Chromium(VI) removal by mechanochemically sulfidated zero valent iron and its effect on dechlorination of trichloroethene as a co-contaminant.
Chromium(VI) removal by mechanochemically sulfidated zero valent iron and its effect on dechlorination of trichloroethene as a co-contaminant.
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DOI：
10.1016/j.scitotenv.2018.09.003
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发表时间：
2019-02
期刊：
影响因子：
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通讯作者：
Haowen Zou;Erdan Hu;Shang-yuan Yang;Li Gong;Feng He
中科院分区：
文献类型：
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作者：
Haowen Zou;Erdan Hu;Shang-yuan Yang;Li Gong;Feng He
机械化学硫化的微量零价铁（S-mZVIbm）是一种很有前途的地下水修复材料，因为它已被证明不仅是有效的脱氯氯化化合物，但也适合放大。然而，它在处理金属污染物方面的效率仍然很少研究。本文研究了S-mZVIb对Cr（VI）的去除机理、去除效率及其对TCE脱氯的影响。S-mZVIbm对Cr（VI）的去除主要是化学吸附过程，其动力学符合准二级动力学模型。碱性pH抑制Cr（VI）的去除，而溶解氧略微抑制Cr（VI）的去除。Cr（VI）的去除在S-mZVibm表面上迅速形成非导电层，以在H+能够接受任何电子以产生H2之前阻碍从Fe 0核的进一步电子转移，这导致100%的Cr（VI）去除的电子效率，但<1%的Fe 0利用效率。Cr（VI）的存在下，也显着抑制脱氯TCE和其电子效率作为一个共同污染物钝化的FeS表面。因此，如果存在的话，Cr（VI）很可能成为电子汇，用于修复地下水中的其他污染物。
Mechanochemically sulfidated microscale zero valent iron (S-mZVIbm) is a promising groundwater remediation material as it has been proven to be not only efficient in dechlorinating chlorinated compounds but also amenable to up-scaling. Yet, its efficiency in treating metal contaminants remains barely studied. In this study, we investigated the mechanism and efficiencies of Cr(VI) removal by S-mZVIbmand its effect on TCE dechlorination as a co-contaminant. The Cr(VI) removal by S-mZVIbmwas mainly a chemisorption process and its kinetics was well fitted by a pseudo-second-order model. Alkaline pH inhibited Cr(VI) removal while dissolved oxygen slightly depressed the Cr(VI) removal. The Cr(VI) removal rapidly formed a non-conductive layer on S-mZVIbmsurface to hinder further electron transfer from Fe0core before H+was able to accept any electrons to produce H2, which resulted in 100% electron efficiencies of Cr(VI) removal but <1% of Fe0utilization efficiency. The presence of Cr(VI) also dramatically inhibited the dechlorination of TCE and its electron efficiency as a co-contaminant by passivating the FeS surface. Therefore, Cr(VI) is likely to be an electron sink if present for remediation of other contaminants in groundwater.