Vacuum ultraviolet-irradiated photocatalysis: advanced process for toluene abatement

Abstract

Photocatalysis with irradiation of a vacuum ultraviolet (VUV) lamp (VUV-PCO) was used to remove toluene in air. Two parallel reactions with irradiation of a 254nm lamp (254nm-PCO) and without TiO 2 (i.e., VUV photolysis) were conducted for comparison. The influencing factors of relative humidity, initial toluene concentration, and air flow rate were investigated. The results showed that VUV-PCO achieved much higher toluene removal efficiency and better PCO durability than 254nm-PCO under different operating conditions. 82.3% toluene conversion was obtained with 1.8ppm outlet O 3 concentration in the former, but only 14.5% with 30ppm outlet concentration of O 3 was obtained in the latter under the conditions of 1% humidity, 50ppm initial toluene concentration, and 1 L/min flow rate. Energetic photons from the VUV lamp could efficiently destruct toluene directly. O 3 formed from VUV irradiation of O 2 enhanced the toluene abatement by catalytic ozonation and inhibited the recombination of electron/hole pairs and deactivation of the photocatalyst. VUV-PCO could simultaneously overcome the limitations of the conventional PCO process. It is a promising technology for toluene abatement. © 2011 American Society of Civil Engineers.