Sonocatalytic performance of ZnO/graphene/TiO2 nanocomposite for degradation of dye pollutants (methylene blue, texbrite BAC-L, texbrite BBU-L and texbrite NFW-L) under ultrasonic irradiation

Abstract

ZnO/graphene/TiO2 (ZGT) was synthesized by a simple solvothermal method. The as-obtained samples were characterized by X-ray diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy. The band gap energy of the as-synthesized catalysts were performed by UV–vis diffuse reflectance spectroscopy. The sonocatalytic activities of catalysts were tested by the oxidation of methylene blue, texbrite BAC-L, texbrite BBU-L and texbrite NFW-L under ultrasonic irradiation, and compared with ZnO/graphene (ZG), graphene, ZnO and TiO2, respectively. The results indicated ZGT displayed higher ultrasound activated sonocatalytic activity than other catalysts. The optimum conditions including irradiation time, pH, dye concentration, catalyst dosage and ultrasonic intensity were 120 min, 9, 20 mg/L, 1.00 g/L and 40%, respectively. The ZGT showed the higher enhanced sonocatalytic degradation of MB than other dyes. It is therefore evident that the ZGT can be applied as a highly effective sonocatalyst for dye pollutants. Moreover, a possible sonocatalytic degradation mechanism is discussed.