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首页> 外文期刊>Journal of Contaminant Hydrology >Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model
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Determination of rate constants and branching ratios for TCE degradation by zero-valent iron using a chain decay multispecies model

机译：使用链衰减多物种模型确定零价铁降解三氯乙烯的速率常数和支化比

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摘要

The applicability of a newly-developed chain-decay multispecies model (CMM) was validated by obtaining kinetic rate constants and branching ratios along the reaction pathways of trichloroethene (TCE) reduction by zero-valent iron (ZVI) from column experiments. Changes in rate constants and branching ratios for individual reactions for degradation products over time for two columns under different geochemical conditions were examined to provide ranges of those parameters expected over the long-term. As compared to the column receiving deionized water, the column receiving dissolved CaCO3 showed higher mean degradation rates for TCE and all of its degradation products. However, the column experienced faster reactivity loss toward TCE degradation due to precipitation of secondary carbonate minerals, as indicated by a higher value for the ratio of maximum to minimum TCE degradation rate observed over time. From the calculated branching ratios, it was found that TCE and cis-dichloroethene (cis-DCE) were dominantly dechlorinated to chloroacetylene and acetylene, respectively, through reductive elimination for both columns. The CMM model, validated by the column test data in this study, provides a convenient tool to determine simultaneously the critical design parameters for permeable reactive barriers and natural attenuation such as rate constants and branching ratios. (C) 2015 Elsevier B.V. All rights reserved.
机译：通过从柱实验获得沿三氯乙烯（TCE）还原为零价铁（ZVI）的反应路径的动力学速率常数和支化比，验证了新开发的链衰减多物种模型（CMM）的适用性。研究了在不同地球化学条件下两根色谱柱的降解产物的各个反应的速率常数和支化比随时间的变化，以提供长期预期的那些参数范围。与接受去离子水的色谱柱相比，接受溶解的CaCO3的色谱柱的TCE及其所有降解产物的平均降解率更高。然而，由于随着时间的推移观察到的最大TCE降解率与最小TCE降解率之比较高，表明该柱由于次生碳酸盐矿物的沉淀而导致对TCE降解的反应性损失更快。根据计算出的支化比，发现通过对两根色谱柱进行还原消除，TCE和顺式二氯乙烯（cis-DCE）分别显着地脱氯为氯乙炔和乙炔。通过这项研究中的柱测试数据验证的CMM模型提供了一种便捷的工具，可同时确定可渗透反应性屏障和自然衰减的关键设计参数，例如速率常数和支化比。 （C）2015 Elsevier B.V.保留所有权利。

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