Abstract
Toluene and xylene are typical volatile organic compounds (VOCs) found in contaminated sites. The photodegradation of toluene and xylene in a photocatalytic fluidized bed system with TiO2/SiO2 have been investigated. TiO2 film was prepared by the sol–gel method and coated on the silica–gel particles. The UV lamp is installed in the center of the reactor, and the toluene and xylene are analyzed by GC/FID/MSD. The effects of different photocatalyst sizes, superficial gas velocity, and sole UV light on the photodegradation of toluene and xylene (m,p-xylene and o-xylene) have been examined in the fluidized bed reactor. At steady-state, operation about 80.1, 99.8, and 99.9% of removal efficiencies have been achieved for toluene, m,p-xylene and o-xylene, respectively, in the optimal conditions (2.0 Umf of superficial gas velocity and 1.43 of height/diameter ratio). Benzene, acetaldehyde, formic acid, and malonic acid were identified as reaction intermediates of toluene. It has been proposed that toluene was oxidized by OH radicals and sequentially led to formation of benzene, acetaldehyde, formic acid, and malonic acid. In addition, benzene, toluene, acetaldehyde, formic acid, and malonic acid were identified as photodegradation intermediates of xylene. It has been proposed that xylene was oxidized by OH radicals and sequentially led to formation of benzene, acetaldehyde, formic acid and malonic acid. In this study, the development of an effective decomposition system to utilize solar energy and TiO2/SiO2 photocatalyst has been investigated for the removal of gaseous contaminants.
