ZnO on rice husk: a sustainable photocatalyst for urban air purification

Abstract

A cost-effective and sustainable De-NOx photocatalyst is prepared usingzinc acetate and rice husk. ZnO@SiO2samples are obtained from the calcination of a homogenised precursor mixture at 600 C. ZnO nanoparticles (70 –180 nm) grow aggregated in spheres and well dispersed (40 –53 m2g-1surface area) covering the silicon skeleton. The corresponding band gap for ZnO@SiO2photocatalysts was estimated at3.1 –3.2 eV. When the samples are irradiated by sunlight in anitrogen oxide atmosphere the NO HNO2NO2NO3-photochemical oxidation takes place. In comparison to unsupported ZnO and TiO2-P25, ZnO@SiO2samples exhibit high NOXremoval values (70 %) and outstanding selectivity (> 90%), the latter related to the sensitivity of zinc oxide towards NO2gas. This new photocatalyst is easily recyclable and reusable