Photocatalytic removal of NOx using TiO2-coated zeolite

Abstract

Application of photocatalytic nanoparticles has been recently gaining an increased attention as air purifying material for sustainable urban development. The present work reports the photocatalytic removal of gaseous phase nitrogen oxides (NOx) using TiO2–coated zeolite to be applied as a filter media for the urban green infrastructure such as raingardens. The TiO2–coated zeolite was synthesized by simple wet chemistry method and tested in a continuous-flow photo-reactor for its removal efficiency of NOx under different conditions of the weight percentage of TiO2 coated on the zeolite, and gas retention time. The removal efficiency of NOx in general increased as the weight percentage of TiO2 coated on the zeolite increased up to 15-20%. Greater than 90% of NOx was removed at a retention time of one minute using the TiO2–coated zeolite (TiO2 weight percentage = 20%). Overall, TiO2–coated zeolite showed greater efficiency of NOx removal compared to TiO2 powder probably by providing additional reaction sites from the porous structure of zeolite. It was presumed that the degradation of NOx is attributed to both the physical adsorption and photocatalytic oxidation that could simultaneously occur at the catalyst surface.