Fibrous silica induced narrow band gap TiO2 catalyst for enhanced visible light-driven photodegradation of methylene blue

Fibrous silica titania (FST) was synthesized via hydrothermal method and evaluated on photodegradation of methylene blue (MB). The catalyst was characterized using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) and N2 adsorption-desorption. The photocatalytic activity was performed under different reaction condition namely pH, catalyst dosage and MB initial concentration. FST demonstrated higher performance (99.9%) for 10 mg L-1 of MB initial concentration than titania (TiO2) using 0.25 g L-1 of catalyst dosage at pH 5 for 2 h. The superior performance towards photodegradation of MB under visible light demonstrated by synthesized FST was due to unique morphology of fibrous, high surface area, narrow band gap and more active site (Si-O-Ti). Kinetics study indicated that the photodegradation of MB was well fitted with pseudo-first order Langmuir-Hinshelwood model and adsorption was the rate-limiting step. The FST maintained its photocatalytic activities for up to five cycles reaction with slightly catalyst deactivation, suggesting that the FST is suitable to be implied in the photocatalytic reaction