Insight into the mechanism for photocatalytic degradation of ciprofloxacin with CeO2

CeO2 was found to be an efficient photocatalyst for the degradation of ciprofloxacin (CIP) under simulated solar light irradiation. The solution pH significantly affected the degradation efficiency and the optimized pH was in the range of 6-9. The scavenger experiment indicates that the photogenerated hole were the main active species for CIP degradation. The interaction between CIP and CeO2 was investigated by ultraviolet-visible diffuse reflectance, electron paramagnetic resonance and X-ray photoelectron spectra. The results demonstrate the electron transfer from the adsorbed CIP to CeO2. The activated CIP can be readily degraded by the holes. This suggests that the interaction between pollutants and photocatalyst plays an important role in pollutants removal. Finally, the intermediates were identified and a possible pathway for CIP degradation was proposed.