The design of stable and highly efficient photocatalysts had emerged as an economic and promising way for eliminating harmful pharmaceutical pollutants. In this study, a series of Ag2O-modified g-C3N4 composites with different Ag2O amounts (denoted as Ag2O-CNx) were fabricated via a facile reflux condensation methodology. Ofloxacin (OFL) was chosen as a model pollutant to evaluate the degradation efficiency of the photocatalytic system. The optimal photocatalytic activity was achieved with Ag2O-CN1.0, which reached up to 99.1% removal of OFL after 15-min reaction and the pseudo-first-order constant was 0.469 min-1, approximately 42 times higher than that of g-C3N4. Considering the complexity of the actual environment, the important influential factors such as catalyst dosage, initial OFL concentration, solution pH, and natural organic matter on the OFL degradation were systematically investigated. Additionally, Ag2O-CN1.0 showed good stability and recyclability in multiple cycle experiments. The feasible photodegradation mechanism of OFL was proposed with radical scavenger experiments, and the degradation products were determined. Furthermore, the enhanced photocatalytic activity could be ascribed to not only the high photogenerated charge separation efficiency and the surface plasmon resonance effect of metallic Ag, but also the p-n heterojunction formed between Ag2O and g-C3N4. Therefore, Ag2O-CN1.0 was a treatment material possessing great application prospects for eliminating OFL in wastewater.
Keywords: Ag2O; Heterojunction; Mechanism; Ofloxacin; Photocatalysis; g-C3N4.