CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Sci Total Environ. 2022 Sep 15;839:156228. doi: 10.1016/j.scitotenv.2022.156228. Epub 2022 May 25.
AC-supported nanoscale zero-valent iron composites (nZVI/AC) exhibit significant environmental implications for trihalomethanes (THMs)-contaminated water remediation. To improve the adsorption and degradation capability of AC, herein, a composite (nZVI/Ag@AC-RGO) consisting of AC, reduced graphene oxide (RGO), nanoscale zero-valent iron (nZVI), and silver (Ag) was synthesized and characterized using several techniques, such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, N adsorption-desorption isotherms, and X-ray photoelectron spectroscopy (XPS). The analysis of textural and morphological structures showed that a tightly-attached RGO film, amorphous iron, and weak crystal silver nanoparticles with a size of 20-30 nm were evenly immobilized on the support. Specific surface area increased by 19.12% after supporting RGO, while it decreased after supporting nZVI and Ag due to the partial blockage of micropores. The Fe surface was concurrently coated by iron oxides (FeO, FeOOH) and Ag. THMs were eliminated through multilayer reaction processes. The values of the adsorption constant (K) of chloroform (CHCl), dichlorobromoethane (CHBrCl), dibromochloroethane (CHBrCl), and tribromomethane (CHBr) adsorbed by nZVI/Ag@AC-RGO increased by 34.4, 33.7, 81.6, and 67.3%, respectively, compared to pristine AC. THMs with more Br atoms exhibited better removal efficiency and adsorption capacity, along with a higher oxidation degree of the Fe surface. CHBrCl and CHBrCl mainly decomposed into chloromethane (CHCl) and dichloromethane (CHCl), and CHBr and CHCl primarily degraded into dibromomethane (CHBr) and CHCl, respectively, along with generating Cl and Br. Conclusively, THMs-contaminated water could be remediated by coupling AC pre-enrichment and the reactivity of nZVI/Ag.
AC 负载纳米零价铁复合材料（nZVI/AC）在三卤甲烷（THMs）污染水修复方面具有重要的环境意义。为了提高 AC 的吸附和降解能力，本文合成了一种由 AC、还原氧化石墨烯（RGO）、纳米零价铁（nZVI）和银（Ag）组成的复合材料（nZVI/Ag@AC-RGO），并采用扫描电子显微镜（SEM）、X 射线衍射（XRD）、拉曼光谱、N2 吸附-脱附等温线和 X 射线光电子能谱（XPS）等技术对其进行了表征。结构和形态分析表明，紧密附着的 RGO 薄膜、无定形铁和尺寸为 20-30nm 的弱结晶银纳米粒子均匀地固定在载体上。负载 RGO 后比表面积增加了 19.12%，而负载 nZVI 和 Ag 后比表面积减小，这是由于部分微孔被堵塞。Fe 表面同时被氧化铁（FeO、FeOOH）和 Ag 覆盖。THMs 通过多层反应过程被去除。与原始 AC 相比，nZVI/Ag@AC-RGO 吸附的氯仿（CHCl）、二氯溴乙烷（CHBrCl）、二溴氯乙烷（CHBrCl）和三溴甲烷（CHBr）的吸附常数（K）值分别增加了 34.4%、33.7%、81.6%和 67.3%。具有更多 Br 原子的 THMs 具有更好的去除效率和吸附能力，同时 Fe 表面的氧化程度更高。CHBrCl 和 CHBrCl 主要分解为氯仿（CHCl）和二氯甲烷（CHCl），CHBr 和 CHCl 主要分别降解为二溴甲烷（CHBr）和 CHCl，同时生成 Cl 和 Br。总之，通过耦合 AC 预富集和 nZVI/Ag 的反应性，可以修复受 THMs 污染的水。
