Photodegradation of aromatic pollutants in water over TiO2 supported on molecular sieves

TiO2 was supported on porous materials, including NaY and Na-mordenite zeolites, as well as mesoporous MCM-41 molecular sieve by using impregnation method with organic solvents. The products were characterized with powder XRD, BET surface area measurement, TEM, IR, Raman and UV–VIS spectroscopies. The supported TiO2 was crystallized in anatase structure and the intensity of its X-ray diffraction peaks increased with TiO2 loading. In contrast, the total surface area of the supported catalyst decreased with TiO2 loading. A blue shift of the absorption edge in the UV–VIS spectra was observed when TiO2 particle size decreased, a phenomenon corresponding to the particle size quantization effect. For photodegradation of aromatic pollutants in water, the activity was found strongly influenced by the chemical nature of the pollutant and the surface property of the support. For volatile pollutants such as benzene and chlorobenzenes, molecular sieve supports facilitated the photodegradation reaction by providing high surface area for adsorption. Moreover, there is an optimal loading of TiO2 to achieve the best photocatalytic activity on various supports. The supports in contrast did not show positive contribution in degradation of hydrophilic pollutants such as phenol.