Toluene removal under humid conditions by synergistic adsorption-photocatalysis using nano TiO2 supported on ZSM-5 synthesized from rice-husk without structure-directing agent

Zeolite ZSM-5 has been successfully produced from rice-husk by a low-cost process. Without expensive and toxic organic structure-directing agent, zeolite ZSM-5 can be obtained at temperature of 160 degrees C, in 96 h at pH 11 by a seed-assisted hydrothermal method. Using this zeolite as a support, nano-sized TiO2/ZSM-5 photocatalysts were obtained by sol-gel method. The materials were characterized the structural and morphological properties. They were also examined activity for photocatalytic removal of toluene in humid condition. Synergistic adsorption photocatalysis using TiO2/ZSM-5 can remove about 70% toluene at its concentration of 2400 ppm, water vapor content of 18.5 mg/L (relative humidity 60% at 25 degrees C), and gas hourly space velocity (GHSV) of 5760 h(-1). The toluene removal efficiency by the nano-sized TiO2/ZSM-5 photocatalyst was significantly higher than that by a commercial photocatalyst TiO2. The toluene removal in humid condition was remarkably enhanced on TiO2/ZSM-5 due to combination adsorption (on ZSM-5)-photocatalysis (on TiO2).