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Jin X, Guo C, Tao X, Li X, Xie Y, Dang Z, Lu G. Divergent redistribution behavior of divalent metal cations associated with Fe(II)-mediated jarosite phase transformation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 350:124004. [PMID: 38641039 DOI: 10.1016/j.envpol.2024.124004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 04/06/2024] [Accepted: 04/16/2024] [Indexed: 04/21/2024]
Abstract
The Fe(II)/Fe(III) cycle is an important driving force for dissolution and transformation of jarosite. Divalent heavy metals usually coexist with jarosite; however, their effects on Fe(II)-induced jarosite transformation and different repartitioning behavior during mineral dissolution-recrystallization are still unclear. Here, we investigated Fe(II)-induced (1 mM Fe(II)) jarosite conversion in the presence of Cd(II), Mn(II), Co(II), Ni(II) and Pb(II) (denoted as Me(II), 1 mM), respectively, under anaerobic condition at neutral pH. The results showed that all co-existing Me(II) retarded Fe(II)-induced jarosite dissolution. In the Fe(II)-only system, jarosite first rapidly transformed to lepidocrocite (an intermediate product) and then slowly to goethite; lepidocrocite was the main product. In Fe(II)-Cd(II), -Mn(II), and -Pb(II) systems, coexisting Cd(II), Mn(II) and Pb(II) retarded the above process and lepidocrocite was still the dominant conversion product. In Fe(II)-Co(II) system, coexisting Co(II) promoted lepidocrocite transformation into goethite. In Fe(II)-Ni(II) system, jarosite appeared to be directly converted into goethite, although small amounts of lepidocrocite were detected in the final product. In all treatments, the appearance or accumulation of lepidocrocite may be also related to the re-adsorption of released sulfate. By the end of reaction, 6.0 %, 4.0 %, 76.0 % 11.3 % and 19.2 % of total Cd(II), Mn(II), Pb(II) Co(II) and Ni(II) were adsorbed on the surface of solid products. Up to 49.6 %, 44.3 %, and 21.6 % of Co(II), Ni(II), and Pb(II) incorporated into solid product, with the reaction indicating that the dynamic process of Fe(II) interaction with goethite may promote the continuous incorporation of Co(II), Ni(II), and Pb(II).
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Affiliation(s)
- Xiaohu Jin
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China
| | - Chuling Guo
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China
| | - Xueqin Tao
- College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou, 510225, China
| | - Xiaofei Li
- School of Environmental and Chemical Engineering, Foshan University, 528000, Foshan, China
| | - Yingying Xie
- School of Chemistry and Environmental Engineering, Hanshan Normal University, Guangdong, Chaozhou, 521041, China
| | - Zhi Dang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China; Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, China
| | - Guining Lu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou, 510006, China.
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2
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Lin W, Peng L, Li H, Xiao T, Wang J, Wang N, Zhang X, Zhang H. Antimony(V) behavior during the Fe(II)-induced transformation of Sb(V)-bearing natural multicomponent secondary iron mineral under acidic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169592. [PMID: 38154637 DOI: 10.1016/j.scitotenv.2023.169592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 12/30/2023]
Abstract
Fe(II)-induced phase transformations of secondary iron minerals have attracted considerable attention due to their influence on antimony (Sb) mobility. However, Fe(II)-induced natural multicomponent secondary iron mineral (nmSIM) transformations and the corresponding repartitioning of Sb on nmSIM under acidic conditions upon Fe(II) exposure have not been systematically examined. Herein, we investigated the effect of Fe(II) on nmSIM mineralogy and Sb mobility in Sb(V)-bearing nmSIM at pH 3.8 and 5.6 at various Fe(II) concentrations over 15 d. The Sb(V)-bearing nmSIM phase transformation occurred under both strongly and weakly acidic conditions without Fe(II) exposure, while the presence of Fe(II) significantly intensified the transformation, and substantial amounts of intermediary minerals, including jarosite, ferrihydrite, lepidocrocite and fougerite, formed during the initial reaction stage, especially at pH 5.6. X-ray diffraction (XRD) analyses confirmed that goethite and hematite were the primary final-stage transformation products of Sb(V)-bearing nmSIM, regardless of Fe(II) exposure. Throughout the Sb(V)-bearing nmSIM transformation at pH 3.8, Sb release was inversely related to the Fe(II) concentration in the initial stage, and after maximum release was achieved, Sb was gradually repartitioned onto the nmSIM. No Sb repartitioning occurred in the absence of Fe(II) at pH 5.6, but the introduction of Fe(II) suppressed Sb release and improved Sb repartitioning on nmSIM. This transformation was conducive to Sb reimmobilization on Sb(V)-bearing nmSIM due to the structural incorporation of Sb into the highly crystalline goethite and hematite generated by the Sb(V)-bearing nmSIM transformation, and no reduction of Sb(V) occurred. These results imply that Fe(II) can trigger mineralogical changes in Sb(V)-bearing nmSIM and have important impacts on Sb partitioning under acidic conditions. These new insights are essential for assessing the mobility and availability of Sb in acid mine drainage areas.
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Affiliation(s)
- Wangjun Lin
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Linfeng Peng
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Hui Li
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Tangfu Xiao
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China
| | - Jianqiao Wang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Nana Wang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
| | - Xiangting Zhang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
| | - Hanmo Zhang
- Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China
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3
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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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4
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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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Yan X, Li W, Zhu C, Peacock CL, Liu Y, Li H, Zhang J, Hong M, Liu F, Yin H. Zinc Stable Isotope Fractionation Mechanisms during Adsorption on and Substitution in Iron (Hydr)oxides. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6636-6646. [PMID: 37042830 DOI: 10.1021/acs.est.2c08028] [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: 06/19/2023]
Abstract
The Zn isotope fingerprint is widely used as a proxy of various environmental geochemical processes, so it is crucial to determine which are the mechanisms responsible for isotopic fractionation. Iron (Fe) (hydr)oxides greatly control the cycling and fate and thus isotope fractionation factors of Zn in terrestrial environments. Here, Zn isotope fractionation and related mechanisms during adsorption on and substitution in three FeOOH polymorphs are explored. Results demonstrate that heavy Zn isotopes are preferentially enriched onto solids, with almost similar isotopic offsets (Δ66/64Znsolid-solution = 0.25-0.36‰) for goethite, lepidocrocite, and feroxyhyte. This is consistent with the same average Zn-O bond lengths for adsorbed Zn on these solids as revealed by Zn K-edge X-ray absorption fine structure spectroscopy. In contrast, at an initial Zn/Fe molar ratio of 0.02, incorporation of Zn into goethite and lepidocrocite by substituting for lattice Fe preferentially sequesters light Zn isotopes with Δ66/64Znsubstituted-stock solution of -1.52 ± 0.09‰ and -1.18 ± 0.15‰, while Zn-substituted feroxyhyte (0.06 ± 0.11‰) indicates almost no isotope fractionation. This is closely related to the different crystal nucleation and growth rates during the Zn-doped FeOOH formation processes. These results provide direct experimental evidence of incorporation of isotopically light Zn into Fe (hydr)oxides and improve our understanding of Zn isotope fractionation mechanisms during mineral-solution interface processes.
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Affiliation(s)
- Xinran Yan
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Wei Li
- Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu 210023, China
| | - Chuanwei Zhu
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002, China
| | | | - Yizhang Liu
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, Guizhou 550002, China
| | - Hui Li
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jing Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China
| | - Mei Hong
- College of Grassland, Resources and Environment, Inner Mongolia Agricultural University, Hohhot 010018, China
| | - Fan Liu
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Hui Yin
- Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture and Rural Affairs, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
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6
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Scullett-Dean G, Hamilton JL, Repina O, Brand HEA, Burton ED, Saunders M, Santini TC. Uptake and incorporation of Al, Cr, V, Zn and Mo in hematite: Competition, synergies and influence on structural properties. JOURNAL OF HAZARDOUS MATERIALS 2023; 445:130630. [PMID: 37056025 DOI: 10.1016/j.jhazmat.2022.130630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 06/19/2023]
Abstract
This study investigated multiple (di-, tri- and tetra-)incorporation of selected minor and trace elements (Al3+, Cr3+, V3-5+, Zn2+, Mo6+ and As5+) into hematite. The purpose was to improve understanding of how hematite may control trace element mobility in the environment, and how physical and chemical properties of hematite are impacted by multi-element incorporation at x/Fe molar ratios of up to 10%. Simultaneous structural incorporation of Al±Cr±V±Zn into hematite was achieved, with both synergistic and antagonistic effects occurring between certain element combinations. Cr+Al had synergistic effects on their co-incorporation, while V negatively affected Al incorporation, and both V and Zn negatively affected Cr incorporation. In contrast, Mo was minimally associated with hematite, and As prevented hematite formation completely. X-ray diffraction indicated contraction and expansion of the hematite unit-cell upon substitution was related to the ionic radius of the substituting element in single-element samples, while V predominantly controlled the direction of deviation in multi-element samples. X-ray absorption near-edge structure spectroscopy indicated V was present as a mixture of V3+-V5+, with a higher average V oxidation state associated with multi-element samples. Results provide new insights into trace element geochemistry within hematite, and highlight the importance of multi-element studies to better understand natural and anthropogenic systems.
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Affiliation(s)
- G Scullett-Dean
- School of Agriculture and Environment, University of Western Australia, Crawley, WA 6009, Australia; School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD 4072, Australia.
| | - J L Hamilton
- School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD 4072, Australia; Australian Nuclear Science and Technology Organisation, 800 Blackburn Road, Clayton, VIC 3168, Australia
| | - O Repina
- School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD 4072, Australia; School of Earth, Atmospheric and Life Sciences, University of Wollongong, NSW 2522, Australia
| | - H E A Brand
- Australian Nuclear Science and Technology Organisation, 800 Blackburn Road, Clayton, VIC 3168, Australia
| | - E D Burton
- Faculty of Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia
| | - M Saunders
- Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, WA 6009, Australia
| | - T C Santini
- School of Agriculture and Environment, University of Western Australia, Crawley, WA 6009, Australia; School of Earth and Environmental Sciences, University of Queensland, St Lucia, QLD 4072, Australia
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7
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He C, Yang Z, Ning Y, Yang S, Jiang F, Zhang J. Effects of montmorillonite on the adsorption of Fe(II) by ferrihydrite and its phase transformation at different pH. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:28975-28989. [PMID: 36402883 DOI: 10.1007/s11356-022-24309-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Recently, there has been a clear understanding of the mechanism and influencing factors of ferrihydrite (Fh) phase transformation catalyzed by Fe(II); however, these factors mainly belong to environmental conditions and exogenous substances. And there is a lack of research on the effect of soil composition and structure on the phase transformation of Fh. Therefore, this study investigated the effects of montmorillonite (Mt) on the adsorption of Fe(II) and phase transformation of Fh under near-neutral pH. The initial rates ([Formula: see text]) of Elovich equation demonstrated the addition of Mt inhibited the adsorption of Fh but simultaneously accelerated the initial adsorption, thus increasing the adsorption of the system (e.g., 22.09-25.03 mg/g as increased Mt under pH 6.5) due to its high surface charge density. Increased pH enhances the surface charge density by promoting the deprotonation of the surface group (Fe-OH, Al-OH, and Si-OH) and consequently increases adsorption of Fe(II) (e.g., 17.97-22.09 mg/g as increased pH of pure Fh). Based on the previous method of extracting labile Fe(III), we found that pH promotes the initial formation of labile Fe(III) by increasing electron transfer and promoting recrystallization caused by bridging condensation, via increased -OH. Although Mt inhibits the adsorption of Fh, it promotes the formation of labile Fe(III) by increasing the system adsorption and bond with Fh. The results of the analysis of variance showed both pH and solid ratio influence significantly on the maximum adsorption (p = 6.81 × 10-9 and 2.54 × 10-3) and the conversion ratios of labile Fe(III) (p = 3.43 × 10-24 and 9.16 × 10-43).
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Affiliation(s)
- Chang He
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
| | - Zhe Yang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
| | - Yu Ning
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China.
| | - Sen Yang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
| | - Fengcheng Jiang
- Institute of Resources and Environment, Henan Polytechnic University, Jiaozuo, 454003, China
| | - Jiayi Zhang
- School of Environmental Studies, China University of Geosciences, Wuhan, 430078, China
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8
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Westrop JP, Tomlinson ZD, Maples BM, Dee KT, Swindle AL, Elwood Madden ME, Hu Q, Elwood Madden AS. Dissolution of Mn-bearing dolomite drives elevated Cr(VI) occurrence in a Permian redbed aquifer. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:2419-2436. [PMID: 36377918 DOI: 10.1039/d2em00395c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Municipalities in central Oklahoma, U.S.A. increasingly rely on water drawn from the Central Oklahoma Aquifer (COA) as surface water resources have not grown in proportion to population and current water demands. However, water drawn from certain regions of the COA frequently contains elevated levels of naturally occurring hexavalent chromium. Rock samples from the Norman Arsenic Test Hole Core (NATHC) were investigated to identify the mineralogic host(s) of Cr and mechanisms of Cr(VI) release via bulk mineralogy and chemistry measurements, selective chemical extractions, and microscale elemental analyses. Results demonstrate most COA Cr is contained in Fe oxides and clays as isomorphic substitutions for Fe(III). Analyses of regional groundwater data, including hierarchical clustering methods and GIS, demonstrate the most intense Cr(VI) occurrence is linked to cation exchange with Na-clays at depth. Cation exchange allows dissolution of Mn-bearing dolomite, which in turn produces Mn oxides in otherwise dolomite-saturated groundwaters. Mn oxides in turn are known to oxidize Cr(III) to Cr(VI). In general, co-occurrence of Mn-bearing carbonates and exchangeable clays in any aquifer, particularly those with Cr(III) present in iron oxide cements, serve as ingredients for groundwater occurrences of oxidizable trace metals.
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Affiliation(s)
- Jeffrey P Westrop
- University of Oklahoma, School of Geosciences, 100 E. Boyd St., Norman, OK 73069, USA.
| | - Zachary D Tomlinson
- University of Oklahoma, School of Geosciences, 100 E. Boyd St., Norman, OK 73069, USA.
| | - Brandon M Maples
- University of Oklahoma, School of Geosciences, 100 E. Boyd St., Norman, OK 73069, USA.
| | - Kato T Dee
- University of Oklahoma, School of Geosciences, 100 E. Boyd St., Norman, OK 73069, USA.
| | - Andrew L Swindle
- Wichita State University, 1845 Fairmount Avenue, Wichita, Kansas 67260, USA
| | - Megan E Elwood Madden
- University of Oklahoma, School of Geosciences, 100 E. Boyd St., Norman, OK 73069, USA.
| | - Qinhong Hu
- University of Texas at Arlington, 500 Yates Street, Arlington, TX 76019, USA
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9
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Grigg ARC, ThomasArrigo LK, Schulz K, Rothwell KA, Kaegi R, Kretzschmar R. Ferrihydrite transformations in flooded paddy soils: rates, pathways, and product spatial distributions. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2022; 24:1867-1882. [PMID: 36131682 PMCID: PMC9580987 DOI: 10.1039/d2em00290f] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 09/15/2022] [Indexed: 06/15/2023]
Abstract
Complex interactions between redox-driven element cycles in soils influence iron mineral transformation processes. The rates and pathways of iron mineral transformation processes have been studied intensely in model systems such as mixed suspensions, but transformation in complex heterogeneous porous media is not well understood. Here, mesh bags containing 0.5 g of ferrihydrite were incubated in five water-saturated paddy soils with contrasting microbial iron-reduction potential for up to twelve weeks. Using X-ray diffraction analysis, we show near-complete transformation of the ferrihydrite to lepidocrocite and goethite within six weeks in the soil with the highest iron(II) release, and slower transformation with higher ratios of goethite to lepidocrocite in soils with lower iron(II) release. In the least reduced soil, no mineral transformations were observed. In soils where ferrihydrite transformation occurred, the transformation rate was one to three orders of magnitude slower than transformation in comparable mixed-suspension studies. To interpret the spatial distribution of ferrihydrite and its transformation products, we developed a novel application of confocal micro-Raman spectroscopy in which we identified and mapped minerals on selected cross sections of mesh bag contents. After two weeks of flooded incubation, ferrihydrite was still abundant in the core of some mesh bags, and as a rim at the mineral-soil interface. The reacted outer core contained unevenly mixed ferrihydrite, goethite and lepidocrocite on the micrometre scale. The slower rate of transformation and uneven distribution of product minerals highlight the influence of biogeochemically complex matrices and diffusion processes on the transformation of minerals, and the importance of studying iron mineral transformation in environmental media.
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Affiliation(s)
- Andrew R C Grigg
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Universitätstrasse 16, CHN, CH-8092 Zurich, Switzerland.
| | - 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.
| | - Katrin Schulz
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Universitätstrasse 16, CHN, CH-8092 Zurich, Switzerland.
| | - Katherine A Rothwell
- 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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10
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Zhang Q, Yuan P, Liang W, Qiao Z, Shao X, Zhang W, Peng C. Exogenous iron alters uptake and translocation of CuO nanoparticles in soil-rice system: A life cycle study. ENVIRONMENT INTERNATIONAL 2022; 168:107479. [PMID: 36007301 DOI: 10.1016/j.envint.2022.107479] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 08/12/2022] [Accepted: 08/13/2022] [Indexed: 06/15/2023]
Abstract
The abundant iron in farmland soil may affect the environmental fate of metal-based nanoparticles (MNPs). In this study, the effect of FeSO4 and nano-zero-valent iron (nZVI) as exogenous iron on the uptake and translocation of CuO nanoparticles (NPs) in soil-rice system was performed in a life cycle study. The results show that exogenous iron basically elevated the soil pH and electrical conductivity but lowered the redox potential. Moreover, the Cu bioavailability in soil was significantly increased by 86-269% with exogenous iron at the tillering stage, while was reduced by 15-45% with medium and high concentrations of Fe(II) at the maturation stage. Meanwhile, the addition of exogenous iron resolved the unfilling of grains caused by CuO NPs. Notably, except for highest Fe(II) treatment, both Fe(II) and nZVI reduced Cu accumulation from 31% to 84% in roots and leaves due to more iron plaque. Especially, medium Fe(II) level markedly decreased the Cu content in the brown rice. μ-XRF analysis suggests that high intensity of Cu was primarily located in the rice hull and embryo under Fe(II) treatment. The reduction of CuO NPs to Cu2O caused by Fe(II) can explain the positive effect of exogenous iron on controlling the environmental risk of MNPs.
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Affiliation(s)
- Qi Zhang
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Peng Yuan
- College of Environmental Science and Engineering, Donghua University, Shanghai 201620, China
| | - Weiyu Liang
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Zhihua Qiao
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xuechun Shao
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Wei Zhang
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China
| | - Cheng Peng
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, China.
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11
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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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12
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Pan W, Ledingham GJ, Catalano JG, Giammar DE. Effects of Cu(II) and Zn(II) on PbO 2 Reductive Dissolution under Drinking Water Conditions: Short-term Inhibition and Long-term Enhancement. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:14397-14406. [PMID: 34517703 DOI: 10.1021/acs.est.1c04887] [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: 06/13/2023]
Abstract
Lead oxide (PbO2) has the lowest solubility with free chlorine among Pb corrosion products, but depletion of free chlorine or a switch from free chlorine to monochloramine can cause its reductive dissolution. We previously reported that Cu(II) and Zn(II) inhibited PbO2 reductive dissolution within 12 h. Here, we expanded on this work by performing longer duration experiments and further exploring the underlying mechanisms. Between 12 and 48 h, Cu(II) and Zn(II) had no discernible effect on PbO2 reductive dissolution. From 48 to 192 h, Cu(II) and Zn(II) enhanced PbO2 reductive dissolution. Dissolved oxygen (DO) concentrations followed the same trends as PbO2 reductive dissolution, indicating that the DO was produced by PbO2 reductive dissolution. On the basis of extended X-ray absorption fine structure spectra, we hypothesize that the inhibitory effect of Cu(II) and Zn(II) on PbO2 reductive dissolution (<12 h) is caused by decreasing abundance of protonated sites on the PbO2 surface. The enhanced dissolution (>48 h) may be caused by competitive adsorption of Cu(II) and Zn(II) with Pb(II), which could limit the adsorption of Pb(II) onto PbO2 that could otherwise inhibit reductive dissolution. This study indicates that stagnation time plays a vital role in determining cations' effects on the stability of Pb corrosion products.
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Affiliation(s)
- Weiyi Pan
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130, United States
| | - Greg J Ledingham
- Department of Earth and Planetary Sciences, Washington University in St. Louis, 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, St. Louis, Missouri 63130, United States
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13
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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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14
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Mergelsberg ST, Prange M, Song D, Bylaska EJ, Saslow SA, Catalano JG, Ilton ES. Resolving Configurational Disorder for Impurities in a Low-Entropy Phase. J Phys Chem Lett 2021; 12:5689-5694. [PMID: 34115494 DOI: 10.1021/acs.jpclett.1c01218] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Hematite (α-Fe2O3) exerts a strong control over the transport of minor but critical metals in the environment and is used in multiple industrial applications; the photocatalysis community has explored the properties of hematite nanoparticles over a wide range of transition metal dopants. Nonetheless, simplistic assumptions are used to rationalize the local coordination environment of impurities in hematite. Here, we use ab initio molecular dynamics (AIMD)-guided structural analysis to model the extended X-ray absorption fine structure (EXAFS) of Cu2+- and Zn2+-doped hematite nanoparticles. Specific defect-impurity associations were identified, and the local coordination environments of Cu and Zn both displayed considerable configurational disorder that, in aggregate, approached Jahn-Teller-like distortion for Cu but, in contrast, maintained hematite-like symmetry for Zn. This study highlights the role of defects in accommodating impurities in a nominally low-entropy phase and the limits to traditional shell-by-shell fitting of EXAFS for dopants/impurities in unprecedented bonding environments.
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Affiliation(s)
| | - Micah Prange
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Duo Song
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Eric J Bylaska
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Sarah A Saslow
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Jeffrey G Catalano
- Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri 63130, United States
| | - Eugene S Ilton
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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15
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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: 166] [Impact Index Per Article: 55.3] [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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16
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Asemaninejad A, Langley S, Mackinnon T, Spiers G, Beckett P, Mykytczuk N, Basiliko N. Blended municipal compost and biosolids materials for mine reclamation: Long-term field studies to explore metal mobility, soil fertility and microbial communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143393. [PMID: 33213923 DOI: 10.1016/j.scitotenv.2020.143393] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/27/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
Application of stable soil amendments is often the key to successful phytostabilization and rehabilitation of mine tailings, and microbial guilds are primary drivers of many geochemical processes promoted by these amendments. Field studies were set up at a tailings management area near Sudbury, Ontario to examine performance of blends of lime stabilized municipal biosolids and compost at nine different rates over thick (1 m) municipal compost covers planted with agricultural crops. Based on biogeochemical variability of the substrates four and ten years after application of the initial compost cover, the experimental plots could be classified into three categories: "Low" rate (0-100 t ha-1 biosolids), "Medium" rate (200-800 t ha-1), and "High" rate (1600-3200 t ha-1) treatments. The addition of biosolids materials to the thick compost cover at rates higher than 100 t ha-1 significantly reduced C:N ratio of the substrates, available phosphorus, and some of the nutrient cations, while notably increasing inorganic carbon and the potential solubility of Ni and Cu. This suggests that increasing biosolids application rates may not equivalently ameliorate soil quality and geochemical stability. Correspondingly, microbial communities were altered by biosolids additions, further intensifying the negative impacts of biosolids on long-term efficiency of the initial compost cover. Abundance of cellulose, hemicellulose, and lignocellulose decomposers (as key drivers of mineralization and humification) was significantly reduced by "Medium" and "High" rate treatments. Most DNA sequences with high affinity to denitrifiers were detected in "High" rate treatments where geochemical conditions were optimal for higher microbial denitrification activities. These findings have implications for improving the long-term efficiency of reclamation and environmental management programs in mine tailings of northern temperate climates.
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Affiliation(s)
- Asma Asemaninejad
- Natural Resources Canada, CanmetMINING, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada.
| | - Sean Langley
- Natural Resources Canada, CanmetMINING, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada
| | - Ted Mackinnon
- Natural Resources Canada, CanmetMINING, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada
| | - Graeme Spiers
- Laurentian University, Vale Living with Lakes Centre, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada; Laurentian University School of the Environment, Canada
| | - Peter Beckett
- Laurentian University, Vale Living with Lakes Centre, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada; Laurentian University Department of Biology, Canada
| | - Nadia Mykytczuk
- Laurentian University, Vale Living with Lakes Centre, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada; Laurentian University School of the Environment, Canada
| | - Nathan Basiliko
- Laurentian University, Vale Living with Lakes Centre, 935 Ramsey Lake Road, Sudbury, Ontario P3E 2C6, Canada; Laurentian University Department of Biology, Canada
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17
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Zhou Z, Latta DE, Scherer MM. Natural organic matter inhibits Ni stabilization during Fe(II)-catalyzed ferrihydrite transformation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142612. [PMID: 33045610 DOI: 10.1016/j.scitotenv.2020.142612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/23/2020] [Accepted: 09/23/2020] [Indexed: 05/26/2023]
Abstract
Trace metals, such as nickel (Ni), are often found associated with ferrihydrite (Fh) in soil and sediment and have been shown to redistribute during Fe(II)-catalyzed transformation of Fh. Fe(II)-catalyzed transformation of Fh, however, is often inhibited when natural organic matter (NOM) is associated with Fh. To explore whether NOM affects the behavior of Ni during Fe(II)-catalyzed transformation of Fh, we tracked Ni distribution, Fe atom exchange, and mineral transformation of Fh and Fh coprecipitated with Suwannee River natural organic matter (SRNOM-Fh). As expected, in the absence of Fe(II), Fh and SRNOM-Fh did not transform to secondary Fe minerals after two weeks. We further observed little difference in Ni adsorption on SRNOM-Fh compared to Fh. In the presence of Fe(II), however, we found that Ni associated with SRNOM-Fh was more susceptible to acid extraction than Fh. Specifically, we found almost double the amount of Ni remaining in the Fh after mild extraction compared to SRNOM-Fh. XRD showed that Fh transformed to goethite and magnetite whereas SRNOM-Fh did not transform despite 57Fe isotope tracer experiments confirmed that SRNOM-Fh underwent extensive atom exchange with aqueous Fe(II). Our findings suggest that Fe atom exchange may not be sufficient for obvious Ni stabilization and that transformation to secondary minerals may be necessary for Ni stabilization to occur.
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Affiliation(s)
- Zhe Zhou
- Department of Civil & Environmental Engineering, The University of Iowa, Iowa City, United States; Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.
| | - Drew E Latta
- Department of Civil & Environmental Engineering, The University of Iowa, Iowa City, United States
| | - Michelle M Scherer
- Department of Civil & Environmental Engineering, The University of Iowa, Iowa City, United States
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18
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Shi M, Min X, Ke Y, Lin Z, Yang Z, Wang S, Peng N, Yan X, Luo S, Wu J, Wei Y. Recent progress in understanding the mechanism of heavy metals retention by iron (oxyhydr)oxides. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 752:141930. [PMID: 32892052 DOI: 10.1016/j.scitotenv.2020.141930] [Citation(s) in RCA: 130] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 07/15/2020] [Accepted: 08/22/2020] [Indexed: 06/11/2023]
Abstract
Heavy metals are widespread toxic environmental pollutants that can generate enormous health and public concern. Iron (oxyhydr)oxides are ubiquitous in both natural and engineered environments and have great retention capacity of heavy metals due to their high surface areas and reactivity. The sequestration of heavy metal by iron (oxyhydr)oxides is one of the most vital geochemical/chemical processes controlling their environmental fate, transport, and bioavailability. In this review, some of the common iron (oxyhydr)oxides are introduced in detail in terms of their formation, occurrence, structure characteristics and interaction with heavy metals. Moreover, the retention mechanisms of metal cations (e.g., Pb, Cu, Cd, Ni, Zn), metal oxyanions (e.g., As, Sb, Cr), and coexisting multiple metals on various iron (oxyhydr)oxides are fully reviewed. Principal mechanisms of surface complexation, surface precipitation and structural incorporation are responsible for heavy metal retention on iron (oxyhydr)oxides, and greatly dependent on mineral species, metal ion species, reacting conditions (i.e., pH, heavy metal concentration, ionic strength, etc.) and chemical process (i.e., adsorption, coprecipitaton and mineral phase transformation process). The retention mechanisms summarized in this review would be helpful for remediating heavy metal contamination and predicting the long-term behavior of heavy metal in natural and engineered environments.
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Affiliation(s)
- Meiqing Shi
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Xiaobo Min
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Yong Ke
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Zhang Lin
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Zhihui Yang
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Sheng Wang
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Ning Peng
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Xu Yan
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China; Water Pollution Control Technology Key Lab of Hunan Province, Changsha 410004, China.
| | - Shuang Luo
- College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China
| | - Jiahui Wu
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
| | - Yangjin Wei
- Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China; Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
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19
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Gubler R, ThomasArrigo LK. Ferrous iron enhances arsenic sorption and oxidation by non-stoichiometric magnetite and maghemite. JOURNAL OF HAZARDOUS MATERIALS 2021; 402:123425. [PMID: 32739723 DOI: 10.1016/j.jhazmat.2020.123425] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/03/2020] [Accepted: 07/05/2020] [Indexed: 05/12/2023]
Abstract
Arsenic-contaminated waters affect millions of people on a daily basis. Because the toxicity of As is dependent on the redox state, understanding As biogeochemistry, particularly in reducing environments, is critical to addressing the environmental risk that As poses. Sorption of As to Fe(III)-(oxyhydr)oxides is an important mechanism for As removal from solution under anoxic conditions. However, dissolved ferrous Fe (Fe(II)) also occurs under anoxic conditions, and the impact that Fe(II)-catalyzed recrystallization of crystalline Fe minerals has on As sorption mechanisms is not clear. Our research investigates the potential for non-stoichiometric magnetite, a commonly occurring mixed-valence Fe oxide in anoxic aquifers, to adsorb and/or incorporate inorganic As species during Fe(II)-catalyzed recrystallization at neutral pH, with particular focus on the impact of mineral stoichiometry (Fe(II):Fe(III) = 0.23 and 0.0) and varying Fe(II) concentrations. By following aqueous As concentrations and speciation over time coupled with As K-edge X-ray absorption spectroscopy, our results demonstrate that the presence of Fe(II) substantially enhanced As removal from solution. In addition, we highlight a Fe(II)-induced mechanism through which highly mobile, toxic As(III) species are oxidized on the mineral surface to form As(V). Furthermore, the presence of Fe(II) promotes the structural incorporation of As(V) into the non-stoichiometric magnetite and maghemite structures. These results highlight the potential of Fe(II)-reacted non-stoichiometric magnetite or maghemite as pathways for long-term As sequestration in anoxic environments.
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Affiliation(s)
- Reto Gubler
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Universitätstrasse 16, CHN, CH-8092 Zurich, Switzerland
| | - 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.
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20
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Cai X, Yin N, Wang P, Du H, Liu X, Cui Y. Arsenate-reducing bacteria-mediated arsenic speciation changes and redistribution during mineral transformations in arsenate-associated goethite. JOURNAL OF HAZARDOUS MATERIALS 2020; 398:122886. [PMID: 32512445 DOI: 10.1016/j.jhazmat.2020.122886] [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] [Received: 02/19/2020] [Revised: 04/17/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
The fate of Fe(III)-(oxyhydr)oxides-bound As was generally regulated by dissimilatory As(V)-reduction. However, the impact of pH and bacterial conditions on the coupled processes of microbially-mediated As speciation changes and Fe-mineral transformation remains unclear. Our study therefore incubated As(V)-associated goethite with different As(V)-reducing bacteria at a range of pH. Results show that As reduction was most prominent at pH 7 as the bacterial growth was optimal. However, aqueous As concentration was the lowest (0.8-3.7 mg/L), due to rapid microbial Fe(II) formation at pH 7 triggered secondary mineralization and significant As-readsorption. Our study provides the first spectroscopic evidence for mineral-phase temporal evolution, and indicates in the presence of phosphate, vivianite will precipitate first and adsorb large amount of As(III) (40-44% of solid As). Thereafter, continuously increased Fe(II) may catalyze lepidocrocite and eventually magnetite formation, which further sequestrate aqueous As(III). Conversely, at pH 5 and 9, bacterial growth was inhibited, the corresponding lower microbially-derived Fe(II) concentrations caused no secondary minerals formation. Released As(III) was therefore largely remained in solution (6-9.7 mg/L). Our study demonstrates that As-bound Fe(III)-(oxyhydr)oxides could pose greater risks under acidic or alkaline conditions in biotic reactions. Additionally, bacterial species could strongly impact Fe-mineral transformation pathways and As solid-solution redistribution.
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Affiliation(s)
- Xiaolin Cai
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Naiyi Yin
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Pengfei Wang
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Huili Du
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Xiaotong Liu
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China
| | - Yanshan Cui
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 101408, People's Republic of China; Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China.
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Bylaska EJ, Catalano JG, Mergelsberg ST, Saslow SA, Qafoku O, Prange MP, Ilton ES. Association of Defects and Zinc in Hematite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:13687-13694. [PMID: 31689102 DOI: 10.1021/acs.est.9b04323] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Zn is an essential micronutrient that is often limited in tropical, lateritic soils in part because it is sequestered in nominally refractory iron oxide phases. Stable phases such as goethite and hematite, however, can undergo reductive recrystallization without a phase change under circumneutral pH conditions and release metal impurities such as Zn into aqueous solutions. Further, the process appears to be driven by Fe vacancies. In this contribution, we used ab initio molecular dynamics informed extended X-ray absorption fine structure spectra to show that Zn incorporated in the structure of hematite is associated with coupled O-Fe and protonated Fe vacancies, providing a potential link between crystal chemistry and the bioavailability of Zn.
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Affiliation(s)
- Eric J Bylaska
- Pacific Northwest National Laboratory , Richland Washington 99352 , United States
| | - Jeffrey G Catalano
- Department of Earth and Planetary Sciences , Washington University , St. Louis , Missouri 63130 , United States
| | | | - Sarah A Saslow
- Pacific Northwest National Laboratory , Richland Washington 99352 , United States
| | - Odeta Qafoku
- Pacific Northwest National Laboratory , Richland Washington 99352 , United States
| | - Micah P Prange
- Pacific Northwest National Laboratory , Richland Washington 99352 , United States
| | - Eugene S Ilton
- Pacific Northwest National Laboratory , Richland Washington 99352 , United States
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22
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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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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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24
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Constraints to Synergistic Fe Mobilization from Calcareous Soil by a Phytosiderophore and a Reductant. SOIL SYSTEMS 2018. [DOI: 10.3390/soilsystems2040067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Synergistic effects between ligand- and reductant-based Fe acquisition strategies can enhance the mobilization of Fe, but also of competing metals from soil. For phytosiderophores, this may alter the time and concentration window of Fe uptake during which plants can benefit from elevated Fe concentrations. We examined how the size of this window is affected by the ligand and reductant concentration and by non-simultaneous addition. To this end, a series of kinetic batch experiments was conducted with a calcareous clay soil to which the phytosiderophore 2′-deoxymugineic acid (DMA) and the reductant ascorbate were added at various concentrations, either simultaneously or with a one- or two-day lag time. Both simultaneous and non-simultaneous addition of the reductant and the phytosiderophore induced synergistic Fe mobilization. Furthermore, initial Fe mobilization rates increased with increasing reductant and phytosiderophore concentrations. However, the duration of the synergistic effect and the window of Fe uptake decreased with increasing reductant concentration due to enhanced competitive mobilization of other metals. Rate laws accurately describing synergistic mobilization of Fe and other metals from soil were parameterized. Synergistic Fe mobilization may be vital for the survival of plants and microorganisms in soils of low Fe availability. However, in order to optimally benefit from these synergistic effects, exudation of ligands and reductants in the rhizosphere need to be carefully matched.
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25
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ThomasArrigo LK, Byrne JM, Kappler A, Kretzschmar R. Impact of Organic Matter on Iron(II)-Catalyzed Mineral Transformations in Ferrihydrite-Organic Matter Coprecipitates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:12316-12326. [PMID: 30991468 DOI: 10.1021/acs.est.8b03206] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Poorly crystalline Fe(III) (oxyhydr)oxides like ferrihydrite are abundant in soils and sediments and are often associated with organic matter (OM) in the form of mineral-organic aggregates. Under anoxic conditions, interactions between aqueous Fe(II) and ferrihydrite lead to the formation of crystalline secondary minerals, like lepidocrocite, goethite, or magnetite. However, the extent to which Fe(II)-catalyzed mineral transformations are influenced by ferrihydrite-associated OM is not well understood. We therefore reacted ferrihydrite-PGA coprecipitates (PGA = polygalacturonic acid, C:Fe molar ratios = 0-2.5) and natural Fe-rich organic flocs (C:Fe molar ratio = 2.2) with 0.5-5.0 mM isotopically labeled 57Fe(II) at pH 7 for 5 weeks. Relying on the combination of stable Fe isotope tracers, a novel application of the PONKCS method to Rietveld fitting of X-ray diffraction (XRD) patterns, and 57Fe Mössbauer spectroscopy, we sought to follow the temporal evolution in Fe mineralogy and elucidate the fate of adsorbed 57Fe(II). At low C:Fe molar ratios (0-0.05), rapid oxidation of surface-adsorbed 57Fe(II) resulted in 57Fe-enriched crystalline minerals and nearly complete mineral transformation within days. With increasing OM content, the atom exchange between the added aqueous 57Fe(II) and Fe in the organic-rich solids still occurred; however, XRD analysis showed that crystalline mineral precipitation was strongly inhibited. For high OM-content materials (C:Fe ≥ 1.2), Mössbauer spectroscopy revealed up to 39% lepidocrocite in the final Fe(II)-reacted samples. Because lepidocrocite was not detectable by XRD, we suggest that the Mössbauer-detected lepidocrocite consisted of nanosized clusters with lepidocrocite-like local structure, similar to the lepidocrocite found in natural flocs. Collectively, our results demonstrate that the C content of ferrihydrite-OM coprecipitates strongly impacts the degree and pathways of Fe mineral transformations and iron atom exchange during reactions with aqueous Fe(II).
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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
| | - James M Byrne
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG) , University of Tübingen , Sigwartstrasse 10 , D-72076 Tübingen , Germany
| | - Andreas Kappler
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG) , University of Tübingen , Sigwartstrasse 10 , D-72076 Tübingen , Germany
| | - 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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26
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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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27
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Aqueous Fe(II)-Induced Phase Transformation of Ferrihydrite Coupled Adsorption/Immobilization of Rare Earth Elements. MINERALS 2018. [DOI: 10.3390/min8080357] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The phase transformation of iron minerals induced by aqueous Fe(II) (Fe(II)aq) is a critical geochemical reaction which greatly affects the geochemical behavior of soil elements. How the geochemical behavior of rare earth elements (REEs) is affected by the Fe(II)aq-induced phase transformation of iron minerals, however, is still unknown. The present study investigated the adsorption and immobilization of REEs during the Fe(II)aq-induced phase transformation of ferrihydrite. The results show that the heavy REEs of Ho(III) were more efficiently adsorbed and stabilized compared with the light REEs of La(III) by ferrihydrite and its transformation products, which was due to the higher adsorptive affinity and smaller atomic radius of Ho(III). Both La(III) and Ho(III) inhibited the Fe atom exchange between Fe(II)aq and ferrihydrite, and sequentially, the Fe(II)aq-induced phase transformation rates of ferrihydrite, because of the competitive adsorption with Fe(II)aq on the surface of iron (hydr)oxides. Owing to the larger amounts of adsorbed and stabilized Ho(III), the inhibition of the Fe(II)aq-induced phase transformation of ferrihydrite affected by Ho(III) was higher than that by La(III). Our findings suggest an important role for the Fe(II)aq-induced phase transformation of iron (hydr)oxides in assessing the mobility and transfer behavior of REEs, as well as for their occurrence in earth surface environments.
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28
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Flynn ED, Catalano JG. Influence of Oxalate on Ni Fate during Fe(II)-Catalyzed Recrystallization of Hematite and Goethite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6920-6927. [PMID: 29806459 DOI: 10.1021/acs.est.8b00641] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
During biogeochemical iron cycling at redox interfaces, dissolved Fe(II) induces the recrystallization of Fe(III) oxides. Oxalate and other organic acids promote dissolution of these minerals and may also induce recrystallization. These processes may redistribute trace metals among the mineral bulk, mineral surface, and aqueous solution. However, the impact of interactions among organic acids, dissolved Fe(II), and iron oxide minerals on trace metal fate in such systems is unclear. The present study thus explores the effect of oxalate on Ni release from and incorporation into hematite and goethite in the absence and presence of Fe(II). When Ni is initially structurally incorporated into the iron oxides, both oxalate and dissolved Fe(II) promote the release of Ni to aqueous solution. When both species are present, their effects on Ni release are synergistic at pH 7 but inhibitory at pH 4, indicating that cooperative and competitive interactions vary with pH. In contrast, oxalate suppresses Ni incorporation into goethite and hematite during Fe(II)-induced recrystallization, decreasing the proportion of Ni substituting in a mineral structure by up to 36%. These observations suggest that at redox interfaces oxalate largely enhances trace metal mobility. In such settings, oxalate, and likely other organic acids, may thus enhance micronutrient availability and inhibit contaminant sequestration.
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Affiliation(s)
- Elaine D Flynn
- Department of Earth and Planetary Sciences , Washington University , St. Louis , Missouri 63130 , United States
| | - Jeffrey G Catalano
- Department of Earth and Planetary Sciences , Washington University , St. Louis , Missouri 63130 , United States
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29
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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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30
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Li Y, Wei G, He H, Liang X, Chu W, Huang D, Zhu J, Tan W, Huang Q. Improvement of zinc substitution in the reactivity of magnetite coupled with aqueous Fe(II) towards nitrobenzene reduction. J Colloid Interface Sci 2018; 517:104-112. [PMID: 29421670 DOI: 10.1016/j.jcis.2018.01.103] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 12/14/2017] [Accepted: 01/29/2018] [Indexed: 11/26/2022]
Abstract
The reduction of nitrobenzene (NB) by Zn-substituted magnetite coupled with aqueous Fe(II) was studied. A series of Zn-substituted magnetites (Fe3-xZnxO4, x = 0, 0.25, 0.49, 0.74, and 0.99) were synthesized by a coprecipitation method followed by systematic analysis of the variation in structure and physicochemical properties of magnetite using XRD, TEM, TG, BET and XAFS. All of the samples had a spinel structure by Zn substitution. Zn2+ primarily occupied the tetrahedral sites, but a portion of them moved to the octahedral sites at higher Zn level. Zn substitution increased the BET specific surface area and surface hydroxyl amount. The electron balance indicated that the NB reduction was primarily through the heterogeneous reaction by Fe3-xZnxO4 and adsorbed Fe(II), where NB in aqueous solution was reduced by structural Fe2+ in magnetite recharged by adsorbed Fe(II). Various factors, such as aqueous Fe(II) concentration, magnetite stoichiometry and Zn level, were investigated to illustrate their effects on the reduction processes. Both the rate constant kobs and electron transfer amount illustrated that Zn substitution generally improved the reduction activity of the Fe3-xZnxO4/Fe(II) system, while overdose of Zn retarded the process. This issue was attributed to the variation in electron conductivity of Fe3-xZnxO4 and Zn2+ occupancy.
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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; University of Chinese Academy of Sciences, Beijing 100049, 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
| | - 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
| | - 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.
| | - Wei Chu
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
| | - Deyin Huang
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangzhou 510650, 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
| | - Wei Tan
- 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
| | - Qiuxin Huang
- CEPREI Environmental Assessment and Monitoring Center, The 5th Electronics Research Institute of the Ministry of Industry and Information Technology, Guangzhou 510610, PR China
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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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32
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Huhmann BL, Neumann A, Boyanov MI, Kemner KM, Scherer MM. Emerging investigator series: As(v) in magnetite: incorporation and redistribution. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2017; 19:1208-1219. [PMID: 28871292 DOI: 10.1039/c7em00237h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Exposure to As in groundwater negatively impacts millions of people around the globe, and As mobility in groundwater is often controlled by Fe mineral dissolution and precipitation. Additionally, trace elements can be released from and incorporated into the structure of Fe oxides in the presence of dissolved Fe(ii). The potential for As to redistribute between sorbed on the magnetite surface and incorporated in the magnetite structure, however, remains unclear. In this study, we use selective chemical extraction and X-ray absorption spectroscopy (XAS) to distinguish magnetite-sorbed and incorporated As(v) and to provide evidence for As(v) incorporation during magnetite precipitation. While As in the As-magnetite coprecipitates did not redistribute between sorbed and incorporated over a 4 month period, a small, but measurable increase in incorporated As(v) of up to 13% was observed for sorbed As(v). We suggest that Fe(ii)-catalyzed recrystallization of magnetite did not significantly influence the redistribution of sorbed As(v) because the extent of Fe atom exchange was small (∼10%). In addition, the extent of As redistribution was the same in the absence and presence of added aqueous Fe(ii), suggesting that aqueous Fe(ii) had, overall, a minor effect on As redistribution for both coprecipitated and sorbed As(v). Our results suggest that coprecipitation of As(v) with magnetite and redistribution of As(v) sorbed on magnetite are potential pathways for irreversible As(v) uptake and sequestration. These pathways are likely to play a significant role in controlling As mobility in natural systems, during human-induced redox cycling of groundwater such as aquifer storage and recovery, as well as in iron oxide-based As removal systems.
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Affiliation(s)
- Brittany L Huhmann
- Department of Civil and Environmental Engineering, University of Iowa, Iowa City, IA 52242, USA
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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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ThomasArrigo LK, Mikutta C, Byrne J, Kappler A, Kretzschmar R. Iron(II)-Catalyzed Iron Atom Exchange and Mineralogical Changes in Iron-rich Organic Freshwater Flocs: An Iron Isotope Tracer Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:6897-6907. [PMID: 28590131 DOI: 10.1021/acs.est.7b01495] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In freshwater wetlands, organic flocs are often found enriched in trace metal(loid)s associated with poorly crystalline Fe(III)-(oxyhydr)oxides. Under reducing conditions, flocs may become exposed to aqueous Fe(II), triggering Fe(II)-catalyzed mineral transformations and trace metal(loid) release. In this study, pure ferrihydrite, a synthetic ferrihydrite-polygalacturonic acid coprecipitate (16.7 wt % C), and As- (1280 and 1230 mg/kg) and organic matter (OM)-rich (18.1 and 21.8 wt % C) freshwater flocs dominated by ferrihydrite and nanocrystalline lepidocrocite were reacted with an isotopically enriched 57Fe(II) solution (0.1 or 1.0 mM Fe(II)) at pH 5.5 and 7. Using a combination of wet chemistry, Fe isotope analysis, X-ray absorption spectroscopy (XAS), 57Fe Mössbauer spectroscopy and X-ray diffraction, we followed the Fe atom exchange kinetics and secondary mineral formation over 1 week. When reacted with Fe(II) at pH 7, pure ferrihydrite exhibited rapid Fe atom exchange at both Fe(II) concentrations, reaching 76 and 89% atom exchange in experiments with 0.1 and 1 mM Fe(II), respectively. XAS data revealed that it transformed into goethite (21%) at the lower Fe(II) concentration and into lepidocrocite (73%) and goethite (27%) at the higher Fe(II) concentration. Despite smaller Fe mineral particles in the coprecipitate and flocs as compared to pure ferrihydrite (inferred from Mössbauer-derived blocking temperatures), these samples showed reduced Fe atom exchange (9-30% at pH 7) and inhibited secondary mineral formation. No release of As was recorded for Fe(II)-reacted flocs. Our findings indicate that carbohydrate-rich OM in flocs stabilizes poorly crystalline Fe minerals against Fe(II)-catalyzed transformation by surface-site blockage and/or organic Fe(II) complexation. This hinders the extent of Fe atom exchange at mineral surfaces and secondary mineral formation, which may consequently impair Fe(II)-activated trace metal(loid) release. Thus, under short-term Fe(III)-reducing conditions facilitating the fast attainment of solid-solution equilibria (e.g., in stagnant waters), Fe-rich freshwater flocs are expected to remain an effective sink for trace elements.
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Affiliation(s)
- Laurel K ThomasArrigo
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich , Universitätstrasse 16, CH-8092 Zurich, Switzerland
| | - Christian Mikutta
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich , Universitätstrasse 16, CH-8092 Zurich, Switzerland
| | - James Byrne
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG), University of Tübingen , Sigwartstrasse 10, D-72076, Tübingen, Germany
| | - Andreas Kappler
- Geomicrobiology Group, Centre for Applied Geosciences (ZAG), University of Tübingen , Sigwartstrasse 10, D-72076, Tübingen, Germany
| | - Ruben Kretzschmar
- Soil Chemistry Group, Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, CHN, ETH Zurich , Universitätstrasse 16, CH-8092 Zurich, Switzerland
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Zhang D, Guo H, Xiu W, Ni P, Zheng H, Wei C. In-situ mobilization and transformation of iron oxides-adsorbed arsenate in natural groundwater. JOURNAL OF HAZARDOUS MATERIALS 2017; 321:228-237. [PMID: 27631685 DOI: 10.1016/j.jhazmat.2016.09.021] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 08/28/2016] [Accepted: 09/08/2016] [Indexed: 05/12/2023]
Abstract
Although reductive dissolution of Fe(III) oxides has been well accepted for As mobilization in alluvial aquifers, the key factors controlling this process are poorly understood. Arsenic(V)-adsorbing ferrihydrite, goethite and hematite were used to examine in-situ mobilization and transformation of adsorbed As(V) and Fe(III) oxides. In the Hetao basin, seven wells with wide ranges of groundwater As were selected to host As(V)-Fe(III) oxides sand. During 80 d experiments, As was firstly desorbed and then released via reductive dissolution of iron oxide from ferrihydrite, while only desorption was observed from goethite/hematite sand. Desorbed As was predominantly controlled by groundwater HCO3- and DOC, while reductive dissolution-related As release was mainly regulated by ORP values, DOC and Fe(II) concentrations. Mineral transformation from ferrihydrite to lepidocrocite and goethite/or mackinawite would also contribute to As release. Arsenic species was transformed from As(V) to As(III) on ferrihydrite, but remained unchanged on goethite and hematite. Arsenic partition between As-Fe(III) oxide sand and real groundwater ranged between 0.012 and 0.102L/g. Kd-sand between As-goethite sand/As-hematite sand and groundwater fell within the ranges observed between sediments and groundwater. This study suggests that As desorption, reductive dissolution and mineral transformation of ferrihydrite would be the major processes controlling As mobility.
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Affiliation(s)
- Di Zhang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Huaming Guo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China.
| | - Wei Xiu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China; School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Ping Ni
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Hao Zheng
- School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing 100083, PR China
| | - Cao Wei
- The National Institute of Metrology, Beijing 100013, PR China
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36
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Elzinga EJ. (54)Mn Radiotracers Demonstrate Continuous Dissolution and Reprecipitation of Vernadite (δ-MnO2) during Interaction with Aqueous Mn(II). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:8670-7. [PMID: 27403960 DOI: 10.1021/acs.est.6b02874] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
(54)Mn radiotracers were used to assess Mn atom exchange between aqueous Mn(II) and vernadite (δ-MnO2) at pH 5.0. Continuous solid-liquid redistribution of (54)Mn atoms occurred, and systems are near isotopic equilibrium after reaction for 3 months. Despite this extensive exchange, X-ray diffraction and X-ray absorption spectroscopy data showed no major changes in vernadite bulk mineralogy. These results demonstrate that the vernadite-Mn(II) interface is dynamic, with the substrate undergoing continuous dissolution and reprecipitation mediated by aqueous Mn(II) without observable impacts on its mineralogy. Interfacial redox reactions between adsorbed Mn(II) and solid-phase Mn(IV) and Mn(III) are proposed as the main drivers of this process. Interaction between aqueous Mn(II) and structural Mn(III) likely involves interfacial electron transfer coupled with Mn atom exchange. The exchange of aqueous Mn(II) and solid-phase Mn(IV) is more complex and is proposed to result from coupled interfacial comproportionation-disproportionation reactions, where electron transfer from adsorbed Mn(II) to lattice Mn(IV) produces transient Mn(III) species that disproportionate to regenerate aqueous Mn(II) and structural Mn(IV). These findings provide further evidence of the importance of Mn(II)(aq)-MnO2(s) interactions and the attendant production of transient Mn(III) intermediates to the geochemical functioning of phyllomanganates in environments undergoing Mn redox cycling.
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Affiliation(s)
- Evert J Elzinga
- Department of Earth & Environmental Sciences, Rutgers University , 101 Warren Street, Newark, New Jersey 07102, United States
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Frierdich AJ, Spicuzza MJ, Scherer MM. Oxygen Isotope Evidence for Mn(II)-Catalyzed Recrystallization of Manganite (γ-MnOOH). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6374-6380. [PMID: 27249316 DOI: 10.1021/acs.est.6b01463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Manganese is biogeochemically cycled between aqueous Mn(II) and Mn(IV) oxides. Aqueous Mn(II) often coexists with Mn(IV) oxides, and redox reactions between the two (e.g., comproportionation) are well known to result in the formation of Mn(III) minerals. It is unknown, however, whether aqueous Mn(II) exchanges with structural Mn(III) in manganese oxides in the absence of any mineral transformation (similar to what has been reported for aqueous Fe(II) and some Fe(III) minerals). To probe whether atoms exchange between a Mn(III) oxide and water, we use a (17)O tracer to measure oxygen isotope exchange between structural oxygen in manganite (γ-MnOOH) and water. In the absence of aqueous Mn(II), about 18% of the oxygen atoms in manganite exchange with the aqueous phase, which is close to the estimated surface oxygen atoms (∼11%). In the presence of aqueous Mn(II), an additional 10% (for a total of 28%) of the oxygen atoms exchange with water, suggesting that some of the bulk manganite mineral (i.e., beyond surface) is exchanging with the fluid. Exchange of manganite oxygen with water occurs without any observable change in mineral phase and appears to be independent of the rapid Mn(II) sorption kinetics. These experiments suggest that Mn(II) catalyzes manganese oxide recrystallization and illustrate a new pathway by which these ubiquitous minerals interact with their surrounding fluid.
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Affiliation(s)
- Andrew J Frierdich
- School of Earth, Atmosphere & Environment, Monash University , Clayton, VIC 3800, Australia
| | - Michael J Spicuzza
- Department of Geoscience, University of Wisconsin , Madison, Wisconsin 53706, United States
| | - Michelle M Scherer
- Department of Civil and Environmental Engineering, University of Iowa , Iowa City, Iowa 52242, United States
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Schenkeveld WDC, Wang Z, Giammar DE, Kraemer SM. Synergistic Effects between Biogenic Ligands and a Reductant in Fe Acquisition from Calcareous Soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:6381-6388. [PMID: 27218689 DOI: 10.1021/acs.est.6b01623] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Organisms have developed different strategies to cope with environmental conditions of low Fe availability based on the exudation of reducing, ligating, and acidifying compounds. In the context of Fe acquisition from soil, the effects of these reactive compounds have generally been considered independent and additive. However, highly efficient Fe acquisition strategies may rely on synergistic effects between reactive exudates. In the present study, we demonstrate that synergistic effects between biogenic ligands and a reductant (ascorbate) can occur in Fe mobilization from soil. Synergistic Fe mobilization was found for all ligands examined (desferrioxamine B (DFOB), 2'-deoxymugineic acid (DMA), esculetin, and citrate). The size and duration of the synergistic effect on Fe mobilization varied with ligand: larger effects were observed for the sideorphores compared to esculetin and citrate. For DFOB, the synergistic effect lasted for the 168 h duration of the experiment; for DMA, an initial synergistic effect turned into an antagonistic effect after 4 h because of enhanced mobilization of competing metals; and for esculetin and citrate, the synergistic effect was temporary (less than 24 h). Our results demonstrate that synergistic effects greatly enhance the reactivity of mixtures of compounds known to be exuded in response to Fe limitation. These synergistic effects could be decisive for the survival of plants and microorganisms under conditions of low Fe availability.
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Affiliation(s)
- Walter D C Schenkeveld
- Department of Environmental Geosciences and Environmental Science Research Network, University of Vienna , Althanstraße 14 (UZA II), 1090 Vienna, Austria
| | - Zimeng Wang
- Department of Civil and Environmental Engineering, Stanford University , 473 Via Ortega Stanford, California 94305, United States
| | - Daniel E Giammar
- Department of Energy, Environmental & Chemical Engineering, Washington University in St. Louis , 1 Brookings Drive, CB 1180, St. Louis, Missouri 63130, United States
| | - Stephan M Kraemer
- Department of Environmental Geosciences and Environmental Science Research Network, University of Vienna , Althanstraße 14 (UZA II), 1090 Vienna, Austria
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Konhauser KO, Robbins LJ, Pecoits E, Peacock C, Kappler A, Lalonde SV. The Archean Nickel Famine Revisited. ASTROBIOLOGY 2015; 15:804-815. [PMID: 26426143 DOI: 10.1089/ast.2015.1301] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Iron formations (IF) preserve a history of Precambrian oceanic elemental abundance that can be exploited to examine nutrient limitations on early biological productivity. However, in order for IF to be employed as paleomarine proxies, lumped-process distribution coefficients for the element of interest must be experimentally determined or assumed. This necessitates consideration of bulk ocean chemistry and which authigenic ferric iron minerals controlled the sorption reactions. It also requires an assessment of metal mobilization reactions that might have occurred in the water column during particle descent and during post-depositional burial. Here, we summarize recent developments pertaining to the interpretation and fidelity of the IF record in reconstructions of oceanic trace element evolution. Using an updated compilation, we reexamine and validate temporal trends previously reported for the nickel content in IF (see Konhauser et al., 2009 ). Finally, we reevaluate the consequences of methanogen Ni starvation in the context of evolving views of the Archean ocean-climate system and how the Ni famine may have ultimately facilitated the rise in atmospheric oxygen.
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Affiliation(s)
- Kurt O Konhauser
- 1 Department of Earth and Atmospheric Sciences, University of Alberta , Edmonton, Canada
| | - Leslie J Robbins
- 1 Department of Earth and Atmospheric Sciences, University of Alberta , Edmonton, Canada
| | - Ernesto Pecoits
- 1 Department of Earth and Atmospheric Sciences, University of Alberta , Edmonton, Canada
- 2 Equipe Géobiosphère, Institut de Physique du Globe-Sorbonne Paris Cité, Université Paris Diderot , CNRS, Paris, France
| | - Caroline Peacock
- 3 School of Earth and Environment, University of Leeds , Leeds, UK
| | - Andreas Kappler
- 4 Geomicrobiology, Center for Applied Geoscience, Eberhard-Karls-University Tuebingen , Tuebingen, Germany
| | - Stefan V Lalonde
- 5 CNRS-UMR6538 Laboratoire Domaines Océaniques, European Institute for Marine Studies , Technopôle Brest-Iroise, Plouzané, France
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40
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Frierdich AJ, Helgeson M, Liu C, Wang C, Rosso KM, Scherer MM. Iron Atom Exchange between Hematite and Aqueous Fe(II). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8479-86. [PMID: 26069932 DOI: 10.1021/acs.est.5b01276] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Aqueous Fe(II) has been shown to exchange with structural Fe(III) in goethite without any significant phase transformation. It remains unclear, however, whether aqueous Fe(II) undergoes similar exchange reactions with structural Fe(III) in hematite, a ubiquitous iron oxide mineral. Here, we use an enriched (57)Fe tracer to show that aqueous Fe(II) exchanges with structural Fe(III) in hematite at room temperature, and that the amount of exchange is influenced by particle size, pH, and Fe(II) concentration. Reaction of 80 nm-hematite (27 m(2) g(-1)) with aqueous Fe(II) at pH 7.0 for 30 days results in ∼5% of its structural Fe(III) atoms exchanging with Fe(II) in solution, which equates to about one surface iron layer. Smaller, 50 nm-hematite particles (54 m(2) g(-1)) undergo about 25% exchange (∼3× surface iron) with aqueous Fe(II), demonstrating that structural Fe(III) in hematite is accessible to the fluid in the presence of Fe(II). The extent of exchange in hematite increases with pH up to 7.5 and then begins to decrease as the pH progresses to 8.0, likely due to surface site saturation by sorbed Fe(II). Similarly, when we vary the initial amount of added Fe(II), we observe decreasing amounts of exchange when aqueous Fe(II) is increased beyond surface saturation. This work shows that Fe(II) can catalyze iron atom exchange between bulk hematite and aqueous Fe(II), despite hematite being the most thermodynamically stable iron oxide.
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Affiliation(s)
- Andrew J Frierdich
- †Department of Civil and Environmental Engineering, University of Iowa, Iowa City, Iowa 52242, United States
- ‡Department of Geoscience, University of Wisconsin, Madison, Wisconsin 53706, United States
| | - Maria Helgeson
- †Department of Civil and Environmental Engineering, University of Iowa, Iowa City, Iowa 52242, United States
| | - Chengshuai Liu
- §Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, 510650, P. R. China
| | - Chongmin Wang
- ∥Pacific Northwest National Laboratory, Richland, Washington 99352, 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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41
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Elzinga EJ, Kustka AB. A Mn-54 radiotracer study of Mn isotope solid-liquid exchange during reductive transformation of vernadite (δ-MnO2) by aqueous Mn(II). ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:4310-6. [PMID: 25751090 DOI: 10.1021/acs.est.5b00022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We employed Mn-54 radiotracers to characterize the extent and dynamics of Mn atom exchange between aqueous Mn(II) and vernadite (δ-Mn(IV)O2) at pH 7.5 under anoxic conditions. Exchange of Mn atoms between the solid and liquid phase is rapid, reaching dynamic equilibrium in 2-4 days. We propose that during the initial stages of reaction, Mn atom exchange occurs through consecutive comproportionation-disproportionation reactions where interfacial electron transfer from adsorbed Mn(II) to lattice Mn(IV) generates labile Mn(III) cations that rapidly disproportionate to reform aqueous Mn(II) and solid-phase Mn(IV). Following nucleation of Mn(III)OOH phases, additional exchange likely occurs through electron transfer from aqueous Mn(II) to solid-phase Mn(III). Our results provide evidence for the fast and extensive production of transient Mn(III) species at the vernadite surface upon contact of this substrate with dissolved Mn(II). We further show that HEPES buffer is a reductant of lattice Mn(IV) in the vernadite structure in our experiments. The methods and results presented here introduce application of Mn-54 tracers as a facile tool to further investigate the formation kinetics of labile Mn(III) surface species and their impacts on Mn-oxide structure and reactivity over a range of environmentally relevant geochemical conditions.
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Zarzycki P, Smith DM, Rosso KM. Proton Dynamics on Goethite Nanoparticles and Coupling to Electron Transport. J Chem Theory Comput 2015; 11:1715-24. [DOI: 10.1021/ct500891a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Piotr Zarzycki
- Institute
of Physical Chemistry, Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Dayle M. Smith
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Kevin M. Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
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Handler RM, Frierdich AJ, Johnson CM, Rosso KM, Beard BL, Wang C, Latta DE, Neumann A, Pasakarnis T, Premaratne WAPJ, Scherer MM. Fe(II)-catalyzed recrystallization of goethite revisited. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:11302-11. [PMID: 25248028 DOI: 10.1021/es503084u] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Results from enriched (57)Fe isotope tracer experiments have shown that atom exchange can occur between structural Fe in Fe(III) oxides and aqueous Fe(II) with no formation of secondary minerals or change in particle size or shape. Here we derive a mass balance model to quantify the extent of Fe atom exchange between goethite and aqueous Fe(II) that accounts for different Fe pool sizes. We use this model to reinterpret our previous work and to quantify the influence of particle size and pH on extent of goethite exchange with aqueous Fe(II). Consistent with our previous interpretation, substantial exchange of goethite occurred at pH 7.5 (≈ 90%) and we observed little effect of particle size between nanogoethite (average size of 81 × 11 nm; ≈ 110 m(2)/g) and microgoethite (average size of 590 × 42 nm; ≈ 40 m(2)/g). Despite ≈ 90% of the bulk goethite exchanging at pH 7.5, we found no change in mineral phase, average particle size, crystallinity, or reactivity after reaction with aqueous Fe(II). At a lower pH of 5.0, no net sorption of Fe(II) was observed and significantly less exchange occurred accounting for less than the estimated proportion of surface Fe atoms in the particles. Particle size appears to influence the amount of exchange at pH 5.0 and we suggest that aggregation and surface area may play a role. Results from sequential chemical extractions indicate that (57)Fe accumulates in extracted Fe(III) goethite components. Isotopic compositions of the extracts indicate that a gradient of (57)Fe develops within the goethite with more accumulation of (57)Fe occurring in the more easily extracted Fe(III) that may be nearer to the surface.
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Affiliation(s)
- Robert M Handler
- Sustainable Futures Institute, Michigan Technological University 1400 Townsend Drive, Houghton, Michigan 49931, United States
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Boland DD, Collins RN, Glover CJ, Payne TE, Waite TD. Reduction of U(VI) by Fe(II) during the Fe(II)-accelerated transformation of ferrihydrite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:9086-9093. [PMID: 25014507 DOI: 10.1021/es501750z] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
X-ray absorption spectroscopy has been used to study the reduction of adsorbed U(VI) during the Fe(II)-accelerated transformation of ferrihydrite to goethite. The fate of U(VI) was examined across a variety of pH values and Fe(II) concentrations, with results suggesting that, in all cases, it was reduced over the course of the Fe(III) phase transformation to a U(V) species incorporated in goethite. A positive correlation between U(VI) reduction and ferrihydrite transformation rate constants implies that U(VI) reduction was driven by the production of goethite under the conditions used in these studies. This interpretation was supported by additional experimental evidence that demonstrated the (fast) reduction of U(VI) to U(V) by Fe(II) in the presence of goethite only. Theoretical redox potential calculations clearly indicate that the reduction of U(VI) by Fe(II) in the presence of goethite is thermodynamically favorable. In contrast, reduction of U(VI) by Fe(II) in the presence of ferrihydrite is largely thermodynamically unfavorable within the range of conditions examined in this study.
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Affiliation(s)
- Daniel D Boland
- School of Civil and Environmental Engineering, University of New South Wales , Sydney, NSW 2052, Australia
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Gomez MA, Hendry MJ, Elouatik S, Essilfie-Dughan J, Paikaray S. Fe(ii)(aq)uptake of Mg(ii)–Al(iii)/Fe(iii)–SO4/CO3HTLCs under alkaline conditions: adsorption and solid state transformation mechanisms. RSC Adv 2014. [DOI: 10.1039/c4ra08802f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Abiotic reduction of Mg(ii)–Al(iii)/Fe(iii)–SO4/CO3hydrotalcites (HTLCs) was investigated under three anoxic abiotic reaction conditions: (1) a target pH of 8 and 10 mM Fe(ii)(aq), (2) a target pH of 8 and 0.5 mM Fe(ii)(aq), and (3) a target pH of 10 and 0.5 mM Fe(ii)(aq).
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Affiliation(s)
- Mario A. Gomez
- Department of Geological Sciences
- University of Saskatchewan
- Saskatoon, Canada
| | - M. Jim Hendry
- Department of Geological Sciences
- University of Saskatchewan
- Saskatoon, Canada
| | - Samir Elouatik
- Department of Chemistry
- University of Montreal
- Montreal, Canada
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Boland DD, Collins RN, Glover CJ, David Waite T. An in situ quick-EXAFS and redox potential study of the Fe(II)-catalysed transformation of ferrihydrite. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2013.02.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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47
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Gomez MA, Jim Hendry M, Hossain A, Das S, Elouatik S. Abiotic reduction of 2-line ferrihydrite: effects on adsorbed arsenate, molybdate, and nickel. RSC Adv 2013. [DOI: 10.1039/c3ra44769c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Abstract
Recent work has indicated that iron (oxyhydr-)oxides are capable of structurally incorporating and releasing metals and nutrients as a result of Fe2+-induced iron oxide recrystallization. In the present paper, we briefly review the current literature examining the mechanisms by which iron oxides recrystallize and summarize how recrystallization affects metal incorporation and release. We also provide new experimental evidence for the Fe2+-induced release of structural manganese from manganese-doped goethite. Currently, the exact mechanism(s) for Fe2+-induced recrystallization remain elusive, although they are likely to be both oxide-and metal-dependent. We conclude by discussing some future research directions for Fe2+-catalysed iron oxide recrystallization.
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Lanzl CA, Baltrusaitis J, Cwiertny DM. Dissolution of hematite nanoparticle aggregates: influence of primary particle size, dissolution mechanism, and solution pH. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15797-15808. [PMID: 23078147 DOI: 10.1021/la3022497] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The size-dependent dissolution of nanoscale hematite (8 and 40 nm α-Fe(2)O(3)) was examined across a broad range of pH (pH 1-7) and mechanisms including proton- and ligand- (oxalate-) promoted dissolution and dark (ascorbic acid) and photochemical (oxalate) reductive dissolution. Empirical relationships between dissolution rate and pH revealed that suspensions of 8 nm hematite exhibit between 3.3- and 10-fold greater reactivity per unit mass than suspensions of 40 nm particles across all dissolution modes and pH, including circumneutral. Complementary suspension characterization (i.e., sedimentation studies and dynamic light scattering) indicated extensive aggregation, with steady-state aggregate sizes increasing with pH but being roughly equivalent for both primary particles. Thus, while the reactivity difference between 8 and 40 nm suspensions is generally greater than expected from specific surface areas measured via N(2)-BET or estimated from primary particle geometry, loss of reactive surface area during aggregation limits the certainty of such comparisons. We propose that the relative reactivity of 8 and 40 nm hematite suspensions is best explained by differences in the fraction of aggregate surface area that is reactive. This scenario is consistent with TEM images revealing uniform dissolution of aggregated 8 nm particles, whereas 40 nm particles within aggregates undergo preferential etching at edges and structural defects. Ultimately, we show that comparably sized hematite aggregates can exhibit vastly different dissolution activity depending on the nature of the primary nanoparticles from which they are constructed, a result with wide-ranging implications for iron redox cycling.
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Affiliation(s)
- Caylyn A Lanzl
- Department of Civil and Environmental Engineering, University of Iowa, Iowa City, Iowa 52242, United States
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Catalano JG, Huhmann BL, Luo Y, Mitnick EH, Slavney A, Giammar DE. Metal release and speciation changes during wet aging of coal fly ashes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:11804-11812. [PMID: 23035817 DOI: 10.1021/es302807b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Introduction of coal fly ash into aquatic systems poses a potential environmental hazard because of its heavy metal content. Here we investigate the relationship between solid phase transformations, fluid composition, and metal release and speciation during prolonged wet aging of a class C and class F coal fly ash. The class C ash causes rapid alkalinization of water that is neutralized over time by CO(2) uptake from air and calcite precipitation. The resulting aqueous metal concentrations are below regulatory limits with the exception of Cr; solubility constraints suggest this is released as chromate. Limited As release is accompanied by no change in solid-phase speciation, but up to 35% of the Zn in the ash dissolves and reprecipitates in secondary phases. Similar processes inhibit Ba and Cu release. In contrast, the class F ash causes rapid acidification of water and initially releases substantial quantities of As, Se, Cr, Cu, Zn, and Ba. Arsenic concentrations decline during aging because of adsorption to the iron oxide-rich ash; this is aided by As(III) oxidation. Precipitation processes lower Ba and Cr concentrations during aging. Se, Cu, and Zn concentrations remain elevated during wet aging and solid-phase Zn speciation is not affected by ash-water reactions. Total metal contents were poor predictors of metal release, which is predominantly controlled by metal speciation and the effects of ash-water reactions on fluid pH. While contact with atmospheric gases has little effect on class F ash, carbonation of class C ash inhibits metal release and neutralizes the alkalinity produced by the ash.
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Affiliation(s)
- Jeffrey G Catalano
- Department of Earth and Planetary Sciences, Washington University, Saint Louis, Missouri 63130, USA.
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