State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, PR China.
Department of Civil Engineering, McGill University, Montreal, Quebec, H3A 0C3, Canada.
Sci Total Environ. 2019 Jun 25;671:254-261. doi: 10.1016/j.scitotenv.2019.03.343. Epub 2019 Mar 23.
Sulfidated nanoscale zerovalent iron (S-NZVI) is a new remediation material with higher reactivity and greater selectivity for chlorinated organic contaminants such as trichloroethene (TCE) than NZVI. The properties of S-NZVI and the effects of groundwater constituents like natural organic matter (NOM) on its reactivity are less well-characterized than for NZVI. In this study, S-NZVI (Fe/S mole ratio = 15) was synthesized by sonicating NZVI in a NaS solution, yielding particles with greater surface charge, less aggregation, and higher reactivity with TCE compared to NZVI. The cytotoxicity of S-NZVI was not mitigated effectively due to the smaller size. The addition of Suwannee River humic acid (SRHA) increased the negative surface charge magnitude and dispersion stability and reduced the toxicity of both NZVI and S-NZVI significantly, but also enhanced the corrosion of particles and the formation of non-conductive film. The degradation rate constant (k) of both NZVI and S-NZVI was thus reduced with the increasing concentration of SRHA, which decreased by 78% and 60% to be 0.0004 and 0.0053 L m h, respectively, with 200 mg C/L SRHA. Additionally, the performance of S-NZVI in field was evaluated to be depressed in simulated groundwater and the negative effect was exacerbated with increased concentration of SRHA. Hydro-chemical conditions like dissolved oxygen (DO), pH, and temperature also influenced the reactivity of S-NZVI. Hence, S-NZVI was a preferred candidate for in-situ remediation of TCE than NZVI. Nevertheless, the integrity of the FeS shell on S-NZVI influenced by NOM need to be considered during the long-term use of S-NZVI in groundwater remediation.
硫化纳米零价铁（S-NZVI）是一种新型修复材料，与 NZVI 相比，其对三氯乙烯（TCE）等氯化有机污染物具有更高的反应活性和更大的选择性。S-NZVI 的性质以及地下水成分（如天然有机物（NOM））对其反应活性的影响，不如 NZVI 那么好。在这项研究中，通过在 NaS 溶液中超声处理 NZVI 合成了 S-NZVI（Fe/S 摩尔比= 15），与 NZVI 相比，其具有更大的表面电荷、更小的聚集和更高的 TCE 反应活性。由于粒径较小，S-NZVI 的细胞毒性不能得到有效缓解。添加苏万尼河腐殖酸（SRHA）增加了负表面电荷大小和分散稳定性，显著降低了 NZVI 和 S-NZVI 的毒性，但也增强了颗粒的腐蚀和非导电膜的形成。随着 SRHA 浓度的增加，NZVI 和 S-NZVI 的降解速率常数（k）均降低，当 SRHA 浓度为 200mg C/L 时，k 值分别降低了 78%和 60%，降至 0.0004 和 0.0053 L mh。此外，还评估了 S-NZVI 在模拟地下水中的现场性能，随着 SRHA 浓度的增加，其性能下降，且负效应加剧。水化学条件如溶解氧（DO）、pH 值和温度也会影响 S-NZVI 的反应活性。因此，与 NZVI 相比，S-NZVI 是 TCE 原位修复的首选候选物。然而，在地下水修复中长期使用 S-NZVI 时，需要考虑 NOM 对 S-NZVI 上的 FeS 壳完整性的影响。
