Nanoscale Zero-Valent Iron (nZVI) assembled on magnetic Fe₃O₄/graphene for Chromium (VI) removal from aqueous solution

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• 作者：Xiaoshu Lv ; Xiaoqin Xue ; Guangming Jiang ; Donglei Wu ; Tiantian Sheng ; Hongyi Zhou ; Xinhua Xu
• 关键词：Nanoscale zero-valent iron ; Magnetic graphene ; Cr(VI) removal ; Synergistic effect
• 刊名：Journal of Colloid and Interface Science
• 出版年：1 March, 2014
• 年：2014
• 卷：417
• 期：Complete
• 页码：51-59
• 全文大小：1916 K

文摘

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^鈭? with decreasing pH from 8.0 to 3.0 at 30 掳C. Negative 螖G and 螖H 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.