College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China.
Chinese Academy for Environmental Planning, Beijing 100012, China.
J Environ Sci (China). 2018 May;67:14-22. doi: 10.1016/j.jes.2017.11.003. Epub 2017 Nov 12.
Zero-valent iron (ZVI) was loaded on expanded graphite (EG) to produce a composite material (EG-ZVI) for efficient removal of hexavalent chromium (Cr(VI)). EG and EG-ZVI were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and Brunauer-Emmett-Teller (BET) analysis. EG-ZVI had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr(VI) removal performance. The results showed that the Cr(VI) removal rate was 98.80% for EG-ZVI, which was higher than that for both EG (10.00%) and ZVI (29.80%). Furthermore, the removal rate of Cr(VI) by EG-ZVI showed little dependence on solution pH within a pH range of 1-9. Even at pH11, a Cr(VI) removal rate of 62.44% was obtained after reaction for 1hr. EG-ZVI could enhance the removal of Cr(VI) via chemical reduction and physical adsorption, respectively. X-ray photoelectron spectroscopy (XPS) was used to analyze the mechanisms of Cr(VI) removal, which indicated that the ZVI loaded on the surface was oxidized, and the removed Cr(VI) was immobilized via the formation of Cr(III) hydroxide and Cr(III)-Fe(III) hydroxide/oxyhydroxide on the surface of EG-ZVI.
零价铁（ZVI）负载在膨胀石墨（EG）上，制备了一种复合材料（EG-ZVI），用于有效去除六价铬（Cr(VI)）。通过 X 射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外（FTIR）光谱和 Brunauer-Emmett-Teller（BET）分析对 EG 和 EG-ZVI 进行了表征。EG-ZVI 具有高比表面积，并包含亚微米尺寸的零价铁颗粒。采用批实验评估了 Cr(VI)去除性能。结果表明，EG-ZVI 对 Cr(VI)的去除率为 98.80%，高于 EG（10.00%）和 ZVI（29.80%）。此外，EG-ZVI 对 Cr(VI)的去除率在 pH 1-9 的范围内几乎不受溶液 pH 的影响。即使在 pH11 下，反应 1 小时后仍可获得 62.44%的 Cr(VI)去除率。EG-ZVI 可以通过化学还原和物理吸附分别增强 Cr(VI)的去除。X 射线光电子能谱（XPS）用于分析 Cr(VI)去除的机制，表明负载在表面上的 ZVI 被氧化，去除的 Cr(VI)通过在 EG-ZVI 表面形成 Cr(III)氢氧化物和 Cr(III)-Fe(III)氢氧化物/氢氧化物而被固定。
