Department of Chemical Engineering and Materials Science/Environmental Technology Research Center, Yuan Ze University, Chung-Li District, Taoyuan City 32003, Taiwan.
Chemosphere. 2019 Jun;224:816-826. doi: 10.1016/j.chemosphere.2019.02.160. Epub 2019 Feb 27.
Zero-valent iron nanoparticles (ZVIN) have found applications in many strategies for on-site soil and groundwater decontamination. A number of studies have reported the prospective utilization of ZVIN in the reduction of chlorinated organic compounds such as dense non-aqueous phase liquids (DNAPLs) in groundwater. Due to their bioaccumulation and carcinogenesis, DNAPLs in groundwater are a human health hazard and pose environmental risks. Therefore, decontamination of these contaminants is necessary. This study presents the in-situ remediation of trichloroethylene (TCE), perchloroethene (PCE), and 1,2-dichloroethene (1,2-DCE) DNAPLs through the direct injection of polyethylenimine (PEI)-coated ZVIN (PEI-ZVIN composite materials) to facilitate the reduction of contaminants in low-permeability media. A field test was conducted at the premises of a petrochemical company, situated in the Miaoli County of Northern Taiwan that discharged significant amounts of DNAPLs. After in-situ injection and one-day of reaction with groundwater contaminants, ZVIN was further characterized to examine its efficacy in the reduction of pollutants. After the direct injection of PEI-ZVIN, a notable reduction in the concentration of DNAPLs was recorded with conversion from toxic to non-toxic substances. Use of resistivity image profiling (RIP) technique suggested similar conductivity data for the PEI-coated ZVIN suspension and groundwater samples. X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (EXAFS) studies depicted that the oxidation of ZVIN and PEI-ZVIN was occurring after the reductive reaction with contaminated groundwater. The reacted samples had bond distance values of 1.98, 2.00, 1.96, and 1.94 Å. Combining floating surface-coated ZVIN and RIP technique seems promising and environmentally attractive.
零价铁纳米颗粒（ZVIN）已在许多原位土壤和地下水修复策略中得到应用。许多研究报告称，ZVIN 有望用于还原地下水中的氯化有机化合物，如致密非水相液体（DNAPLs）。由于其生物累积性和致癌性，地下水中的 DNAPLs 对人类健康构成威胁，并带来环境风险。因此，必须对这些污染物进行去污处理。本研究通过直接注入聚乙烯亚胺（PEI）包覆的 ZVIN（PEI-ZVIN 复合材料），原位修复三氯乙烯（TCE）、全氯乙烯（PCE）和 1,2-二氯乙烯（1,2-DCE）DNAPLs，以促进在低渗透介质中还原污染物。在台湾北部苗栗县的一家石化公司进行了现场试验，该公司排放了大量的 DNAPLs。在现场注入和与地下水污染物反应一天后，进一步对 ZVIN 进行了表征，以检验其在减少污染物方面的效果。在直接注入 PEI-ZVIN 后，记录到 DNAPLs 的浓度显著降低，毒性物质转化为无毒物质。电阻率图像剖面（RIP）技术的使用表明，PEI 包覆的 ZVIN 悬浮液和地下水样品具有相似的电导率数据。X 射线吸收近边结构（XANES）和 X 射线吸收精细结构（EXAFS）研究表明，ZVIN 和 PEI-ZVIN 在与受污染的地下水发生还原反应后发生氧化。反应后的样品的键距值分别为 1.98、2.00、1.96 和 1.94 Å。结合浮动表面包覆的 ZVIN 和 RIP 技术似乎具有很大的应用前景和环境吸引力。
