A comparison of the effects of natural organic matter on sulfidated and nonsulfidated nanoscale zerovalent iron colloidal stability, toxicity, and reactivity to trichloroethylene
A comparison of the effects of natural organic matter on sulfidated and nonsulfidated nanoscale zerovalent iron colloidal stability, toxicity, and reactivity to trichloroethylene
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DOI：
10.1016/j.scitotenv.2019.03.343
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发表时间：
2019-06-25
影响因子：
9.8
通讯作者：
Chen, Jiawei
中科院分区：
文献类型：
--
作者：
Han, Yitong;Ghoshal, Subhasis;Chen, Jiawei
硫化纳米零价铁（S-NZVI）是一种新型的修复材料，对三氯乙烯（TCE）等氯代有机污染物具有更高的反应性和选择性。S-NZVI的性质和地下水成分如天然有机物（NOM）对其反应性的影响不如NZVI的特征。在这项研究中，S-NZVI（Fe/S摩尔比= 15）的合成超声NZVI在Na2S溶液中，产生的颗粒具有更大的表面电荷，较少的聚集，和更高的反应性与TCE相比，NZVI。由于尺寸较小，S-NZVI的细胞毒性未得到有效缓解。添加苏旺尼河腐殖酸（SRHA）后，NZVI和S-NZVI的表面负电荷增加，分散稳定性提高，毒性明显降低，但同时也增强了颗粒的腐蚀性和非导电膜的形成。随着SRHA浓度的增加，NZVI和S-NZVI的降解速率常数（k（sa））均降低，当SRHA浓度为200 mgC/L时，k（sa）分别降低了78%和60%，为0.0004和0.0053 Lm（-2）h（-1）。此外，在模拟地下水中，S-NZVI的田间性能被评估为被抑制，并且随着SRHA浓度的增加，负面影响加剧。水化学条件，如溶解氧（DO），pH值和温度也影响S-NZVI的反应性。因此，S-NZVI比NZVI更适合用于TCE的原位修复。然而，在长期使用S-NZVI修复地下水时，需要考虑NOM对S-NZVI上FeS壳层的完整性的影响。(C)2019 Elsevier B.V.版权所有。
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 Na2S 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(sa)) 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 Lm(-2) h(-1), respectively, with 200 mgC/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. (C) 2019 Elsevier B.V. All rights reserved.