Degradation of ciprofloxacin by the Electrochemical Peroxidation process using stainless steel electrodes

Abstract

The performance of the electrochemical peroxidation (EP) process on the degradation of ciprofloxacin (CIP) was investigated. Different EP process conditions were assessed using an electrolytic cell based on stainless steel electrodes and O2 injection. Parameters, such as H2O2 (25–1000 mg L−1), electrical current density (ECD) (19.71–164.26 A m−2), Fe2+ (0.5 and 2.0 mg L−1), initial solution pH (2.5–9.0), and electrolysis treatments (5–90 min), were varied to determine the best EP performance. Changes in CIP, total organic carbon, and residual H2O2, as well as solution pH, were monitored during the EP performance analysis. Additionally, a set of intermediary by-products and chemical element concentrations was identified and quantified. The toxicity levels of the samples, in terms of the median lethal concentration (LC50), were assessed with Lactuca sativa-based bioassays tests. By setting the ECD, initial H2O2 concentration, initial pH, and electrolysis treatment to 32.85 A m−2, 100 mg L−1, 3, and 30 min, respectively, the optimal EP performance on CIP removal was attained. Conversely, low toxicity levels were observed for shorter electrolytic treatments (<45 min), with LC50 reduced to 40% of their initial values due to a strong drop in intermediate by-products and metals, and 30 min electrolytic treatments being more suitable for yielding efficient EP process performance. Finally, it is recommended that this EP process is considered as a complementary treatment to assist in reducing the negative impacts of the inappropriate discharge of pharmaceuticals in water bodies.