College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082, China.
College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082, China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, Hunan 410082, China.
Water Res. 2018 May 15;135:1-10. doi: 10.1016/j.watres.2018.02.017. Epub 2018 Feb 7.
Sulfide-modified nanoscale zero-valent iron (S/NZVI) has been considered as an efficient material to degrade trichloroethylene (TCE) in groundwater. However, some critical factors influencing the dechlorination of TCE by S/NZVI have not been investigated clearly. In this study, the effects of Fe/S molar ratio, initial pH, dissolved oxygen and particle aging on TCE dechlorination by S/NZVI (using dithionite as sulfidation reagent) were studied. Besides, the feasibility of reactivation of the aged-NZVI by sulfidation treatment was looked into. The results show that the Fe/S molar ratio and initial pH significantly influenced the TCE dechlorination, and a higher TCE dechlorination was observed at Fe/S molar ratio of ∼60 under alkaline condition. Spectroscopic analyses demonstrate that the enhanced TCE dechlorination was associated with the presence of FeS on the surface of S/NZVI. Dissolved oxygen had little effect on TCE dechlorination by S/NZVI, revealing that the FeS layer could be able to alleviate the surface passivation of NZVI caused by oxidation. Aging of S/NZVI up to 10-20 d only slightly decreased the dechlorination efficiency of TCE. Although an obvious drop in dechorination efficiency was observed for the S/NZVI aged for 30 d, it still exhibited a higher reactivity than the bare NZVI. This indicates that sulfidation of NZVI did prolong its lifetime. Additionally, sulfidation treatment was used to reactivate the aged NZVI, and the results show that the reactivated NZVI even had higher reactivity than the fresh NZVI, suggesting that sulfidation treatment would be a promising method to reactivate the aged NZVI.
硫化纳米零价铁（S/NZVI）已被认为是一种有效降解地下水三氯乙烯（TCE）的材料。然而，一些影响 S/NZVI 脱氯 TCE 的关键因素尚未得到明确研究。在这项研究中，研究了 Fe/S 摩尔比、初始 pH 值、溶解氧和颗粒老化对 S/NZVI（使用连二亚硫酸盐作为硫化试剂）脱氯 TCE 的影响。此外，还研究了通过硫化处理使老化-NZVI 再活化的可行性。结果表明，Fe/S 摩尔比和初始 pH 值对 TCE 脱氯有显著影响，在碱性条件下，Fe/S 摩尔比约为 60 时观察到更高的 TCE 脱氯率。光谱分析表明，增强的 TCE 脱氯与 S/NZVI 表面存在的 FeS 有关。溶解氧对 S/NZVI 脱氯 TCE 的影响很小，表明 FeS 层能够缓解 NZVI 氧化引起的表面钝化。S/NZVI 的老化高达 10-20 d 仅略微降低了 TCE 的脱氯效率。尽管老化 30 d 的 S/NZVI 的脱氯效率明显下降，但它仍表现出比裸 NZVI 更高的反应性。这表明 NZVI 的硫化延长了其寿命。此外，还使用硫化处理来使老化的 NZVI 再活化，结果表明，再活化的 NZVI 甚至比新鲜的 NZVI 具有更高的反应性，表明硫化处理是一种有前途的再活化老化 NZVI 的方法。
