Mn(IV) promotion mechanism for the photocatalytic oxidation of arsenite by anatase-TiO2

A Ti-Mn hybrid oxide (Ti-Mn-HO) that simultaneously contained anatase-TiO2 and Mn3O4 was prepared and applied to arsenite photocatalytic oxidization (PCO) under UV irradiation. X-ray diffraction (XRD), scanning electron microscopy with an energy dispersive spectrometer (SEM/EDS), transmission electron microscopy (TEM) and a N-2 adsorption-desorption method were employed to characterize the morphology of the catalyst. Kinetics experiments indicated that Mn3O4 promoted the PCO-adsorption process of arsenite [As(III)] better than either pure anatase-TiO2 under UV irradiation or Ti-Mn-HO without UV exposure. The cause of this phenomenon was investigated using Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Finally, a synergistic effect for the transformation of photoproduct holes and electrons between the TiO2 and Mn3O4 phases is assumed. (C) 2014 Elsevier B.V. All rights reserved.