Department of Civil and Environmental Engineering, Western University, 1151 Richmond Rd., London, Ontario, N6A 5B8, Canada.
Department of Civil and Environmental Engineering, Western University, 1151 Richmond Rd., London, Ontario, N6A 5B8, Canada; Department of Civil and Mineral Engineering, University of Toronto, 35 St. George Street, Toronto, Ontario, M5S 1A4, Canada.
Water Res. 2020 May 1;174:115594. doi: 10.1016/j.watres.2020.115594. Epub 2020 Feb 7.
Sulfidated nano zerovalent iron (S-nZVI), stabilized with carboxymethyl cellulose (CMC), was successfully synthesized on site and injected into the subsurface at a site contaminated with a broad range of chlorinated volatile organic compounds (cVOCs). Transport of CMC-S-nZVI to the monitoring wells, both downgradient and upgradient, resulted in a significant decrease in concentrations of aqueous-phase cVOCs. Short-term (0-17 days) total boron and chloride measurements indicated dilution and displacement in these wells. Importantly however, compound specific isotope analysis (CSIA), changes in concentrations of intermediates, and increase in ethene concentrations confirmed dechlorination of cVOCs. Dissolution from the DNAPL pool into the aqueous phase at the deepest levels (4.0-4.5 m bgs) was identifiable from the increased cVOCs concentrations during long-term monitoring. However, at the uppermost levels (∼1.5 m above the source zone) a contrasting trend was observed indicating successful dechlorination. Changes in cVOCs concentrations and CSIA data suggest both sequential hydrogenolysis as well as reductive β-elimination as the possible transformation mechanisms during the short-term abiotic and long-term biotic dechlorination. One of the most positive outcomes of this CMC-S-nZVI field treatment is the non-accumulation of lower chlorinated VOCs, particularly vinyl chloride. Post-treatment soil cores also revealed significant decreases in cVOCs concentrations throughout the targeted treatment zones. Results from this field study show that sulfidation is a suitable amendment for developing more efficient nZVI-based in situ remediation technologies.
采用羧甲基纤维素（CMC）稳定的硫化纳米零价铁（S-nZVI）在受多种氯化挥发性有机化合物（cVOCs）污染的地点现场成功合成，并注入地下。CMC-S-nZVI 向下游和上游的监测井中的迁移导致水相 cVOCs 浓度显著降低。短期（0-17 天）总硼和氯的测量表明这些井中存在稀释和置换。然而，重要的是，化合物特异性同位素分析（CSIA）、中间产物浓度的变化以及乙烯浓度的增加证实了 cVOCs 的脱氯作用。从 DNAPL 池向最深处（4.0-4.5 m bgs）的水相溶解可通过长期监测期间 cVOCs 浓度的增加来识别。然而，在最高处（距源区约 1.5 m）观察到相反的趋势，表明成功脱氯。cVOCs 浓度和 CSIA 数据的变化表明，在短期非生物和长期生物脱氯过程中，可能存在顺序氢解和还原β消除等转化机制。这种 CMC-S-nZVI 现场处理的最积极结果之一是不会积累低氯化 VOCs，特别是氯乙烯。处理后的土壤芯也显示出整个目标处理区 cVOCs 浓度的显著降低。该现场研究的结果表明，硫化是开发更有效的基于 nZVI 的原位修复技术的合适添加剂。
