Effectiveness and Mechanisms of CdS/Porous g-C₃N₄ Heterostructures for Adsorption and Photocatalytic Degradation of Tetracycline Hydrochloride Wastewater in Visible Light

In this study, CdS/porous g-C₃N₄ heterostructures were successfully synthesized via in situ co-precipitation to efficiently degrade tetracycline hydrochloride (TCH) under visible light. The heterostructures, particularly at a 2:1 mass ratio of CdS to porous g-C₃N₄, demonstrated significant improvements in both adsorption and photocatalytic performance. The adsorption and degradation rates increased 4-fold and 9.64-fold, respectively, compared to pure porous g-C₃N₄, with optimal removal rates achieved at a catalyst dosage of 0.2 g/L. Detailed mechanistic studies revealed that photogenerated holes (h⁺) and superoxide radicals (·O₂⁻) were the primary active species driving the degradation process, while hydroxyl radicals (·OH) played a minimal role. The composite material also maintained over 70% degradation efficiency after five cycles, indicating excellent stability. This research presents a promising route for the photocatalytic treatment of wastewater containing persistent organic pollutants, offering practical insights into dosage optimization, reaction kinetics, and mechanistic pathways that enhance performance.