Microwave-assisted preparation of TiO2/activated carbon composite photocatalyst for removal of methanol in humid air streams

TiO2/activated carbon composite photocatalyst was prepared by a microwave-assisted impregnation method and was employed for the removal of methanol from humid air streams. A commercial microwave oven (800 W) was used as the microwave source. Under 2450 MHz microwave irradiation, titanium tetra-isopropoxide (TTIP) was quickly hydrolyzed and anatase TiO2 was formed in a short time (<20 min). As a result of the volumetric heating and selective heating of the microwave, the solvent and byproducts were quickly removed which reduced energy consumption and processing time. The formed submicrometer TiO2 particles mainly deposited on the external surface of carbon. In a packed bed reactor with an empty bed contact time of 0.35 s, the prepared materials maintained a 40% removal efficiency at an inlet methanol concentration of 39 ppm. When the TTIP conversion was complete, neither the irradiation time nor the water/TTIP ratio could further change the photocatalytic activity.