Preparation of MWCNTs-TiO₂ photocatalysts in thin liquid films under continuous flow conditions and their photocatalytic activities for quinoline degradation

MWCNTs-TiO₂ photocatalysts were formed within a very thin liquid film generated on a continuous flow spinning disc surface, in which two jets located in the center of the disc were fed with a suspension of HNO₃-purified MWCNTs (0.5 g) in a mixture of tetra-n-butyl titanate (40 mL), ethanol (100 mL) and acetic acid (10 mL), and a solution of ethanol (30 mL), acetic acid (20 mL) and water (8 mL). The collected products were gelled at room temperature for 24 h, dried at 80℃ for 4 h and calcined at 350, 400 and 450℃ for 4 h. The samples were characterized by XRD, FT-IR, SEM, TEM and UV-vis DRS. The photocatalytic properties were evaluated by the degradation of quinoline under visible light irradiation. Results showed that TiO₂ nanoparticles of the photocatalyst were smaller (5-10 nm) than when there were no MWCNTs present (10-15 nm), and were well distributed between the MWCNTs. MWCNTs promoted the visible light absorption of the samples. The photocatalyst calcined at 450℃ showed the strongest visible light absorption and best catalytic activity, andproduced a quinoline degradation of 86.6% after 180 min.