Mechanistic insight into Photocatalytic mineralization of dyes using metal oxide- Parametric and kinetic study

Abstract In the present study, the photocatalytic degradation of Rhodamine-B dye was carried out. bismuth oxide (α − Bi₂O₃) and copper oxide (CuO) photo catalyst was prepared for the degradation analysis. During the photocatalysis of Rhodamine-B degradation, the order of removal with different semiconductors was followed in the following order: α − Bi₂O₃ > CuO. The effect of operating parameters, including solution pH (3–8), catalysts dose (0.2–1.5 g/L), temperature change (5–20 oC), and initial Rhodamine B dye concentration (10–25 mg/L), were systematically examined using α − Bi₂O₃ photocatalyst under UV-light irradiation. The Rhodamine-B dyes showed the best removal efficiency of 97% at operating conditions of natural pH = 7.0, catalyst dose = 1.5 g/L, temperature = 20 ◦C, and Rh-B concentration = 10 mg/L under control conditions. As − prepared semiconductor materials such as α − Bi₂O₃ and CuO were characterized by using many techniques like scanning electron microscope, energy dispersive X-ray, Fourier Transmission Infrared spectroscopy, and X − ray diffraction technique. A degradation pathway was also suggested by the identification of reaction intermediates. The reusability test analysis of bismuth oxide confirmed that photocatalysts can be separated after degradation and reused many times, and there were no other changes in structure and morphologies. This study confirmed the simple synthesis approach of semiconductor materials and their uses for the treatment of Rhodamine-B dye.