Studies on ZnO/g-C₃N₄ Heterojunction Photocatalyst for RhB Degradation Under Vis-Light in a MNB-Agitated Pilot Reactor

A pilot scale micro-nano bubble (MNB) enhanced photocatalytic degradation system was developed by using heterojunction ZnO/g-C₃N₄ composite as the visible light catalyst. The composite ZnO/g-C₃N₄ was prepared with a thermal polymerization procedure and the best catalytic performance of the ZnO/g-C₃N₄ composite (ZC6.2%) was obtained when the 6.2% zinc acetate was used in the preparation. The structure of the composite was confirmed by X-ray photoelectron spectroscopy, XPS, SEM, FT-IR, and BET techniques. Based on the photocatalyst ZC6.2%, a pilot-scale micro-nano bubble-enhanced photocatalytic degradation system was developed and its effectiveness was manifested by the rapid degradation of RhB at a kinetic constant of 0.01302 min⁻¹ under visible light irradiation, which is 3.1 times greater than that obtained in the absence of MNB. The enhancement in degradation rate can be attributed to the increase in dissolved oxygen content and reduced catalyst sedimentation in the MNB system.