Photocatalytic degradation of antibiotic ciprofloxacin using TiO₂:Ag nanograins

The effective degradation of antibiotics like ciprofloxacin (CPF) has become a critical global concern due to their environmental persistence and associated health risks. This study presents the highly efficient photocatalytic activity of hydrothermally synthesized metal-doped TiO₂ nanograins for the CPF degradation under natural solar light irradiation (∼830 W/m²). Electron microscopy confirmed that all samples consisted of uniformly distributed spherical nanograins, forming well-defined surface microstructures. Among the synthesized metal-doped TiO₂ samples, Ag-doped TiO₂ (TiO₂:Ag) exhibited the highest photocatalytic CPF degradation efficiency, attributed to the coexistence of both Ag⁺ and Ag⁰ species. The incorporation of Ag⁺ dopants reduced the optical bandgap energy of TiO₂:Ag, thereby enhancing light absorption across a broader spectral range. Furthermore, the dopant energy levels introduced by Ag⁺, along with the plasmonically active Ag⁰ neutral atoms, suppressed photocarrier recombination and promoted efficient charge separation. As a result, the TiO₂:Ag nanograins achieved a photocatalytic CPF degradation efficiency of up to 99.25 % within a relatively short reaction time of 120 min. These findings suggest that hydrothermally synthesized spherical TiO₂:Ag nanograins hold significant potential for application in membrane technologies aimed at the effective degradation of antibiotic contaminants such as CPF.