Degradation of ciprofloxacin by UV/S2O82− process in a large photoreactor

• An effective degradation of ciprofloxacin using UV/S2O82− process was achieved.
• SO4− was a predominant radical in UV/S2O82− process.
• This study provides a novel treatment of wastewater contaminated with ciprofloxacin.

This study evaluates the effectiveness of the UV/S2O82− process in the degradation of ciprofloxacin in aqueous solutions without adjusting their pH using a large photoreactor. The effect of Na2S2O8 concentration on the efficiency of degradation of ciprofloxacin was examined. A larger Na2S2O8 concentration was associated with a higher efficiency of degradation of ciprofloxacin. However, excessive Na2S2O8 concentration inhibited the degradation of ciprofloxacin. UV/S2O82− process exhibited pseudo-first-order kinetics. SO4− was detected by performing quenching studies using specific alcohols, revealing that SO4− was found to be the predominant radical. Additionally, the presence of HCO3− inhibited the degradation of ciprofloxacin at a high concentration. An efficiency of degradation of ciprofloxacin was 95% within 30 min using an Na2S2O8 concentration of 1.92 g/L in the absence of inorganic anions. Comparison of both UV/S2O82− and heat/S2O82− processes demonstrates that the degradation of ciprofloxacin at ambient temperature can be enhanced by the UV/S2O82− process, leading to a reduced operating time. These promising results obviously reveal the potential of the UV/S2O82− process application for the effective degradation of ciprofloxacin in aqueous solutions without adjusting the pH.