AgNO_3-lnduced Photocatalytic Degradation of Odorous Methyl Mercaptan in Gaseous Phase: Mechanism of Chemisorption and Photocatalytic Reaction

摘要

In this study, AgNO_3 films prepared by a simple dip-coating method were used to remove gaseous methyl mercaptan (CH_3SH) for odor control. The AgNO_3 films were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive X-ray spectrometry(SEM/EDX), and X-ray photoelectron spectroscopy (XPS) before and after the reaction, and as-obtained products were identified by means of gas chromatog-raphy/mass spectrometry (GC/MS) and ion chromatography. The experiments demonstrated that the AgNO_3 film can induce a quick chemisorption of gaseous CH3SH to form AgSCH_3 and other intermediate products such as a-Ag_2S, Ag_4S_2, and AgSH on its surface. Under UVA illumination, these sulfur products can be photocatalytically oxidized to AgSO_3CH_3 and Ag_2SO_4. Then AgSO_3CH_3 and Ag_2SO_4 will continue the chemisorption of gaseous CH_3SH, similar to AgNO_3, to form AgSCH_3 again and release two final products, HSO_3CH_3 and H_2SO_4. Hence it is a AgNO_3-induced photocatalytic reaction for odorous CH_3SH degradation in gaseous phase. This fundamental research about the mechanism of chemisorption and photocatalytic reaction provides essential knowledge with potential to further develop a new process for gaseous CH_3SH degradation in odor control.