Synthesis, characterization and kinetics of bentonite supported nZVI for the removal of Cr(VI) from aqueous solution

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• 作者：Li-na Shi^a ; Yu-Man Lin^a ; Xin Zhang^b ; Zu-liang Chen^a ; ^{zlchen@fjnu.edu.cn"" rel=""nofollow}
• 关键词：Nanoscale ; Zero-valent iron ; Cr(VI) ; Synthesis ; Characterization
• 刊名：Chemical Engineering Journal
• 出版年：2011
• 出版时间：1 July 2011
• 年：2011
• 卷：171
• 期：2
• 页码：612-617
• 全文大小：709 K

文摘

Bentonite supported nanoscale zero-valent iron (B-nZVI) was synthesized by the sodium borohydride reduction method, characterized with SEM, and used for aqueous Cr(VI) removal. Bentonite decreased nano-Fe⁰ aggregation and thus increase Cr(VI) removal efficiency. At 35 °C and 250 r min⁻¹, 99 % Cr(VI) removal was achieved from aqueous solution containing 50 mg L⁻¹ of Cr(VI) by B-nZVI, while only 66 % removal was achieved with unsupported nZVI after an experimental duration of 3 h when the Fe⁰ loadings were 1.5 g L⁻¹. XRD indicated the existence of iron oxide and iron-chromium hydroxide coprecipitation on the surface of B-nZVI after exposure to an aqueous solution of Cr(VI). Kinetics studies under a series of different conditions showed that reduction of Cr(VI) to Cr(III) could be expressed by pseudo first-order reaction kinetics, with initial Cr(VI) and B-nZVI concentrations, pH and temperature as variables. The apparent activation energy of Cr(VI) remediation by B-nZVI was 21 kJ mol⁻¹, which was characteristic of a chemically controlled reaction. These results demonstrated that B-nZVI could potentially be used as a new material for use in situ remediation.