Facile synthesis of reusable Ag/TiO₂ composites for efficient removal of antibiotic oxytetracycline under UV and solar light irradiation

Backgrounds: In this work, Ag-doped TiO₂ nanomaterials (TiAgx, where x denotes the weight percentage of Ag) were prepared using a facile one-step sol-gel technique. The combination of Ag with TiO₂ promises to enhance the lifetime of photogenerated electron-hole pairs and widen the photocatalytic activity in the visible light region, leading to improved photocatalytic activity. Methods: The synthesized materials were characterized using different analyses and afterwards applied as photocatalysts to degrade oxytetracycline (OTC) in aqueous solution under ultraviolet (UV) and solar light illumination. Significant findings: The highest photocatalysis was achieved for TiAg2 with 99.6% OTC removal after 120-min UV irradiation. Moreover, the best OTC removal under solar light irradiation was gotten for TiAg5, of which 94.1% of OTC was removed after 180 min. Reactive species of ^∙O₂⁻ radicals were presented as the dominant agents in OTC oxidization; meanwhile, ^∙OH and h⁺ contributed to the photodegradation process. The mineralization efficiency of OTC using TiAg2 reached 59.6% after 240-min UV irradiation. Furthermore, the OTC removal of TiAg2 by photocatalysis still maintained over 97% after 5 cycles.