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Rossomme E, Hart-Cooper WM, Orts WJ, McMahan CM, Head-Gordon M. Computational Studies of Rubber Ozonation Explain the Effectiveness of 6PPD as an Antidegradant and the Mechanism of Its Quinone Formation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:5216-5230. [PMID: 36961979 PMCID: PMC10079164 DOI: 10.1021/acs.est.2c08717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 03/09/2023] [Accepted: 03/10/2023] [Indexed: 06/18/2023]
Abstract
The discovery that the commercial rubber antidegradant 6PPD reacts with ozone (O3) to produce a highly toxic quinone (6PPDQ) spurred a significant research effort into nontoxic alternatives. This work has been hampered by lack of a detailed understanding of the mechanism of protection that 6PPD affords rubber compounds against ozone. Herein, we report high-level density functional theory studies into early steps of rubber and PPD (p-phenylenediamine) ozonation, identifying key steps that contribute to the antiozonant activity of PPDs. In this, we establish that our density functional theory approach can achieve chemical accuracy for many ozonation reactions, which are notoriously difficult to model. Using adiabatic energy decomposition analysis, we examine and dispel the notion that one-electron charge transfer initiates ozonation in these systems, as is sometimes argued. Instead, we find direct interaction between O3 and the PPD aromatic ring is kinetically accessible and that this motif is more significant than interactions with PPD nitrogens. The former pathway results in a hydroxylated PPD intermediate, which reacts further with O3 to afford 6PPD hydroquinone and, ultimately, 6PPDQ. This mechanism directly links the toxicity of 6PPDQ to the antiozonant function of 6PPD. These results have significant implications for development of alternative antiozonants, which are discussed.
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Affiliation(s)
- Elliot Rossomme
- Bioproducts
Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710, United States
- Berkeley
Center for Green Chemistry, University of
California, Berkeley, California 94720, United States
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - William M. Hart-Cooper
- Bioproducts
Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710, United States
| | - William J. Orts
- Bioproducts
Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710, United States
| | - Colleen M. McMahan
- Bioproducts
Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Albany, California 94710, United States
| | - Martin Head-Gordon
- Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California 94720, United States
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
- Kenneth
S. Pitzer Center for Theoretical Chemistry, University of California, Berkeley, California 94720, United States
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2
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Cardona AL, Rivela CB, Gibilisco RG, Blanco MB, Ventura ON, Teruel M. Experimental and Theoretical Kinetic Studies of the Ozonolysis of Selected Allyl Sulfides (H 2C═CHCH 2SR, R = CH 3, CH 3CH 2): The Effect of Nascent OH Radicals. J Phys Chem A 2022; 126:6751-6761. [DOI: 10.1021/acs.jpca.2c04547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alejandro L. Cardona
- (L.U.Q.C.A), Laboratorio Universitario de Química y Contaminación del Aire, Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Cynthia B. Rivela
- (L.U.Q.C.A), Laboratorio Universitario de Química y Contaminación del Aire, Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Rodrigo G. Gibilisco
- Institute for Atmospheric and Environmental Research, Faculty for Mathematics and Natural Sciences, University of Wuppertal, D-42097 Wuppertal, Germany
| | - María Belén Blanco
- (L.U.Q.C.A), Laboratorio Universitario de Química y Contaminación del Aire, Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Oscar N. Ventura
- CCBG-Detema, Facultad de Química, Universidad de la República, 11200 Montevideo, Uruguay
| | - Mariano Teruel
- (L.U.Q.C.A), Laboratorio Universitario de Química y Contaminación del Aire, Instituto de Investigaciones en Fisicoquímica de Córdoba (I.N.F.I.Q.C.), Dpto. de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
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3
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Salta Z, Vega-Teijido M, Katz A, Tasinato N, Barone V, Ventura ON. Dipolar 1,3-cycloaddition of thioformaldehyde S-methylide (CH 2 SCH 2 ) to ethylene and acetylene. A comparison with (valence) isoelectronic O 3 , SO 2 , CH 2 OO and CH 2 SO. J Comput Chem 2022; 43:1420-1433. [PMID: 35662073 DOI: 10.1002/jcc.26946] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 11/08/2022]
Abstract
Methods rooted in the density functional theory and in the coupled cluster ansatz were employed to investigate the cycloaddition reactions to ethylene and acetylene of 1,3-dipolar species including ozone and the derivatives issued from replacement of the central oxygen atom by the valence-isoelectronic sulfur atom, and/or of one or both terminal oxygen atoms by the isoelectronic CH2 group. This gives rise to five different 1,3-dipolar compounds, namely ozone itself (O3 ), sulfur dioxide (SO2 ), the simplest Criegee intermediate (CH2 OO), sulfine (CH2 SO), and thioformaldehyde S-methylide (CH2 SCH2 , TSM). The experimental and accurate theoretical data available for some of those molecules were employed to assess the accuracy of two last-generation composite methods employing conventional or explicitly correlated post-Hartree-Fock contributions (jun-Cheap and SVECV-f12, respectively), which were then applied to investigate the reactivity of TSM. The energy barriers provided by both composite methods are very close (the average values for the two composite methods are 7.1 and 8.3 kcal mol-1 for the addition to ethylene and acetylene, respectively) and comparable to those ruling the corresponding additions of ozone (4.0 and 7.7 kcal mol-1 , respectively). These and other evidences strongly suggest that, at least in the case of cycloadditions, the reactivity of TSM is similar to that of O3 and very different from that of SO2 .
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Affiliation(s)
- Zoi Salta
- SMART Lab, Scuola Normale Superiore, Pisa, Italy
| | - Mauricio Vega-Teijido
- Computational Chemistry and Biology Group, CCBG, DETEMA, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | - Aline Katz
- Computational Chemistry and Biology Group, CCBG, DETEMA, Facultad de Química, Universidad de la República, Montevideo, Uruguay
| | | | | | - Oscar N Ventura
- Computational Chemistry and Biology Group, CCBG, DETEMA, Facultad de Química, Universidad de la República, Montevideo, Uruguay
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4
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Kozuch S, Schleif T, Karton A. Quantum mechanical tunnelling: the missing term to achieve sub-kJ mol -1 barrier heights. Phys Chem Chem Phys 2021; 23:10888-10898. [PMID: 33908522 DOI: 10.1039/d1cp01275d] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
To predict barrier heights at low temperatures, it is not enough to employ highly accurate electronic structure methods. We discuss the influence of quantum tunnelling on the comparison of experimental and theoretical activation parameters (Ea, ΔH‡, ΔG‡, or ΔS‡), since the slope-based experimental techniques to obtain them completely neglect the tunnelling component. The intramolecular degenerate rearrangement of four fluxional molecules (bullvalene, barbaralane, semibullvalene, and norbornadienylidene) were considered, systems that cover the range between fast deep tunneling and small but significant shallow tunnelling correction. The barriers were computed with the composite W3lite-F12 method at the CCSDT(Q)/CBS level, and the tunnelling contribution with small curvature tunnelling. While at room temperature the effect is small (∼1 kJ mol-1), at low temperatures it can be considerable (in the order of tens of kJ mol-1 at ∼80 K).
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Affiliation(s)
- Sebastian Kozuch
- Chemistry Department, Ben-Gurion University of the Negev, Beer-Sheva, 841051, Israel.
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Shen Q, Liu YD, Zhong R. Degradation mechanisms of simple aliphatic amines under ozonation: a DFT study. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:480-490. [PMID: 33595042 DOI: 10.1039/d0em00476f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Aliphatic amines as common constituents of dissolved organic nitrogen (DON) exhibit high reactivity during ozonation; however, our understanding of their degradation mechanisms is very limited. In this study, methylamine (MA) and ethylamine (EA), as well as their secondary and tertiary amines (DMA, DEA, TMA and TEA) were chosen as aliphatic amine models and their degradation mechanisms during ozonation were investigated by using the DFT method. The oxygen-transfer reaction occurs initially and rapidly in the ozonation of all the above amines with a ΔG≠ value of 8-10 kcal mol-1 in great agreement with the experimental rate constant of 104 to 107 M-1 s-1. Moreover, N-oxide as the main degradation product for tertiary amines directly forms after oxygen-transfer, while nitroalkanes as main products for secondary and primary amines are yielded after a series of reactions mediated by hydroxylamine and nitrosoalkane with a ΔG≠ value of 10-13 kcal mol-1. Regarding the minor N-dealkylated products for all amines, alkylamino alcohol is an important intermediate possibly generated via a radical reaction pathway with a ΔG≠ value of 21-34 kcal mol-1. Additionally, comparison of the reactivity of aliphatic amines, hydroxylamines and alkylamino alcohols with ozone was made and elucidated in this study. The results are expected to expand our understanding of the degradation mechanisms for nitrogenous compounds during ozonation.
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Affiliation(s)
- Qunfang Shen
- Beijing Key Laboratory of Environmental and Viral Oncology, College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100124, China.
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6
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Gladich I, Chen S, Vazdar M, Boucly A, Yang H, Ammann M, Artiglia L. Surface Propensity of Aqueous Atmospheric Bromine at the Liquid-Gas Interface. J Phys Chem Lett 2020; 11:3422-3429. [PMID: 32283032 DOI: 10.1021/acs.jpclett.0c00633] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Multiphase reactions of halide ions in aqueous solutions exposed to the atmosphere initiate the formation of molecular halogen compounds in the gas phase. Their photolysis leads to halogen atoms, which are catalytic sinks for ozone, making these processes relevant for the regional and global tropospheric ozone budget. The affinity of halide ions in aqueous solution for the liquid-gas interface, which may influence their reactivity with gaseous species, has been debated. Our study focuses on the surface properties of the bromide ion and its oxidation products. In situ X-ray photoelectron spectroscopy carried out on a liquid jet combined with classical and first-principles molecular dynamics calculations was used to investigate the interfacial depth profile of bromide, hypobromite, hypobromous acid, and bromate. The simulated core electron binding energies support the experimentally observed values, which follow a correlation with bromine oxidation state for the anion series. Bromide ions are homogeneously distributed in the solution. Hypobromous acid, a key species in the multiphase cycling of bromine, is the only species showing surface propensity, which suggests a more important role of the interface in multiphase bromine chemistry than thought so far.
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Affiliation(s)
- Ivan Gladich
- Qatar Environment & Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 34110, Doha, Qatar
| | - Shuzhen Chen
- Laboratory of Environmental Chemistry, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Institute of Atmospheric and Climate Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Mario Vazdar
- Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
| | - Anthony Boucly
- Laboratory of Environmental Chemistry, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Huanyu Yang
- Laboratory of Environmental Chemistry, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Institute of Atmospheric and Climate Sciences, ETH Zurich, 8092 Zurich, Switzerland
| | - Markus Ammann
- Laboratory of Environmental Chemistry, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
| | - Luca Artiglia
- Laboratory of Environmental Chemistry, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
- Laboratory for Sustainable Chemistry and Catalysis, Paul Scherrer Institut, Forschungsstrasse 111, 5232 Villigen, Switzerland
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7
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Karton A. Highly Accurate CCSDT(Q)/CBS Reaction Barrier Heights for a Diverse Set of Transition Structures: Basis Set Convergence and Cost-Effective Approaches for Estimating Post-CCSD(T) Contributions. J Phys Chem A 2019; 123:6720-6732. [DOI: 10.1021/acs.jpca.9b04611] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Amir Karton
- School of Molecular Sciences, The University of Western Australia, Perth, WA 6009, Australia
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8
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Lim S, McArdell CS, von Gunten U. Reactions of aliphatic amines with ozone: Kinetics and mechanisms. WATER RESEARCH 2019; 157:514-528. [PMID: 30986698 DOI: 10.1016/j.watres.2019.03.089] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 03/13/2019] [Accepted: 03/27/2019] [Indexed: 06/09/2023]
Abstract
Aliphatic amines are common constituents in micropollutants and dissolved organic matter and present in elevated concentrations in wastewater-impacted source waters. Due to high reactivity, reactions of aliphatic amines with ozone are likely to occur during ozonation in water and wastewater treatment. We investigated the kinetics and mechanisms of the reactions of ozone with ethylamine, diethylamine, and triethylamine as model nitrogenous compounds. Species-specific second-order rate constants for the neutral parent amines ranged from 9.3 × 104 to 2.2 × 106 M-1s-1 and the apparent second-order rate constants at pH 7 for potential or identified transformation products were 6.8 × 105 M-1s-1 for N,N-diethylhydroxylamine, ∼105 M-1s-1 for N-ethylhydroxylamine, 1.9 × 103 M-1s-1 for N-ethylethanimine oxide, and 3.4 M-1s-1 for nitroethane. Product analyses revealed that all amines were transformed to products containing a nitrogen-oxygen bond (e.g., triethylamine N-oxide and nitroethane) with high yields, i.e., 64-100% with regard to the abated target amines. These findings could be confirmed by measurements of singlet oxygen and hydroxyl radical which are formed during the amine-ozone reactions. Based on the high yields of nitroethane from ethylamine and diethylamine, a significant formation of nitroalkanes can be expected during ozonation of waters containing high levels of dissolved organic nitrogen, as expected in wastewaters or wastewater-impaired source waters. This may pose adverse effects on the aquatic environment and human health.
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Affiliation(s)
- Sungeun Lim
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Christa S McArdell
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, 8600, Duebendorf, Switzerland; School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
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9
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Khan SN, Miliordos E. Methane to Methanol Conversion Facilitated by Transition-Metal Methyl and Methoxy Units: The Cases of FeCH3+ and FeOCH3+. J Phys Chem A 2019; 123:5590-5599. [DOI: 10.1021/acs.jpca.9b04005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Shahriar N. Khan
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
| | - Evangelos Miliordos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849-5312, United States
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10
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Tentscher PR, Lee M, von Gunten U. Micropollutant Oxidation Studied by Quantum Chemical Computations: Methodology and Applications to Thermodynamics, Kinetics, and Reaction Mechanisms. Acc Chem Res 2019; 52:605-614. [PMID: 30829468 DOI: 10.1021/acs.accounts.8b00610] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The abatement of organic micropollutants during oxidation processes has become an emerging issue for various urban water systems such as drinking water, wastewater, and water reuse. Reaction kinetics and mechanisms play an important role in terms of efficiency of these processes and the formation of transformation products, which are controlled by functional groups in the micropollutants and the applied oxidants. So far, the kinetic and mechanistic information on the underlying reactions was obtained by experimental studies; additionally, predictive quantitative structure-activity relationships (QSARs) were applied to determine reaction kinetics for the oxidation of emerging compounds. Since this experimental approach is very laborious and there are tens of thousands potential contaminants, alternative strategies need to be developed to predict the fate of micropollutants during oxidative water treatment. Due to significant developments in quantum chemical (QC) computations in recent years and increased computational capacity, QC-based methods have become an alternative or a supplement to the current experimental approach. This Account provides a critical assessment of the current state-of-the-art of QC-based methods for the assessment of oxidation of micropollutants. Starting from a given input structure, QC computations need to locate energetic minima on the potential energy surface (PES). Then, useful thermodynamic and kinetic information can be estimated by different approaches: Experimentally determined reaction mechanisms can be validated by identification of transition structures on the PES, which can be obtained for addition reactions, heavy atom transfer (Cl+, Br+, O·) and H atom transfer (simultaneous proton and electron transfer) reactions. However, transition structures in the PES cannot be obtained for e--transfer reactions. Second-order rate constants k for the reactions of micropollutants with chemical oxidants can be obtained by ab initio calculations or by QSARs with various QC descriptors. It has been demonstrated that second-order rate constants from ab initio calculations are within factors 3-750 of the measured values, whereas QSAR-based methods can achieve factors 2-4 compared to the experimental data. The orbital eigenvalue of the highest occupied molecular orbital ( EHOMO) is the most commonly used descriptor for QSAR-based computations of k-values. In combination with results from experimental studies, QC computations can also be applied to investigate reaction mechanisms for verification/understanding of oxidative mechanisms, calculation of branching ratios or regioselectivity, evaluation of the experimental product distribution and assessment of substitution effects. Furthermore, other important physical-chemical constants such as unknown equilibria for species, which are not measurable due to low concentrations, or p Ka values of reactive transient species can be estimated. With further development of QC-based methods, it will become possible to implement kinetic and mechanistic information from such computations in in silico models to predict oxidative transformation of micropollutants. Such predictions can then be complemented by tailored experimental studies to confirm/falsify the computations.
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Affiliation(s)
- Peter R. Tentscher
- Department of Chemistry and Bioscience, Aalborg University, 9220 Aalborg East, Denmark
| | - Minju Lee
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Urs von Gunten
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600 Duebendorf, Switzerland
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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