20 ± 0.16‰ (ε202Hg) and 0.21 ± 0.02‰ (E199Hg). In closed system experiments, allowing reequilibration, the initial kinetic fractionation was overprinted by isotope exchange and followed a linear equilibrium model with -2.44 ± 0.17‰ (ε202Hg) and 0.34 ± 0.02‰ (E199Hg). Heterogeneous Hg(II) reduction by magnetite caused a smaller isotopic fractionation (-1.38 ± 0.07 and 0.13 ± 0.01‰), whereas the extent of isotopic fractionation of the sorbed Fe(II) experiments was similar to the kinetic homogeneous case. Small mass-independent fractionation of even-mass Hg isotopes with 0.02 ± 0.003‰ (E200Hg) and ≈ -0.02 ± 0.01‰ (E204Hg) was consistent with theoretical predictions for the nuclear volume effect. This study contributes significantly to the database of Hg isotope enrichment factors for specific processes. Our findings show that Hg(II) reduction by dissolved Fe(II) in open systems results in a kinetic MDF with a larger ε compared to other abiotic reduction pathways, and combining MDF with the observed MIF allows the distinction from photochemical or microbial Hg(II) reduction pathways.
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Affiliation(s)
- Lorenz Schwab
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
- Doctoral
School in Microbiology and Environmental Science, University of Vienna, 1030 Vienna, Austria
- Environmental
Engineering Institute IIE-ENAC, Soil Biogeochemistry Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), Route
des Ronquos 86, 1951 Sion, Switzerland
| | - Niklas Gallati
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Sofie M. Reiter
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Richard L. Kimber
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Naresh Kumar
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
- Soil
Chemistry and Chemical Soil Quality Group, Department of Environmental
Sciences, University of Wageningen, Droevendaalsesteeg 3a, 6708 Wageningen, Netherlands
| | - David S. McLagan
- Environmental
Geochemistry Group, Institute of Geoecology, Technische Universität Braunschweig, Langer Kamp 19c, 38106 Braunschweig, Germany
- Department
of Geological Sciences and Geological Engineering, Queen’s University, Kingston, Ontario K7L 3N6, Canada
- School
of Environmental Studies, Queen’s
University, Kingston, Ontario K7L 3N6, Canada
| | - Harald Biester
- Environmental
Geochemistry Group, Institute of Geoecology, Technische Universität Braunschweig, Langer Kamp 19c, 38106 Braunschweig, Germany
| | - Stephan M. Kraemer
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
| | - Jan G. Wiederhold
- Department
of Environmental Geosciences, Centre for Microbiology and Environmental
Systems Science, University of Vienna, Josef-Holaubek-Platz 2, 1090 Vienna, Austria
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4
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Couasnon T, Fritsch B, Jank MPM, Blukis R, Hutzler A, Benning LG. Goethite Mineral Dissolution to Probe the Chemistry of Radiolytic Water in Liquid-Phase Transmission Electron Microscopy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301904. [PMID: 37439408 PMCID: PMC10477898 DOI: 10.1002/advs.202301904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/20/2023] [Indexed: 07/14/2023]
Abstract
Liquid-Phase Transmission Electron Microscopy (LP-TEM) enables in situ observations of the dynamic behavior of materials in liquids at high spatial and temporal resolution. During LP-TEM, incident electrons decompose water molecules into highly reactive species. Consequently, the chemistry of the irradiated aqueous solution is strongly altered, impacting the reactions to be observed. However, the short lifetime of these reactive species prevent their direct study. Here, the morphological changes of goethite during its dissolution are used as a marker system to evaluate the influence of radiation on the changes in solution chemistry. At low electron flux density, the morphological changes are equivalent to those observed under bulk acidic conditions, but the rate of dissolution is higher. On the contrary, at higher electron fluxes, the morphological evolution does not correspond to a unique acidic dissolution process. Combined with kinetic simulations of the steady state concentrations of generated reactive species in the aqueous medium, the results provide a unique insight into the redox and acidity interplay during radiation induced chemical changes in LP-TEM. The results not only reveal beam-induced radiation chemistry via a nanoparticle indicator, but also open up new perspectives in the study of the dissolution process in industrial or natural settings.
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Affiliation(s)
- Thaïs Couasnon
- GFZ German Research Center for GeosciencesTelegrafenberg14473PotsdamGermany
| | - Birk Fritsch
- Department of Electrical, Electronic, and Communication EngineeringElectron DevicesFriedrich‐Alexander‐Universität Erlangen‐Nürnberg91058ErlangenGermany
- Department of Materials Science and EngineeringInstitute of Micro‐ and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM)Friedrich‐Alexander‐Universität Erlangen‐Nürnberg91058ErlangenGermany
- Forschungszentrum Jülich GmbHHelmholtz Institute Erlangen‐Nürnberg for Renewable Energy (IEK‐11)91058ErlangenGermany
| | - Michael P. M. Jank
- Fraunhofer Institute for Integrated Systems and Device Technology IISBSchottkystr. 1091058ErlangenGermany
| | - Roberts Blukis
- GFZ German Research Center for GeosciencesTelegrafenberg14473PotsdamGermany
- Leibniz‐Institut für KristallzüchtungMax‐Born Str. 212489BerlinGermany
| | - Andreas Hutzler
- Department of Electrical, Electronic, and Communication EngineeringElectron DevicesFriedrich‐Alexander‐Universität Erlangen‐Nürnberg91058ErlangenGermany
- Forschungszentrum Jülich GmbHHelmholtz Institute Erlangen‐Nürnberg for Renewable Energy (IEK‐11)91058ErlangenGermany
| | - Liane G. Benning
- GFZ German Research Center for GeosciencesTelegrafenberg14473PotsdamGermany
- Department of Earth SciencesFreie Universität Berlin12249BerlinGermany
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5
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Chen C, Dong Y, Thompson A. Electron Transfer, Atom Exchange, and Transformation of Iron Minerals in Soils: The Influence of Soil Organic Matter. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37449758 DOI: 10.1021/acs.est.3c01876] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2023]
Abstract
Despite substantial experimental evidence of electron transfer, atom exchange, and mineralogical transformation during the reaction of Fe(II)aq with synthetic Fe(III) minerals, these processes are rarely investigated in natural soils. Here, we used an enriched Fe isotope approach and Mössbauer spectroscopy to evaluate how soil organic matter (OM) influences Fe(II)/Fe(III) electron transfer and atom exchange in surface soils collected from Luquillo and Calhoun Experimental Forests and how this reaction might affect Fe mineral composition. Following the reaction of 57Fe-enriched Fe(II)aq with soils for 33 days, Mössbauer spectra demonstrated marked electron transfer between sorbed Fe(II) and the underlying Fe(III) oxides in soils. Comparing the untreated and OM-removed soils indicates that soil OM largely attenuated Fe(II)/Fe(III) electron transfer in goethite, whereas electron transfer to ferrihydrite was unaffected. Soil OM also reduced the extent of Fe atom exchange. Following reaction with Fe(II)aq for 33 days, no measurable mineralogical changes were found for the Calhoun soils enriched with high-crystallinity goethite, while Fe(II) did drive an increase in Fe oxide crystallinity in OM-removed LCZO soils having low-crystallinity ferrihydrite and goethite. However, the presence of soil OM largely inhibited Fe(II)-catalyzed increases in Fe mineral crystallinity in the LCZO soil. Fe atom exchange appears to be commonplace in soils exposed to anoxic conditions, but its resulting Fe(II)-induced recrystallization and mineral transformation depend strongly on soil OM content and the existing soil Fe phases.
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Affiliation(s)
- Chunmei Chen
- School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Yanjun Dong
- School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Aaron Thompson
- Department of Crop and Soil Sciences, University of Georgia, Athens, Georgia 30602, United States
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6
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Zhao X, Yuan Z, Wang S, Pan Y, Chen N, Tunc A, Cheung K, Alparov A, Chen W, Deevsalar R, Lin J, Jia Y. Iron(II)-activated phase transformation of Cd-bearing ferrihydrite: Implications for cadmium mobility and fate under anaerobic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 848:157719. [PMID: 35914597 DOI: 10.1016/j.scitotenv.2022.157719] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/06/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
The factors and mechanisms affecting the fate of the associated Cd during the Fe(II)-activated Cd-bearing ferrihydrite transformation remain poorly understood. Herein we have conducted a series of batch reactions containing ferrihydrite with diverse pH values and initial Fe(II) and Cd concentrations coupled with chemical analyses and spectroscopic examination on the transformation products to probe the mechanisms of the Cd partitioning and the processes of Fe(II)-activated Cd-bearing ferrihydrite transformation under anaerobic conditions. Chemical analyses, Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD) results show that the initial Fe(II) and Cd concentrations as well as pH values all have significant effects on the rates and pathways of ferrihydrite transformation. Increasing Cd loading enhances the inhibition of the Fe(II)-activated ferrihydrite transformation rates. High Cd loading alters the Fe(II)-activated ferrihydrite transformation pathways by hindering the recrystallization of both ferrihydrite to more stable iron minerals and the newly formed lepidocrocite to goethite. Chemical analyses show that the release of Cd to solutions during ferrihydrite transformation is accompanied by a reduction in the 0.4 M HCl extractable Cd fraction and that a significant amount of the released Cd is transformed to a 0.4 M HCl unextractable form. Moreover, enhanced Cd release during the Fe(II)-activated ferrihydrite transformation is observed by reducing the pH value or increasing the initial Cd concentration. Results from synchrotron X-ray absorption spectroscopy (XAS) confirm that the majority of the 0.4 M HCl unextractable Cd form is associated with structural incorporation into the recrystallized iron (hydr)oxides via isomorphous substitution for Fe(III). These findings not only provide molecular-level understanding on the behavior of Cd under natural anoxic environments, but also are useful in predicting the geochemical cycling of Cd and developing long-term Cd contaminant management strategies.
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Affiliation(s)
- Xiaoming Zhao
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Zidan Yuan
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China
| | - Shaofeng Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, PR China.
| | - Yuanming Pan
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Ning Chen
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada; Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4, Canada
| | - Ayetullah Tunc
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Kalong Cheung
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Aslan Alparov
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Weifeng Chen
- Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4, Canada
| | - Reza Deevsalar
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Jinru Lin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China
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7
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Notini L, ThomasArrigo LK, Kaegi R, Kretzschmar R. Coexisting Goethite Promotes Fe(II)-Catalyzed Transformation of Ferrihydrite to Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:12723-12733. [PMID: 35998342 PMCID: PMC9454240 DOI: 10.1021/acs.est.2c03925] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 05/13/2023]
Abstract
In redox-affected soil environments, electron transfer between aqueous Fe(II) and solid-phase Fe(III) catalyzes mineral transformation and recrystallization processes. While these processes have been studied extensively as independent systems, the coexistence of iron minerals is common in nature. Yet it remains unclear how coexisting goethite influences ferrihydrite transformation. Here, we reacted ferrihydrite and goethite mixtures with Fe(II) for 24 h. Our results demonstrate that with more goethite initially present in the mixture more ferrihydrite turned into goethite. We further used stable Fe isotopes to label different Fe pools and probed ferrihydrite transformation in the presence of goethite using 57Fe Mössbauer spectroscopy and changes in the isotopic composition of solid and aqueous phases. When ferrihydrite alone underwent Fe(II)-catalyzed transformation, Fe atoms initially in the aqueous phase mostly formed lepidocrocite, while those from ferrihydrite mostly formed goethite. When goethite was initially present, more goethite was formed from atoms initially in the aqueous phase, and nanogoethite formed from atoms initially in ferrihydrite. Our results suggest that coexisting goethite promotes formation of more goethite via Fe(II)-goethite electron transfer and template-directed nucleation and growth. We further hypothesize that electron transfer onto goethite followed by electron hopping onto ferrihydrite is another possible pathway to goethite formation. Our findings demonstrate that mineral transformation is strongly influenced by the composition of soil solid phases.
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Affiliation(s)
- Luiza Notini
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zurich, CHN, Universitätstrasse 16, CH-8092 Zurich, Switzerland
| | - Laurel K. ThomasArrigo
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zurich, CHN, Universitätstrasse 16, CH-8092 Zurich, Switzerland
| | - Ralf Kaegi
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstraße 133, CH-8600 Dübendorf, Switzerland
| | - Ruben Kretzschmar
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zurich, CHN, Universitätstrasse 16, CH-8092 Zurich, Switzerland
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8
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Pan W, Catalano JG, Giammar DE. Redox-Driven Recrystallization of PbO 2. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:7864-7872. [PMID: 35654758 DOI: 10.1021/acs.est.1c08767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Lead(IV) oxide (PbO2) is one of the lead corrosion products that forms on the inner surface of lead pipes used for drinking water supply. It can maintain low dissolved Pb(II) concentrations when free chlorine is present. When free chlorine is depleted, PbO2 and soluble Pb(II) will co-occur in these systems. This study used a stable lead isotope (207Pb) as a tracer to examine the interaction between aqueous Pb(II) and solid PbO2 at conditions with no net change in dissolved Pb concentration. While the dissolved Pb(II) concentration remained unchanged, significant isotope exchange occurred that indicated that substantial amounts (24.3-35.0% based on the homogeneous recrystallization model) of the Pb atoms in the PbO2 solids had been exchanged with those in solution over 264 h. Neither α-PbO2 nor β-PbO2 displayed a change in mineralogy, particle size, or oxidation state after reaction with aqueous Pb(II). The combined isotope exchange and solid characterization results indicate that redox-driven recrystallization of PbO2 had occurred. Such redox-driven recrystallization is likely to occur in water that stagnates in lead pipes that contain PbO2, and this recrystallization may alter the reactivity of PbO2 with respect to its stability and susceptibility to reductive dissolution.
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Affiliation(s)
- Weiyi Pan
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, Campus Box 1180, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Jeffrey G Catalano
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Daniel E Giammar
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, Campus Box 1180, One Brookings Drive, St. Louis, Missouri 63130, United States
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9
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Schulz K, ThomasArrigo LK, Kaegi R, Kretzschmar R. Stabilization of Ferrihydrite and Lepidocrocite by Silicate during Fe(II)-Catalyzed Mineral Transformation: Impact on Particle Morphology and Silicate Distribution. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:5929-5938. [PMID: 35435661 PMCID: PMC9069687 DOI: 10.1021/acs.est.1c08789] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Interactions between aqueous ferrous iron (Fe(II)) and secondary Fe oxyhydroxides catalyze mineral recrystallization and/or transformation processes in anoxic soils and sediments, where oxyanions, such as silicate, are abundant. However, the effect and the fate of silicate during Fe mineral recrystallization and transformation are not entirely understood and especially remain unclear for lepidocrocite. In this study, we reacted (Si-)ferrihydrite (Si/Fe = 0, 0.05, and 0.18) and (Si-)lepidocrocite (Si/Fe = 0 and 0.08) with isotopically labeled 57Fe(II) (Fe(II)/Fe(III) = 0.02 and 0.2) at pH 7 for up to 4 weeks. We followed Fe mineral transformations with X-ray diffraction and tracked Fe atom exchange by measuring aqueous and solid phase Fe isotope fractions. Our results show that the extent of ferrihydrite transformation in the presence of Fe(II) was strongly influenced by the solid phase Si/Fe ratio, while increasing the Fe(II)/Fe(III) ratio (from 0.02 to 0.2) had only a minor effect. The presence of silicate increased the thickness of newly formed lepidocrocite crystallites, and elemental distribution maps of Fe(II)-reacted Si-ferrihydrites revealed that much more Si was associated with the remaining ferrihydrite than with the newly formed lepidocrocite. Pure lepidocrocite underwent recrystallization in the low Fe(II) treatment and transformed to magnetite at the high Fe(II)/Fe(III) ratio. Adsorbed silicate inactivated the lepidocrocite surfaces, which strongly reduced Fe atom exchange and inhibited mineral transformation. Collectively, the results of this study demonstrate that Fe(II)-catalyzed Si-ferrihydrite transformation leads to the redistribution of silicate in the solid phase and the formation of thicker lepidocrocite platelets, while lepidocrocite transformation can be completely inhibited by adsorbed silicate. Therefore, silicate is an important factor to include when considering Fe mineral dynamics in soils under reducing conditions.
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Affiliation(s)
- Katrin Schulz
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, CHN, 8092 Zürich, Switzerland
| | - Laurel K. ThomasArrigo
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, CHN, 8092 Zürich, Switzerland
| | - Ralf Kaegi
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, 8060 Dübendorf, Switzerland
| | - Ruben Kretzschmar
- Soil
Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics,
Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, CHN, 8092 Zürich, Switzerland
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10
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Stagg O, Morris K, Lam A, Navrotsky A, Velázquez JM, Schacherl B, Vitova T, Rothe J, Galanzew J, Neumann A, Lythgoe P, Abrahamsen-Mills L, Shaw S. Fe(II) Induced Reduction of Incorporated U(VI) to U(V) in Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:16445-16454. [PMID: 34882383 DOI: 10.1021/acs.est.1c06197] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Over 60 years of nuclear activities have resulted in a global legacy of radioactive wastes, with uranium considered a key radionuclide in both disposal and contaminated land scenarios. With the understanding that U has been incorporated into a range of iron (oxyhydr)oxides, these minerals may be considered a secondary barrier to the migration of radionuclides in the environment. However, the long-term stability of U-incorporated iron (oxyhydr)oxides is largely unknown, with the end-fate of incorporated species potentially impacted by biogeochemical processes. In particular, studies show that significant electron transfer may occur between stable iron (oxyhydr)oxides such as goethite and adsorbed Fe(II). These interactions can also induce varying degrees of iron (oxyhydr)oxide recrystallization (<4% to >90%). Here, the fate of U(VI)-incorporated goethite during exposure to Fe(II) was investigated using geochemical analysis and X-ray absorption spectroscopy (XAS). Analysis of XAS spectra revealed that incorporated U(VI) was reduced to U(V) as the reaction with Fe(II) progressed, with minimal recrystallization (approximately 2%) of the goethite phase. These results therefore indicate that U may remain incorporated within goethite as U(V) even under iron-reducing conditions. This develops the concept of iron (oxyhydr)oxides acting as a secondary barrier to radionuclide migration in the environment.
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Affiliation(s)
- Olwen Stagg
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | - Andy Lam
- Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California Davis, Davis, California 95616, United States
| | - Alexandra Navrotsky
- School of Molecular Sciences and Navrotsky Eyring Center for Materials of the Universe, Arizona State University, Tempe, Arizona 85287, United States
| | - Jesús M Velázquez
- Department of Chemistry, University of California─Davis, Davis, California 95616, United States
| | - Bianca Schacherl
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Tonya Vitova
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Jörg Rothe
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Jurij Galanzew
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, Karlsruhe 76131, Germany
| | - Anke Neumann
- School of Engineering, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Paul Lythgoe
- Manchester Analytical Geochemistry Unit, The University of Manchester, Manchester, M13 9PL, United Kingdom
| | | | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom
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11
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Elzinga EJ. Mechanistic Study of Ni(II) Sorption by Green Rust Sulfate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:10411-10421. [PMID: 34283583 DOI: 10.1021/acs.est.1c01442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The sorption of Ni(II) by green rust sulfate (GR-sulfate) was studied in anoxic pre-equilibrated suspensions at pH 7.0 and pH 7.8 with combined batch kinetic experiments, X-ray diffraction measurements, and Ni K-edge X-ray absorption spectroscopy (XAS) analyses. Continuous removal of aqueous Ni(II) was observed over the course of the reaction (1-2.5 weeks) at both pH values, with no concurrent changes in aqueous Fe(II) levels or detectable mineralogical modifications of the GR sorbent. XAS results indicate that Ni(II) is not retained as mononuclear adsorption complexes on the GR surface but rather incorporated in the octahedral layers of an FeII0.67-xNiIIxFeIII0.33(OH)2-layered double hydroxide (LDH) phase with 0 < x < 0.67. The combined macroscopic and spectroscopic data suggest that Ni(II) substitutes into the GR lattice during Fe(II)-catalyzed recrystallization of the sorbent and/or forms secondary Ni(II)/Fe(II)-Fe(III)-LDH phases with a higher stability than that of GR, complemented likely by Ni(II)-Fe(II) exchange at GR particle edges. The results of this study reveal GR to be a dynamic sorbent that engages in dissolution-reprecipitation and exchange reactions, causing extensive incorporation of trace metal Ni(II)aq. Additional work is needed to further define the mechanisms involved and to assess the sorptive reactivity of GR with other trace metal species.
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Affiliation(s)
- Evert J Elzinga
- Department of Earth & Environmental Sciences, Rutgers University, 101Warren Street, Newark, New Jersey 07102, United States
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12
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Huang J, Jones A, Waite TD, Chen Y, Huang X, Rosso KM, Kappler A, Mansor M, Tratnyek PG, Zhang H. Fe(II) Redox Chemistry in the Environment. Chem Rev 2021; 121:8161-8233. [PMID: 34143612 DOI: 10.1021/acs.chemrev.0c01286] [Citation(s) in RCA: 147] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Iron (Fe) is the fourth most abundant element in the earth's crust and plays important roles in both biological and chemical processes. The redox reactivity of various Fe(II) forms has gained increasing attention over recent decades in the areas of (bio) geochemistry, environmental chemistry and engineering, and material sciences. The goal of this paper is to review these recent advances and the current state of knowledge of Fe(II) redox chemistry in the environment. Specifically, this comprehensive review focuses on the redox reactivity of four types of Fe(II) species including aqueous Fe(II), Fe(II) complexed with ligands, minerals bearing structural Fe(II), and sorbed Fe(II) on mineral oxide surfaces. The formation pathways, factors governing the reactivity, insights into potential mechanisms, reactivity comparison, and characterization techniques are discussed with reference to the most recent breakthroughs in this field where possible. We also cover the roles of these Fe(II) species in environmental applications of zerovalent iron, microbial processes, biogeochemical cycling of carbon and nutrients, and their abiotic oxidation related processes in natural and engineered systems.
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Affiliation(s)
- Jianzhi Huang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Adele Jones
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Yiling Chen
- Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Xiaopeng Huang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Kevin M Rosso
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Andreas Kappler
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Muammar Mansor
- Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, 72076 Tuebingen, Germany
| | - Paul G Tratnyek
- School of Public Health, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Huichun Zhang
- Department of Civil and Environmental Engineering, Case Western Reserve University, 2104 Adelbert Road, Cleveland, Ohio 44106, United States
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13
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Galili N, Shemesh A, Yam R, Brailovsky I, Sela-Adler M, Schuster EM, Collom C, Bekker A, Planavsky N, Macdonald FA, Préat A, Rudmin M, Trela W, Sturesson U, Heikoop JM, Aurell M, Ramajo J, Halevy I. The geologic history of seawater oxygen isotopes from marine iron oxides. Science 2020; 365:469-473. [PMID: 31371609 DOI: 10.1126/science.aaw9247] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 07/02/2019] [Indexed: 11/02/2022]
Abstract
The oxygen isotope composition (δ18O) of marine sedimentary rocks has increased by 10 to 15 per mil since Archean time. Interpretation of this trend is hindered by the dual control of temperature and fluid δ18O on the rocks' isotopic composition. A new δ18O record in marine iron oxides covering the past ~2000 million years shows a similar secular rise. Iron oxide precipitation experiments reveal a weakly temperature-dependent iron oxide-water oxygen isotope fractionation, suggesting that increasing seawater δ18O over time was the primary cause of the long-term rise in δ18O values of marine precipitates. The 18O enrichment may have been driven by an increase in terrestrial sediment cover, a change in the proportion of high- and low-temperature crustal alteration, or a combination of these and other factors.
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Affiliation(s)
- Nir Galili
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Aldo Shemesh
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ruth Yam
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Irena Brailovsky
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Sela-Adler
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Elaine M Schuster
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Andrey Bekker
- Department of Earth Sciences, University of California, Riverside, CA, USA
| | - Noah Planavsky
- Department of Geology and Geophysics, Yale University, New Haven, CT, USA
| | - Francis A Macdonald
- Department of Earth Science, University of California, Santa Barbara, CA, USA
| | - Alain Préat
- Department of Biogeochemistry and Modeling of the Earth System, University of Brussels, Brussels, Belgium
| | - Maxim Rudmin
- Division for Geology, Tomsk Polytechnic University, Tomsk, Russia
| | | | - Ulf Sturesson
- The Institute of Earth Sciences, Uppsala University, Uppsala, Sweden
| | - Jeffrey M Heikoop
- Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Marcos Aurell
- Department of Earth Sciences, University of Zaragoza, Zaragoza, Spain
| | - Javier Ramajo
- Department of Earth Sciences, University of Zaragoza, Zaragoza, Spain
| | - Itay Halevy
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel.
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14
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Wang S, Lei L, Zhang D, Zhang G, Cao R, Wang X, Lin J, Jia Y. Stabilization and transformation of selenium during the Fe(II)-induced transformation of Se(IV)-adsorbed ferrihydrite under anaerobic conditions. JOURNAL OF HAZARDOUS MATERIALS 2020; 384:121365. [PMID: 31593863 DOI: 10.1016/j.jhazmat.2019.121365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 09/27/2019] [Accepted: 09/29/2019] [Indexed: 06/10/2023]
Abstract
Selenium (Se) is an essential nutrient for human beings at trace concentrations, but also a hazardous contaminant at high concentrations. As an important geological adsorbent, the transformation of 2-line ferrihydrite (Fh) strongly influences the geochemical behavior of selenium. However, little is known about the effect of the recrystallization of Fh on the fate of adsorbed Se(IV) in the reducing environments. We investigated the redistribution and transformation of Se(IV) during the recrystallization of Se(IV)-adsorbed Fh accelerated by Fe(II) under anaerobic conditions. Synchrotron based X-ray absorption near edge structure (XANES) spectroscopy was utilized to characterize oxidation state of Se. Results revealed that the adsorbed Se(IV) inhibited the Fe(II)-catalyzed recrystallization of ferrihydrite to goethite. Transmission electron microscopy (TEM) images showed that pH and the presence of Se(IV) had significant impacts on the morphology of the produced goethite. Approximately 30-75% adsorbed Se(IV) transformed to phosphate-unextractable form, indicating that the adsorbed Se transformed to more stable phase during the recrystallization of Fh. The XANES results indicated that a small fraction of Se(IV) was reduced to elemental Se. Our study demonstrated that the stability of adsorbed Se(IV) on ferrihydrite could be enhanced during Fe(II)-catalytic transformation of Fh under anoxic environments.
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Affiliation(s)
- Shaofeng Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Lei Lei
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China
| | - Danni Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Guoqing Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China
| | - Rui Cao
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, United States
| | - Xin Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Jinru Lin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
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15
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Biswakarma J, Kang K, Schenkeveld WDC, Kraemer SM, Hering JG, Hug SJ. Linking Isotope Exchange with Fe(II)-Catalyzed Dissolution of Iron(hydr)oxides in the Presence of the Bacterial Siderophore Desferrioxamine-B. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:768-777. [PMID: 31846315 PMCID: PMC6978810 DOI: 10.1021/acs.est.9b04235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 05/27/2023]
Abstract
Dissolution of Fe(III) phases is a key process in making iron available to biota and in the mobilization of associated trace elements. Recently, we have demonstrated that submicromolar concentrations of Fe(II) significantly accelerate rates of ligand-controlled dissolution of Fe(III) (hydr)oxides at circumneutral pH. Here, we extend this work by studying isotope exchange and dissolution with lepidocrocite (Lp) and goethite (Gt) in the presence of 20 or 50 μM desferrioxamine-B (DFOB). Experiments with Lp at pH 7.0 were conducted in carbonate-buffered suspensions to mimic environmental conditions. We applied a simple empirical model to determine dissolution rates and a more complex kinetic model that accounts for the observed isotope exchange and catalytic effect of Fe(II). The fate of added tracer 57Fe(II) was strongly dependent on the order of addition of 57Fe(II) and ligand. When DFOB was added first, tracer 57Fe remained in solution. When 57Fe(II) was added first, isotope exchange between surface and solution could be observed at pH 6.0 but not at pH 7.0 and 8.5 where 57Fe(II) was almost completely adsorbed. During dissolution of Lp with DFOB, ratios of released 56Fe and 57Fe were largely independent of DFOB concentrations. In the absence of DFOB, addition of phenanthroline 30 min after tracer 57Fe desorbed predominantly 56Fe(II), indicating that electron transfer from adsorbed 57Fe to 56Fe of the Lp surface occurs on a time scale of minutes to hours. In contrast, comparable experiments with Gt desorbed predominantly 57Fe(II), suggesting a longer time scale for electron transfer on the Gt surface. Our results show that addition of 1-5 μM Fe(II) leads to dynamic charge transfer between dissolved and adsorbed species and to isotope exchange at the surface, with the dissolution of Lp by ligands accelerated by up to 60-fold.
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Affiliation(s)
- Jagannath Biswakarma
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland
- Swiss
Federal Institute of Technology (ETH) Zurich, IBP, CH-8092 Zürich, Switzerland
| | - Kyounglim Kang
- Dept.
of Environmental Geosciences, University
of Vienna, 1090 Vienna, Austria
| | | | - Stephan M. Kraemer
- Dept.
of Environmental Geosciences, University
of Vienna, 1090 Vienna, Austria
| | - Janet G. Hering
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland
- Swiss
Federal Institute of Technology (ETH) Zurich, IBP, CH-8092 Zürich, Switzerland
- Swiss
Federal Institute of Technology Lausanne (EPFL), ENAC, CH-1015 Lausanne, Switzerland
| | - Stephan J. Hug
- Eawag,
Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Dübendorf, Switzerland
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16
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ThomasArrigo LK, Kaegi R, Kretzschmar R. Ferrihydrite Growth and Transformation in the Presence of Ferrous Iron and Model Organic Ligands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:13636-13647. [PMID: 31718167 DOI: 10.1021/acs.est.9b03952] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Ferrihydrite (Fh) is a poorly crystalline Fe(III)-oxyhydroxide found in abundance in soils and sediments. With a high specific surface area and sorption capacity at circumneutral pH, ferrihydrite is an important player in the biogeochemical cycling of nutrients and trace elements in redox-dynamic environments. Under reducing conditions, exposure to Fe(II) induces mineral transformations in ferrihydrite; the extent and trajectory of which may be greatly influenced by organic matter (OM). However, natural OM is heterogeneous and comprises a range of molecular weights (MWs) and varied functional group compositions. To date, the impact that the chemical composition of the associated OM has on Fe(II)-catalyzed mineral transformations is not clear. To address this knowledge gap, we coprecipitated ferrihydrite with model organic ligands selected to cover a range of MWs (25 000-50 000 vs <200 Da) as well as carboxyl content (polygalacturonic acid (PGA) > citric acid (CA) > galacturonic acid (GA)). Coprecipitates (C:Fe ≈ 0.6) were reacted with 1 mM 57Fe(II) for 1 week at pH 7, with time-resolved solid-phase analysis (via X-ray diffraction, X-ray absorption spectroscopy, and electron microscopy) revealing that all ligands inhibited Fe(II)-catalyzed ferrihydrite mineral transformations and the formation of crystalline secondary mineral phases compared to a pure ferrihydrite. For carboxyl-rich coprecipitates (Fh-PGA and Fh-CA), mineral transformations were less inhibited than in the carboxyl poor Fh-GA, and a crystalline lepidocrocite "shell" was formed surrounding the residual ferrihydrite core. However, Fe isotope analysis revealed that all coprecipitates underwent near complete atom exchange. Collectively, our results highlight that ferrihydrite is indeed an active mineral phase in redox-dynamic environments, but that its stability under reducing conditions, and thus capacity for nutrient and trace element retention, depends on the chemical characteristic of the associated OM, specifically OM-induced changes in the particle surface charge and the distribution of organic functional groups.
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Affiliation(s)
- Laurel K ThomasArrigo
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science , ETH Zurich , Universitätstraße 16 , CHN, CH-8092 Zurich , Switzerland
| | - Ralf Kaegi
- Eawag , Swiss Federal Institute of Aquatic Science and Technology , Überlandstraße 133 , CH-8600 Dübendorf , Switzerland
| | - Ruben Kretzschmar
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science , ETH Zurich , Universitätstraße 16 , CHN, CH-8092 Zurich , Switzerland
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17
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Frierdich AJ, Saxey DW, Adineh VR, Fougerouse D, Reddy SM, Rickard WDA, Sadek AZ, Southall SC. Direct Observation of Nanoparticulate Goethite Recrystallization by Atom Probe Analysis of Isotopic Tracers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:13126-13135. [PMID: 31657213 DOI: 10.1021/acs.est.9b04191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Goethite (α-FeOOH) is dispersed throughout the earth's surface, and its propensity to recrystallize in aqueous solutions determines whether this mineral is a source or sink for critical trace elements in the environment. Under reducing conditions, goethite commonly coexists with aqueous Fe(II) (Fe(II)aq), which accelerates recrystallization by coupled electron transfer and atom exchange. Quantifying the amount of the mineral phase that exchanges its structural Fe(III) atoms with Fe(II)aq is complicated by recrystallization models with untested assumptions of whether, and to what extent, the recrystallized portion of the mineral continues to interact with the solution. Here, we reacted nanoparticulate goethite with 57Fe-enriched Fe(II)aq and used atom probe tomography (APT) to resolve the three-dimensional distribution of Fe isotopes in goethite at the sub nm scale. We found that the 57Fe tracer isotope is enriched in the bulk structure (tens of nanometers deep), with some samples having 57Fe penetration throughout at a level that is similar to the isotopic composition of Fe(II)aq. This suggests that some particles undergo near-complete recrystallization. In other cases, however, the distribution of 57Fe is more heterogeneous and generally concentrates near the particle periphery. Nanoparticle encapsulation and subsequent APT can hence capture hidden recrystallization mechanisms which are critical to predicting mineral reactivity in aqueous solutions.
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Affiliation(s)
- Andrew J Frierdich
- School of Earth, Atmosphere & Environment , Monash University , Clayton , Victoria 3800 , Australia
| | | | - Vahid R Adineh
- Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility , Clayton , Victoria 3168 , Australia
| | | | | | | | - Abu Z Sadek
- Melbourne Centre for Nanofabrication, Victorian Node of the Australian National Fabrication Facility , Clayton , Victoria 3168 , Australia
| | - Scarlett C Southall
- School of Earth, Atmosphere & Environment , Monash University , Clayton , Victoria 3800 , Australia
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18
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Notini L, Byrne JM, Tomaszewski EJ, Latta DE, Zhou Z, Scherer MM, Kappler A. Mineral Defects Enhance Bioavailability of Goethite toward Microbial Fe(III) Reduction. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:8883-8891. [PMID: 31284712 DOI: 10.1021/acs.est.9b03208] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Surface defects have been shown to facilitate electron transfer between Fe(II) and goethite (α-FeOOH) in abiotic systems. It is unclear, however, whether defects also facilitate microbial goethite reduction in anoxic environments where electron transfer between cells and Fe(III) minerals is the limiting factor. Here, we used stable Fe isotopes to differentiate microbial reduction of goethite synthesized by hydrolysis from reduction of goethite that was further hydrothermally treated to remove surface defects. The goethites were reduced by Geobacter sulfurreducens in the presence of an external electron shuttle, and we used ICP-MS to distinguish Fe(II) produced from the reduction of the two types of goethite. When reduced separately, goethite with more defects has an initial rate of Fe(III) reduction about 2-fold higher than goethite containing fewer defects. However, when reduced together, the initial rate of reduction is 6-fold higher for goethite with more defects. Our results suggest that there is a suppression of the reduction of goethite with fewer defects in favor of the reduction of minerals with more defects. In the environment, minerals are likely to contain defects and our data demonstrates that even small changes at the surface of iron minerals may change their bioavailability and determine which minerals will be reduced.
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Affiliation(s)
- Luiza Notini
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - James M Byrne
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG) , University of Tübingen , Sigwartstrasse 10 , D-72076 , Tübingen , Germany
| | - Elizabeth J Tomaszewski
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG) , University of Tübingen , Sigwartstrasse 10 , D-72076 , Tübingen , Germany
| | - Drew E Latta
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Zhe Zhou
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Michelle M Scherer
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Andreas Kappler
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG) , University of Tübingen , Sigwartstrasse 10 , D-72076 , Tübingen , Germany
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19
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Li Y, Wei G, Zhang C, Liang X, Chu W, He H, Stucki JW, Ma L, Lin X, Zhu J. Remarkable effect of Co substitution in magnetite on the reduction removal of Cr(VI) coupled with aqueous Fe(II): Improvement mechanism and Cr fate. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 656:400-408. [PMID: 30513430 DOI: 10.1016/j.scitotenv.2018.11.344] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 06/09/2023]
Abstract
The interaction between magnetite and aqueous Fe(II) profoundly impacts the mineral recrystallization, trace-metal sequestration, and contaminant reduction. The iron ions in natural magnetite are extensively substituted by other cations. It is still unclear whether the substitution with thermodynamically favorable redox repairs (e.g., Co2+/Co3+) plays a vital role in the reducing capability of the coupled system. Herein, a series of Co-substituted magnetite samples (Fe3-xCoxO4, 0.00 ≤ x ≤ 1.00) were synthesized and tested for the reductive removal of Cr(VI) in the presence of Fe(II). Fe3-xCoxO4 had a spinel structure with the preferential occupancy of Co2+ on octahedral sites. No visible variation in the BET surface area was observed, whereas the surface site density increased gradually with Co substitution. Cr(VI) was found first adsorbed on the Fe3-xCoxO4 surface and then reduced to Cr(III) by the structural Fe2+ and the absorbed Fe(II), accompanied by the oxidation of bulk Fe2+ and surface Fe(II) in Fe3-xCoxO4 without phase transformation. The Cr(III) was precipitated on the Fe3-xCoxO4 surface with Fe(III), or substituted octahedral Fe in Fe3-xCoxO4. Both the reaction kinetics and the electron transfer efficiency revealed that Co substitution significantly improved the reactivity of Fe3-xCoxO4/Fe(II) towards Cr(VI) reduction. This was ascribed to the presence of the redox pairs Co2+/Co3+ and Fe2+/Fe3+ accelerating electron transfer from the Fe3-xCoxO4 interface to Cr(VI).
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Affiliation(s)
- Ying Li
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, IL 61801, United States; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China
| | - Gaoling Wei
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangzhou 510650, PR China
| | - Caihua Zhang
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China
| | - Xiaoliang Liang
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China.
| | - Wei Chu
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
| | - Hongping He
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China
| | - Joseph W Stucki
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, IL 61801, United States
| | - Lingya Ma
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China
| | - Xiaoju Lin
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China
| | - Jianxi Zhu
- CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Institutions of Earth Science, Chinese Academy of Sciences, Beijing 100029, PR China
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Visualizing the iron atom exchange front in the Fe(II)-catalyzed recrystallization of goethite by atom probe tomography. Proc Natl Acad Sci U S A 2019; 116:2866-2874. [PMID: 30733289 DOI: 10.1073/pnas.1816620116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The autocatalytic redox interaction between aqueous Fe(II) and Fe(III)-(oxyhydr)oxide minerals such as goethite and hematite leads to rapid recrystallization marked, in principle, by an atom exchange (AE) front, according to bulk iron isotopic tracer studies. However, direct evidence for this AE front has been elusive given the analytical challenges of mass-resolved imaging at the nanoscale on individual crystallites. We report successful isolation and characterization of the AE front in goethite microrods by 3D atom probe tomography (APT). The microrods were reacted with Fe(II) enriched in tracer 57Fe at conditions consistent with prior bulk studies. APT analyses and 3D reconstructions on cross-sections of the microrods reveal an AE front that is spatially heterogeneous, at times penetrating several nanometers into the lattice, in a manner consistent with defect-accelerated exchange. Evidence for exchange along microstructural domain boundaries was also found, suggesting another important link between exchange extent and initial defect content. The findings provide an unprecedented view into the spatial and temporal characteristics of Fe(II)-catalyzed recrystallization at the atomic scale, and substantiate speculation regarding the role of defects controlling the dynamics of electron transfer and AE interaction at this important redox interface.
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21
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Biswakarma J, Kang K, Borowski SC, Schenkeveld WDC, Kraemer SM, Hering JG, Hug SJ. Fe(II)-Catalyzed Ligand-Controlled Dissolution of Iron(hydr)oxides. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:88-97. [PMID: 30571098 DOI: 10.1021/acs.est.8b03910] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Dissolution of iron(III)phases is a key process in soils, surface waters, and the ocean. Previous studies found that traces of Fe(II) can greatly increase ligand controlled dissolution rates at acidic pH, but the extent that this also occurs at circumneutral pH and what mechanisms are involved are not known. We addressed these questions with infrared spectroscopy and 57Fe isotope exchange experiments with lepidocrocite (Lp) and 50 μM ethylenediaminetetraacetate (EDTA) at pH 6 and 7. Addition of 0.2-10 μM Fe(II) led to an acceleration of the dissolution rates by factors of 7-31. Similar effects were observed after irradiation with 365 nm UV light. The catalytic effect persisted under anoxic conditions, but decreased as soon as air or phenanthroline was introduced. Isotope exchange experiments showed that added 57Fe remained in solution, or quickly reappeared in solution when EDTA was added after 57Fe(II), suggesting that catalyzed dissolution occurred at or near the site of 57Fe incorporation at the mineral surface. Infrared spectra indicated no change in the bulk, but changes in the spectra of adsorbed EDTA after addition of Fe(II) were observed. A kinetic model shows that the catalytic effect can be explained by electron transfer to surface Fe(III) sites and rapid detachment of Fe(III)EDTA due to the weaker bonds to reduced sites. We conclude that the catalytic effect of Fe(II) on dissolution of Fe(III)(hydr)oxides is likely important under circumneutral anoxic conditions and in sunlit environments.
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Affiliation(s)
- Jagannath Biswakarma
- Eawag , Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf , Switzerland
- Swiss Federal Institute of Technology (ETH) Zürich , IBP , CH-8092 Zürich , Switzerland
| | - Kyounglim Kang
- University of Vienna , Dept. of Environmental Geosciences , 1090 Vienna , Austria
| | - Susan C Borowski
- Eawag , Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf , Switzerland
| | | | - Stephan M Kraemer
- University of Vienna , Dept. of Environmental Geosciences , 1090 Vienna , Austria
| | - Janet G Hering
- Eawag , Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf , Switzerland
- Swiss Federal Institute of Technology (ETH) Zürich , IBP , CH-8092 Zürich , Switzerland
- Swiss Federal Institute of Technology Lausanne (EPFL) , ENAC , CH-1015 Lausanne , Switzerland
| | - Stephan J Hug
- Eawag , Swiss Federal Institute of Aquatic Science and Technology , CH-8600 Dübendorf , Switzerland
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22
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Cr Release from Cr-Substituted Goethite during Aqueous Fe(II)-Induced Recrystallization. MINERALS 2018. [DOI: 10.3390/min8090367] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The interaction between aqueous Fe(II) (Fe(II)aq) and iron minerals is an important reaction of the iron cycle, and it plays a critical role in impacting the environmental behavior of heavy metals in soils. Metal substitution into iron (hydr)oxides has been reported to reduce Fe atom exchange rates between Fe(II)aq and metal-substituted iron (hydr)oxides and inhibit the recrystallization of iron (hydr)oxides. However, the environmental behaviors of the substituted metal during these processes remain unclear. In this study, Fe(II)aq-induced recrystallization of Cr-substituted goethite (Cr-goethite) was investigated, along with the sequential release behavior of substituted Cr(III). Results from a stable Fe isotopic tracer and Mössbauer characterization studies show that Fe atom exchange occurred between Fe(II)aq and structural Fe(III) (Fe(III)oxide) in Cr-goethites, during which the Cr-goethites were recrystallized. The Cr substitution inhibited the rates of Fe atom exchange and Cr-goethite recrystallization. During the recrystallization of Cr-goethites induced by Fe(II)aq, Cr(III) was released from Cr-goethite. In addition, Cr-goethites with a higher level of Cr-substituted content released more Cr(III). The highest Fe atom exchange rate and the highest amount of released Cr(III) were observed at a pH of 7.5. Under reaction conditions involving a lower pH of 5.5 or a higher pH of 8.5, there were substantially lower rates of Fe atom exchange and Cr(III) release. This trend of Cr(III) release was similar with changes in Fe atom exchange, suggesting that Cr(III) release is driven by Fe atom exchange. The release and reincorporation of Cr(III) occurred simultaneously during the Fe(II)aq-induced recrystallization of Cr-goethites, especially during the late stage of the observed reactions. Our findings emphasize an important role for Fe(II)aq-induced recrystallization of iron minerals in changing soil metal characteristics, which is critical for the evaluation of soil metal activities, especially those in Fe-rich soils.
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Notini L, Latta DE, Neumann A, Pearce CI, Sassi M, N'Diaye AT, Rosso KM, Scherer MM. The Role of Defects in Fe(II)-Goethite Electron Transfer. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2751-2759. [PMID: 29405066 DOI: 10.1021/acs.est.7b05772] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Despite substantial experimental evidence for Fe(II)-Fe(III) oxide electron transfer, computational chemistry calculations suggest that oxidation of sorbed Fe(II) by goethite is kinetically inhibited on structurally perfect surfaces. We used a combination of 57Fe Mössbauer spectroscopy, synchrotron X-ray absorption and magnetic circular dichroism (XAS/XMCD) spectroscopies to investigate whether Fe(II)-goethite electron transfer is influenced by defects. Specifically, Fe L-edge and O K-edge XAS indicates that the outermost few Angstroms of goethite synthesized by low temperature Fe(III) hydrolysis is iron deficient relative to oxygen, suggesting the presence of defects from Fe vacancies. This nonstoichiometric goethite undergoes facile Fe(II)-Fe(III) oxide electron transfer, depositing additional goethite consistent with experimental precedent. Hydrothermal treatment of this goethite, however, appears to remove defects, decrease the amount of Fe(II) oxidation, and change the composition of the oxidation product. When hydrothermally treated goethite was ground, surface defect characteristics as well as the extent of electron transfer were largely restored. Our findings suggest that surface defects play a commanding role in Fe(II)-goethite redox interaction, as predicted by computational chemistry. Moreover, it suggests that, in the environment, the extent of this interaction will vary depending on diagenetic history, local redox conditions, as well as being subject to regeneration via seasonal fluctuations.
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Affiliation(s)
- Luiza Notini
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Drew E Latta
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
| | - Anke Neumann
- School of Engineering , Newcastle University , Newcastle upon Tyne , NE1 7RU , United Kingdom
| | - Carolyn I Pearce
- Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Michel Sassi
- Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Alpha T N'Diaye
- Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Kevin M Rosso
- Pacific Northwest National Laboratory , Richland , Washington 99352 , United States
| | - Michelle M Scherer
- Department of Civil and Environmental Engineering , University of Iowa , Iowa City , Iowa 52242 , United States
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Aeppli M, Voegelin A, Gorski CA, Hofstetter TB, Sander M. Mediated Electrochemical Reduction of Iron (Oxyhydr-)Oxides under Defined Thermodynamic Boundary Conditions. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:560-570. [PMID: 29200267 DOI: 10.1021/acs.est.7b04411] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Iron (oxyhydr-)oxide reduction has been extensively studied because of its importance in pollutant redox dynamics and biogeochemical processes. Yet, experimental studies linking oxide reduction kinetics to thermodynamics remain scarce. Here, we used mediated electrochemical reduction (MER) to directly quantify the extents and rates of ferrihydrite, goethite, and hematite reduction over a range of negative reaction free energies, ΔrG, that were obtained by systematically varying pH (5.0 to 8.0), applied reduction potentials (-0.53 to -0.17 V vs SHE), and Fe2+ concentrations (up to 40 μM). Ferrihydrite reduction was complete and fast at all tested ΔrG values, consistent with its comparatively low thermodynamic stability. Reduction of the thermodynamically more stable goethite and hematite changed from complete and fast to incomplete and slow as ΔrG values became less negative. Reductions at intermediate ΔrG values showed negative linear correlations between the natural logarithm of the reduction rate constants and ΔrG. These correlations imply that thermodynamics controlled goethite and hematite reduction rates. Beyond allowing to study iron oxide reduction under defined thermodynamic conditions, MER can also be used to capture changes in iron oxide reducibility during phase transformations, as shown for Fe2+-facilitated transformation of ferrihydrite to goethite.
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Affiliation(s)
- Meret Aeppli
- Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH) , 8092 Zurich, Switzerland
- Swiss Federal Institute of Aquatic Science and Technology (Eawag) , 8600 Duebendorf, Switzerland
| | - Andreas Voegelin
- Swiss Federal Institute of Aquatic Science and Technology (Eawag) , 8600 Duebendorf, Switzerland
| | - Christopher A Gorski
- Department of Civil and Environmental Engineering, Pennsylvania State University, University Park , Pennsylvania 16802, United States
| | - Thomas B Hofstetter
- Swiss Federal Institute of Aquatic Science and Technology (Eawag) , 8600 Duebendorf, Switzerland
| | - Michael Sander
- Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH) , 8092 Zurich, Switzerland
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25
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Joshi P, Fantle MS, Larese-Casanova P, Gorski CA. Susceptibility of Goethite to Fe 2+-Catalyzed Recrystallization over Time. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:11681-11691. [PMID: 28895726 DOI: 10.1021/acs.est.7b02603] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Recent work has shown that iron oxides, such as goethite and hematite, may recrystallize in the presence of aqueous Fe2+ under anoxic conditions. This process, referred to as Fe2+-catalyzed recrystallization, can influence water quality by causing the incorporation/release of environmental contaminants and biological nutrients. Accounting for the effects of Fe2+-catalyzed recrystallization on water quality requires knowing the time scale over which recrystallization occurs. Here, we tested the hypothesis that nanoparticulate goethite becomes less susceptible to Fe2+-catalyzed recrystallization over time. We set up two batches of reactors in which 55Fe2+ tracer was added at two different time points and tracked the 55Fe partitioning in the aqueous and goethite phases over 60 days. Less 55Fe uptake occurred between 30 and 60 days than between 0 and 30 days, suggesting goethite recrystallization slowed with time. Fitting the data with a box model indicated that 17% of the goethite recrystallized after 30 days of reaction, and an additional 2% recrystallized between 30 and 60 days. The decreasing susceptibility of goethite to recrystallize as it reacted with aqueous Fe2+ suggested that recrystallization is likely only an important process over short time scales.
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Affiliation(s)
- Prachi Joshi
- Department of Civil & Environmental Engineering, Pennsylvania State University , 212 Sackett Building, University Park, Pennsylvania 16802, United States
| | - Matthew S Fantle
- Department of Geosciences, Pennsylvania State University , 212 Deike Building, University Park, Pennsylvania 16802, United States
| | - Philip Larese-Casanova
- Department of Civil & Environmental Engineering, Snell Engineering Center, Northeastern University , 360 Huntington Avenue, Boston, Massachusetts 02115, United States
| | - Christopher A Gorski
- Department of Civil & Environmental Engineering, Pennsylvania State University , 212 Sackett Building, University Park, Pennsylvania 16802, United States
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26
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Zarzycki P, Rosso KM. Stochastic Simulation of Isotopic Exchange Mechanisms for Fe(II)-Catalyzed Recrystallization of Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7552-7559. [PMID: 28602094 DOI: 10.1021/acs.est.7b01491] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding Fe(II)-catalyzed transformations of Fe(III)-(oxyhydr)oxides is critical for correctly interpreting stable isotopic distributions and for predicting the fate of metal ions in the environment. Recent Fe isotopic tracer experiments have shown that goethite undergoes rapid recrystallization without phase change when exposed to aqueous Fe(II). The proposed explanation is oxidation of sorbed Fe(II) and reductive Fe(II) release coupled 1:1 by electron conduction through crystallites. Given the availability of two tracer exchange data sets that explore pH and particle size effects (e.g., Handler et al. Environ. Sci. Technol. 2014 , 48 , 11302 - 11311 ; Joshi and Gorski Environ. Sci. Technol. 2016 , 50 , 7315 - 7324 ), we developed a stochastic simulation that exactly mimics these experiments, while imposing the 1:1 constraint. We find that all data can be represented by this model, and unifying mechanistic information emerges. At pH 7.5 a rapid initial exchange is followed by slower exchange, consistent with mixed surface- and diffusion-limited kinetics arising from prominent particle aggregation. At pH 5.0 where aggregation and net Fe(II) sorption are minimal, that exchange is quantitatively proportional to available particle surface area and the density of sorbed Fe(II) is more readily evident. Our analysis reveals a fundamental atom exchange rate of ∼10-5 Fe nm-2 s-1, commensurate with some of the reported reductive dissolution rates of goethite, suggesting Fe(II) release is the rate-limiting step in the conduction mechanism during recrystallization.
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Affiliation(s)
- Piotr Zarzycki
- Energy Geoscience Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
- Institute of Physical Chemistry, Polish Academy of Sciences , 01-224 Warsaw, Poland
| | - Kevin M Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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