Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Sci Total Environ. 2022 Jul 10;829:154304. doi: 10.1016/j.scitotenv.2022.154304. Epub 2022 Mar 16.
Sulfidated zero-valent iron (S-ZVI) is commonly used to degrade trichloroethylene (TCE). The reactivity of S-ZVI is related to not only the properties of S-ZVI but also the geochemical conditions in groundwater, such as coexisted NO. Therefore, the effect of NO on TCE degradation by S-ZVI and its mechanism were systematically studied. 95.17% of TCE was degraded to acetylene, dichloroethene, ethene, ethane and multi‑carbon products via β-elimination by fresh S-ZVI that contained 85.31% Fe and 14.69% FeS in the presence of NO, demonstrating that NO did not affect the degradation pathway of TCE. While high concentration of NO (> 10 mg/L) competed for electrons at the Fe/FeO interface with degradation products, leading to a continuous rising of acetylene. Moreover, the rapid reduction of NO to NH (89.79%) at the Fe interface contributed to the release of 5.08 mM Fe from S-ZVI, which promoted the formation of FeO with excellent electron conduction properties on the surface of S-ZVI. Accordingly, NO improved the degradation and electron selectivity of TCE by 51.07% and 2.79 fold, respectively. This study demonstrated that S-ZVI could remediate the contamination of NO and TCE simultaneously and the presence of NO could effectively enhance the degradation of TCE in groundwater.
硫化零价铁（S-ZVI）常用于降解三氯乙烯（TCE）。S-ZVI 的反应性不仅与 S-ZVI 的性质有关，还与地下水的地球化学条件有关，如共存的 NO。因此，系统研究了 NO 对 S-ZVI 降解 TCE 的影响及其机制。在含有 85.31%Fe 和 14.69%FeS 的新鲜 S-ZVI 存在下，NO 通过 β-消除将 95.17%的 TCE 降解为乙炔、二氯乙烯、乙烯、乙烷和多碳产物，表明 NO 不影响 TCE 的降解途径。然而，高浓度的 NO（>10mg/L）与降解产物在 Fe/FeO 界面上竞争电子，导致乙炔不断上升。此外，NO 在 Fe 界面上迅速还原为 NH（89.79%），促使 S-ZVI 释放出 5.08mM 的 Fe，这促进了具有优异电子传导性能的 FeO 在 S-ZVI 表面的形成。因此，NO 分别提高了 TCE 的降解和电子选择性 51.07%和 2.79 倍。本研究表明，S-ZVI 可以同时修复 NO 和 TCE 的污染，而 NO 的存在可以有效地增强地下水 TCE 的降解。
