Solid-phase photocatalytic degradation of polystyrene with modified nano-TiO2 catalyst

A novel photodegradable polystyrene-grafted-TiO2 (PS-g-TiO2) nanocomposite was prepared by embedding the grafted-TiO2 into the commercial polystyrene. Solid-phase photocatalytic degradation of the PS-g-TiO2 nanocomposite was carried out in ambient air at room temperature under ultraviolet lamp and/or sunlight irradiation. The properties of composite film were compared with those of the pure PS film by methods such as weight loss measurement, scanning electron microscope (SEM), gel permeation chromatogram (GPC), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, and UV-vis spectroscopy. The results show that the photo-induced degradation of PS-g-TiO2 composite film is significantly higher than that of pure PS film. The weight loss of composite film reached 31.9%, average molecular weight (Mw) of composite film decreased by 53.1%, and the number average molecular weight (Mn) decreased by 73.2% after 396 h of UV-light irradiation. FT-IR analysis and weight loss indicated that the benzene rings in PS-matrix of composite film were cleaved during UV-light irradiation. The photocatalytic degradation mechanism of the films is briefly discussed.