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Ma B, Yao J, Knudsen TŠ, Pang W, Liu B, Zhu X, Cao Y, Zhao C. Dithionite accelerated copper slag heterogeneous-homogeneous coupled Fenton degradation of organic pollutants. JOURNAL OF HAZARDOUS MATERIALS 2023; 457:131797. [PMID: 37302188 DOI: 10.1016/j.jhazmat.2023.131797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/09/2023] [Accepted: 06/05/2023] [Indexed: 06/13/2023]
Abstract
The heterogeneous-homogeneous coupled Fenton (HHCF) processes combine the advantages of rapid reaction and the catalyst reuse, which makes them attractive for wastewater treatment. Nevertheless, the lack of both, cost-effective catalysts and the desirable Fe3+/Fe2+ conversion mediators limit the development of HHCF processes. This study investigates a prospective HHCF process, in which solid waste copper slag (CS) and dithionite (DNT) act as catalyst and mediator of Fe3+/Fe2+ transformation, respectively. DNT enables controlled leaching of iron and a highly efficient homogeneous Fe3+/Fe2+ cycle by dissociating to SO2- • under acidic conditions, leading to the enhanced H2O2 decomposition and •OH generation (from 48 μmol/L to 399 μmol/L) for p-chloroaniline (p-CA) degradation. The removal rate of p-CA in the CS/DNT/H2O2 system increased by 30 times in comparison with the CS/H2O2 system (increased from 1.21 × 10-3 min-1 to 3.61 × 10-2 min-1). Moreover, batch dosing of H2O2 can greatly promote the yield of •OH (from 399 μmol/L to 627 μmol/L), by mitigating the side reactions between H2O2 and SO2- •. This study highlights the importance of the iron cycle regulation for improvement of the Fenton efficiency and develops a cost-effective Fenton system for organic contaminants elimination in wastewater.
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Affiliation(s)
- Bo Ma
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Jun Yao
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
| | - Tatjana Šolević Knudsen
- University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Department of Chemistry, Njegoševa 12, 11000 Belgrade, Serbia
| | - Wancheng Pang
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Bang Liu
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China; Equipe Environnement et Microbiologie, MELODY group, Universit´e de Pau et des Pays de l'Adour, E2S-UPPA, IPREM UMR CNRS 5254, BP 1155, 64013 Pau Cedex, France
| | - Xiaozhe Zhu
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Ying Cao
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Chenchen Zhao
- School of Water Resources and Environment, Research Center of Environmental Science and Engineering, China University of Geosciences (Beijing), Beijing 100083, China
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Yin X, Hua H, Dyer J, Landis R, Fennell D, Axe L. Degradation of chlorinated solvents with reactive iron minerals in subsurface sediments from redox transition zones. JOURNAL OF HAZARDOUS MATERIALS 2023; 445:130470. [PMID: 36493644 DOI: 10.1016/j.jhazmat.2022.130470] [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: 08/02/2022] [Revised: 11/08/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
Reactive iron (Fe) mineral coatings found in subsurface reduction-oxidation transition zones (RTZs) contribute to the attenuation of contaminants. An 18.3-m anoxic core was collected from the site, where constituents of concern (COCs) in groundwater included chlorinated solvents. Reactive Fe mineral coatings were found to be abundant in the RTZs. This research focused on evaluating reaction kinetics with anoxic sediments bearing ferrous mineral nano-coatings spiked with either tetrachloroethylene (PCE), trichloroethylene (TCE), or 1,4-dichlorobenzene (1,4-DCB). Reaction kinetics with RTZ sediments followed pseudo-first-order reactions for the three contaminants with 90% degradation achieved in less than 39 days. The second-order rate constants for the three COCs ranged from 6.20 × 10-4 to 1.73 × 10-3 Lg-1h-1 with pyrite (FeS2), 4.97 × 10-5 to 1.24 × 10-3 Lg-1h-1with mackinawite (FeS), 1.25 × 10-4 to 1.89 × 10-4 Lg-1h-1 with siderite (FeCO3), and 1.79 × 10-4 to 1.10 × 10-3 Lg-1h-1 with magnetite (Fe3O4). For these three chlorinated solvents, the trend for the rate constants followed: Fe(II) sulfide minerals > magnetite > siderite. The high reactivity of Fe mineral coatings is hypothesized to be due to the large surface areas of the nano-mineral coatings. As a result, these surfaces are expected to play an important role in the attenuation of chlorinated solvents in contaminated subsurface environments.
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Affiliation(s)
- Xin Yin
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07032, USA
| | - Han Hua
- Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07032, USA; Department of Civil, Construction & Environmental Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - James Dyer
- Savannah River National Laboratory, Aiken, SC 29808, USA
| | | | - Donna Fennell
- Rutgers University, Department of Environmental Sciences, 14 College Farm Road, New Brunswick, NJ 08901, USA
| | - Lisa Axe
- Otto H. York Department of Chemical and Materials Engineering, New Jersey Institute of Technzhaology, Newark, NJ 07032, USA.
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Reductive degradation of carbon tetrachloride with guava leaf extract. J IND ENG CHEM 2022. [DOI: 10.1016/j.jiec.2022.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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4
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Yang S, Liu A, Liu J, Liu Z, Zhang W. Advance of Sulfidated Nanoscale Zero-Valent Iron: Synthesis, Properties and Environmental Application. ACTA CHIMICA SINICA 2022. [DOI: 10.6023/a22080345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Hou Y, Liang C. Bisulfite reduction of soil iron for the reductive degradation of trichloroethylene. CHEMOSPHERE 2022; 286:131818. [PMID: 34416591 DOI: 10.1016/j.chemosphere.2021.131818] [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: 05/07/2021] [Revised: 07/17/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
This study explored the potential reactivities of various reductants in inducing subsurface TCE degradation in natural soils. It was found that bisulfite (HSO3-) exhibited the ability to induce reduction in soil iron minerals, and increase the degradation of TCE in the soil slurry system; however, no TCE degradation occurred in the aqueous system. The role of TCE degradation by soil constituents, such as major soil mineral elements, Fe and humic acid (HA) on HSO3-, was examined in aqueous phase. It was seen that by themselves, the presence of Fe3+, HA, Fe2O3, FeOOH, and Fe3O4 did not result in substantial TCE removals. However, the presence of HSO3- can significantly induce iron reduction, producing a reducing condition that can result in complete TCE degradation. Furthermore, the reductive pathway was identified as the dominant degradation route via electron scavenging with periodate ion. To demonstrate the applicability of HSO3- reduction enhancement, a HSO3-/TCE mixed solution was flushed through a soil column, with gradually increased HSO3- concentrations, at a fixed flow rate, and also with varied flushing rates at a fixed HSO3- concentration. Based on our study, a 10 mM HSO3- solution may be effective for some environmental sites; however, each site requires specific evaluation based on contaminant concentrations and subsurface conditions.
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Affiliation(s)
- Yuwen Hou
- Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-kuang Road, Taichung, 402, Taiwan
| | - Chenju Liang
- Department of Environmental Engineering, National Chung Hsing University, 250 Kuo-kuang Road, Taichung, 402, Taiwan.
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Review: Clay-Modified Electrodes in Heterogeneous Electro-Fenton Process for Degradation of Organic Compounds: The Potential of Structural Fe(III) as Catalytic Sites. MATERIALS 2021; 14:ma14247742. [PMID: 34947335 PMCID: PMC8703352 DOI: 10.3390/ma14247742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/06/2021] [Accepted: 12/10/2021] [Indexed: 11/17/2022]
Abstract
Advanced oxidation processes are considered as a promising technology for the removal of persistent organic pollutants from industrial wastewaters. In particular, the heterogeneous electro-Fenton (HEF) process has several advantages such as allowing the working pH to be circumneutral or alkaline, recovering and reusing the catalyst and avoiding the release of iron in the environment as a secondary pollutant. Among different iron-containing catalysts, studies using clay-modified electrodes in HEF process are the focus in this review. Fe(III)/Fe(II) within the lattice of clay minerals can possibly serve as catalytic sites in HEF process. The description of the preparation and application of clay-modified electrodes in the degradation of model pollutants in HEF process is detailed in the review. The absence of mediators responsible for transferring electrons to structural Fe(III) and regenerating catalytic Fe(II) was considered as a milestone in the field. A comprehensive review of studies investigating the use of electron transfer mediators as well as the mechanism behind electron transfer from and to the clay mineral structure was assembled in order to uncover other milestones to be addressed in this study area.
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Garcia AN, Zhang Y, Ghoshal S, He F, O'Carroll DM. Recent Advances in Sulfidated Zerovalent Iron for Contaminant Transformation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:8464-8483. [PMID: 34170112 DOI: 10.1021/acs.est.1c01251] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
2021 marks 10 years since controlled abiotic synthesis of sulfidated nanoscale zerovalent iron (S-nZVI) for use in site remediation and water treatment emerged as an area of active research. It was then expanded to sulfidated microscale ZVI (S-mZVI) and together with S-nZVI, they are collectively referred to as S-(n)ZVI. Heightened interest in S-(n)ZVI stemmed from its significantly higher reactivity to chlorinated solvents and heavy metals. The extremely promising research outcomes during the initial period (2011-2017) led to renewed interest in (n)ZVI-based technologies for water treatment, with an explosion in new research in the last four years (2018-2021) that is building an understanding of the novel and complex role of iron sulfides in enhancing reactivity of (n)ZVI. Numerous studies have focused on exploring different S-(n)ZVI synthesis approaches, and its colloidal, surface, and reactivity (electrochemistry, contaminant selectivity, and corrosion) properties. This review provides a critical overview of the recent milestones in S-(n)ZVI technology development: (i) clear insights into the role of iron sulfides in contaminant transformation and long-term aging, (ii) impact of sulfidation methods and particle characteristics on reactivity, (iii) broader range of treatable contaminants, (iv) synthesis for complete decontamination, (v) ecotoxicity, and (vi) field implementation. In addition, this review discusses major knowledge gaps and future avenues for research opportunities.
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Affiliation(s)
- Ariel Nunez Garcia
- Department of Civil and Environmental Engineering, Western University, 1151 Richmond Rd., London, Ontario N6A 5B8, Canada
| | - Yanyan Zhang
- Department of Civil Engineering, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
- Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou 310024, Zhejiang Province China
| | - Subhasis Ghoshal
- Department of Civil Engineering, McGill University, 817 Sherbrooke Street West, Montreal, Quebec H3A 0C3, Canada
| | - Feng He
- Institute of Environmental Chemistry and Pollution Control College of Environment, Zhejiang University of Technology 18 Chaowang Rd, Hangzhou, China 310014
| | - Denis M O'Carroll
- School of Civil and Environmental Engineering, Water Research Centre, University of New South Wales, Sydney New South Wales 2052, Australia
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Yazdanbakhsh A, Eslami A, Mahdipour F, Ghanbari F, Ghasemi SM, Atamaleki A, Maleksari HS, Lin KYA. Dye degradation in aqueous solution by dithionite/UV-C advanced reduction process (ARP): Kinetic study, dechlorination, degradation pathway and mechanism. J Photochem Photobiol A Chem 2021. [DOI: 10.1016/j.jphotochem.2020.112995] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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9
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Entwistle J, Latta DE, Scherer MM, Neumann A. Abiotic Degradation of Chlorinated Solvents by Clay Minerals and Fe(II): Evidence for Reactive Mineral Intermediates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:14308-14318. [PMID: 31802666 DOI: 10.1021/acs.est.9b04665] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
For decades, there has been evidence that Fe-containing minerals might contribute to abiotic degradation of chlorinated ethene (CE) plumes. Here, we evaluated whether Fe(II) in clay minerals reduces tetrachloroethene (PCE) and trichloroethene (TCE). We found that structural Fe(II) in both low (SWy-2) and high (NAu-1) Fe clay minerals did not reduce PCE or TCE under anoxic conditions. There was also no reduction of PCE or TCE after adding 5 mM dissolved Fe(II) to the clay mineral suspensions. In the presence of high Fe(II) concentrations (20 mM), however, PCE and TCE reduction products were observed in the presence of low Fe-content clay mineral SWy-2. Mössbauer spectroscopy results indicate that a mixed-valent Fe(II)-Fe(III) precipitate formed in the reactive SWy-2 suspensions. In contrast, in suspensions containing 20 mM Fe(II) alone or Fe-free clay mineral (Syn-1), we observed a purely Fe(II)-containing precipitate (Fe(OH)2) and also PCE and TCE reduction products. Interestingly, the amount of CE products decreased in the order of Fe-free clay mineral Syn-1 > Fe(OH)2 > low Fe-content clay mineral SWy-2, suggesting that clay mineral Fe controlled the formation of the reactive mineral phase. Additional experiments with hexachloroethane (HCA) revealed that faster HCA reduction occurred with decreasing clay mineral Fe content. Kinetic modeling yielded invariable second-order rate constants and increasing concentrations of reactive Fe(II) as the Fe(II)/Fe(total) content of the precipitates increased. Our data suggest that clay mineral Fe(III) is a sink for electrons from added Fe(II) that otherwise might have reduced the CEs. Furthermore, our findings are consistent with the hypothesis that active precipitation of Fe(II)-containing reactive mineral intermediates (RMI) may be important to CE reduction and suggest that RMI formation depends on clay mineral presence and Fe content.
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Affiliation(s)
- James Entwistle
- School of Engineering , Newcastle University , Newcastle upon Tyne , NE1 7RU , U.K
| | - Drew E Latta
- Civil and Environmental Engineering , The University of Iowa , Iowa City , Iowa 52242 , United States
| | - Michelle M Scherer
- Civil and Environmental Engineering , The University of Iowa , Iowa City , Iowa 52242 , United States
| | - Anke Neumann
- School of Engineering , Newcastle University , Newcastle upon Tyne , NE1 7RU , U.K
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Liu Y, Zhang Y, Zhou A. A potential novel approach for in situ chemical oxidation based on the combination of persulfate and dithionite. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 693:133635. [PMID: 31377376 DOI: 10.1016/j.scitotenv.2019.133635] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/24/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
Although persulfate (PS) activation has been commonly applied to remove organic contaminants on the subsurface, it is valuable to further explore PS activation methods. In this study, a novel combined process based on PS coupled with dithionite was investigated using trichloroethene (TCE) as a typical organic contaminant. PS/dithionite was demonstrated to be an effective system for TCE degradation depending on the operating parameters such as the initial PS and dithionite dosages. The optimal molar ratio of PS/dithionite/TCE was 5/5/1. Sulfate radicals (SO4•-) were the dominant reactive species responsible for TCE degradation in the PS/dithionite system. Two pathways for SO4•- generation were proposed in the PS/dithionite system. The generation of SO4•- increased in the presence of oxygen but was still effective in an anaerobic environment. This study is the first to report a novel combined process based on PS coupled with dithionite, which is expected to be an efficient and environmentally friendly approach for in situ chemical oxidation (ISCO) remediation of contaminated soil and groundwater, whether in aerobic or anaerobic environments.
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Affiliation(s)
- Yunde Liu
- School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
| | - Yuanzheng Zhang
- Geological Survey Institute, China University of Geosciences, Wuhan 430074, China
| | - Aiguo Zhou
- School of Environmental Studies & State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; Geological Survey Institute, China University of Geosciences, Wuhan 430074, China.
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11
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Schneider HA, Jackson WA, Rainwater K, Reible D, Morse S, Hatzinger PB, Garza-Rubalcava U. Estimation of Interstitial Velocity Using a Direct Drive High-Resolution Passive Profiler. GROUND WATER 2019; 57:915-924. [PMID: 30811585 DOI: 10.1111/gwat.12874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 02/17/2019] [Accepted: 02/22/2019] [Indexed: 06/09/2023]
Abstract
The fate and transport of groundwater contaminants depends partially on groundwater velocity, which can vary appreciably in highly stratified aquifers. A high-resolution passive profiler (HRPP) was developed to evaluate groundwater velocity, contaminant concentrations, and microbial community structure at ∼20 cm vertical depth resolution in shallow heterogeneous aquifers. The objective of this study was to use mass transfer of bromide (Br- ), a conservative tracer released from cells in the HRPP, to estimate interstitial velocity. Laboratory experiments were conducted to empirically relate velocity and the mass transfer coefficient of Br- based on the relative loss of Br- from HRPP cells. Laboratory-scale HRPPs were deployed in flow boxes containing saturated soils with differing porosities, and the mass transfer coefficient of Br- was measured at multiple interstitial velocities (0 to 100 cm/day). A two-dimensional (2D) quasi-steady-state model was used to relate velocity to mass transfer of Br- for a range of soil porosities (0.2-0.5). The laboratory data indicate that the mass transfer coefficient of Br- , which was directly-but non-linearly-related to velocity, can be determined with a single 3-week deployment of the HRPP. The mass transfer coefficient was relatively unaffected by sampler orientation, length of deployment time, or porosity. The model closely simulated the experimental results. The data suggest that the HRPP will be applicable for estimating groundwater velocity ranging from 1 to 100 cm/day in the field at a minimum depth resolution of 10 cm, depending on sampler design.
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Affiliation(s)
- Haley A Schneider
- Geosyntec Consultants, Inc., 924 Anacapa Street #4a, Santa Barbara, CA, 93101
| | | | - Ken Rainwater
- Department of Civil, Environmental, and Construction Engineering, Texas Tech University, 911 Boston Avenue, Lubbock, TX, 79409
| | - Danny Reible
- Department of Civil, Environmental, and Construction Engineering, Texas Tech University, 911 Boston Avenue, Lubbock, TX, 79409
| | - Stephen Morse
- Department of Civil and Environmental Engineering, Department of Mechanical Engineering, 1400 Townsend Drive, Michigan Technological University, Houghton, MI, 49931
| | - Paul B Hatzinger
- Biotechnology Development and Applications, APTIM, 17 Princess Road, Lawrenceville, NJ, 08648
| | - Uriel Garza-Rubalcava
- Department of Chemical Engineering, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409
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Liu X, Yuan S, Tong M, Liu D. Oxidation of trichloroethylene by the hydroxyl radicals produced from oxygenation of reduced nontronite. WATER RESEARCH 2017; 113:72-79. [PMID: 28199864 DOI: 10.1016/j.watres.2017.02.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 02/01/2017] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
Reduction by Fe(II)-bearing silicate minerals has been proposed as an important mechanism for the attenuation of chlorinated hydrocarbons (CHCs) in anoxic subsurfaces. The redox condition of subsurface often changes from anoxic to oxic due to natural processes and human activities, but little is known about the transformation of CHCs induced by Fe(II)-bearing silicate minerals under oxic conditions. This study reveals that trichloroethylene (TCE) can be efficiently oxidized during the oxygenation of reduced nontronite at pH 7.5, whereas the reduction was negligible under anoxic conditions. The maximum oxidation of TCE (initially 1 mg/L) attained 89.6% for 3 h oxygenation of 2 g/L nontronite with 50% reduction extent. TCE oxidation is attributed to the strongly oxidizing hydroxyl radicals (OH) produced by the oxygenation of Fe(II) in nontronite. Fe(II) on the edges is preferentially oxygenated for OH production, and the interior Fe(II) serves as an electron pool to regenerate the Fe(II) on the edges. Oxidation of TCE could be sustainable through chemically or biologically reducing the oxidized silicate minerals. Our findings present a new mechanism for the transformation of CHCs and other redox-active substances in the redox-fluctuation environments.
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Affiliation(s)
- Xixiang Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Songhu Yuan
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China.
| | - Man Tong
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
| | - Deng Liu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Wuhan 430074, PR China
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Nunez Garcia A, Boparai HK, O'Carroll DM. Enhanced Dechlorination of 1,2-Dichloroethane by Coupled Nano Iron-Dithionite Treatment. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:5243-5251. [PMID: 27128632 DOI: 10.1021/acs.est.6b00734] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
1,2-Dichloroethane (1,2-DCA) is a chlorinated solvent classified as a probable human carcinogen. Due to its extensive use in industrial applications, widespread contamination, and recalcitrance toward abiotic dechlorination, 1,2-DCA remains a challenging compound for the remediation community. Over the past decade, nano zerovalent iron (nZVI) has been efficiently used to treat many of the chlorinated compounds of concern. However, thus far, even nZVI (monometallic or bimetallic) has been unable to dechlorinate 1,2-DCA. Therefore, an alternative treatment coupling nZVI with dithionite to treat 1,2-DCA is proposed in this work. Coupled nZVI-dithionite was able to degrade >90% 1,2-DCA over the course of a year. The effects of dithionite and nZVI loadings, carboxymethyl cellulose (CMC) coating, addition of palladium, and other iron species as metal surfaces on the degradation kinetics were also investigated. Observed pseudo-first-order rate constants (kobs) ranged from 3.8 × 10(-3) to 7.8 × 10(-3) d(-1). Both nucleophilic substitution and reductive dechlorination are the proposed mechanisms for 1,2-DCA degradation by coupled nZVI-dithionite treatment. Characterization analysis of the nZVI-dithionite nanoparticles shows that most of the iron was still preserved in the zerovalent state even after more than one year of reactivity with some iron sulfide (FeS) formation. Scanning electron microscopy (SEM) analysis shows that the nanosized spherical particles were still present along with the FeS platelets. This novel treatment represents the first nZVI-based formulation to achieve nearly complete degradation of 1,2-DCA.
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Affiliation(s)
- Ariel Nunez Garcia
- Civil and Environmental Engineering, Western University , 1151 Richmond Road, London, Ontario N6A 5B8, Canada
| | - Hardiljeet K Boparai
- Civil and Environmental Engineering, Western University , 1151 Richmond Road, London, Ontario N6A 5B8, Canada
| | - Denis M O'Carroll
- Civil and Environmental Engineering, Western University , 1151 Richmond Road, London, Ontario N6A 5B8, Canada
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Ma X, He D, Jones AM, Collins RN, Waite TD. Reductive reactivity of borohydride- and dithionite-synthesized iron-based nanoparticles: A comparative study. JOURNAL OF HAZARDOUS MATERIALS 2016; 303:101-110. [PMID: 26513569 DOI: 10.1016/j.jhazmat.2015.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
In this study sodium dithionite (NaS2O4) and sodium borohydride (NaBH4) were employed as reducing agents for the synthesis of nanosized iron-based particles. The particles formed using NaBH4 (denoted nFe(BH4)) principally contained (as expected) Fe(0) according to XAS and XRD analyses while the particles synthesized using NaS2O4, (denoted nFe(S2O4)) were dominated by the mixed Fe(II)/Fe(III) mineral magnetite (Fe3O4) though with possible presence of Fe(0). The ability of both particles to reduce trichloroethylene (TCE) under analogous conditions demonstrated remarkable differences with nFe(BH4) resulting in complete reduction of 1.5mM of TCE in 2h while nFe(S2O4) were unable to effect complete reduction of TCE in 120 h. Moreover, acetylene was the major reaction product formed in the presence of nFe(S2O4) while the major reaction product formed following reaction with nFe(BH4) was ethylene, which was further reduced to ethane as the reaction proceeded. Considering that effective Pd reduction to Pd(0) requires the presence of Fe(0), this is consistent with our finding that Fe(0) is not the dominant phase formed when employing dithionite as a reducing agent under the conditions employed in this study.
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Affiliation(s)
- Xiaoming Ma
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Di He
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Adele M Jones
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Richard N Collins
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - T David Waite
- School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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Nano-magnetite catalyzed heterogeneous Fenton-like degradation of emerging contaminants carbamazepine and ibuprofen in aqueous suspensions and montmorillonite clay slurries at neutral pH. ACTA ACUST UNITED AC 2013. [DOI: 10.1016/j.molcata.2013.01.027] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Liu CS, Shih K, Wei L, Wang F, Li FB. Kinetics and mechanism of propachlor reductive transformation through nucleophilic substitution by dithionite. CHEMOSPHERE 2011; 85:1438-1443. [PMID: 21893332 DOI: 10.1016/j.chemosphere.2011.08.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/07/2011] [Accepted: 08/08/2011] [Indexed: 05/31/2023]
Abstract
Chloroacetanilide herbicides are extensively used in the control of weeds and have widely resulted in nonpoint contamination of groundwater and soil resources. In the attempt to achieve better remediation for herbicide-contaminated resources, we investigated the reductive transformation of propachlor through nucleophilic substitution by dithionite (S(2)O(4)(2-)). Results showed that propachlor underwent rapid dechlorination in the presence of dithionite. The reaction was of second-order kinetics and strongly influenced by pH and temperature. At pH 7.0 and temperature 308K, the rate constant of propachlor dechlorination was estimated at 123.4±0.7M(-1)h(-1). Within the pH range tested (3.0-9.5), higher pH promoted the ionization of dithionite, resulting in a more active nucleophilic reagent of S(2)O(4)(2-) to enhance the propachlor transformation rate. Similarly, higher reaction temperature overcame the activation barrier of steric hindrance in propachlor structure and accelerated the excitation of dithionite, in which higher rate constants of propachlor reductive dechlorination were obtained. Dechlorination was found to be the first and necessary step of propachlor nucleophilic substitution by dithionite. Sulfur nucleophile substituted compounds, including propachlor dithionite, propachlor ethanesulfonic acid (ESA), and hydroxyl propachlor, were identified as the dechlorination products of propachlor, indicating bimolecular nucleophilic substitution (S(N)2) as the mechanism for propachlor transformation initiated by dithionite.
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Affiliation(s)
- C S Liu
- Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China; Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, China
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Choi K, Lee W. Reductive dechlorination of carbon tetrachloride in acidic soil manipulated with iron(II) and bisulfide ion. JOURNAL OF HAZARDOUS MATERIALS 2009; 172:623-630. [PMID: 19660864 DOI: 10.1016/j.jhazmat.2009.07.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 07/10/2009] [Accepted: 07/12/2009] [Indexed: 05/28/2023]
Abstract
Batch and column tests were conducted to investigate the effect of reductant concentration, reductant contact time, and suspension pH on reductive dechlorination of carbon tetrachloride (CT) by soil manipulated with Fe(II) and HS(-). Kinetic rate constants for the reductive dechlorination increased as the reductant concentrations increased. Fe(II) was more effective reductant than HS(-), resulting in higher rate constants. The contact time of 1 day for the soil with HS(-) and that of 4h with Fe(II) showed the highest reaction rates, respectively. The kinetic rate constants increased as the pH of soil suspensions with Fe(II) (5.2-8.0) and HS(-) (8.3-10.3) increased. Soil column with Fe(II) showed larger bed volumes (13.8) to reach a column breakthrough than that with HS(-) (4.0). Fe(II) treatment showed better removal of CT in the soil column with the addition of CaO than HS(-) treatment did. In contrast, HS(-) treatment not producing toxic products could be considered as an environmentally favorable reductant.
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Affiliation(s)
- Kyunghoon Choi
- Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea.
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18
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Nasser A, Buchanovsky N, Gerstl Z, Mingelgrin U. Mineral induced mechanochemical degradation: the imazaquin case. CHEMOSPHERE 2009; 75:20-27. [PMID: 19135700 DOI: 10.1016/j.chemosphere.2008.11.077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 11/25/2008] [Accepted: 11/25/2008] [Indexed: 05/27/2023]
Abstract
The potential role of mechanochemical processes in enhancing degradation of imazaquin by soil components is demonstrated. The investigated components include montmorillonite saturated with Na(+), Ca(2+), Cu(2+)and Al(3+), Agsorb (a commercial clay mix), birnessite and hematite. The mechanical force applied was manual grinding of mixtures of imazaquin and the minerals, using mortar and pestle. The degradation rates of imazaquin in these mixtures were examined as a function of the following parameters: time of grinding, herbicide load (3.9, 8.9, 16.7 and 26.6 mg imazaquin per g mineral), temperature (10, 25, 40 and 70 degrees C), acidic/basic conditions, and dry or wet grinding. Dry grinding of imazaquin for 5 min with Al-montmorillonite or with hematite resulted in 56% and 71% degradation of the imazaquin, respectively. Wet grinding slightly reduced the degradation rate with hematite and entirely cancelled the enhancing effect of grinding with Al-montmorillonite. Wet grinding in the presence of the transition metals: Ni(2+), Cu(2+), Fe(3+) added as chlorides was carried out. Addition of Cu(2+) to Na-montmorillonite loaded with imazaquin was the most effective treatment in degrading imazaquin (more than 90% of the imazaquin degraded after 5 min of grinding). In this treatment, Cu-montmorillonite formation during the grinding process was confirmed by XRD and accordingly, grinding with Cu-montmorillonite gave similar degradation values. LC-MS analysis revealed that the mechanochemical transformation of imazaquin resulted in the formation of a dimer and several breakdown products. The reported results demonstrate once again that mechanochemical procedures offer a remediation avenue applicable to soils polluted with organic contaminants.
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Affiliation(s)
- Ahmed Nasser
- Institute of Soils, Water and Environmental Sciences, ARO, Volcani Center, P.O. Box 6, Bet Dagan 50-250, Israel.
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19
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Boparai HK, Comfort SD, Shea PJ, Szecsody JE. Remediating explosive-contaminated groundwater by in situ redox manipulation (ISRM) of aquifer sediments. CHEMOSPHERE 2008; 71:933-941. [PMID: 18086486 DOI: 10.1016/j.chemosphere.2007.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 10/31/2007] [Accepted: 11/01/2007] [Indexed: 05/25/2023]
Abstract
In situ chemical reduction of clays and iron oxides in subsurface environments is an emerging technology for treatment of contaminated groundwater. Our objective was to determine the efficacy of dithionite-reduced sediments from the perched Pantex Aquifer (Amarillo, TX) to abiotically degrade the explosives RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine), and TNT (2,4,6-trinitrotoluene). The effects of dithionite/buffer concentrations, sediments-solution ratios, and the contribution of Fe(II) were evaluated in batch experiments. Results showed that reduced Pantex sediments were highly effective in degrading all three high explosives. Degradation rates increased with increasing dithionite/buffer concentrations and soil to solution ratios (1:80-1:10 w/v). When Fe(II) was partially removed from the reduced sediments by washing (citrate-bicarbonate buffer), RDX degradation slowed, but degradation efficiency could be restored by adding Fe(II) back to the treated sediments and maintaining an alkaline pH. These data support in situ redox manipulation as a remedial option for treating explosive-contaminated groundwater at the Pantex site.
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Affiliation(s)
- H K Boparai
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
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20
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Jung B, Batchelor B. Influence of iron-bearing phyllosilicates on the dechlorination kinetics of 1,1,1-trichloroethane in Fe(II)/cement slurries. CHEMOSPHERE 2007; 68:1254-61. [PMID: 17368506 DOI: 10.1016/j.chemosphere.2007.01.057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2006] [Revised: 01/22/2007] [Accepted: 01/24/2007] [Indexed: 05/14/2023]
Abstract
This study examines the effect of iron-bearing phyllosilicates on dechlorination rates of chlorinated aliphatic hydrocarbons (CAHs) in iron-based degradative solidification/stabilization (DS/S-Fe(II)). Laboratory batch experiments were conducted to evaluate dechlorination rates of 1,1,1-trichloroethane (1,1,1-TCA) in a mixture solution of Fe(II), cement and three different iron-bearing phyllosilicates (biotite, vermiculite, and montmorillonite). A first-order rate model was generally used to describe the dechlorination kinetics and the rate constants were dependent on soil mineral type (biotite, vermiculite, and montmorillonite), Fe(II) dose, and the mass ratio of cement to soil mineral. The pseudo-first-order rate constant for montmorillonite was lower than that for biotite and vermiculite by factors of 11-27 when the mass ratio of cement to phyllosilicates was fixed at one. The presence of biotite and vermiculite increase and the presence of montmorillonite decrease the degradation rate that would be observed in their absence. The effect of cement/mineral ratio on rate constants with three different soil minerals indicates that biotite was more reactive than the other two phyllosilicates. This may be due to high accessible natural Fe(II) content in biotite. Montmorillonite appears to inhibit dechlorination by either inactivating Fe(II) by ion exchange or by physically blocking active sites on cement hydration products.
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Affiliation(s)
- Bahngmi Jung
- Department of Civil Engineering, Texas A&M University, College Station, TX 77843-3136, USA.
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21
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Merola RB, Fournier ED, McGuire MM. Spectroscopic investigations of Fe2+ complexation on nontronite clay. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:1223-6. [PMID: 17241036 DOI: 10.1021/la062467e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Diffuse reflectance (visible) and attenuated total internal reflection Fourier-transform infrared (ATR-FTIR) spectroscopies were used to examine a colloidal nontronite clay in the presence of Fe2+(aq). pH-dependent changes are observed in both types of spectra. In the visible region, a broad feature at approximately 750 nm appears as the pH is raised to circumneutral values. This absorbance band overlaps with a portion of the spectrum of the chemically reduced clay which is dominated by an intervalence charge-transfer transition between Fe2+ and Fe3+ within the mineral structure. The similarities between these spectra suggest that Fe2+(aq) adsorbs to the clay in such a way that it can undergo charge transfer with structural Fe3+ within the clay. ATR-FTIR spectra at pH 5-8 reveal a transformation in the Si-O stretching region between pH 6 and pH 7 with a shift of the component peaks to lower frequency. Taken together, these spectroscopic studies indicate that Fe2+ forms an inner-sphere complex with the clay at higher pH values. The pH threshold for these observed changes in physical and electronic structure is in good agreement with the point of zero charge (pzc) of the hydroxyl groups on the edge surfaces of the clay, suggesting that complexation of Fe2+ to deprotonated edge sites leads to the observed spectroscopic features.
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Affiliation(s)
- Rose B Merola
- Department of Chemistry, Bucknell University, Lewisburg, PA 17837, USA
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Boparai HK, Shea PJ, Comfort SD, Snow DD. Dechlorinating chloroacetanilide herbicides by dithionite-treated aquifer sediment and surface soil. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2006; 40:3043-9. [PMID: 16719109 DOI: 10.1021/es051915m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The prevalent use of chloroacetanilide herbicides has resulted in nonpoint contamination of some groundwater and surface water. We determined the efficacy of dithionite-treated sediment and soils to transform chloroacetanilides. When used alone, dithionite rapidly dechlorinates chloroacetanilides in water, with the following order of reactivity: propachlor > alachlor > acetochlor > metolachlor. Stoichiometric release of chloride occurs during reaction with dithionite, and thiosulfate herbicide derivatives are produced. Treating aquifer sediment with dithionite reduces native Fe(lII), creating a redox barrier of Fe(ll)-bearing minerals and surface-bound Fe(ll). Washing the reduced sediment (buffered with citrate-bicarbonate) with oxygen-free water removed Fe(ll) and excess dithionite and no alachlor transformation was observed. In contrast, a dithionite-treated surface soil, rich in clay and iron, effectively dechlorinated alachlor after washing. Exposing alachlor to aquifer sediment treated with dithionite in potassium carbonate buffer (pH 8.5-9.0) produced dechlorinated alachlor as the major degradation product. Our results provide proof-of-concept that dechlorination of chloroacetanilide herbicides by dithionite and dithionite-treated aquifer sediment and soil is a remediation option in natural environments where iron-bearing minerals are abundant.
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Affiliation(s)
- Hardiljeet K Boparai
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0915, USA
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Stucki J. Chapter 8 Properties and Behaviour of Iron in Clay Minerals. DEVELOPMENTS IN CLAY SCIENCE 2006. [DOI: 10.1016/s1572-4352(05)01013-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Obare SO, Ito T, Meyer GJ. Controlling reduction potentials of semiconductor-supported molecular catalysts for environmental remediation of organohalide pollutants. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2005; 39:6266-72. [PMID: 16173591 DOI: 10.1021/es048058r] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The spectroscopic and redox properties of iron(lll) protoporphyrin chloride (hemin) and cobalt(lll) meso-tetra-(4-carboxyphenyl) porphyrin chloride (CoTCP) were quantified in fluid solution and when anchored to mesoporous nanocrystalline TiO2 thin films. Surface binding was well-described by the Langmuir adsorption isotherm model from which adduct formation constants of 10(5) M(-1) and limiting surface coverages of 10(-8) mol/cm2 were abstracted. In acetonitrile and dimethyl sulfoxide electrolytes, TiO2 binding was found to induce a substantial negative shift in the M(III/II) formal reduction potentials. In DMSO electrolyte, the Co(III/II) and Fe(III/II) potentials were -559 and -727 mV versus ferrocenium/ferrocene (Fc+/Fc) and shifted to -782 and -1063 mV, respectively, after surface binding. The Bronsted acidity of the TiO2 surface was found to correlate with the measured reduction potentials. For TiO2 pretreated with aqueous solutions from pH 4-9, the Co(III/II) potential showed a -66 mV/pH unit change, while the Fe(llI/II) potential of hemin changed by -40 mV/pH from pH 1 to 14. Spectroelectrochemical data gave isosbestic, reversible spectral changes in the visible region assigned to M(III/II) redox chemistry with lambda(iso) = 410, 460, 530, 545, 568, and 593 nm for CoTCP/TiO2 and lambda(iso) = 408, 441, 500, 576, and 643 nm for hemin/TiO2. In aqueous solution, the CoTCP reduction potentials were also found to be pH dependent upon surface binding, with CoTCP = -583 mV and CoTCP/TiO2 = -685 mV versus Fc+/Fc at pH 6. For CoTCP/TiO2, the aqueous pH dependence of the potentials was -52 mV/pH. The rate constant for heme/TiO2 reduction of CCl4 increased from 3.9 +/- 0.7 x 10(-4) to 2.0 +/- 0.1 x 10(-3) s(-1) when the pH was raised from 4 to 8.
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Affiliation(s)
- Sherine O Obare
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Affiliation(s)
- Biqiong Chen
- Department of Materials, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Julian R. G. Evans
- Department of Materials, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
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Lee W, Batchelor B. Abiotic reductive dechlorination of chlorinated ethylenes by iron-bearing phyllosilicates. CHEMOSPHERE 2004; 56:999-1009. [PMID: 15268967 DOI: 10.1016/j.chemosphere.2004.05.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Revised: 03/24/2004] [Accepted: 05/03/2004] [Indexed: 05/24/2023]
Abstract
Abiotic reductive dechlorination of chlorinated ethylenes (tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (c-DCE), and vinylchloride (VC)) by iron-bearing phyllosilicates (biotite, vermiculite, and montmorillonite) was characterized to obtain better understanding of the behavior of these contaminants in systems undergoing remediation by natural attenuation and redox manipulation. Batch experiments were conducted to evaluate dechlorination kinetics and some experiments were conducted with addition of Fe(II) to simulate impact of microbial iron reduction. A modified Langmuir-Hinshelwood kinetic model adequately described reductive dechlorination kinetics of target organics by the iron-bearing phyllosilicates. The rate constants stayed between 0.08 (+/-10.4%) and 0.401 (+/-8.1%) day(-1) and the specific initial reductive capacity of iron-bearing phyllosilicates for chlorinated ethylenes stayed between 0.177 (+/-6.1%) and 1.06 (+/-7.1%) microM g(-1). The rate constants for the reductive dechlorination of TCE at reactive biotite surface increased as pH (5.5-8.5) and concentration of sorbed Fe(II) (0-0.15 mM g(-1)) increased. The appropriateness of the model is supported by the fact that the rate constants were independent of solid concentration (0.0085-0.17 g g(-1)) and initial TCE concentration (0.15-0.60 mM). Biotite had the greatest rate constant among the phyllosilicates both with and without Fe(II) addition. The rate constants were increased by a factor of 1.4-2.5 by Fe(II) addition. Between 1.8% and 36% of chlorinated ethylenes removed were partitioned to the phyllosilicates. Chloride was produced as a product of degradation and no chlorinated intermediates were observed throughout the experiment.
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Affiliation(s)
- Woojin Lee
- Environment and Process Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea.
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