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研究报告

布林朝克,郭婷,张邦文,俞慧涛,符圣主,邢瑞光,葛鑫.部分还原氧化石墨烯-Fe₃O₄对水中Cd (Ⅱ)的吸附性能及机理[J].环境科学学报,2017,37(8):2968-2976

Adsorption performance and mechanism of partially reduced graphene oxide-Fe₃O₄ towards aqueous Cd(Ⅱ)

摘要：当前，治理可溶性重金属污染是环境保护的迫切任务.以氧化石墨烯（GO）和铁盐为前驱体，一步合成了部分还原氧化石墨烯-Fe₃O₄复合材料（rGO-Fe₃O₄），探索其作为Cd（Ⅱ）高效吸附剂的潜力.同时，采用多种手段表征吸附剂结构和特性，重点研究了吸附剂对Cd（Ⅱ）的吸附特性和动力学.结果表明，在吸附剂中，纳米Fe₃O₄颗粒均匀地锚在石墨烯片层之间，避免了片层团聚，赋予其优良的吸附性能.在中性溶液中，使用rGO-Fe₃O₄（500 mg·L^-1）吸附200.09 mg·L^-1 Cd（Ⅱ），5 min即可达到吸附平衡，吸附率和吸附量分别为90.88%和363.99 mg·g^-1.另外，磁分离回收吸附剂仅需10 s，且循环吸附性良好.进一步研究显示，复合材料对Cd（Ⅱ）的吸附为吸热、自发的化学吸附，过程受化学吸附和液膜扩散控制.

Abstract：The control of water-soluble heavy metal pollution is one of the urgent issues in environmental protection in the present scenario. In this work, a facile one step strategy for the preparation of partially reduced graphene oxide-Fe₃O₄ hybrid (rGO-Fe₃O₄) was demonstrated in which graphene oxide (GO) and iron salts were used as the precursors. The feasibility of the obtained hybrid being utilized as an efficient adsorbent towards aqueous Cd(Ⅱ) was evaluated. The structure and properties of the hybrid were characterized via various techniques, the adsorption performance and kinetics were analyzed in detail. The results show that Fe₃O₄ nano particles distributed homogeneously in the interlayer space of the graphene sheets in the hybrid, avoiding the agglomeration whereby rendering superior adsorption performance. The adsorption of Cd(Ⅱ) (200.09 mg·L^-1) onto rGO-Fe₃O₄ (500 mg·L^-1) in a pH neutral solution was equilibrated in 5 min with the adsorption percent and capacity of 90.88% and 363.99 mg·g^-1, respectively. Besides, the magnetic separation of rGO-Fe₃O₄ from water take only 10 s, which proves that the adsorption cyclability is also excellent. Further analysis exhibits the adsorption is an endothermic and spontaneous chemical adsorption, whose overall rate is controlled by both chemical adsorption and liquid film diffusion.