The Development of a New Bi12ZnO20/AgI Heterosystem for the Degradation of Dye-Contaminated Water by Photocatalysis Under Solar Irradiation: Synthesis, Characterization and Kinetics

This study explores the efficiency of heterogeneous photocatalysis in wastewater treatment, which is recognized for inducing significant rates of degradation and mineralization of various contaminants, including dyes. The study focuses on the development of an innovative composite via a combination of the sillenite type semiconductor Bi12ZnO20 and the halide-type semiconductor AgI. Both semiconductors were synthesized via co-precipitation, and their phases were identified using X-ray diffraction and characterized by scanning electron microscopy, Raman spectroscopy, Brunauer–Emmett–Teller analysis for specific surface area, UV–Visible diffuse reflectance spectroscopy, and the point of zero charge. The evaluation of the photocatalytic activity of the Bi12ZnO20/AgI heterosystem was carried out by monitoring the degradation process of Basic Blue 41 (BB41) under solar irradiation conditions. The results of this study revealed that the Bi12ZnO20/AgI heterosystem achieved the efficient degradation of BB41, with a removal rate of 98% after 150 min of treatment. The mineralization study showed that the TOC value decreased from 19.89 mg L−1 to 6.87 mg L−1, indicating that a significant portion of BB41 was mineralized. Via kinetic research, it was established that the degradation process followed a pseudo-first-order mechanism. Furthermore, recycling tests showed that the synthesized heterostructures maintained good structural stability and acceptable reusability over several cycles. These findings highlight the potential of heterogeneous photocatalysis as a promising approach to addressing environmental challenges associated with azo dyes.