Characteristics And Mechanisms Of Synthetic Photocatalysis Of Gaseous Toluene By TiO₂-Organobentonite

Indoor environment is relatively occlusive with intensely using of products containing volatized organic compounds (VOCs) and it has been seriously polluted by the VOCs. Since people spend most of their time in the house, the polluted air would cause illnesses like SBS (Sick Building Syndrome). Adsorption or photocatalysis method has been commonly adopted to control VOCs. Yet these two methods have their inherent shortcomings. Sorbent used faces reuse/treatment problem while photocatalyst performs poorly in contaminated atmosphere of dilute VOCs. The combination of adsorption and photocatalysis could be a promising and beneficial advanced oxidation processes (AOP) for purification of contaminated air.In this study, homogeneous and efficient organobentonite-TiO₂ composite photocatalyst was prepared by mechanical grinding. The influence of preparing method on photocatalysis was discussed, then the ideal proportioning of sorbent and catalysis was reached. Different organobentonites, with long/short alkyl chain length or high/low organic cation exchange content or organic cation/anion, were seriously studied. As the number of alkyl increased, the adsorption property of organobentonite mended, so the adsorption-photocatalysis process was promoted. But when the alkyl number exceeded 12, the diffusion process was halfway blocked by the formation of partition phase which induced the decrease in reaction activity. The hydrophobic surface of organobentonite made composite catalysis an effective material in atmosphere of relatively high RH. The influence of content of organic modification was alike the alkyl chain length effect, as the degree of organic modification increased, the performance of composite catalyst ameliorated then decreased, the formation of partition phase turned to block the adsorption-diffusion path again. Anion-bentonite of low modification content showed ideal result in degrading toluene. This study figured out the feasibility of mechanical grinding method in preparing composite catalyst, the relation between the property of organobentonite and the performance of composite catalyst in principium. This work may provide theoretical base for the application of adsorption-photocatalysis in indoor air purification.