1
|
Dai W, Wang Y, Guo W, Wang G, Qiu M. Effects of Fe(II) and humic acid on U(VI) mobilization onto oxidized carbon nanofibers derived from the pyrolysis of bacterial cellulose. Int J Biol Macromol 2024; 266:131210. [PMID: 38552692 DOI: 10.1016/j.ijbiomac.2024.131210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Revised: 03/18/2024] [Accepted: 03/26/2024] [Indexed: 04/02/2024]
Abstract
The effects of Fe(II) and humic acid on U(VI) immobilization onto oxidized carbon nanofibers (Ox-CNFs, pyrolysis of bacterial cellulose) were investigated by batch, spectroscopic and modeling techniques, with results suggesting that, Ox-CNFs exhibited fast adsorption rate (adsorption equilibrium within 3 h), high adsorption performance (maximum adsorption capacity of 208.4 mg/g), good recyclability (no notable change after five regenerations) in the presence of Fe(II) towards U(VI) from aqueous solutions (e.g., 40 % reduction and 10 % adsorption at pH 8.0), which was attributed to the various oxygen-containing functional groups, excellent chemical stability, large specific surface area and high redox effect. U(VI) adsorption increased with increasing pH from 2.0 to 5.0, then high-level plateau and remarkable decrease were observed at 5.0-6.0 and at pH > 6.0, respectively. According to FT-IR and XPS analysis, a negative correlation between U(VI) reduction and organic in the presence of Fe(II) implied that U(VI) reduction was driven by Fe(II) while inhibited by humic acid. The interaction mechanism of U(VI) on Ox-CNFs was demonstrated to be adsorption and ion exchange at low pH and reduction at high pH according to XPS and surface complexation modeling. These findings filled the knowledge gaps pertaining to the effect of Fe(II) on the transformation and fate of U(VI) in the actual environment. This carbon material with distinctive performance and unique topology offers a potential platform for actual application in environmental remediation.
Collapse
Affiliation(s)
- Weisheng Dai
- College of Life and Environmental Science, Shaoxing University, Shaoxing 312000, PR China; Shaoxing Raw Water Group Co., LTD., Shaoxing 312000, PR China
| | - Yao Wang
- College of Life and Environmental Science, Shaoxing University, Shaoxing 312000, PR China
| | - Weijuan Guo
- College of Life and Environmental Science, Shaoxing University, Shaoxing 312000, PR China
| | - Guofu Wang
- College of Life and Environmental Science, Shaoxing University, Shaoxing 312000, PR China; School of Architectural Engineering, Shaoxing University Yuanpei College, Shaoxing 312000, PR China.
| | - Muqing Qiu
- College of Life and Environmental Science, Shaoxing University, Shaoxing 312000, PR China.
| |
Collapse
|
2
|
Pan Z, Loreggian L, Roebbert Y, Bartova B, Hunault MOJ, Weyer S, Bernier-Latmani R. Pentavalent U Reactivity Impacts U Isotopic Fractionation during Reduction by Magnetite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:6595-6604. [PMID: 38573735 PMCID: PMC11025122 DOI: 10.1021/acs.est.3c10324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024]
Abstract
Meaningful interpretation of U isotope measurements relies on unraveling the impact of reduction mechanisms on the isotopic fractionation. Here, the isotope fractionation of hexavalent U [U(VI)] was investigated during its reductive mineralization by magnetite to intermediate pentavalent U [U(V)] and ultimately tetravalent U [U(IV)]. As the reaction proceeded, the remaining aqueous phase U [containing U(VI) and U(V)] systematically carried light isotopes, whereas in the bicarbonate-extracted solution [containing U(VI) and U(V)], the δ238U values varied, especially when C/C0 approached 0. This variation was interpreted as reflecting the variable relative contribution of unreduced U(VI) (δ238U < 0‰) and bicarbonate-extractable U(V) (δ238U > 0‰). The solid remaining after bicarbonate extraction included unextractable U(V) and U(IV), for which the δ238U values consistently followed the same trend that started at 0.3-0.5‰ and decreased to ∼0‰. The impact of PIPES buffer on isotopic fractionation was attributed to the variable abundance of U(V) in the aqueous phase. A few extremely heavy bicarbonate-extracted δ238U values were due to mass-dependent fractionation resulting from several hypothesized mechanisms. The results suggest the preferential accumulation of the heavy isotope in the reduced species and the significant influence of U(V) on the overall isotopic fractionation, providing insight into the U isotope fractionation behavior during its abiotic reduction process.
Collapse
Affiliation(s)
- Zezhen Pan
- Department
of Environmental Science and Engineering, Fudan University, Shanghai 200438, China
- EML,
École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Institute
of Eco-Chongming (IEC), Shanghai 200062, China
| | - Luca Loreggian
- EML,
École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Yvonne Roebbert
- Institut
für Mineralogie, Leibniz Universität
Hannover, D-30167 Hannover, Germany
| | - Barbora Bartova
- EML,
École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | - Stefan Weyer
- Institut
für Mineralogie, Leibniz Universität
Hannover, D-30167 Hannover, Germany
| | | |
Collapse
|
3
|
Pang C, Li Y, Wu H, Deng Z, Yuan S, Tan W. Microbial removal of uranyl from aqueous solution by Leifsonia sp. in the presence of different forms of iron oxides. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2024; 272:107367. [PMID: 38171110 DOI: 10.1016/j.jenvrad.2023.107367] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/22/2023] [Accepted: 12/28/2023] [Indexed: 01/05/2024]
Abstract
Immobilization of uranyl by indigenous microorganisms has been proposed as an economic and clean in-situ approach for removal of uranium, but the potential mechanisms of the process and the stability of precipitated uranium in the presence of widespread Fe(III) (hydr)oxides remain elusive. The potential of iron to serve as a reductant and/or an oxidant of uranium indicates that bioemediation strategies which mainly rely on the reduction of highly soluble U(VI) to poorly soluble U(IV) minerals to retard uranium transport in groundwater may be enhanced or hindered under different environmental conditions. This study purposes to determine the effect of ubiquitous Fe(III) (hydr)oxides (two-line ferrihydrite, hematite and goethite) on the removal of U(VI) by Leifsonia sp. isolated from an acidic tailings pond in China. The removal mechanism was elucidated via SEM-EDS, XPS and Mössbauer. The results show that the removal of U(VI) was retarded by Fe(III) (hydr)oxides when the initial concentration of U(VI) was 10 mg/L, pH was 6, temperature was 25 °C. Particularly, the retardatory effect of hematite on U(VI) removal was blindingly obvious. Also, it is worth noting that the U(VI) in the precipitate slow-released in the Fe(III) (hydrodr) oxide treatment groups, accompanied by an increase in Fe(II) concentration. SEM-EDS results demonstrated that the ferrihydrite converted to goethite may be the reason for U(VI) release in the process of 15 days culture. Mössbauer spectra fitting results further imply that the metastable iron oxides were transformed into stable Fe3O4 state. XPS measurements results showed that uranium product is most likely a mixture of Iron-U(IV) and Iron-U(VI), which indicated that the hexavalent uranium was converted into tetravalent uranium. These observations imply that the stability of the uranium in groundwater may be impacted on the prevailing environmental conditions, especially the solid-phase Fe(III) (hydr)oxide in groundwater or sediment.
Collapse
Affiliation(s)
- Chao Pang
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China
| | - Yuan Li
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China
| | - Han Wu
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China
| | - Zhiwen Deng
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China
| | - Shanlin Yuan
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China
| | - Wenfa Tan
- School of Resources Environment and Safety Engineering, University of South China, Hengyang, 421001, China; Hengyang Key Laboratory of Soil Pollution Control and Remediation, University of South China, Hengyang, 421001, China.
| |
Collapse
|
4
|
Huang X, Ding Y, Zhu N, Li L, Fang Q. Enhanced sequestration of uranium by coexisted lead and organic matter during ferrihydrite transformation. CHEMOSPHERE 2023; 341:140041. [PMID: 37660796 DOI: 10.1016/j.chemosphere.2023.140041] [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: 04/24/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 09/05/2023]
Abstract
The dynamic reactions of uranium (U) with iron (Fe) minerals change its behaviors in soil environment, however, how the coexisted constituents in soil affect U sequestration and release on Fe minerals during the transformation remains unclear. Herein, coupled effects of lead (Pb) and dissolved organic matter (DOM) on U speciation and release kinetics during the catalytic transformations of ferrihydrite (Fh) by Fe(II) were investigated. Our results revealed that the coexistence of Pb and DOM significantly reduced U release and increased the immobilization of U during Fh transformation, which were attributed to the enhanced inhibition of Fh transformation, the declined release of DOM and the increased U(VI) reduction. Specifically, the presence of Pb increased the coprecipitation of condensed aromatics, polyphenols and phenols, and these molecules were preferentially maintained by Fe (oxyhydr)oxides. The sequestrated polyphenols and phenols could further facilitate U(VI) reduction to U(IV). Additionally, a higher Pb content in coprecipitates caused a slower U release, especially when DOM was present. Compared with Pb, the concentrations of the released U were significantly lower during the transformation. Our results contribute to predicting U sequestration and remediating U-contaminated soils.
Collapse
Affiliation(s)
- Xixian Huang
- School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan, 421001, PR China; School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, PR China
| | - Yang Ding
- School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan, 421001, PR China; Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang, 421001, PR China.
| | - Nengwu Zhu
- School of Environment and Energy, Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, Guangdong, 510006, PR China
| | - Liuqin Li
- School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan, 421001, PR China
| | - Qi Fang
- School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan, 421001, PR China
| |
Collapse
|
5
|
Cheng W, Li J, Sun J, Luo T, Marsac R, Boily JF, Hanna K. Nalidixic Acid and Fe(II)/Cu(II) Coadsorption at Goethite and Akaganéite Surfaces. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15680-15692. [PMID: 37796760 DOI: 10.1021/acs.est.3c05727] [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: 10/07/2023]
Abstract
Interactions between aqueous Fe(II) and solid Fe(III) oxy(hydr)oxide surfaces play determining roles in the fate of organic contaminants in nature. In this study, the adsorption of nalidixic acid (NA), a representative redox-inactive quinolone antibiotic, on synthetic goethite (α-FeOOH) and akaganéite (β-FeOOH) was examined under varying conditions of pH and cation type and concentration, by means of adsorption experiments, attenuated total reflectance-Fourier transform infrared spectroscopy, surface complexation modeling (SCM), and powder X-ray diffraction. Batch adsorption experiments showed that Fe(II) had marginal effects on NA adsorption onto akaganéite but enhanced NA adsorption on goethite. This enhancement is attributed to the formation of goethite-Fe(II)-NA ternary complexes, without the need for heterogeneous Fe(II)-Fe(III) electron transfer at low Fe(II) loadings (2 Fe/nm2), as confirmed by SCM. However, higher Fe(II) loadings required a goethite-magnetite composite in the SCM to explain Fe(II)-driven recrystallization and its impact on NA binding. The use of a surface ternary complex by SCM was supported further in experiments involving Cu(II), a prevalent environmental metal incapable of transforming Fe(III) oxy(hydr)oxides, which was observed to enhance NA loadings on goethite. However, Cu(II)-NA aqueous complexation and potential Cu(OH)2 precipitates counteracted the formation of ternary surface complexes, leading to decreased NA loadings on akaganéite. These results have direct implications for the fate of organic contaminants, especially those at oxic-anoxic boundaries.
Collapse
Affiliation(s)
- Wei Cheng
- College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Jiabin Li
- College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Jie Sun
- College of Resources and Environmental Science, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Tao Luo
- Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
- Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France
| | - Rémi Marsac
- Université de Rennes, CNRS, Géosciences Rennes─UMR 6118, F-35000 Rennes, France
| | | | - Khalil Hanna
- Université de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France
| |
Collapse
|
6
|
Jia QQ, Zhang X, Deng J, Huang LZ. Labile Fe(III) phase mediates the electron transfer from Fe(II,III) (oxyhydr)oxides to carbon tetrachloride. WATER RESEARCH 2023; 245:120636. [PMID: 37748348 DOI: 10.1016/j.watres.2023.120636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 09/09/2023] [Accepted: 09/15/2023] [Indexed: 09/27/2023]
Abstract
Labile Fe(III) phase (includes Fe(III)aq, Fe(III)ads, or Fe(III)s species) is an important intermediate during the interaction between Fe(II) and Fe(III) (oxyhydr)oxides, but how does labile Fe(III) influence the electron transfer from Fe(II) to oxidant environmental pollutant during this Fe(II)-Fe(III) interaction is unclear. In this work, the dynamic change of Fe(II,III) (oxyhydr)oxides at the same time scale is simulated by synthesizing Fe(III)-Fe(II)-I (Fe(III)+NaOH+Fe(II)+NaOH) with different Fe(II)/Fe(III) ratios. CCl4 is used as a convenient probe to test the reduction kinetics of mixed valence Fe(II,III)(oxyhydr)oxides with different Fe(II):Fe(III) ratios. The Mössbauer spectra results reveal the Fe(III)labile in the solid phase is in octahedral coordination. The electron-donating capability of Fe(II) was improved with increasing Fe(III) content, but suppressed when [Fe(III)] ≥ 30 mM. The reductive dechlorination of CT by Fe(III)-Fe(II)-I decreased gradually with the increase of Fe(III) content, because more amount Fe(III)labile in solid phase is accumulated. This shows that the electron transfer from Fe(II) to Fe(III)labile rather than to CT is enhanced with increasing Fe(III) content. FTIR data shows that the hydroxylation of Fe(II) with Fe(OH)3 occurs preferentially in the non-hydrogen bonded hydroxyl group, causing the decrease of its reductive reactivity. The presence of [Fe(III)-O-Fe(II)]+ in Fe(III)-Fe(II)-I can stabilize the dichlorocarbene anion (:CCl2-), favouring the conversion of CT to CH4 (13.1%). The aging experiment shows that Fe(III)labile surface may maintain the reductive reactivity of Fe(II) during aging when [Fe(III)] = 5-20 mM. This study deepens our understanding of the mass transfer pathway of iron oxyhydroxides induced by Fe(II) and its impact on the reductive dechlorination of CT.
Collapse
Affiliation(s)
- Qian-Qian Jia
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, PR China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Xuejie Zhang
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, PR China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Jia Deng
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, PR China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
| | - Li-Zhi Huang
- School of Civil Engineering, Wuhan University, No. 8, East Lake South Road, Wuhan, PR China; State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China.
| |
Collapse
|
7
|
Molinas M, Meibom KL, Faizova R, Mazzanti M, Bernier-Latmani R. Mechanism of Reduction of Aqueous U(V)-dpaea and Solid-Phase U(VI)-dpaea Complexes: The Role of Multiheme c-Type Cytochromes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7537-7546. [PMID: 37133831 DOI: 10.1021/acs.est.3c00666] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The biological reduction of soluble U(VI) complexes to form immobile U(IV) species has been proposed to remediate contaminated sites. It is well established that multiheme c-type cytochromes (MHCs) are key mediators of electron transfer to aqueous phase U(VI) complexes for bacteria such as Shewanella oneidensis MR-1. Recent studies have confirmed that the reduction proceeds via a first electron transfer forming pentavalent U(V) species that readily disproportionate. However, in the presence of the stabilizing aminocarboxylate ligand, dpaea2- (dpaeaH2═bis(pyridyl-6-methyl-2-carboxylate)-ethylamine), biologically produced U(V) persisted in aqueous solution at pH 7. We aim to pinpoint the role of MHC in the reduction of U(V)-dpaea and to establish the mechanism of solid-phase U(VI)-dpaea reduction. To that end, we investigated U-dpaea reduction by two deletion mutants of S. oneidensis MR-1-one lacking outer membrane MHCs and the other lacking all outer membrane MHCs and a transmembrane MHC-and by the purified outer membrane MHC, MtrC. Our results suggest that solid-phase U(VI)-dpaea is reduced primarily by outer membrane MHCs. Additionally, MtrC can directly transfer electrons to U(V)-dpaea to form U(IV) species but is not strictly necessary, underscoring the primary involvement of outer membrane MHCs in the reduction of this pentavalent U species but not excluding that of periplasmic MHCs.
Collapse
Affiliation(s)
- Margaux Molinas
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Karin Lederballe Meibom
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Radmila Faizova
- Group of Coordination Chemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Marinella Mazzanti
- Group of Coordination Chemistry, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| | - Rizlan Bernier-Latmani
- Environmental Microbiology Laboratory, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
| |
Collapse
|
8
|
Ding Y, Huang X, Zhang H, Ding D. Effects of dissolved organic matter molecules on the sequestration and stability of uranium during the transformation of Fe (oxyhydr)oxides. WATER RESEARCH 2023; 229:119387. [PMID: 36459895 DOI: 10.1016/j.watres.2022.119387] [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: 09/19/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 06/17/2023]
Abstract
Amorphous ferrihydrite (Fh) is abundant in aquatic environments and sediments, and often coprecipitates with dissolved organic matter (DOM) to form mineral-organic aggregates. The Fe(II)-catalyzed transformation of Fh to crystalline Fe (oxyhydr)oxides (e.g., goethite) can result in the changes of uranium (U) species, but the effects of DOM molecules on the sequestration and stability of U during Fe (oxyhydr)oxides transformation are poorly understood. In this study, the associations of DOM molecules with U during the coprecipitation of DOM with Fh were evaluated, and the effects of DOM molecules on the kinetics of U release during Fe (oxyhydr)oxides transformation were investigated using a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), X-ray photoelectron spectroscopy (XPS), and kinetic experiments. FT-ICR-MS results indicated that, in addition to phenolic and polyphenolic compounds with higher O/C ratios, portions of phenolic compounds with lower O/C ratios and aliphatic compounds were also contributed to UO22+ binding when Fh coprecipitated with DOM. In comparison, phenolic and polyphenolic compounds with higher O/C ratios and condensed aromatics were preferentially retained on Fe (oxyhydr)oxides during the transformation. XPS results further suggested that the coprecipitated DOM molecules facilitated the reduction of U(VI) to U(IV) during the transformation, possibly through providing electrons or acting as electron shuttles. The kinetic experiment results indicated that the transformation processes accelerated U release from Fe (oxyhydr)oxides, but the coprecipitated DOM molecules slowed down U release. Our results contribute to understanding the behaviors of U and predicting the sequestration of U in the environment.
Collapse
Affiliation(s)
- Yang Ding
- Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan 421001, China
| | - Xixian Huang
- School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan 421001, China.
| | - Hui Zhang
- Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan 421001, China
| | - Dexin Ding
- Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy, University of South China, Hengyang 421001, China; School of Resource & Environment and Safety Engineering, University of South China, Hengyang, Hunan 421001, China.
| |
Collapse
|
9
|
Stagg O, Morris K, Townsend LT, Kvashnina KO, Baker ML, Dempsey RL, Abrahamsen-Mills L, Shaw S. Sulfidation and Reoxidation of U(VI)-Incorporated Goethite: Implications for U Retention during Sub-Surface Redox Cycling. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:17643-17652. [PMID: 36449568 PMCID: PMC9775214 DOI: 10.1021/acs.est.2c05314] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/06/2022] [Accepted: 11/08/2022] [Indexed: 06/17/2023]
Abstract
Over 60 years of nuclear activity have resulted in a global legacy of contaminated land and radioactive waste. Uranium (U) is a significant component of this legacy and is present in radioactive wastes and at many contaminated sites. U-incorporated iron (oxyhydr)oxides may provide a long-term barrier to U migration in the environment. However, reductive dissolution of iron (oxyhydr)oxides can occur on reaction with aqueous sulfide (sulfidation), a common environmental species, due to the microbial reduction of sulfate. In this work, U(VI)-goethite was initially reacted with aqueous sulfide, followed by a reoxidation reaction, to further understand the long-term fate of U species under fluctuating environmental conditions. Over the first day of sulfidation, a transient release of aqueous U was observed, likely due to intermediate uranyl(VI)-persulfide species. Despite this, overall U was retained in the solid phase, with the formation of nanocrystalline U(IV)O2 in the sulfidized system along with a persistent U(V) component. On reoxidation, U was associated with an iron (oxyhydr)oxide phase either as an adsorbed uranyl (approximately 65%) or an incorporated U (35%) species. These findings support the overarching concept of iron (oxyhydr)oxides acting as a barrier to U migration in the environment, even under fluctuating redox conditions.
Collapse
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, ManchesterM13 9PL, U.K.
| | - 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, ManchesterM13 9PL, U.K.
| | - Luke Thomas Townsend
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences, The University of Manchester, ManchesterM13 9PL, U.K.
| | - Kristina O. Kvashnina
- The
Rossendorf Beamline at ESRF—The European Synchrotron, CS40220, Grenoble Cedex 938043France
- Institute
of Resource Ecology, Helmholtz Zentrum Dresden
Rossendorf (HZDR), Dresden01314, Germany
| | - Michael L. Baker
- Department
of Chemistry, The University of Manchester, ManchesterM13 9PL, U.K.
- The
University of Manchester at Harwell, The University of Manchester, Diamond Light Source, Harwell Campus, DidcotOX11 0DE, U.K.
| | - Ryan L. Dempsey
- Department
of Chemistry, The University of Manchester, ManchesterM13 9PL, U.K.
| | | | - 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, ManchesterM13 9PL, U.K.
| |
Collapse
|
10
|
Zhao X, Yuan Z, Wang S, Pan Y, Chen N, Tunc A, Cheung K, Alparov A, Chen W, Deevsalar R, Lin J, Jia Y. Iron(II)-activated phase transformation of Cd-bearing ferrihydrite: Implications for cadmium mobility and fate under anaerobic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 848:157719. [PMID: 35914597 DOI: 10.1016/j.scitotenv.2022.157719] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/06/2022] [Accepted: 07/26/2022] [Indexed: 06/15/2023]
Abstract
The factors and mechanisms affecting the fate of the associated Cd during the Fe(II)-activated Cd-bearing ferrihydrite transformation remain poorly understood. Herein we have conducted a series of batch reactions containing ferrihydrite with diverse pH values and initial Fe(II) and Cd concentrations coupled with chemical analyses and spectroscopic examination on the transformation products to probe the mechanisms of the Cd partitioning and the processes of Fe(II)-activated Cd-bearing ferrihydrite transformation under anaerobic conditions. Chemical analyses, Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD) results show that the initial Fe(II) and Cd concentrations as well as pH values all have significant effects on the rates and pathways of ferrihydrite transformation. Increasing Cd loading enhances the inhibition of the Fe(II)-activated ferrihydrite transformation rates. High Cd loading alters the Fe(II)-activated ferrihydrite transformation pathways by hindering the recrystallization of both ferrihydrite to more stable iron minerals and the newly formed lepidocrocite to goethite. Chemical analyses show that the release of Cd to solutions during ferrihydrite transformation is accompanied by a reduction in the 0.4 M HCl extractable Cd fraction and that a significant amount of the released Cd is transformed to a 0.4 M HCl unextractable form. Moreover, enhanced Cd release during the Fe(II)-activated ferrihydrite transformation is observed by reducing the pH value or increasing the initial Cd concentration. Results from synchrotron X-ray absorption spectroscopy (XAS) confirm that the majority of the 0.4 M HCl unextractable Cd form is associated with structural incorporation into the recrystallized iron (hydr)oxides via isomorphous substitution for Fe(III). These findings not only provide molecular-level understanding on the behavior of Cd under natural anoxic environments, but also are useful in predicting the geochemical cycling of Cd and developing long-term Cd contaminant management strategies.
Collapse
Affiliation(s)
- Xiaoming Zhao
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Zidan Yuan
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China
| | - Shaofeng Wang
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, PR China.
| | - Yuanming Pan
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Ning Chen
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada; Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4, Canada
| | - Ayetullah Tunc
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Kalong Cheung
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Aslan Alparov
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Weifeng Chen
- Canadian Light Source, University of Saskatchewan, Saskatoon, SK S7N 0X4, Canada
| | - Reza Deevsalar
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada
| | - Jinru Lin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110016, PR China
| |
Collapse
|
11
|
Ilton ES, Collins RN, Ciobanu CL, Cook NJ, Verdugo-Ihl M, Slattery AD, Paterson DJ, Mergelsberg ST, Bylaska EJ, Ehrig K. Pentavalent Uranium Incorporated in the Structure of Proterozoic Hematite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11857-11864. [PMID: 35876701 DOI: 10.1021/acs.est.2c02113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Characterizing the chemical state and physical disposition of uranium that has persisted over geologic time scales is key for modeling the long-term geologic sequestration of nuclear waste, accurate uranium-lead dating, and the use of uranium isotopes as paleo redox proxies. X-ray absorption spectroscopy coupled with molecular dynamics modeling demonstrated that pentavalent uranium is incorporated in the structure of 1.6 billion year old hematite (α-Fe2O3), attesting to the robustness of Fe oxides as waste forms and revealing the reason for the great success in using hematite for petrogenic dating. The extreme antiquity of this specimen suggests that the pentavalent state of uranium, considered a transient, is stable when incorporated into hematite, a ubiquitous phase that spans the crustal continuum. Thus, it would appear overly simplistic to assume that only the tetravalent and hexavalent states are relevant when interpreting the uranium isotopic record from ancient crust and contained ore systems.
Collapse
Affiliation(s)
- Eugene S Ilton
- Pacific Northwest National Laboratory, Richland, Washington 99353, United States
| | - Richard N Collins
- University of New South Wales, Sydney New South Wales 2052, Australia
| | - Cristiana L Ciobanu
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Nigel J Cook
- School of Civil, Environmental, and Mining Engineering, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Max Verdugo-Ihl
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Ashley D Slattery
- Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - David J Paterson
- Australian Synchrotron, 800 Blackburn Road, Clayton Victoria 3168, Australia
| | | | - Eric J Bylaska
- Pacific Northwest National Laboratory, Richland, Washington 99353, United States
| | - Kathy Ehrig
- BHP Olympic Dam, 10 Franklin Street, Adelaide, South Australia 5000, Australia
| |
Collapse
|
12
|
Zhou J, Liu Y, Bu H, Liu P, Sun J, Wu F, Hua J, Liu C. Effects of Fe(II)-induced transformation of scorodite on arsenic solubility. JOURNAL OF HAZARDOUS MATERIALS 2022; 429:128274. [PMID: 35066222 DOI: 10.1016/j.jhazmat.2022.128274] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/26/2021] [Accepted: 01/11/2022] [Indexed: 06/14/2023]
Abstract
Scorodite (FeAsO4·2H2O) is a pivotal secondary ferric arsenate that immobilizes most of arsenic (As) in acidic As-contaminated environments, but secondary As pollution may occur during dissolution of scorodite in environments involving redox changes. Reductive dissolution of scorodite by coexisting dissolved Fe2+ (Fe(II)aq) under anaerobic conditions and its effects on the behavior of As have yet to be examined. Here, this study monitored the changes in mineralogy, solubility and speciation of As during scorodite transformation induced by Fe(II) under anaerobic conditions at pH 7.0 and discussed the underlying mechanisms. Mössbauer and X-ray diffraction (XRD) analysis showed the formation of parasymplesite and ferrihydrite-like species during scorodite transformation, which was highly controlled by Fe(II)aq concentrations. 1 mM Fe(II)aq enhanced As mobilization into the solution, whereas As was repartitioned to the PO43--extractable and HCl-extractable phases with 5 and 10 mM Fe(II). The neo-formed parasymplesite and ferrihydrite-like species immobilized dissolved As(V) through adsorption and incorporation. Additionally, As(V) reduction occurred during Fe(II)-induced scorodite transformation. Our results provide new insights into the stability and risk of scorodite in anaerobic environments as well as the geochemical behavior of As in response to Fe cycling.
Collapse
Affiliation(s)
- Jimei Zhou
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Yizhang Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Hongling Bu
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, PR China
| | - Peng Liu
- School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, PR China
| | - Jing Sun
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China
| | - Fei Wu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, PR China
| | - Jian Hua
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; School of Resources and Environmental Science, Wuhan University, Wuhan 430079, PR China
| | - Chengshuai Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, PR China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, PR China.
| |
Collapse
|
13
|
Jia X, Ma L, Liu J, Liu P, Yu L, Zhou J, Li W, Zhou W, Dong Z. Reduction of antimony mobility from Sb-rich smelting slag by Shewanella oneidensis: Integrated biosorption and precipitation. JOURNAL OF HAZARDOUS MATERIALS 2022; 426:127385. [PMID: 34929592 DOI: 10.1016/j.jhazmat.2021.127385] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/14/2021] [Accepted: 09/27/2021] [Indexed: 06/14/2023]
Abstract
The dissimilatory Fe(III)-reducing bacteria play a significant role in the mobility of antimony (Sb) under reducing environment. Sb-rich smelting slag is iron (Fe)-containing antimonic mine waste, which is one of the main sources of antimony pollution. In this study, the soluble antimony reacted with Fe(III) by S. oneidensis (Shewanella oneidensis strain MR-1) was performed in reduction condition, then the dissolution behavior of the Sb-rich smelting slag with S. oneidensis was investigated. The results showed that the released Sb was immobilized by S. oneidensis and the strain adsorbed Sb(III) preferentially. Sb(V) can be reduced by S. oneidensis without aqueous Fe. In the presence of Fe(III), S. oneidensis mediated Sb bio-adsorption and the chemical redox of Sb-Fe occurred simultaneously. Sb was co-precipitated with Fe to form the Sb(V)-O-Fe(III) secondary mineral, which was identified as the bidentate mononuclear edge-sharing structure by extended X-ray absorption fine structure (EXAFS) analysis. These results suggest that S. oneidensis has a positive effect on the immobilization and minimizing toxicity of antimony in anoxic soil and groundwater, which provides a theoretical basis for the treatment of antimony contamination.
Collapse
Affiliation(s)
- Xiaocen Jia
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| | - Liyuan Ma
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| | - Jing Liu
- College of Resources and Environment, Southwest University, Chongqing 400715, China
| | - Peng Liu
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| | - Lu Yu
- Qiaokou Branch of Wuhan Ecological Environment Bureau, Wuhan 430000, China
| | - Jianwei Zhou
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China; Hubei Key Laboratory of Yangtze Catchment Environmental Aquatic Science, Wuhan 430000, China.
| | - Wanyu Li
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| | - Weiqing Zhou
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| | - Zichao Dong
- School of Environmental Studies, China University of Geosciences, Wuhan 430078, China
| |
Collapse
|
14
|
Xu Z, Yu Y, Xu X, Tsang DCW, Yao C, Fan J, Zhao L, Qiu H, Cao X. Direct and Indirect Electron Transfer Routes of Chromium(VI) Reduction with Different Crystalline Ferric Oxyhydroxides in the Presence of Pyrogenic Carbon. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:1724-1735. [PMID: 34978795 DOI: 10.1021/acs.est.1c06642] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electron transfer mediated by iron minerals is considered as a critical redox step for the dynamics of pollutants in soil. Herein, we explored the reduction process of Cr(VI) with different crystalline ferric oxyhydroxides in the presence of pyrogenic carbon (biochar). Both low- and high-crystallinity ferric oxyhydroxides induced Cr(VI) immobilization mainly via the sorption process, with a limited reduction process. However, the Cr(VI) reduction immobilization was inspired by the copresence of biochar. Low-crystallinity ferric oxyhydroxide had an intense chemical combination with biochar and strong sorption for Cr(VI) via inner-sphere complexation, leading to the indirect electron transfer route for Cr(VI) reduction, that is, the electron first transferred from biochar to iron mineral through C-O-Fe binding and then to Cr(VI) with Fe(III)/Fe(II) transformation on ferric oxyhydroxides. With increasing crystallinity of ferric oxyhydroxides, the direct electron transfer between biochar and Cr(VI) became the main electron transfer avenue for Cr(VI) reduction. The indirect electron transfer was suppressed in the high-crystallinity ferric oxyhydroxides due to less sorption of Cr(VI), limited combination with biochar, and higher iron stability. This study demonstrates that electron transfer mechanisms involving iron minerals change with the mineral crystallization process, which would affect the geochemical process of contaminants with pyrogenic carbon.
Collapse
Affiliation(s)
- Zibo Xu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon 852, Hong Kong, 999077, China
| | - Yulu Yu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xiaoyun Xu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon 852, Hong Kong, 999077, China
| | - Chengbo Yao
- Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, United States
| | - Jin Fan
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ling Zhao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hao Qiu
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xinde Cao
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
- Shanghai Engineering Research Center for Solid Waste Treatment and Resource Recovery, Shanghai 200240, China
| |
Collapse
|
15
|
Yu W, Chu C, Chen B. Enhanced Microbial Ferrihydrite Reduction by Pyrogenic Carbon: Impact of Graphitic Structures. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:239-250. [PMID: 34932354 DOI: 10.1021/acs.est.1c04440] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electron-shuttling agents such as pyrogenic carbon (PC) can mediate long-distance electron transfer and play numerous key roles in aquatic and soil biogeochemical processes. The electron-shuttling capacity of PC relies on both the surface oxygen-containing functional groups and bulk graphitic structures. Although the impacts of oxygen-containing functional groups on the electron-shuttling performance of PC are well studied, there remains insufficient understanding on the function of graphitic structures. Here, we studied the functions of PC in mediating microbial (Shewanella oneidensis MR-1) reduction of ferrihydrite, a classic and geochemically important soil redox process. The results show that PC enhanced microbial ferrihydrite reduction by 20-115% and the reduction rates increased with PC pyrolysis temperature increasing from 500 to 900 °C. For PC prepared at low temperature (500-600 °C), the electron-shuttling capacity of PC is mainly attributed to its oxygen-containing functional groups, as indicated by a 50-60% decline in the ferrihydrite reduction rate when PC was reduced under a H2 atmosphere to remove surface oxygen-containing functional groups. In stark contrast, for PC prepared at higher temperature (700-900 °C), the formation of PC graphitic structures was enhanced, as suggested by the higher electrical conductivity; accordingly, the graphitic structure exhibits greater importance in shuttling electrons, as demonstrated by a minor decline (10-18%) in the ferrihydrite reduction rate after H2 treatment of PC. This study provides new insights into the nonlinear and combined role of graphitic structures and oxygen-containing functional groups of PC in mediating electron transfer, where the pyrolysis temperature of PC acts as a key factor in determining the electron-shuttling pathways.
Collapse
Affiliation(s)
- Wentao Yu
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
| | - Chiheng Chu
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
| | - Baoliang Chen
- Department of Environmental Science, Zhejiang University, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou 310058, China
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
Townsend LT, Kuippers G, Lloyd JR, Natrajan LS, Boothman C, Mosselmans JFW, Shaw S, Morris K. Biogenic Sulfidation of U(VI) and Ferrihydrite Mediated by Sulfate-Reducing Bacteria at Elevated pH. ACS EARTH & SPACE CHEMISTRY 2021; 5:3075-3086. [PMID: 34825123 PMCID: PMC8607498 DOI: 10.1021/acsearthspacechem.1c00126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 06/13/2023]
Abstract
Globally, the need for radioactive waste disposal and contaminated land management is clear. Here, gaining an improved understanding of how biogeochemical processes, such as Fe(III) and sulfate reduction, may control the environmental mobility of radionuclides is important. Uranium (U), typically the most abundant radionuclide by mass in radioactive wastes and contaminated land scenarios, may have its environmental mobility impacted by biogeochemical processes within the subsurface. This study investigated the fate of U(VI) in an alkaline (pH ∼9.6) sulfate-reducing enrichment culture obtained from a high-pH environment. To explore the mobility of U(VI) under alkaline conditions where iron minerals are ubiquitous, a range of conditions were tested, including high (30 mM) and low (1 mM) carbonate concentrations and the presence and absence of Fe(III). At high carbonate concentrations, the pH was buffered to approximately pH 9.6, which delayed the onset of sulfate reduction and meant that the reduction of U(VI)(aq) to poorly soluble U(IV)(s) was slowed. Low carbonate conditions allowed microbial sulfate reduction to proceed and caused the pH to fall to ∼7.5. This drop in pH was likely due to the presence of volatile fatty acids from the microbial respiration of gluconate. Here, aqueous sulfide accumulated and U was removed from solution as a mixture of U(IV) and U(VI) phosphate species. In addition, sulfate-reducing bacteria, such as Desulfosporosinus species, were enriched during development of sulfate-reducing conditions. Results highlight the impact of carbonate concentrations on U speciation and solubility in alkaline conditions, informing intermediate-level radioactive waste disposal and radioactively contaminated land management.
Collapse
Affiliation(s)
- Luke T. Townsend
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| | - Gina Kuippers
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| | - Jonathan R. Lloyd
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| | - Louise S. Natrajan
- Centre
for Radiochemistry Research, Department of Chemistry, School of Natural
Sciences, The University of Manchester, Manchester M13 9PL, U.K.
| | - Christopher Boothman
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| | - J. Frederick W. Mosselmans
- Diamond
Light Source Ltd., Diamond
House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K.
| | - Samuel Shaw
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| | - Katherine Morris
- Research
Centre for Radwaste Disposal and Williamson Research Centre for Molecular
Environmental Science, Department of Earth and Environmental Sciences,
School of Natural Sciences, The University
of Manchester, Manchester M13 9PL, U.K.
| |
Collapse
|
18
|
Yin X, Zhang G, Su R, Zeng X, Yan Z, Zhang D, Ma X, Lei L, Lin J, Wang S, Jia Y. Oxidation and incorporation of adsorbed antimonite during iron(II)-catalyzed recrystallization of ferrihydrite. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 778:146424. [PMID: 34030383 DOI: 10.1016/j.scitotenv.2021.146424] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/08/2021] [Accepted: 03/08/2021] [Indexed: 06/12/2023]
Abstract
The toxicity and mobility of antimony (Sb) are strongly influenced by the redox transformation of widely spread 2-line ferrihydrite (Fh) in natural soils and sediments. This study investigated the transformation and redistribution of adsorbed antimonite (Sb(III)) during Fe(II)-catalyzed recrystallization of Fh under anaerobic conditions. X-ray diffraction (XRD), transmission electron microscopy (TEM), and synchrotron based X-ray absorption spectroscopy (XAS) were utilized to characterize the mineralogy and morphology of generated minerals as well as the speciation of Sb and Fe. Chemical analysis and Sb LIII-edge XANES spectra demonstrated that a great part of Sb(III) (80%-90%) was oxidized to Sb(V) by reactive oxygen species (ROS) during the Fe(II)-catalyzed transformation of Fh. Chemical extraction results showed that the mobility of Sb was significantly reduced with 50%-70% of initially adsorbed Sb(III) transformed to phosphate-unextractable phase. Antimony K-edge EXAFS analysis showed the SbO6 octahedra were incorporated into secondary minerals by substituting the Fe atoms. Our findings shed new light on the understanding of the geochemical behavior of Sb(III) under anoxic conditions.
Collapse
Affiliation(s)
- Xiuling Yin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Guoqing Zhang
- Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, School of Environment, Henan Normal University, Xinxiang 453007, China
| | - Rui Su
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xiangfeng Zeng
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Zelong Yan
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Danni Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Xu Ma
- Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education, China), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China
| | - Lei Lei
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jinru Lin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Shaofeng Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| |
Collapse
|
19
|
Wang J, Qiang S, Wang Y, Wu W, Li P, Qin H, Fan Q. Adsorption of U(VI) on the natural soil around a very low-level waste repository. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 233:106619. [PMID: 33894498 DOI: 10.1016/j.jenvrad.2021.106619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 03/31/2021] [Accepted: 04/07/2021] [Indexed: 06/12/2023]
Abstract
The behaviors of U(VI) in environmental media around radioactive waste disposal site are important for safety assessment of geological repositories. However, the estimation of environmental behaviors of U(VI) in natural media was insufficient. This work aimed to determine the adsorption of U(VI) on natural soil surrounding a candidate very low-level radioactive waste (VLLW) disposal site in southwest China. Results showed that the adsorption process of U(VI) on soils could be well supported by pseudo-second-order kinetic and Freundlich model. The adsorption of U(VI) was pH-dependent but temperature-independent. High ionic strength (NaCl) strongly affected the adsorption process at low pH (2.0-5.5). CO32- remarkably inhibited the U(VI) adsorption, while the adsorption of U(VI) was promoted by PO43- and SO42-. Naturally occurred soil organic matters (SOMs) showed high affinity for U(VI), while the presence of additional humic acid (HA) strongly inhibited U(VI) adsorption. The occurrence of ferrous iron could result in the reduction of U(VI) at low pH values (pH < 4), leading to the promotion of immobilization of U(VI). These findings would provide some guidance for the safety assessments of the VLLW disposal as well as the remediation of contaminated soil.
Collapse
Affiliation(s)
- Jingjing Wang
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China; Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
| | - Shirong Qiang
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Institute of Physiology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yun Wang
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Wangsuo Wu
- School of Nuclear Science and Technology, Lanzhou University, Lanzhou, 730000, China.
| | - Ping Li
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
| | - Haibo Qin
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China.
| | - Qiaohui Fan
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Petroleum Resources, Gansu Province, Lanzhou, 730000, China.
| |
Collapse
|
20
|
Ilton ES, Kovarik L, Nakouzi E, Mergelsberg ST, McBriarty ME, Bylaska EJ. Using Atom Dynamics to Map the Defect Structure Around an Impurity in Nano-Hematite. J Phys Chem Lett 2020; 11:10396-10400. [PMID: 33238102 DOI: 10.1021/acs.jpclett.0c02798] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The bulk behavior of materials is often controlled by minor impurities that create nonperiodic localized defect structures due to ionic size, symmetry, and charge balance mismatches. Here, we used transmission electron microscopy (TEM) of atom-resolved dynamics to directly map the topology of Fe vacancy clusters surrounding structurally incorporated U6+ in nanohematite (α-Fe2O3). Ab initio molecular dynamic simulations provided additional independent constraints on coupled U, Fe, and vacancy mobility in the solid. A clearer understanding of how such an apparently incompatible element can be accommodated by hematite emerged. The results were readily interpretable without the need for sophisticated data reconstruction methods, model structures, or ultrathin samples, and with the proliferation of aberration-corrected TEM facilities, the approach is accessible. Given sufficient z-contrast, the ability to observe impurity-vacancy structures by means of atom hopping can be used to directly probe the association of impurities and such defects in other materials, with promising applications across a broad range of disciplines.
Collapse
Affiliation(s)
- Eugene S Ilton
- Pacific Northwest National Laboratory, Richland, Washington 99352 United States
| | - Libor Kovarik
- Pacific Northwest National Laboratory, Richland, Washington 99352 United States
| | - Elias Nakouzi
- Pacific Northwest National Laboratory, Richland, Washington 99352 United States
| | | | - Martin E McBriarty
- Pacific Northwest National Laboratory, Richland, Washington 99352 United States
| | - Eric J Bylaska
- Pacific Northwest National Laboratory, Richland, Washington 99352 United States
| |
Collapse
|
21
|
Romanchuk AY, Vlasova IE, Kalmykov SN. Speciation of Uranium and Plutonium From Nuclear Legacy Sites to the Environment: A Mini Review. Front Chem 2020; 8:630. [PMID: 32903456 PMCID: PMC7434977 DOI: 10.3389/fchem.2020.00630] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 06/17/2020] [Indexed: 12/02/2022] Open
Abstract
The row of 15 chemical elements from Ac to Lr with atomic numbers from 89 to 103 are known as the actinides, which are all radioactive. Among them, uranium and plutonium are the most important as they are used in the nuclear fuel cycle and nuclear weapon production. Since the beginning of national nuclear programs and nuclear tests, many radioactively contaminated nuclear legacy sites, have been formed. This mini review covers the latest experimental, modeling, and case studies of plutonium and uranium migration in the environment, including the speciation of these elements and the chemical reactions that control their migration pathways.
Collapse
Affiliation(s)
| | | | - Stepan N. Kalmykov
- Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia
| |
Collapse
|
22
|
Sheng A, Li X, Arai Y, Ding Y, Rosso KM, Liu J. Citrate Controls Fe(II)-Catalyzed Transformation of Ferrihydrite by Complexation of the Labile Fe(III) Intermediate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:7309-7319. [PMID: 32421322 DOI: 10.1021/acs.est.0c00996] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ferrihydrite (Fh) is generally associated with dissolved organic matter (DOM) in natural environments due to a strong sorption affinity at circumneutral pH and its high specific surface area. In suboxic conditions, aqueous Fe(II) (Fe(II)aq) can catalyze transformation of Fh into more stable crystalline Fe(III) phases, but how DOM influences the transformation kinetics and pathway is still unclear. Using citrate as a surrogate, we have examined Fh transformation with 1 mM Fe(II)aq and 0-60 μM citrate at pH 7.2. We focus on quantifying the time-dependent concentrations of sorbed Fe(II), structural Fe(II), and a key intermediate species, labile Fe(III) (Fe(III)labile), resulting from interfacial electron transfer (IET), and how these species correlate with the evolution of lepidocrocite (Lp), magnetite (Mt), and goethite (Gt) products. Low concentrations of citrate significantly impact the proportions of Lp/Gt, and the collective results reveal that its effect is primarily through its ability to complex labile Fe(III) and thereby disrupt polymerization into product crystallites, as opposed to modifying the surface properties of Fh or inhibiting IET. The emergence of a Mt coprecipitate is observed in the transformation experiments with 5-10 μM citrate, when the Fe(II)/Fe(III)labile ratio on/near the Fh surface is close to 0.5, the stoichiometric Fe(II)/Fe(III) ratio in Mt. At the molecular level, the findings suggest that citrate, and by extension DOM, can modify the relative rates of olation and oxolation reactions that assemble labile Fe(III) into various product minerals.
Collapse
Affiliation(s)
- Anxu Sheng
- The Key Laboratory of Water and Sediment Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Xiaoxu Li
- The Key Laboratory of Water and Sediment Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Yuji Arai
- Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 1102 South Goodwin Avenue, Urbana, Illinois 61801, United States
| | - Yuefei Ding
- The Key Laboratory of Water and Sediment Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| | - Kevin M Rosso
- Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Juan Liu
- The Key Laboratory of Water and Sediment Sciences, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
| |
Collapse
|
23
|
Li X, Xiao B, Wu M, Wang L, Chen R, Wei Y, Liu H. In-situ generation of multi-homogeneous/heterogeneous Fe-based Fenton catalysts toward rapid degradation of organic pollutants at near neutral pH. CHEMOSPHERE 2020; 245:125663. [PMID: 31877454 DOI: 10.1016/j.chemosphere.2019.125663] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/01/2019] [Accepted: 12/12/2019] [Indexed: 06/10/2023]
Abstract
In this study, an in-situ generated multi-homogeneous/heterogeneous Fe-based catalytic system was developed, which exhibited a high efficiency for the production of •OH and rapid degradation of various organic pollutants in a near neutral pH range (5-8). The mechanism for the rapid decomposition of H2O2 and the generation of •OH were investigated in detail. The results indicated that, besides the introduced Fe2+, the in-situ generated various iron species including Fe(OH)+, Fe(OH)2, Fe3+, ferrihydrite (Fh), γ-FeOOH and α-FeOOH as well as FeII/Fh, FeII/γ-FeOOH and FeII/α-FeOOH could simultaneously act as homogeneous and heterogeneous Fenton reaction catalysts. The dropwise addition manner of Fe2+ greatly improved the catalytic efficiency of Fe2+ ions in near neutral pH environment, while the in-situ generated nanosized Fh, γ-FeOOH and α-FeOOH could supply numerous active catalytic sites. After degradation, the ferrous ions could be transformed to various crystalline iron oxides by the catalytic phase transformation. This study presents a method towards the rational design of novel Fenton catalysts for wastewater treatment.
Collapse
Affiliation(s)
- Xuqing Li
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Bing Xiao
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Meng Wu
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Lin Wang
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Rufen Chen
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Yu Wei
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China
| | - Hui Liu
- School of Chemistry and Material Science, Key Laboratory of Inorganic Nanomaterials of Hebei Province, National Demonstration Center for Experimental Chemistry Education, Hebei Normal University, Shijiazhuang, 050024, China.
| |
Collapse
|
24
|
Wang S, Lei L, Zhang D, Zhang G, Cao R, Wang X, Lin J, Jia Y. Stabilization and transformation of selenium during the Fe(II)-induced transformation of Se(IV)-adsorbed ferrihydrite under anaerobic conditions. JOURNAL OF HAZARDOUS MATERIALS 2020; 384:121365. [PMID: 31593863 DOI: 10.1016/j.jhazmat.2019.121365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 09/27/2019] [Accepted: 09/29/2019] [Indexed: 06/10/2023]
Abstract
Selenium (Se) is an essential nutrient for human beings at trace concentrations, but also a hazardous contaminant at high concentrations. As an important geological adsorbent, the transformation of 2-line ferrihydrite (Fh) strongly influences the geochemical behavior of selenium. However, little is known about the effect of the recrystallization of Fh on the fate of adsorbed Se(IV) in the reducing environments. We investigated the redistribution and transformation of Se(IV) during the recrystallization of Se(IV)-adsorbed Fh accelerated by Fe(II) under anaerobic conditions. Synchrotron based X-ray absorption near edge structure (XANES) spectroscopy was utilized to characterize oxidation state of Se. Results revealed that the adsorbed Se(IV) inhibited the Fe(II)-catalyzed recrystallization of ferrihydrite to goethite. Transmission electron microscopy (TEM) images showed that pH and the presence of Se(IV) had significant impacts on the morphology of the produced goethite. Approximately 30-75% adsorbed Se(IV) transformed to phosphate-unextractable form, indicating that the adsorbed Se transformed to more stable phase during the recrystallization of Fh. The XANES results indicated that a small fraction of Se(IV) was reduced to elemental Se. Our study demonstrated that the stability of adsorbed Se(IV) on ferrihydrite could be enhanced during Fe(II)-catalytic transformation of Fh under anoxic environments.
Collapse
Affiliation(s)
- Shaofeng Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Lei Lei
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China
| | - Danni Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Guoqing Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China; University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China
| | - Rui Cao
- Stanford Synchrotron Radiation Lightsource (SSRL), SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, United States
| | - Xin Wang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Jinru Lin
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
| | - Yongfeng Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
| |
Collapse
|
25
|
Townsend LT, Shaw S, Ofili NER, Kaltsoyannis N, Walton AS, Mosselmans JFW, Neill TS, Lloyd JR, Heath S, Hibberd R, Morris K. Formation of a U(VI)-Persulfide Complex during Environmentally Relevant Sulfidation of Iron (Oxyhydr)oxides. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:129-136. [PMID: 31838844 DOI: 10.1021/acs.est.9b03180] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Uranium is a risk-driving radionuclide in both radioactive waste disposal and contaminated land scenarios. In these environments, a range of biogeochemical processes can occur, including sulfate reduction, which can induce sulfidation of iron (oxyhydr)oxide mineral phases. During sulfidation, labile U(VI) is known to reduce to relatively immobile U(IV); however, the detailed mechanisms of the changes in U speciation during these biogeochemical reactions are poorly constrained. Here, we performed highly controlled sulfidation experiments at pH 7 and pH 9.5 on U(VI) adsorbed to ferrihydrite and investigated the system using geochemical analyses, X-ray absorption spectroscopy (XAS), and computational modeling. Analysis of the XAS data indicated the formation of a novel, transient U(VI)-persulfide complex as an intermediate species during the sulfidation reaction, concomitant with the transient release of uranium to the solution. Extended X-ray absorption fine structure (EXAFS) modeling showed that a persulfide ligand was coordinated in the equatorial plane of the uranyl moiety, and formation of this species was supported by computational modeling. The final speciation of U was nanoparticulate U(IV) uraninite, and this phase was evident at 2 days at pH 7 and 1 year at pH 9.5. Our identification of a new, labile U(VI)-persulfide species under environmentally relevant conditions may have implications for U mobility in sulfidic environments pertinent to radioactive waste disposal and contaminated land scenarios.
Collapse
Affiliation(s)
| | | | | | | | | | - J Frederick W Mosselmans
- Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, U.K
| | | | | | | | | | | |
Collapse
|
26
|
Liao W, Ye Z, Yuan S, Cai Q, Tong M, Qian A, Cheng D. Effect of Coexisting Fe(III) (oxyhydr)oxides on Cr(VI) Reduction by Fe(II)-Bearing Clay Minerals. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:13767-13775. [PMID: 31702131 DOI: 10.1021/acs.est.9b05208] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Fe(II)-bearing clay minerals are important electron sources for Cr(VI) reduction in subsurface environments. However, it is not clear how iron (oxyhydr)oxides impact Cr(VI) reduction by Fe(II)-bearing clays as the two minerals can coexist in soil and sediment aggregates. This study investigated Cr(VI) reduction in the mixed suspensions of reduced nontronite NAu-2 (rNAu-2) and ferrihydrite (Fe(II)/Cr(VI) = 3:1). When the mineral premixing time increased from 0 to 72 h, Cr(VI) reduction was accelerated prominently in the initial stage, while Cr(VI) sorption was inhibited drastically. Mineral premixing led to electron transfer from structural Fe(II) in rNAu-2 to ferrihydrite with formation of reactive-surface-associated Fe(II), which catalyzed ferrihydrite transformation to lepidocrocite. Reactive-surface-associated Fe(II) accelerated Cr(VI) reduction initially, and ferrihydrite transformation to lepidocrocite was responsible for the inhibited sorption. When the reactive-surface-associated Fe(II) was consumed in the initial stage, the Cr(VI) reduction rate decreased dramatically due to the limitation of slow electron transfer from structural Fe(II) in rNAu-2 to surface-reactive sites. The main reduction sites shifted from rNAu-2 to ferrihydrite/lepidocrocite when rNAu-2 coexisted with ferrihydrite. Our findings demonstrate that electron transfer between minerals has important implications for Cr(VI) and other high-valence contaminant reduction by Fe(II)-bearing clay minerals in subsurface environments.
Collapse
Affiliation(s)
- Wenjuan Liao
- State Key Laboratory of Biogeology and Environmental Geology , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Zilu Ye
- School of Environmental Studies , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Songhu Yuan
- State Key Laboratory of Biogeology and Environmental Geology , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Qizheng Cai
- School of Environmental Studies , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Man Tong
- State Key Laboratory of Biogeology and Environmental Geology , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Ao Qian
- State Key Laboratory of Biogeology and Environmental Geology , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| | - Dong Cheng
- State Key Laboratory of Biogeology and Environmental Geology , China University of Geosciences , 388 Lumo Road , Wuhan 430074 , P. R. China
| |
Collapse
|
27
|
Removal of soluble uranium by illite supported nanoscale zero-valent iron: electron transfer processes and incorporation mechanisms. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06959-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
28
|
Wang H, Guo H, Zhang N, Chen Z, Hu B, Wang X. Enhanced Photoreduction of U(VI) on C 3N 4 by Cr(VI) and Bisphenol A: ESR, XPS, and EXAFS Investigation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:6454-6461. [PMID: 31081617 DOI: 10.1021/acs.est.8b06913] [Citation(s) in RCA: 140] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The effect of Cr(VI) and bisphenol A (BPA) on U(VI) photoreduction by C3N4 photocatalyst was demonstrated by the batch experiments, electron spin resonance (ESR), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) techniques. The batch experiments manifested that Cr(VI) and BPA enhanced the photocatalytic activity of C3N4 for U(VI) photoreduction, whereas U(VI) photoreduction was significantly diminished with increased pH from 4.0 to 8.0. According to radical scavengers and ESR analysis, U(VI) was photoreduced to U(IV) by photogenerated electrons of conduction band edge, whereas Cr(VI) was reduced to Cr(III) by H2O2. BPA and its products such as organic acid and alcohols can capture photoinduced holes, which resulted in the enhancement of U(VI) photoreduction to U(IV). XPS and XANES analyses demonstrated that U(VI) was gradually photoreduced to U(IV) by C3N4 within irradiation 60 min, whereas U(IV) was reoxidized to U(VI) with increasing irradiation time. EXAFS analysis determined that the dominant interaction mechanisms of U(VI) on C3N4 after irradiation for 240 min were reductive precipitation and inner-sphere surface complexation. This work highlights the synergistic removal of radionuclides, heavy metals, and persistent organic pollutants by C3N4, which is crucial for the design and application of a high-performance photocatalyst in actual environmental cleanup.
Collapse
Affiliation(s)
- Huihui Wang
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , P. R. China
- School for Radiological and Interdisciplinary Sciences , Soochow University and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions , 215123 Suzhou , P. R. China
- School of Life Science , Shaoxing University , Huancheng West Road 508 , Shaoxing 312000 , P. R. China
| | - Han Guo
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , P. R. China
| | - Ning Zhang
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , P. R. China
| | - Zhongshan Chen
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , P. R. China
| | - Baowei Hu
- School of Life Science , Shaoxing University , Huancheng West Road 508 , Shaoxing 312000 , P. R. China
| | - Xiangke Wang
- MOE Key Laboratory of Resources and Environmental System Optimization, College of Environmental Science and Engineering , North China Electric Power University , Beijing 102206 , P. R. China
- School for Radiological and Interdisciplinary Sciences , Soochow University and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions , 215123 Suzhou , P. R. China
| |
Collapse
|
29
|
Wu Y, Wang Y, Guo W. Behavior and fate of geogenic uranium in a shallow groundwater system. JOURNAL OF CONTAMINANT HYDROLOGY 2019; 222:41-55. [PMID: 30827739 DOI: 10.1016/j.jconhyd.2019.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 01/09/2019] [Accepted: 02/21/2019] [Indexed: 06/09/2023]
Abstract
To unveil behavior and fate of uranium (U) in the Quaternary aquifer system of Datong basin (China), we analyzed sediment and groundwater samples, and performed geochemical modeling. The analyses for sediments were implemented by a sequential extraction procedure and measurements including X-ray power diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Concentrations of main elements and U, and 234U/238U activity ratios for groundwater were determined. Results show that sediment U contents range from 1.93 to 8.80 (average 3.00 ± 1.69) mg/kg. In relation to the total U, average fractions of residual U (probably as betafite) and U(VI) bound to carbonates and FeMn oxides are 74.4 ± 18.7%, 17.2 ± 13.3%, and 4.3 ± 2.9%, respectively. Lower average fractions were determined for both organic matter- and sulfide-bound U (mainly as U(IV), e.g., brannerite) (2.0 ± 0.7%) and exchangeable U(VI) (2.0 ± 2.8%). For the groundwater (pH 7.36-8.86), Ca2UO2(CO3)30, CaUO2(CO3)32-, and UO2(CO3)34- constitute >99.5% of the total dissolved U; and elevated U concentrations occur mainly in shallow aquifers (3-40 m deep below land surface) of the west flow-through and discharge areas, with 50% of the sampled points exceeding 30 μg/L. We argue that betafite and carbonate weathering and U(VI) desorption from ferrihydrite are the primary geochemical processes responsible for U mobilization, with a minor contrition from U(IV) oxidation. Abiotic U(IV) oxidation may be induced mainly by dissolved oxygen under oxic/suboxic conditions (e.g., in the recharge and flow-through areas), but significantly linked to amorphous ferrihydrite under Fe(III)- and sulfate-reducing conditions. Abiotic U(VI) reduction could be caused principally by siderite and mackinawite. Under alkaline conditions, higher HCO3- concentrations and lower Ca2+/HCO3- molar ratios (<~0.2) cause formation of CaUO2(CO3)32- and UO2(CO3)34-, and U(VI) desorption. With increases in concentrations of Ca2+ and Ca2+/HCO3- ratios (>~0.2), these anionic forms may shift to neutral Ca2UO2(CO3)30, which can facilitate further desorption of U(VI). Our results improve the understanding of U environmental geochemistry and are important for groundwater resources management in this and similar other Quaternary aquifer systems.
Collapse
Affiliation(s)
- Ya Wu
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
| | - Yanxin Wang
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 430074 Wuhan, China.
| | - Wei Guo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 430074 Wuhan, China
| |
Collapse
|
30
|
Xiao W, Jones AM, Collins RN, Waite TD. Investigating the effect of ascorbate on the Fe(II)-catalyzed transformation of the poorly crystalline iron mineral ferrihydrite. Biochim Biophys Acta Gen Subj 2018; 1862:1760-1769. [DOI: 10.1016/j.bbagen.2018.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/07/2018] [Accepted: 05/07/2018] [Indexed: 01/04/2023]
|
31
|
Xiong YY, Wu HQ, Luo F. The MOF+
Technique: A Potential Multifunctional Platform. Chemistry 2018; 24:13701-13705. [DOI: 10.1002/chem.201801348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/06/2018] [Indexed: 01/05/2023]
Affiliation(s)
- Yang Yang Xiong
- School of Biology; Chemistry and Material Science; East China University of Technology; Nanchang Jiangxi 344000 China
| | - Hui Qiong Wu
- School of Biology; Chemistry and Material Science; East China University of Technology; Nanchang Jiangxi 344000 China
| | - Feng Luo
- School of Biology; Chemistry and Material Science; East China University of Technology; Nanchang Jiangxi 344000 China
- College of Chemistry and Chemical Engineering; Hunan University of Science and Technology; HuNan, TanXiang China
| |
Collapse
|
32
|
McBriarty ME, Kerisit S, Bylaska EJ, Shaw S, Morris K, Ilton ES. Iron Vacancies Accommodate Uranyl Incorporation into Hematite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:6282-6290. [PMID: 29757622 DOI: 10.1021/acs.est.8b00297] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Radiotoxic uranium contamination in natural systems and nuclear waste containment can be sequestered by incorporation into naturally abundant iron (oxyhydr)oxides such as hematite (α-Fe2O3) during mineral growth. The stability and properties of the resulting uranium-doped material are impacted by the local coordination environment of incorporated uranium. While measurements of uranium coordination in hematite have been attempted using extended X-ray absorption fine structure (EXAFS) analysis, traditional shell-by-shell EXAFS fitting yields ambiguous results. We used hybrid functional ab initio molecular dynamics (AIMD) simulations for various defect configurations to generate synthetic EXAFS spectra which were combined with adsorbed uranyl spectra to fit experimental U L3-edge EXAFS for U6+-doped hematite. We discovered that the hematite crystal structure accommodates a trans-dioxo uranyl-like configuration for U6+ that substitutes for structural Fe3+, which requires two partially protonated Fe vacancies situated at opposing corner-sharing sites. Surprisingly, the best match to experiment included significant proportions of vacancy configurations other than the minimum-energy configuration, pointing to the importance of incorporation mechanisms and kinetics in determining the state of an impurity incorporated into a host phase under low temperature hydrothermal conditions.
Collapse
Affiliation(s)
| | | | | | - Samuel Shaw
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences , The University of Manchester , Manchester M13 9PL , United Kingdom
| | - Katherine Morris
- Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth, Atmospheric and Environmental Sciences , The University of Manchester , Manchester M13 9PL , United Kingdom
| | | |
Collapse
|
33
|
Wu W, Chen D, Li J, Su M, Chen N. Enhanced adsorption of uranium by modified red muds: adsorption behavior study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2018; 25:18096-18108. [PMID: 29691747 DOI: 10.1007/s11356-018-2027-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/12/2018] [Indexed: 06/08/2023]
Abstract
Uranium is a hazardous and radioactive element. Effective removal of uranium from wastewater stream requires advanced functional materials and reliable technologies. Red mud is a type of low-cost adsorbent which is widely used in the adsorption process. In the present work, we successfully modified the raw red mud to gain a series of highly efficient sorbents for uranium removal. They are nitric acid dealkalized red mud (DRM), aluminum nitrate modified red mud (ARM), and ferric nitrate modified red mud (FRM). The adsorption efficiencies of uranium(VI) by DRM, ARM, and FRM were 74.50, 95.56, and 98.75% in their optimal immobilization regions, respectively. The chemisorption of uranium dominates the adsorption process of FRM, while as to physical adsorption dominates the adsorption process of ARM and DRM. Both DRM and ARM reached their maximum adsorption capacities at 10 min while that for FRM occurred at 30 min. FRM performed much stronger anti-interference ability to the influence of carbonate and calcium. The outstanding adsorption ability of these modified red muds is mainly due to the enhancement of ion exchange, co-precipitation, and electrostatic attraction by red mud's active components and functional groups.
Collapse
Affiliation(s)
- Wanying Wu
- Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 51006, China
| | - Diyun Chen
- Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 51006, China
| | - Jinwen Li
- Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 51006, China
| | - Minhua Su
- Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 51006, China.
| | - Nan Chen
- Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources, School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 51006, China.
| |
Collapse
|
34
|
Wu Y, Li J, Wang Y, Xie X. Variations of uranium concentrations in a multi-aquifer system under the impact of surface water-groundwater interaction. JOURNAL OF CONTAMINANT HYDROLOGY 2018; 211:65-76. [PMID: 29559163 DOI: 10.1016/j.jconhyd.2018.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2017] [Revised: 01/24/2018] [Accepted: 03/05/2018] [Indexed: 06/08/2023]
Abstract
Understanding uranium (U) mobility is vital to minimizing its concentrations in potential drinking water sources. In this study, we report spatial-seasonal variations in U speciation and concentrations in a multi-aquifer system under the impact of Sanggan River in Datong basin, northern China. Hydrochemical and H, O, Sr isotopic data, thermodynamic calculations, and geochemical modeling are used to investigate the mechanisms of surface water-groundwater mixing-induced mobilization and natural attenuation of U. In the study site, groundwater U concentrations are up to 30.2 μg/L, and exhibit strong spatial-seasonal variations that are related to pH and Eh values, as well as dissolved Ca2+, HCO3-, and Fe(III) concentrations. For the alkaline aquifers of this site (pH 7.02-8.44), U mobilization is due to the formation and desorption of Ca2UO2(CO3)30 and CaUO2(CO3)32- caused by groundwater Ca2+ elevation via mineral weathering and Na-Ca exchange, incorporated U(VI) release from calcite, and U(IV) oxidation by Fe(OH)3. U immobilization is linked to the adsorption of CaUO2(CO3)32- and UO2(CO3)34- shifted from Ca2UO2(CO3)30 because of HCO3- elevation and Ca2+ depletion, U(VI) co-precipitation with calcite, and U(VI) reduction by adsorbed Fe2+ and FeS. Those results are of great significance for the groundwater resource management of this and similar other surface water-groundwater interaction zones.
Collapse
Affiliation(s)
- Ya Wu
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
| | - Junxia Li
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China
| | - Yanxin Wang
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China.
| | - Xianjun Xie
- School of Environmental Studies, China University of Geosciences, 430074 Wuhan, China
| |
Collapse
|
35
|
Xiao W, Jones AM, Collins RN, Bligh MW, Waite TD. Use of fourier transform infrared spectroscopy to examine the Fe(II)-Catalyzed transformation of ferrihydrite. Talanta 2017; 175:30-37. [DOI: 10.1016/j.talanta.2017.07.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/03/2017] [Accepted: 07/04/2017] [Indexed: 10/19/2022]
|
36
|
Collins RN, Rosso KM. Mechanisms and Rates of U(VI) Reduction by Fe(II) in Homogeneous Aqueous Solution and the Role of U(V) Disproportionation. J Phys Chem A 2017; 121:6603-6613. [PMID: 28809500 DOI: 10.1021/acs.jpca.7b05965] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular-level pathways in the aqueous redox transformation of uranium by iron remain unclear, despite the importance of this knowledge for predicting uranium transport and distribution in natural and engineered environments. As the relative importance of homogeneous versus heterogeneous pathways is difficult to probe experimentally, here we apply computational molecular simulation to isolate rates of key one electron transfer reactions in the homogeneous pathway. By comparison to experimental observations the role of the heterogeneous pathway also becomes clear. Density functional theory (DFT) and Marcus theory calculations for all primary monomeric species at pH values ≤7 show for UO22+ and its hydrolysis species UO2OH+ and UO2(OH)20 that reduction by Fe2+ is thermodynamically favorable, though kinetically limited for UO22+. An inner-sphere encounter complex between UO2OH+ and Fe2+ was the most stable for the first hydrolysis species and displayed an electron transfer rate constant ket = 4.3 × 103 s-1. Three stable inner- and outer-sphere encounter complexes between UO2(OH)20 and Fe2+ were found, with electron transfer rate constants ranging from ket = 7.6 × 102 to 7.2 × 104 s-1. Homogeneous reduction of these U(VI) hydrolysis species to U(V) is, therefore, predicted to be facile. In contrast, homogeneous reduction of UO2+ by Fe2+ was found to be thermodynamically unfavorable, suggesting the possible importance of U(V)-U(V) disproportionation as a route to U(IV). Calculations on homogeneous disproportionation, however, while yielding a stable outer-sphere U(V)-U(V) encounter complex, indicate that this electron transfer reaction is not feasible at circumneutral pH. Protonation of both axial O atoms of acceptor U(V) (i.e., by H3O+) was found to be a prerequisite to stabilize U(IV), consistent with the experimental observation that the rate of this reaction is inversely correlated with pH. Thus, despite prevailing notions that U(V) is rapidly eliminated by homogeneous disproportionation, this pathway is irrelevant at environmental conditions.
Collapse
Affiliation(s)
- Richard N Collins
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia , Sydney, NSW, Australia 2052
| | - Kevin M Rosso
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia , Sydney, NSW, Australia 2052.,Physical Sciences Division, Pacific Northwest National Laboratory , Richland, Washington 99336, United States
| |
Collapse
|
37
|
Pidchenko I, Kvashnina KO, Yokosawa T, Finck N, Bahl S, Schild D, Polly R, Bohnert E, Rossberg A, Göttlicher J, Dardenne K, Rothe J, Schäfer T, Geckeis H, Vitova T. Uranium Redox Transformations after U(VI) Coprecipitation with Magnetite Nanoparticles. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:2217-2225. [PMID: 28094921 DOI: 10.1021/acs.est.6b04035] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Uranium redox states and speciation in magnetite nanoparticles coprecipitated with U(VI) for uranium loadings varying from 1000 to 10 000 ppm are investigated by X-ray absorption spectroscopy (XAS). It is demonstrated that the U M4 high energy resolution X-ray absorption near edge structure (HR-XANES) method is capable to clearly characterize U(IV), U(V), and U(VI) existing simultaneously in the same sample. The contributions of the three different uranium redox states are quantified with the iterative transformation factor analysis (ITFA) method. U L3 XAS and transmission electron microscopy (TEM) reveal that initially sorbed U(VI) species recrystallize to nonstoichiometric UO2+x nanoparticles within 147 days when stored under anoxic conditions. These U(IV) species oxidize again when exposed to air. U M4 HR-XANES data demonstrate strong contribution of U(V) at day 10 and that U(V) remains stable over 142 days under ambient conditions as shown for magnetite nanoparticles containing 1000 ppm U. U L3 XAS indicates that this U(V) species is protected from oxidation likely incorporated into octahedral magnetite sites. XAS results are supported by density functional theory (DFT) calculations. Further characterization of the samples include powder X-ray diffraction (pXRD), scanning electron microscopy (SEM) and Fe 2p X-ray photoelectron spectroscopy (XPS).
Collapse
Affiliation(s)
- Ivan Pidchenko
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Kristina O Kvashnina
- European Synchrotron Radiation Facility (ESRF) , CS40220, 38043 Grenoble Cedex 9, France
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , P.O. Box 510119, D-01314 Dresden, Germany
| | - Tadahiro Yokosawa
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Nicolas Finck
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Sebastian Bahl
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Dieter Schild
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Robert Polly
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Elke Bohnert
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - André Rossberg
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Resource Ecology , P.O. Box 510119, D-01314 Dresden, Germany
| | - Jörg Göttlicher
- Karlsruhe Institute of Technology, Institute for Photon Science and Synchrotron Radiation (IPS) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Kathy Dardenne
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Jörg Rothe
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Thorsten Schäfer
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Horst Geckeis
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| | - Tonya Vitova
- Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE) , P.O. Box 3640, D-76021 Karlsruhe, Germany
| |
Collapse
|
38
|
Jones AM, Kinsela AS, Collins RN, Waite TD. The reduction of 4-chloronitrobenzene by Fe(II)-Fe(III) oxide systems - correlations with reduction potential and inhibition by silicate. JOURNAL OF HAZARDOUS MATERIALS 2016; 320:143-149. [PMID: 27529649 DOI: 10.1016/j.jhazmat.2016.08.031] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 08/09/2016] [Accepted: 08/10/2016] [Indexed: 06/06/2023]
Abstract
Recent studies have demonstrated that the rate at which Fe(II)-Fe(III) oxyhydroxide systems catalyze the reduction of reducible contaminants, such as 4-chloronitrobenzene, is well correlated to their thermodynamic reduction potential. Here we confirm this effect in the presence of Fe(III) oxyhydroxide phases not previously assessed, namely ferrihydrite and nano-goethite, as well as Fe(III) oxyhydroxide phases previously examined. In addition, silicate is found to decrease the extent of Fe(II) sorption to the Fe(III) oxyhydroxide surface, increasing the reduction potential of the Fe(II)-Fe(III) oxyhydroxide suspension and, accordingly, decreasing the rate of 4-chloronitrobenzene reduction. A linear relationship between the reduction potential of the Fe(II)-Fe(III) oxyhydroxide suspensions and the reduction rate of 4-chloronitrobenzene (normalized to surface area and concentration of sorbed Fe(II)) was obtained in the presence and absence of silicate. However, when ferrihydrite was doped with Si (through co-precipitation) the reduction of 4-chloronitrobenzene was much slower than predicted from its reduction potential. The results obtained have significant implications to the likely effectiveness of naturally occurring contaminant degradation processes involving Fe(II) and Fe(III) oxyhydroxides in groundwater environments containing high concentrations of silicate, or other species which compete with Fe(II) for sorption sites.
Collapse
Affiliation(s)
- Adele M Jones
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia, Sydney, NSW, 2052, Australia.
| | - Andrew S Kinsela
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia, Sydney, NSW, 2052, Australia
| | - Richard N Collins
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia, Sydney, NSW, 2052, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia, Sydney, NSW, 2052, Australia.
| |
Collapse
|
39
|
Kerisit S, Bylaska EJ, Massey MS, McBriarty ME, Ilton ES. Ab Initio Molecular Dynamics of Uranium Incorporated in Goethite (α-FeOOH): Interpretation of X-ray Absorption Spectroscopy of Trace Polyvalent Metals. Inorg Chem 2016; 55:11736-11746. [DOI: 10.1021/acs.inorgchem.6b01773] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Michael S. Massey
- Department
of Earth and Environmental Sciences, California State University—East Bay, Hayward, California 94542, United States
| | | | | |
Collapse
|
40
|
Tsarev S, Collins RN, Fahy A, Waite TD. Reduced Uranium Phases Produced from Anaerobic Reaction with Nanoscale Zerovalent Iron. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:2595-2601. [PMID: 26840619 DOI: 10.1021/acs.est.5b06160] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Nanoscale zerovalent iron (nZVI) has shown potential to be an effective remediation agent for uranium-contaminated subsurface environments, however, the nature of the reaction products and their formation kinetics have not been fully elucidated over a range of environmentally relevant conditions. In this study, the oxygen-free reaction of U(VI) with varying quantities of nZVI was examined at pH 7 in the presence of both calcium and carbonate using a combination of X-ray absorption spectroscopy, X-ray diffraction and transmission electron microscopy. It was observed that the structure of the reduced U solid phases was time dependent and largely influenced by the ratio of nZVI to U in the system. At the highest U:Fe molar ratio examined (1:4), nanoscale uraninite (UO2) was predominantly formed within 1 day of reaction. At lower U:Fe molar ratios (1:21), evidence was obtained for the formation of sorbed U(IV) and U(V) surface complexes which slowly transformed to UO2 nanoparticles that were stable for up to 1 year of anaerobic incubation. After 8 days of reaction at the lowest U:Fe molar ratio examined (1:110), sorbed U(IV) was still the major form of U associated with the solid phase. Regardless of the U:Fe molar ratio, the anaerobic corrosion of nZVI resulted in the slow formation of micron-sized fibrous chukanovite (Fe2(OH)2CO3) particles.
Collapse
Affiliation(s)
- Sergey Tsarev
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Richard N Collins
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
| | - Adam Fahy
- Centre for Organic Electronics, University of Newcastle , Callaghan, New South Wales 2038, Australia
| | - T David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia , Sydney, New South Wales 2052, Australia
| |
Collapse
|
41
|
Gao T, Shen Y, Jia Z, Qiu G, Liu F, Zhang Y, Feng X, Cai C. Interaction mechanisms and kinetics of ferrous ion and hexagonal birnessite in aqueous systems. GEOCHEMICAL TRANSACTIONS 2015; 16:16. [PMID: 26435697 PMCID: PMC4585411 DOI: 10.1186/s12932-015-0031-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 09/17/2015] [Indexed: 05/31/2023]
Abstract
BACKGROUND In soils and sediments, manganese oxides and oxygen usually participate in the oxidation of ferrous ions. There is limited information concerning the interaction process and mechanisms of ferrous ions and manganese oxides. The influence of air (oxygen) on reaction process and kinetics has been seldom studied. Because redox reactions usually occur in open systems, the participation of air needs to be further investigated. RESULTS To simulate this process, hexagonal birnessite was prepared and used to oxidize ferrous ions in anoxic and aerobic aqueous systems. The influence of pH, concentration, temperature, and presence of air (oxygen) on the redox rate was studied. The redox reaction of birnessite and ferrous ions was accompanied by the release of Mn2+ and K+ ions, a significant decrease in Fe2+ concentration, and the formation of mixed lepidocrocite and goethite during the initial stage. Lepidocrocite did not completely transform into goethite under anoxic condition with pH about 5.5 within 30 days. Fe2+ exhibited much higher catalytic activity than Mn2+ during the transformation from amorphous Fe(III)-hydroxide to lepidocrocite and goethite under anoxic conditions. The release rates of Mn2+ were compared to estimate the redox rates of birnessite and Fe2+ under different conditions. CONCLUSIONS Redox rate was found to be controlled by chemical reaction, and increased with increasing Fe2+ concentration, pH, and temperature. The formation of ferric (hydr)oxides precipitate inhibited the further reduction of birnessite. The presence of air accelerated the oxidation of Fe2+ to ferric oxides and facilitated the chemical stability of birnessite, which was not completely reduced and dissolved after 18 days. As for the oxidation of aqueous ferrous ions by oxygen in air, low and high pHs facilitated the formation of goethite and lepidocrocite, respectively. The experimental results illustrated the single and combined effects of manganese oxide and air on the transformation of Fe2+ to ferric oxides. Graphical abstract:Lepidocrocite and goethite were formed during the interaction of ferrous ion and birnessite at pH 4-7. Redox rate was controlled by the adsorption of Fe2+ on the surface of birnessite. The presence of air (oxygen) accelerated the oxidation of Fe2+ to ferric oxides and facilitated the chemical stability of birnessite.
Collapse
Affiliation(s)
- Tianyu Gao
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Yougang Shen
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Zhaoheng Jia
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Guohong Qiu
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Fan Liu
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Yashan Zhang
- />Department of Chemistry, University of Connecticut, Storrs, 55 North Eagleville Road, Storrs, CT 06269 USA
| | - Xionghan Feng
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| | - Chongfa Cai
- />Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtse River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070 People’s Republic of China
| |
Collapse
|
42
|
Stewart BD, Cismasu AC, Williams KH, Peyton BM, Nico PS. Reactivity of Uranium and Ferrous Iron with Natural Iron Oxyhydroxides. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10357-10365. [PMID: 26226398 DOI: 10.1021/acs.est.5b02645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Determining key reaction pathways involving uranium and iron oxyhydroxides under oxic and anoxic conditions is essential for understanding uranium mobility as well as other iron oxyhydroxide mediated processes, particularly near redox boundaries where redox conditions change rapidly in time and space. Here we examine the reactivity of a ferrihydrite-rich sediment from a surface seep adjacent to a redox boundary at the Rifle, Colorado field site. Iron(II)-sediment incubation experiments indicate that the natural ferrihydrite fraction of the sediment is not susceptible to reductive transformation under conditions that trigger significant mineralogical transformations of synthetic ferrihydrite. No measurable Fe(II)-promoted transformation was observed when the Rifle sediment was exposed to 30 mM Fe(II) for up to 2 weeks. Incubation of the Rifle sediment with 3 mM Fe(II) and 0.2 mM U(VI) for 15 days shows no measurable incorporation of U(VI) into the mineral structure or reduction of U(VI) to U(IV). Results indicate a significantly decreased reactivity of naturally occurring Fe oxyhydroxides as compared to synthetic minerals, likely due to the association of impurities (e.g., Si, organic matter), with implications for the mobility and bioavailability of uranium and other associated species in field environments.
Collapse
Affiliation(s)
- Brandy D Stewart
- Chemical and Biological Engineering, Montana State University , Bozeman, Montana 59717, United States
| | - A Cristina Cismasu
- Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, California 94720, United States
| | - Kenneth H Williams
- Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, California 94720, United States
| | - Brent M Peyton
- Chemical and Biological Engineering, Montana State University , Bozeman, Montana 59717, United States
| | - Peter S Nico
- Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, California 94720, United States
| |
Collapse
|
43
|
Yuan K, Ilton ES, Antonio MR, Li Z, Cook PJ, Becker U. Electrochemical and Spectroscopic Evidence on the One-Electron Reduction of U(VI) to U(V) on Magnetite. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:6206-13. [PMID: 25893535 DOI: 10.1021/acs.est.5b00025] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Reduction of U(VI) to U(IV) on mineral surfaces is often considered a one-step two-electron process. However, stabilized U(V), with no evidence of U(IV), found in recent studies indicates U(VI) can undergo a one-electron reduction to U(V) without further progression to U(IV). We investigated reduction pathways of uranium by reducing U(VI) electrochemically on a magnetite electrode at pH 3.4. Cyclic voltammetry confirms the one-electron reduction of U(VI) to U(V). Formation of nanosize uranium precipitates on the magnetite surface at reducing potentials and dissolution of the solids at oxidizing potentials are observed by in situ electrochemical atomic force microscopy. XPS analysis of the magnetite electrodes polarized in uranium solutions at voltages from -0.1 to -0.9 V (E(0)(U(VI)/U(V))= -0.135 V vs Ag/AgCl) show the presence of only U(V) and U(VI). The sample with the highest U(V)/U(VI) ratio was prepared at -0.7 V, where the longest average U-O(axial) distance of 2.05 ± 0.01 Å was evident in the same sample revealed by extended X-ray absorption fine structure analysis. The results demonstrate that the electrochemical reduction of U(VI) on magnetite only yields U(V), even at a potential of -0.9 V, which favors the one-electron reduction mechanism. U(V) does not disproportionate but stabilizes on magnetite through precipitation of mixed-valence state U(V)/U(VI) solids.
Collapse
Affiliation(s)
- Ke Yuan
- †Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Eugene S Ilton
- ‡Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Mark R Antonio
- §Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Zhongrui Li
- †Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Peter J Cook
- †Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Udo Becker
- †Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States
| |
Collapse
|
44
|
Klein AR, Silvester E, Hogan CF. Mediated electron transfer between Fe(II) adsorbed onto hydrous ferric oxide and a working electrode. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:10835-10842. [PMID: 25157830 DOI: 10.1021/es501561d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The redox properties of Fe(II) adsorbed onto mineral surfaces have been highly studied over recent years due to the wide range of environmental contaminants that react with this species via abiotic processes. In this work the reactivity of Fe(II) adsorbed onto hydrous ferric oxide (HFO) has been studied using ferrocene (bis-cyclopentadienyl iron(II); Fc) derivatives as electron shuttles in cyclic voltammetry (CV) experiments. The observed amplification of the ferrocene oxidation peak in CV is attributed to reaction between the electrochemically generated ferrocenium (Fc(+)) ion and adsorbed Fe(II) species in a catalytic process (EC' mechanism). pH dependence studies show that the reaction rate increases with Fe(II) adsorption and is maintained in the absence of aqueous Fe(2+), providing strong evidence that the electron transfer process involves the adsorbed species. The rate of reaction between Fc(+) and adsorbed Fe(II) increases with the redox potential of the ferrocene derivative, as expected, with bimolecular rate constants in the range 10(3)-10(5) M(-1) s(-1). The ferrocene-mediated electrochemical method described has considerable promise in the development of a technique for measuring electron-transfer rates in geochemical and environmental systems.
Collapse
Affiliation(s)
- Annaleise R Klein
- Department of Environmental Management and Ecology (DEME), La Trobe University , Albury-Wodonga, Victoria 3690, Australia
| | | | | |
Collapse
|