title: Synthesis and characterization of porous zero-valent iron nanoparticles for remediation of chromium-contaminated wastewater.
abstract: The physical and chemical properties of porous zero-valent iron nanoparticles (ZVINs) have highly been acknowledged in the decontamination of heavy metal containing wastes and groundwater. In the present work, the treatment of Cr-contaminant through adsorption onto the ZVINs has been studied. The morphology, crystal structure, and surface composition of Fe(O) nanoparticles were investigated by field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. X-ray absorption near edge structure (XANES) revealed that the Cr(VI) species reduce to Cr(III) while oxidizing the ZVINs to Fe2O3, Fe3O4 or FeO electrochemically. Furthermore, the nitrogen adsorption-desorption isotherm of the porous nanoparticles was similar to a type IV curve with an obvious mesopore-characteristic H3 hysteresis loop, whereas the sizes of mesopores were in the range of 30-50 nm. Experimentally, the efficiency for Cr(VI) removal in the range of 150-300 ppm was found to be > 99.9%. Remarkably, the reduction reaction was completed within 10 min in the absence of additional pH controls. This work also highlights the utility of X-ray absorption spectroscopy (XAS) coupled with conventional characterization methods to comprehensively study the speciation and possible reaction pathway in adsorption process.
authors.affiliation: Department of Chemical Engineering and Materials Science/Fuel Cell Center, Yuan Ze University, Chung-Li City, Taiwan 320, ROC.
authors.forename: Kuen-Song
authors.initials: KS
authors.lastname: Lin
authors.forename: Khalilalrahman
authors.initials: K
authors.lastname: Dehvari
authors.forename: Yeu-Jye
authors.initials: YJ
authors.lastname: Liu
authors.forename: Hua
authors.initials: H
authors.lastname: Kuo
authors.forename: Pei-Ju
authors.initials: PJ
authors.lastname: Hsu