Journal article
Carbon Isotope Fractionation of Substituted Benzene Analogs during Oxidation with Ozone and Hydroxyl Radicals: How Should Experimental Data Be Interpreted?
- Willach S Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Lutze HV Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Somnitz H Faculty of Chemistry, Theoretical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Terhalle J Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Stojanovic N Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Lüling M Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Jochmann MA Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- Hofstetter TB Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, CH-8600 Dübendorf, Switzerland.
- Schmidt TC Faculty of Chemistry, Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstrasse 5, D-45141 Essen, Germany.
- 2020-05-09
Published in:
- Environmental science & technology. - 2020
English
Oxidative processes frequently contribute to organic pollutant degradation in natural and engineered systems, such as during the remediation of contaminated sites and in water treatment processes. Because a systematic characterization of abiotic reactions of organic pollutants with oxidants such as ozone or hydroxyl radicals by compound-specific stable isotope analysis (CSIA) is lacking, stable isotope-based approaches have rarely been applied for the elucidation of mechanisms of such transformations. Here, we investigated the carbon isotope fractionation associated with the oxidation of benzene and several methylated and methoxylated analogs, namely, toluene, three xylene isomers, mesitylene, and anisole, and determined their carbon isotope enrichments factors (εC) for reactions with ozone (εC = -3.6 to -4.6 ‰) and hydroxyl radicals (εC = 0.0 to -1.2‰). The differences in isotope fractionation can be used to elucidate the contribution of the reactions with ozone or hydroxyl radicals to overall transformation. Derivation of apparent kinetic isotope effects (AKIEs) for the reaction with ozone, however, was nontrivial due to challenges in assigning reactive positions in the probe compounds for the monodentate attack leading to an ozone adduct. We present several options for this step and compare the outcome to quantum chemical characterizations of ozone adducts. Our data show that a general assignment of reactive positions for reactions of ozone with aromatic carbons in ortho-, meta-, or para-positions is not feasible and that AKIEs of this reaction should be derived on a compound-by-compound basis.
- Language
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- English
- Open access status
- closed
- Identifiers
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- DOI 10.1021/acs.est.0c00620
- PMID 32383866
- Persistent URL
- https://sonar.ch/global/documents/140059
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