Preparation of Ag₂O/Ag₂CO₃/MWNTs composite photocatalysts for enhancement of ciprofloxacin degradation

Graphical abstract: - Highlights: • Ag₂O/Ag₂CO₃/MWNTs were prepared by calcination of the obtained precipitate. • The holes were main contributor for the degradation processes of ciprofloxacin. • The synergistic effect enhanced the activity and stability of composites. - Abstract: The Ag₂O/Ag₂CO₃/multi-walled carbon nanotube (MWNTs) composite photocatalysts were prepared by calcination of the obtained precipitate. The structures and morphology of as-prepared composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS). The Ag₂O/Ag₂CO₃/MWNTs composite photocatalysts exhibit higher degradation rate of ciprofloxacin (CIP) than the pure Ag₂CO₃, Ag₂O/Ag₂CO₃ and Ag₂CO₃/MWNTs under visible light irradiation. The amount of loaded Ag₂CO₃ onto MWNTs and calcined time for Ag₂CO₃/MWNTs were systematically investigated, and the optimal amount of loaded Ag₂CO₃ and calcined time of Ag₂CO₃/MWNTs are 150 wt% and 10 min, respectively. The highest photocatalytic degradation rate of CIP could reach 76% under optimal conditions. The active species trapping experiments were also analyzed, the results show that the holes are main contributor for the degradation processes of CIP, furthermore the electrons, ·O₂⁻ and ·OH are also crucially influenced the photocatalytic degradation processes of CIP. The possible photocatalytic processes of CIP with Ag₂O/Ag₂CO₃/MWNTs composite photocatalyst are also proposed.