Microwave-assisted preparation of TiO ₂/activated carbon composite photocatalyst for removal of methanol in humid air streams

TiO ₂/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 TiO ₂ 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 TiO ₂ 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.