Enhanced Mechanism of Electrochemical Oxidation of Antibiotic Norfloxacin using a Ti/SnO2-Sb2O3/α,β-Co-PbO2 Electrode

This study focused on the enhanced mechanism of electrochemical degradation of antibiotic norfloxacin (NOR) using a self-made Ti/SnO2-Sb2O3/alpha,beta-Co-PbO2 electrode. The electrode characterization, reaction mechanism, degradation performance, and toxicity assessment were studied. In contrast to the conventional Ti/SnO2-Sb2O3/alpha,beta-PbO2 electrode, our prepared Co-doped PbO2 electrode showed the characteristics of more compact surface, smaller crystal size, higher oxygen evolution potential (OEP) and an increased yield of center dot OH concentration. The application of Co-doped PbO2 electrode for the electrochemical oxidation of NOR was systematically analyzed. The optimal operating parameters were found to be Na2SO4 concentration of 0.1 mol L-1, initial NOR concentration of 50 mg L-1, initial pH of 5 and current density of 20 mA cm(-2). Under these conditions, NOR, chemical oxygen demand (COD) and total organic carbon (TOC) removals reached 85.29%, 43.65% and 41.89% after 60 min of electrolysis, respectively. Through the intermediates detected during the electrochemical treatment process, a reaction pathway involving decarboxylation, defluorination and piperazine ring-opening was proposed. Finally, the toxicity assessment of the treated NOR solution towards Vibrio fischeri rapidly fell to non-toxicity and even reached to negative values after 50 min of electrolysis, indicating that electrochemical oxidation of NOR is an effective approach to reduce its toxicity to environmental ecosystem. (c) 2021 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.