纳米铁广泛用于水中重金属离子的去除, 但由于其易团聚的特性, 在地下水中迁移性差, 使其修复效果降低。 氧化石墨烯具有吸附重金属的作用, 但由于其表面带有负电荷, 对带负电的高价铬（Cr2O2-7, CrO2-4）吸附作用较弱。 以氧化石墨烯（GO）为载体, 采用液相还原法制备的氧化石墨烯负载纳米铁（rGO-nZⅥ）, 在改善纳米铁的分散性的同时, 利用nZⅥ将带负电的高价铬（Cr2O2-7, CrO2-4）还原为带正电的三价铬（Cr3+）, 增强了氧化石墨烯对其吸附的性能。 利用XRD和TEM对制备的rGO-nZⅥ进行表征, 表明制备的rGO-nZⅥ近似球形, 粒径为20～100 nm; 零价铁负载在GO表面。 应用rGO-nZⅥ处理Cr（Ⅵ）污染的地下水, Cr（Ⅵ）的去除效率可达到100%, 材料的最佳投加量与Cr（Ⅵ）浓度呈线性正相关。 采用X光电子能谱（XPS）分析铬和铁的存在形态, 并通过XPAPEAK41分峰后证实, Cr（Ⅵ）首先被还原为Cr（Ⅲ）, 进而生成Cr(OH)3吸附到材料表面。 由XPS图看出, 经24 h反应, 69.8%的Cr（Ⅵ）转化为Cr（Ⅲ）吸附到材料表面, 此时仍具有Fe0的峰, 证实材料具有很强的还原吸附铬的能力, 且仍具有缓慢释放电子的能力, 有利于后续长时间的修复。 该结果对于利用rGO-nZⅥ处理地下水Cr(Ⅵ)污染具有重要的理论意义和实用价值。

Iron nanoparticles are widely used in heavy metal ions removal from water, but because of the characteristics of easily aggregation and transference in the groundwater, remediation effect was reduced. GO with a negative charge containing oxygen-containing functional groups on the surfaces of graphene, are widely used for the removal of heavy metal ions from water, but it has little on remediating hexavalent chromium (Cr2O2-7, CrO2-4) with negatively charged electrons. Therefore, rGO-nZⅥ was synthesized via liquid phase reduction method to overcome the aggregation and transference of FeO, changing the negative charged Cr2O2-7 or CrO2-4 to positive charged Cr3+. The material behavior characteristics of Cr(Ⅵ) removal were discussed. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to test the prepared rGO-nZⅥ. Results indicated that nZⅥ was successfully loaded on the surface of GO, and the shape of the particles was approximate ball and the granular diameter ranged from 20 to 100 nm. Removal efficiency of Cr(Ⅵ) (40 mg·L-1) from water was nearly 100% within 24 h using rGO-nZⅥ. X-ray photoelectron spectroscopy (XPS) analyses using the XPSPEAK41 program indicated that FeO firstly reduced negatively charged Cr(Ⅵ) to positively charged Cr(Ⅲ) by providing electron, then the chromium in the solution can be removed as chromium hydroxide (Cr(OH)3) by a hydrolysis precipitation process. As the reaction progress, materials charges were changing, which benefited adsorpting Cr(Ⅵ). After 24 h reaction, the residual nZⅥ loading on rGO-nZⅥ remained, which showed the potential of sequentially remediating contamination. The results showed important theoretical value and practicability.