Agradecimentos: The authors are sincerely grateful to the Brazilian research funding agencies, including the Brazilian National Council for Scientific and Technological Development - CNPq (grants no. 465571/2014-0, 302874/2017-8, and 427452/2018-0), São Paulo Research Foundation (FAPESP – grants #2011/14314-1, #2014/50945-4, #2013/02762-5, #2019/00239-0, #2021/12053-8 and #2017/10118-0) and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES – Finance Code 001) for the financial support granted in the course of this research Ver menos

Abstract: The present work sought to investigate H2O2 generation using a gas diffusion electrode composed of carbon with niobium oxide for the degradation of levofloxacin. Results showed that the oxide formed was Nb2O5 (crystallographic structure was confirmed by XRD; chemical composition detected by XPS) and the increase in the Nb/C ratio led to more crystalline structure and higher crystallite size. The carbon with 5% Nb2O5 presented an average particle size of 5.6 nm and this material led to the generation of the highest amount of H2O2 (317.6 mg L-?1). The C/5% Nb2O5-modified GDE was applied for the degradation of levofloxacin in an acid medium, in the presence and absence of Fe2+ ions. Long-term experiments conducted for the analysis of the time required for the total removal of levofloxacin showed that 96% of levofloxacin and 66% of organic load were removed in 270 min of treatment at the current density of 100 mA cm-2 Ver menos