Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles
Removal and recovery of Cr(VI) from wastewater by maghemite nanoparticles
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DOI：
10.1016/j.watres.2005.05.051
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发表时间：
2005-11-01
期刊：
影响因子：
12.8
通讯作者：
Lo, IMC
中科院分区：
文献类型：
--
作者：
Hu, J;Chen, GH;Lo, IMC
废水中存在的六价铬是金属加工厂的主要担忧。本研究开发了一种纳米颗粒吸附与磁分离相结合的新方法来去除和回收废水中的铬(VI)。合成了纳米磁赤铁矿，对其进行了表征，并对其作为铬(VI)的吸附剂进行了评价。研究了pH、温度、初始浓度、共存常见离子等因素对吸附的影响。吸附在15min内达到平衡，与初始铬浓度无关。最大吸附量出现在pH为2.5时。用Freundlich等温式对吸附数据进行了分析和拟合。磁铁矿纳米颗粒对铬(VI)的吸附能力优于其他吸附剂，如活性碳和粘土。常见共存离子Na+、Ca~(2+)、Mg~(2+)、Cu2+、Ni2+、NO_3~-、Cl~-的竞争可以忽略不计，说明废水中的铬(VI)具有选择性吸附作用。再生研究证实，经过六次连续吸附-脱附的磁铁矿纳米颗粒仍保持原有的金属去除能力。此外，利用X射线衍射仪、X射线光电子能谱和拉曼光谱技术对吸附机理进行了研究。(C)2005爱思唯尔有限公司。保留所有权利。
Hexavalent chromium existing in the effluent is a major concern for the metal-processing plant. In this study, a new method combining nanoparticle adsorption and magnetic separation was developed for the removal and recovery of Cr(VI) from wastewater. The nanoscale maghemite was synthesized, characterized, and evaluated as adsorbents of Cr(VI). Various factors influencing the adsorption of Cr(VI), e.g., pH, temperature, initial concentration, and coexisting common ions were studied. Adsorption reached equilibrium within 15 min and was independent of initial Cr concentration. The maximum adsorption occurred at pH 2.5. The adsorption data were analyzed and fitted well by Freundlich isotherm. Cr(VI) adsorption capacity of maghemite nanoparticles was compared favorably with other adsorbents like activated carbon and clay. Competition from common coexisting ions such as Na+, Ca2+, mg(2+), Cu2+, Ni2+, NO3-, and Cl- was ignorable, which illustrated the selective adsorption of Cr(VI) from wastewater. Regeneration studies verified that the maghemite nanoparticles, which underwent six successive adsorption-desorption processes, still retained the original metal removal capacity. In addition, the adsorption mechanisms were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopic techniques. (c) 2005 Elsevier Ltd. All rights reserved.