Selective removal of heavy metals from industrial wastewater using maghemite nanoparticle: Performance and mechanisms

This study investigated the applicability of maghemite -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 m 2 / g using the Brunauer-Emmett-Teller method. Batch experiments were carried out to determine the adsorption kinetics and mechanisms of CrVI ,C uII, and NiII 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 CrVI and CuII could be due to electrostatic attraction and ion exchange, and the adsorption of NiII could be as a result of electrostatic attraction only.

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