Visible Light Photocatalytic Ozonation of Oxalic Acid by MnOx-g-C3N4 Composite

Abstract

MnOx-g-C3N4 composite is prepared and characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet–visible (UV-vis) spectroscopy, and surface area analysis. The prepared MnOx-g-C3N4 composite is used as a catalyst to examine the performance of visible light photocatalytic ozonation. The results prove that the MnOx-g-C3N4 composite has good catalytic activity for oxalic acid removal during the photocatalytic ozonation process. Compared with bare g-C3N4, the 1∶2 MnOx-g-C3N4 increases the removal of oxalic acid from 24.8 to 91.2% in 6 min. The manganese combined in the g-C3N4 mainly exists in the form of oxide with valences of III and IV. The oxalic acid removal is partly through the oxidation by reactive oxygen species such as O2−· and partly through the charge transfer between different valences of manganese species, whereas OH· accounts for only a negligible part of the oxalic acid removal.