Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, People's Republic of China.
J Colloid Interface Sci. 2014 Mar 1;417:51-9. doi: 10.1016/j.jcis.2013.11.044. Epub 2013 Nov 24.
Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe3O4/graphene (nZVI@MG) nanocomposites was synthesized for Cr(VI) removal from aqueous solution. nZVI particles were perfectly dispersed either among Fe3O4 nanoparticles (Fe3O4 NPs) or above the basal plane of graphene. This material shows Cr(VI) removal efficiency of 83.8%, much higher than those of individuals (18.0% for nZVI, 21.6% for Fe3O4 NPs and 23.7% for graphene) and even their sum of 63.3%. The removal process obeys pseudo-second-order adsorption model, suggesting that adsorption is rate-controlling step. Maximum Cr(VI) adsorption capacity varies from 66.2 to 101.0 mg g(-1) with decreasing pH from 8.0 to 3.0 at 30°C. Negative ΔG and ΔH indicate spontaneous tendency and exothermic nature. Robust performance of nZVI@MG arises from the formation of micro-nZVI-graphene/nZVI-Fe3O4 batteries and strong adsorption capability of broad graphene sheet/Fe3O4 surfaces. Electrons released by nZVI spread all over the surfaces of graphene and Fe3O4, and the adsorbed Cr(VI) ions on them capture these floating electrons and reduce to Cr(III). Fe3O4 NPs also served as protection shell to prevent nZVI from agglomeration and passivation.
用于从水溶液中去除六价铬的纳米零价铁（nZVI）组装在磁性 Fe3O4/石墨烯（nZVI@MG）纳米复合材料上。nZVI 颗粒完美地分散在 Fe3O4 纳米颗粒（Fe3O4 NPs）之间或石墨烯的基面之上。该材料显示出 83.8%的六价铬去除效率，远高于个体（nZVI 为 18.0%，Fe3O4 NPs 为 21.6%，石墨烯为 23.7%）甚至它们总和的 63.3%。去除过程遵循拟二级吸附模型，表明吸附是速率控制步骤。在 30°C 下，pH 值从 8.0 降低到 3.0 时，最大 Cr(VI)吸附容量从 66.2 到 101.0mg g-1 变化。负的 ΔG 和 ΔH 表明自发趋势和放热性质。nZVI@MG 的稳健性能源于微 nZVI-石墨烯/nZVI-Fe3O4 电池的形成和宽石墨烯片/Fe3O4 表面的强吸附能力。nZVI 释放的电子在石墨烯和 Fe3O4 的表面上扩散，吸附在它们上面的六价铬离子捕获这些浮移电子并还原为 Cr(III)。Fe3O4 NPs 还充当保护壳，防止 nZVI 团聚和钝化。
