Photocatalytic degradation of tetracycline hydrochloride by ZnO/TiO2 composite photocatalyst

Semiconductor photocatalytic technology is widely used in the degradation of antibiotic pollutants due to its easy operation, low energy consumption, and no secondary pollution. In this study, ZnO/TiO2 composite photocatalysts with the different sturcture and the different content were constructed using layered double hydroxide as precursor. The structure and physicochemical properties of the photocatalysts were characterized by the different characterization technologyies, such as XRD, SEM, FT-IR, LRS, UV–vis DRS, N2 adsorption–desorption isotherm, XPS, UPS, EIS, and so on. The photocatalytic degradation performance and mechanism for tetracycline hydrochloride were studied. The results show that the light response performances of the as-prepared samples are improved by a calcination process. The surface active sites are increased and the transport and separation efficiency of photogenerated electrons and holes are improved. Among them, ZnO/TiO2-200 has the fastest degradation rate and the best catalytic activity, and its maximum apparent rate constant is 0.9576 × 10–3 L·mg−1·min−1. The analysis of photocatalytic mechanism and energy band structure shows that the main active substance of the system is ·O2−, and the photocatalytic degradation process follows the type II heterojunction photocatalytic reaction mechanism. This study provides ideas for the design and construction of high-efficiency photocatalytic composites, and provides a reference for the photocatalytic degradation of other organic pollutants.