Performance and mechanism of ciprofloxacin removal in water via catalytic ozonation using Fe-Mg/PDA@Al2O3

Abstract

There is currently an urgent need to develop technologies for ciprofloxacin (CIP) removal in wastewater owing to its widespread usage in human and animal populations and subsequent transmission into surface water. Aluminum (Al₂O₃) is an excellent carrier, and polydopamine (PDA) is a surface modifier with a high nitrogen content and strong adhesion, and may represent a potential tool for CIP removal in wastewater. However, minimal research has been conducted on using PDA to improve the interactions between carrier and active components and thus improve the ozone utilization efficiency as well as catalytic activity and stability in CIP removal schemes. To address this research gap, study successfully prepared Fe-Mg/PDA@Al₂O₃ composite materials for the catalytic ozone removal of CIP from water. The influencing factors and degradation mechanisms of the catalytic ozone treatment of ciprofloxacin wastewater and possible antibiotic degradation pathways were proposed. The removal of CIP was mainly carried out through indirect oxidation dominated by hydroxyl radicals (•OH), in addition to catalyst adsorption and direct ozone oxidation, and the oxidative degradation of CIP conformed to a pseudo-first-order reaction kinetic model. Under ideal operating conditions, the CIP degradation efficiency of Fe-Mg/PDA@Al₂O₃/O₃ system reached 91.35 % after 15 min. The mineralization efficiency of Fe-Mg/PDA@Al₂O₃/O₃ system was significantly higher than that of the single-ozone system. After four repeated uses of Fe-Mg/PDA@Al₂O₃, the CIP degradation efficiency remained stable, and the metal ion leaching concentration was within the limit, indicating that Fe-Mg/PDA@Al₂O₃ demonstrated a high catalytic performance and stability.