title: Nanoscale zero-valent iron (nZVI) assembled on magnetic Fe3O4/graphene for chromium (VI) removal from aqueous solution.
abstract: 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.
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Xiaoshu
authors.initials: X
authors.lastname: Lv
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Xue
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Jiang
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Donglei
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Sheng
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, People's Republic of China.
authors.forename: Hongyi
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, People's Republic of China. Electronic address: xuxinhua@zju.edu.cn.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Xu
keywords: Cr(VI) removal; Magnetic graphene; Nanoscale zero-valent iron; Synergistic effect