The Study of Photocatalytic Degradation of Formaldehyde Under the Action of Mass Transfer

Photocatalysis is an emerging and promising technology for indoor air purification, which has the higher reaction rate at the higher pollutant concentration and vice versa, and the toxic intermediate products were produced meantime. However, the concentration of indoor pollutant is usually very low. So how to improve the photocatalytic reaction rates in indoor contaminant levels in building and to eliminate the intermediate toxic products are the keys of commercialization of this technology. This paper immobilized the TiO₂ on the active carbon and analyzed the effect of mass transfer due to the absorption of AC on the photocatalytic reaction rate. The experimental results shown that the photocatalytic reaction rate was improved for the local concentration of contaminants on the surface photocatalyst TiO₂ was enhanced by adsorbent activated carbon. With the increase of air stream velocity, the photocatalytic reaction switched from mass transfer control process to photocatalytic reaction control process. The switch point was advanced for the absorption of AC comparing with TiO₂ immobilized on the surface of glass. The indoor formaldehyde with low level concentration can be decomposed to the range of indoor air quality standards by the TiO₂/AC filter.