Project 6: Oxidative Remediation of Recalcitrant Contaminants with Persulfate
Persulfate (S2O82-) is a relatively inexpensive reagent that can be used to oxidize many of the most recalcitrant contaminants present at hazardous waste sites. Although it is becoming more popular for hazardous waste site remediation, the chemical reactions through which persulfate oxidizes contaminants are not well understood. The overall goal of our research is to develop and test new approaches for oxidizing contaminants that are difficult to treat with existing technologies (e.g., PCBs, 1,4-dioxane and PFOA) and apply it to make treatment systems more robust and efficient. Through the use of kinetic models and detailed research on reaction mechanisms, we will develop the means of predicting contaminant transformation rates and optimizing system performance. This mechanistic understanding of persulfate chemistry will require that we build increasing complexity into our model in stages. Initially, we will calibrate our kinetic model for the homogeneous reactions through which persulfate is converted into oxidants using experiments with various compounds that react predominantly with sulfate radical or hydroxyl radical. After calibrating the model over the range of conditions likely to be encountered during remediation, we will investigate the role of heterogeneous reactions of iron-containing solids on the initiation of radical production. By applying findings from experiments in heterogeneous systems with state-of-the-art surface characterization techniques we will synthesize new types of heterogeneous catalysts for ex situ treatment of contaminated groundwater. We also will use results from the heterogeneous experiments to improve the predictive ability of the model and identify optimal conditions for remediation. After defining the conditions that are best suited for contaminant remediation, we will assess the potential formation of toxic intermediate products during the remediation process using high content screening assays and mass spectrometry. Our research will lead to a mechanistic understanding of persulfate chemistry that should, in turn, lead to a level of understanding that will allow engineers to avoid excessive use of reagents and the formation of toxic intermediates when persulfate is used for remediation.
This is relevant because successful completion of the proposed research will result in new oxidative treatment systems that will substantially reduce the costs of remediating contaminants that are difficult to treat with existing technologies. Our research will also result in the development of a better understanding of when ISCO will be effective, thereby facilitating the broader application of the technology and a reduction in public health risks at hazardous waste sites.
David Sedlak, PhD
Malozemoff Professor in Mineral Engineering
Co-director of Berkeley Water Center, and
Director of Institute for Environmental Science and Engineering (IESE)
Civil & Environmental Engineering,
College of Engineering
University of California, Berkeley
Fiona Doyle, PhD
Donald H. McLaughlin Professor of Mineral Engineering
Department of Materials Science and Engineering, College of Engineering
University of California, Berkeley
One of our major findings this year is that chemical oxidants introduced into groundwater wells unexpectedly cause aromatic compounds, like benzene and chlorophenol, to undergo ring cleavage reactions during the first step of oxidant attack, generating relatively toxic products. We also identified the kinds of contaminated waters that are most amendable to treatment with electrochemical cells and to predict the conditions under which unsafe levels of oxidant disinfection byproducts might be produced.
The main goal of our research is to advance new, cost-effective ways of cleaning up groundwater and soil that has been contaminated by organic chemical from hazardous waste sites. One strategy for remediating contamination involves the introduction of chemical oxidants into groundwater wells. In our previous research, we determined the mechanisms through which naturally occurring minerals react with the oxidants to initiate the contaminant degradation process. This year, we studied the ways in which the oxidants degrade the contaminants. One of our major findings was that the oxidants unexpectedly caused aromatic compounds, like benzene and chlorophenol, to undergo ring cleavage reactions during he first step of oxidant attack. Some of the products of these reactions are known to be relatively toxic and need to be understood if this technique is to be applied widely. The second strategy for degrading contaminants employs electrochemical cells, with or without an ultraviolet lamp, to produce oxidants directly in the contaminated water. This year, we focused our attention on the anode chamber of an electrochemical system that we had previously shown to be effective in producing hydrogen peroxide and reactive hydroxyl radicals. Using a suite of chemicals that each exhibited different reactivity with the oxidants suspected of being present, we were able to ascertain the oxidants that were formed under different conditions. This allowed us to identify the kinds of contaminated waters that are most amendable to treatment and to anticipate the conditions under which unsafe levels of disinfection byproducts might be produced.
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Barazesh JM, Prasse C, Sedlak DL (2016) Electrochemical Transformation of Trace Organic Contaminants in the Presence of Halide and Carbonate Ions. Environ Sci Technol. Sep 6. PMID: 27599127. DOI: 10.1021/acs.est.6b02232. [Epub ahead of print]. [PDF]
Sun B, Ma J, Sedlak DL. (2016) Chemisorption of Perfluorooctanoic Acid on Powdered Activated Carbon Initiated by Persulfate in Aqueous Solution. Environ Sci Technol. Jul 19;50(14):7618-24. PMID: 27336204. DOI: 10.1021/acs.est.6b00411. [PDF]
Liu H, Bruton TA, Li W, Van Buren J, Prasse C, Doyle FM, Sedlak DL (2016) Oxidation of Benzene by Persulfate in the Presence of Fe(III)- and Mn(IV)-Containing Oxides: Stoichiometric Efficiency and Transformation Products. Environmental Science & Technology, Jan 19;50(2):890-8. PMID: 26687229. DOI: 10.1021/acs.est.5b04815. [PDF]
Harding-Marjanovic KC, Yi S, Weathers TS, Sharp JO, Sedlak DL, Alvarez-Cohen L (2016) Effects of Aqueous Film-Forming Foams (AFFFs) on Trichloroethene (TCE) Dechlorination by a Dehalococcoides mccartyi-Containing Microbial Community. Environ Sci Technol. Apr 5;50(7):3352-61. PMID: 26894610. DOI: 10.1021/acs.est.5b04773. [PDF]
Barazesh JM, Hennebel T, Jasper JT, Sedlak DL (2015) Modular Advanced Oxidation Process Enabled by Cathodic Hydrogen Peroxide Production. Environmental Science & Technology, Jun 16;49 (12):7391-99. PMCID: PMC4473729. [PDF]
Prasse C, Wenk J, Jasper JT, Ternes TA, Sedlak DL (2015) Co-occurrence of Photochemical and Microbiological Transformation Processes in Open-Water Unit Process Wetlands. Environ Sci Technol. Dec 15;49(24):14136-45. PMID: 26562588. DOI: 10.1021/acs.est.5b03783. [PDF]
Radjenovic J, Sedlak DL (2015) Challenges and Opportunities for Electrochemical Processes as Next-Generation Technologies for the Treatment of Contaminated Water. Environmental Science & Technology. Oct 6;49(19):11292-302. PMID: 26370517. DOI: 10.1021/acs.est.5b02414. [PDF]
Sedlak DL (2015) The essential functions. Environ Sci Technol. Jan 6;49(1):1-2. PMID: 25564280. DOI: 10.1021/es505864c. [PDF]
Liu H, Bruton TA, Doyle FM, Sedlak DL (2014) In Situ Chemical Oxidation of Contaminated Groundwater by Persulfate: Decomposition by Fe(III)- and Mn(IV)-Containing Oxides and Aquifer Materials. Environmental Science and Technology. Sep 2;48(17):10330-336. PMCID: PMC4151705. [PDF]
Lee H, Lee HJ, Sedlak DL, Lee C (2013) pH-Dependent Reactivity of Oxidants Formed by Iron and Copper-Catalyzed Decomposition of Hydrogen Peroxide. Chemosphere, Jul;92 (6):652-58. PMID: 23433935. DOI: 10.1016/j.chemosphere.2013.01.073. [PDF]
Pham ALT*, Doyle FM and Sedlak DL (2012) Kinetics and efficiency of H2O2 activation by iron-containing minerals and aquifer materials. Water Research. Dec 1;46(19):6454-62. PMCID: PMC3891917.
Pham AL, Doyle FM, Sedlak DL (2012) Dissolution of mesoporous silica supports in aqueous solutions: Implications for mesoporous silica-based water treatment processes. Applied Catalysis B: Environmental. Sep 25;126: 258-264. PMCID: PMC3465675. [PDF]
Gui MH, Smuleac V, Ormsbee LE, Sedlak DL, Bhattacharyya D (2012) Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water. J. Nanoparticle Res. 14(5):861. doi: 10.1007/s11051-012-0861-1. (PMC Journal – In Process). [PDF]
Pham AL, Doyle FM, Sedlak DL (2102) Inhibitory Effect of Dissolved Silica on H2O2 Decomposition by Iron(III) and Manganese(IV) Oxides: Implications for H2O2-Based In Situ Chemical Oxidation. Environ. Sci. Technol. Jan 17;46(2):1055-1062. PMCID: PMC3262894. [PDF]
Pham AL, Lee C, Doyle FM, Sedlak DL (2009) A silica-supported iron oxide catalyst capable of activating hydrogen peroxide at neutral pH values. Environ Sci Technol. Dec 1; 43(23):8930-5. PMID: 19943668. PMCID: PMC2792909. [PDF]
Keenan CR, Goth-Goldstein R, Lucas D, Sedlak DL (2009) Oxidative stress induced by zero-valent iron nanoparticles and Fe(II) in human bronchial epithelial cells. Environ Sci Technol. Jun 15; 43(12):4555-60. PMID: 19603676. [PDF]
Lee C, Sedlak DL (2009) A novel homogeneous Fenton-like system with Fe(III)-phosphotungstate for oxidation of organic compounds at neutral pH values. J Molec Catal A. 311(1-2):1-6. NIHMS131170. [PDF]
Lee C, Sedlak DL (2008) Enhanced formation of oxidants from bimetallic nickel-iron nanoparticles in the presence of oxygen. Environ Sci Technol. Nov 15; 42(22):8528-33. PMID: 19068843. PMCID: PMC2628954. [PDF]
Keenan CR, Sedlak DL (2008) Ligand-enhanced reactive oxidant generation by nanoparticulate zero-valent iron and oxygen. Environ Sci Technol. Sep 15; 42(18):6936-41. PMID: 18853812. PMCID: PMC2701397. [PDF]
Lee C, Keenan CR, Sedlak DL (2008) Polyoxometalate-enhanced oxidation of organic compounds by nanoparticulate zero-valent iron and ferrous ion in the presence of oxygen.Environ Sci Technol. Jul 1; 42(13):4921-6. PMID: 18678027. PMCID: PMC2536720. [PDF]
Lee C, Kim JY, Lee WI, Nelson KL, Yoon J, Sedlak DL (2008) Bactericidal effect of zero-valent iron nanoparticles on Escherichia coli. Environ Sci Technol. Jul 1; 42(13):4927-33. PMID: 18678028. PMCID: PMC2536719. [PDF]
Keenan CR, Sedlak DL (2008) Factors affecting the yield of oxidants from the reaction of nanoparticulate zero-valent iron and oxygen. Environ Sci Technol. Feb 15; 42(4):1262-7. PMID: 18351103. [PDF]