INFLUENCE OF RELATIVE HUMIDITY ON TiO2/ACF PHOTOCATALYTIC OXIDATION OF TOLUENE: PCO RATE AND INTERMEDIATES ACCUMULATION

Photocatalytic oxidation (PCO) tests have been carried out for toluene adsorbed on the TiO2/ACFcatalyst in an environmental condition controlled chamber. TiO2/ACF catalyst was made andcharacterized by N2 adsorption isotherm for pore structure and scanning electron microscopy (SEM) formorphology respectively. Through exploring the remnant of toluene and the accumulation ofintermediates on the TiO2/ACF catalyst including species, amount and their change processes underdifferent relative humidity (RH), this study aimed to explore the influence of RH on the PCO of tolueneand the role of water vapor in the PCO process: PCO reaction paths and the accumulation ofintermediates on the TiO2/ACF catalyst. Results suggested that: (1) RH affects both the PCO rate andthe PCO reaction path of toluene; (2) although methyl group oxidation is the major path, aromatic ringoxidation, which is not the expected path for the PCO of toluene, is enhanced when the RH increases;(3) apart from the role of hydroxyl radical (OH) arose from water by TiO2, water molecular also directlytakes part in the PCO process. A hypothesis has been proposed.