Efficient photo-, sono-, and sonophoto-fenton-like degradation of the organic pollutant methylene blue using a BiFeO₃/graphene composite

In this study, we investigated the degradation of the organic pollutant methylene blue (MB) using photo-, sono-, and sonophoto-fenton processes under visible light, ultrasonic irradiation, and a combination of the two, respectively, in the presence of an iron-containing perovskite catalyst BiFeO₃/graphene composite. The sample structure was characterized using X-ray diffraction; thermal analyses were performed using thermogravimetric analysis and differential thermal analysis; and the BiFeO₃/graphene composite was prepared using a hydrothermal method. We observed better MB degradation via the BiFeO₃/graphene composite using the sonophoto-fenton method relative to either the photo- or sono-fenton methods, with increased MB degradation occurring through the synergistic effects of both the photo- and sono-fenton techniques. Furthermore, addition of a chelating agent, such as ascorbic acid, to the photo- and sono-fenton reactions enhanced MB degradation.