Catalytic Degradation of Ciprofloxacin in Aqueous Solution by Peroxymonosulfate Activated with a Magnetic CuFeO@Biochar Composite

A magnetic copper ferrite and biochar composite (CuFeO@BC) catalyst was prepared by an improved sol-gel calcination method and initially used for the removal of antibiotics ciprofloxacin (CIP) by activated peroxymonosulfate (PMS). Using CuFeO@BC as the activator, 97.8% CIP removal efficiency could be achieved in 30 min. After a continuous degradation cycle, CuFeO@BC catalyst still exhibited great stability and repeatability and could also be quickly recovered by an external magnetic field. Meanwhile, the CuFeO@BC/PMS system presented good stability for metal ion leaching, which was far less than the leaching of metal ions in the CuFeO/PMS system. Moreover, the effects of various influencing factors, such as initial solution pH, activator loading, PMS dosage, reaction temperature, humic acid (HA), and the inorganic anions were explored. The quenching experiments and the electron paramagnetic resonance (EPR) analysis manifested that hydroxyl radical (•OH), sulfate radical (SO), superoxide radical (O), and singlet oxygen (O) were generated in the CuFeO@BC/PMS system, while O and O are mainly involved in the degradation process. The synergistic effect between CuFeO and BC enhanced the structural stability and electrical conductivity of the material, which promoted the bonding between the catalyst and PMS, resulting in the enhanced catalytic activity of CuFeO@BC. This indicates that CuFeO@BC activating PMS is a promising remediation technique for CIP-contaminated water.