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首页> 外文期刊>Environmental Science & Technology >Isotopic Analysis of Oxidative Pollutant Degradation Pathways Exhibiting Large H Isotope Fractionation
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Isotopic Analysis of Oxidative Pollutant Degradation Pathways Exhibiting Large H Isotope Fractionation

机译：表现出大氢同位素分馏的氧化性污染物降解途径的同位素分析

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摘要

Oxidation of aromatic rings and its alkyl substituents are often competing initial steps of organic pollutant transformation.The use of compound-specific isotope analysis (CSIA) to distinguish between these two pathways quantitatively,however,can be hampered by large H isotope fractionation that precludes calculation of apparent ~2H-kinetic isotope effects (KIE) as well as the process identification in multi-element isotope fractionation analysis.Here,we investigated the C and H isotope fractionation associated with the transformation of toluene,nitrobenzene,and four substituted nitrotoluenes by permanganate,MnO_4~-,to propose a refined evaluation procedure for the quantitative distinction of CH_3-group oxidation and dioxygenation.On the basis of batch experiments,an isotopomer-specific kinetic model,and density functional theory (DFT) calculations,we successfully derived the large apparent ~2H-KIE of 4.033 ± 0.20 for the CH_3-group oxidation of toluene from H isotope fractionation exceeding ＞1300‰ as well as the corresponding ~(13)C-KIE (1.0324 ± 0.0011).Experiment and theory also agreed well for the dioxygenation of nitrobenzene,which was associated with ~2H- and ~(13)C-KIEs of 0.9410 ± 0.0030 (0.9228 obtained by DFT) and 1.0289 ± 0.0003 (1.025).Consistent branching ratios for the competing CH~3-group oxidation and dioxygenation of nitrotoluenes by MnO_4~- were obtained from the combined modeling of concentration as well as C and H isotope signature trends.Our approach offers improved estimates for the identification of contaminant microbial and abiotic oxidation pathways by CSIA.
机译：芳环及其烷基取代基的氧化通常是有机污染物转化的竞争初始步骤。使用化合物特异性同位素分析（CSIA）定量区分这两种途径，但是由于H同位素分馏较大，因此无法进行计算〜2H-动力学同位素效应（KIE）的特征以及多元素同位素分馏分析的过程鉴定。在这里，我们研究了高锰酸盐转化甲苯，硝基苯和四种取代的硝基甲苯相关的C和H同位素分馏MnO_4〜-，提出了一种精细的评估方法，用于定量区分CH_3-基团的氧化和双加氧作用。在分批实验的基础上，建立了同位素异构体特异性动力学模型和密度泛函理论（DFT）计算，成功地推导了H同位素分馏对甲苯的CH_3基团氧化的大表观〜2H-KIE为4.033±0.20 eeding＞ 1300‰，以及相应的〜（13）C-KIE（1.0324±0.0011）。实验和理论也很好地吻合了硝基苯的双氧合反应，这与〜2H-和〜（13）C-KIEs有关0.9410±0.0030（通过DFT获得0.9228）和1.0289±0.0003（1.025）。通过浓度，C和C的组合模型获得了MnO_4〜-对硝基甲苯进行CH〜3-竞争氧化和双加氧的一致支化比。 H同位素特征趋势。我们的方法为CSIA鉴定污染物微生物和非生物氧化途径提供了改进的估计。

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  • 来源
    《Environmental Science & Technology》 |2013年第23期|13459-13468|共10页
  • 作者

    Reto S.Wijker; Pawel Adamczyk; Jakov Bolotin; Piotr Paneth; Thomas B.Hofstetter;

  • 作者单位

    Eawag,Swiss Federal Institute of Aquatic Science and Technology,CH-8600 Duebendorf,Switzerland,Institute of Biogeochemistry and Pollutant Dynamics (IBP),ETH Zuerich,CH-8092 Zuerich,Switzerland;

    Switzerland Institute of Applied Radiation Chemistry,Technical University of Lodz,Zeromskiego 116,90-924 Lodz,Poland;

    Eawag,Swiss Federal Institute of Aquatic Science and Technology,CH-8600 Duebendorf,Switzerland;

    Switzerland Institute of Applied Radiation Chemistry,Technical University of Lodz,Zeromskiego 116,90-924 Lodz,Poland;

    Eawag,Swiss Federal Institute of Aquatic Science and Technology,CH-8600 Duebendorf,Switzerland,Institute of Biogeochemistry and Pollutant Dynamics (IBP),ETH Zuerich,CH-8092 Zuerich,Switzerland;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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