Photocatalytic degradation of ciprofloxacin by a novel visible light activated Ag2O-AgI/TiO2 nanocomposite: Activity, kinetic, mineralization and continuous-flow stability test

Abstract

ABSTRACT This study examined effective elimination of Ciprofloxacin (CIP) from an aqueous flow using Ag2O-AgI/TiO2 nanocomposite stabilised on glass under visible light radiation. The synthesised catalyst was characterised using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray (EDX), and Ultraviolet–visible spectroscopy (UV-VIS) methods. Some important parameters including initial pH, CIP concentration, and reaction kinetics were investigated. Stability of the catalyst under continuous operating conditions was measured in an aqueous solution and real wastewater medium. Modification of TiO2 with AgI and Ag2O resulted in its improved photocatalytic properties in the presence of visible light. CIP concentration and pH of the solution affected the process efficiency. Specifically, 92.8% of CIP with initial concentration of 10 mg/L and pH 9.5 was removed using Ag2O-AgI/TiO2 nanocomposite within 120 min, and the resulting effluent degradability increased. Minor leakage of silver and titanium as well as maintained photocatalytic activity of the synthesised catalyst within six days of continuous CIP treatment showed high stability of the catalyst. The photocatalytic degradation process using Ag2O-AgI/TiO2 nanocomposite under visible light radiation can be a suitable method for removing resistant organic compounds due to high efficiency and high stability during the CIP removal process.