Gas-phase photocatalytic degradation of acetone and toluene, and their mixture in the presence of ozone in continuous multi-section reactor as possible air post-treatment for exhaust from pulsed corona discharge

Abstract

Photocatalytic oxidation (PCO) of acetone and toluene, and their mixture was performed using a unique multi-section photocatalytic apparatus with adjustable catalytic surface area. Both volatile organic compounds (VOCs) were treated under the UVA irradiation and over the photocatalytic surface of P25 TiO2 in the presence and absence of ozone at humidity levels of 6 and 40%. The presence of ozone along with the VOCs in the air simulated the exhaust from pulsed corona discharge treatment. The degradation of ozone as a toxic air pollutant in addition to the study of its effect on the PCO process performance was also monitored. The contribution of ozone to the oxidation of acetone and toluene was not observed at any inlet concentration of a single present VOC, except for higher concentration (60 ppm) of toluene as well as for mixtures, where higher conversions of acetone and toluene were obtained. The presence of ozone in the air hindered the deactivation of the catalyst by toluene oxidation by-products. Changes in relative humidity demonstrated no major effect on the oxidation of acetone and toluene either in the presence or absence of ozone, while higher humidity slightly inhibited the oxidation of VOCs in the mixture. The only PCO products observed in gas-phase were water vapour, CO2, and CO. The multi-section configuration of the reactor allowed obtaining prompt PCO results, characterising the degree of recalcitrance of VOCs under consideration as well as essential operating conditions including photocatalytic surface.