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 °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 °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).