Enhanced electrochemical oxidation of oxytetracycline on oxygen vacancy-rich MnO@N-doped C anode: Transformation pathway and toxicity assessment

Abstract

Oxytetracycline (OTC) is a widely used antibiotic found in the environmental systems that may threaten human health. In this study, the degradation of OTC was investigated using an electrochemical oxidation system with oxygen vacancy-rich MnO@N-doped carbon (ov-MnO@NC) electrodes. It is found that nearly 95% of OTC could be degraded within 60 min using the ov-MnO@NC anode. The effects of electrolytes, OTC concentration, ov-MnO@NC dosage, current density and solution pH on OTC degradation were examined. Radical quenching tests and EPR spectra reveal that 1O2, •O2– and •OH all contributed to OTC elimination. A total of 11 transformation products were identified by LC-MS during electrochemical degradation. To assess toxicity, T.E.S.T calculations were performed for each of the transformation compounds. In the flow cytometry test, the reaction solution was tested for cytotoxicity when mixed with transformation products and other reactants at different reaction times. Furthermore, the removal efficiency of OTC at ov-MnO@NC anode maintained over 85% after recycling for four times, demonstrating the considerable durability. Overall, this study provides new insight into the development of metal oxide-based anodes with tuned oxygen vacancies, as well as comprehension of the transformation pathway and potential toxicity of the parent pollutants.