Electrochemical degradation of the antibiotic metronidazole in aqueous solution by the Ti/SnO2–Sb–Ce anode

Abstract

Metronidazole (MNZ) is an antibiotic pollutant with a high occurrence in the ambient medium. In this study, the anode material Ti/SnO2–Sb–Ce prepared in the lab was employed to investigate the feasibility of the electrochemical process to treat antibiotic in wastewater. The result showed that metronidazole could be effectively removed using Ti/SnO2–Sb–Ce. The degradation efficiency of 88% was obtained under the current density 1.6 mA cm−2, pH=5.6 (not adjusted), electrolyte (Na2SO4) concentration of 0.2 M for electrolysis 2 h. The removal percentage was higher by 17% compared with the control when the bare Ti was applied. Meanwhile, the energy consumption on Ti/SnO2–Sb–Ce was about one-seventh of that on Ti. The characterization of the material was conducted by the thermal field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectrometer (EDS) and cyclic voltammetry (CV). The Ti/SnO2–Sb–Ce anode displayed compact, multi-porous morphology and good redox reversibility. The influencing factors such as current density, pH, concentration of Na2SO4, initial MNZ concentration were studied to obtain main factors and optimum conditions. In addition, a preliminary study on the mechanism of the electro-oxidation was carried out. The results demonstrate that chemisorbed oxygen has a dominant role in MNZ removal.