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Selective Removal of Heavy Metals from Industrial Wastewater Using Maghemite Nanoparticle: Performance and Mechanisms |
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| Authors: | Jing Hu Guohua Chen Irene M. C. Lo |
| Affiliation: | 1Post-Doc Fellow, Dept. of Civil Engineering, The Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; formerly, Research Assistant, Dept. of Environmental Engineering, School of Engineering, The Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. E-mail: hujing@ust.hk 2Associate Professor, Dept. of Chemical Engineering, The Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. E-mail: kechengh@ust.hk 3Associate Professor, Dept. of Civil Engineering, The Hong Kong Univ. of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (corresponding author). E-mail: cemclo@ust.hk |
| Abstract: | This study investigated the applicability of maghemite (γ-Fe2O3) nanoparticles for the selective removal of toxic heavy metals from electroplating wastewater. The maghemite nanoparticles of 10?nm were synthesized using a sol–gel method and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface area of the nanoparticles was determined to be 198?m2/g using the Brunauer–Emmett–Teller method. Batch experiments were carried out to determine the adsorption kinetics and mechanisms of Cr(VI), Cu(II), and Ni(II) by maghemite nanoparticles. The adsorption process was found to be highly pH dependent, which made the nanoparticles selectively adsorb these three metals from wastewater. The adsorption of heavy metals reached equilibrium rapidly within 10?min and the adsorption data were well fitted with the Langmuir isotherm. Regeneration studies indicated that the maghemite nanoparticles undergoing successive adsorption–desorption processes retained original metal removal capacity. Mechanism studies using TEM, XRD, and X-ray photoelectron spectroscopy suggested that the adsorption of Cr(VI) and Cu(II) could be due to electrostatic attraction and ion exchange, and the adsorption of Ni(II) could be as a result of electrostatic attraction only. |
| Keywords: | Adsorption Desorption Heavy metals Industrial wastes Industrial water |