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首页> 外文期刊>Environmental Science & Technology >Reduction of Nitroaromatics Sorbed to Black Carbon by Direct Reaction with Sorbed Sulfides
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Reduction of Nitroaromatics Sorbed to Black Carbon by Direct Reaction with Sorbed Sulfides

机译：与吸附的硫化物直接反应还原吸附成黑碳的硝基芳烃

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摘要

Sorption to black carbons is an important sink for organic contaminants in sediments. Previous research has suggested that black carbons (graphite, activated carbon, and biochar) mediate the degradation of nitrated compounds by sulfides by at least two different pathways: reduction involving electron transfer from sulfides through conductive carbon regions to the target contaminant (nitroglycerin) and degradation by sulfur-based intermediates formed by sulfide oxidation (RDX). In this study, we evaluated the applicability of black carbon-mediated reactions to a wider variety of contaminant structures, including nitrated and halogenated aromatic compounds, halogenated heterocyclic aromatic compounds, and halogenated alkanes. Among these compounds, black carbon-mediated transformation by sulfides over a 3-day time scale was limited to nitroaromatic compounds. The reaction for a series of substituted nitroaromatics proceeded by reduction, as indicated by formation of 3-bromoaniline from 3-bromonitrobenzene, and inverse correlation of log k_(obs) with energy of the lowest unoccupied molecular orbital (E_(LUMO)). The log k_(obs) was correlated with sorbed sulfide concentration, but no reduction of 3- bromonitrobenzene was observed in the presence of graphite and sulfite, thiosulfate, or polysulfides. Whereas nitroglycerin reduction occurred in an electrochemical cell containing sheet graphite electrodes in which the reagents were placed in separate compartments, nitroaromatic reduction only occurred when sulfides were present in the same compartment. The results suggest that black carbon-mediated reduction of sorbed nitroaromatics by sulfides involves electron transfer directly from sorbed sulfides rather than transfer of electrons through conductive carbon regions. The existence of three different reaction pathways suggests a complexity to the sulfide-carbon system compared to the iron-carbon system, where contaminants are reduced by electron transfer through conductive carbon regions.
机译：对黑碳的吸附是沉积物中有机污染物的重要吸收器。先前的研究表明，黑碳（石墨，活性炭和生物炭）通过至少两种不同的途径介导硫化物对硝化化合物的降解：还原涉及电子从硫化物通过导电碳区域转移到目标污染物（硝酸甘油）和降解由硫化物氧化（RDX）形成的硫基中间体。在这项研究中，我们评估了黑碳介导的反应对各种污染物结构的适用性，包括硝化和卤化的芳族化合物，卤化的杂环芳族化合物和卤化的烷烃。在这些化合物中，硫化物在3天的时间内进行的黑碳介导的转化仅限于硝基芳族化合物。一系列取代的硝基芳香族化合物的反应通过还原而进行，如由3-溴硝基苯形成3-溴苯胺，以及log k_（obs）与最低未占据分子轨道的能量（E_（LUMO））呈反相关。 log k_（obs）与吸附的硫化物浓度相关，但是在石墨和亚硫酸盐，硫代硫酸盐或多硫化物的存在下，未观察到3-溴硝基苯的还原。硝酸甘油还原发生在包含片状石墨电极的电化学电池中，其中试剂被放置在单独的隔室中，而硝基芳香族还原仅在硫化物存在于同一隔室中时发生。结果表明，硫化物在黑碳介导的吸附的硝基芳烃还原反应中的作用是直接从吸附的硫化物转移电子，而不是通过导电碳区域转移电子。与铁-碳系统相比，存在三种不同的反应路径表明硫化物-碳系统的复杂性，在铁碳系统中，污染物通过电子通过导电碳区域的转移而减少。

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  • 来源
    《Environmental Science & Technology》 |2015年第6期|3419-3426|共8页
  • 作者

    Wenqing Xu; Joseph J. Pignatello; William A. Mitch;

  • 作者单位

    Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States,Department of Civil and Environmental Engineering, Villanova University, Villanova, Pennsylvania 19085, United States;

    Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States,Department of Environmental Sciences, Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, Connecticut 06504-1106, United States;

    Department of Civil and Environmental Engineering, Stanford University, Stanford, California 94305-4020, United States;

  • 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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  • 正文语种 eng
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