Enhanced Simultaneous Photocatalytic Removal of SO2 and CO2 Using Powder and Coated Zeolites-Supported TiO2 Under Concentrated Sunlight Irradiation

Abstract

Single-step process for simultaneous removal of gaseous pollutants is more advantageous than multi-steps one. In this study, the efficiency of a novel synthetic zeolite (Ze) prepared from stone cutting sludge and a natural zeolite (clinoptilolite, Cp) as the supports of TiO2 photocatalyst were examined for the separate and simultaneous removal of SO2 and CO2 under solar irradiation using a parabolic trough collector (PTC). The composites exhibited a higher efficiency than raw zeolites and TiO2 for the removal of both gases. The maximum removal of SO2 by TiO2-Ze and TiO2-Cp under sunlight was 41.9 % and 56.2 % that enhanced to 53.4 % and 78.8 %, respectively in the presence of CO2. Correspondingly, it was 61.8 % and 68.7 % for single CO2 removal that increased to 74.2 % and 79.0 % in the binary gas stream. This behavior could be due to the enhanced simultaneous SO2 oxidation and CO2 reduction. The performance of coated composite for SO2 was higher than of powder one (54.3% vs. 41.9%) and for CO2 removal was almost close together (58.9% vs. 61.2%). This work promises the application of photocatalytic co-removal of SO2 and CO2 by using synthetic and natural zeolite under solar irradiation.