Mineralization of the antibiotic levofloxacin by the electro-peroxone process using a filter-press flow cell with a 3D air-diffusion electrode

This paper concerns the degradation of the antibiotic levofloxacin (LVN) by the electro-peroxone (E-peroxone) process in a lab-scale flow plant operated in recirculation mode. The flow plant consists of a filter-press type electrolyzer, the ECO-cell, equipped with a Ti vertical bar IrSnSb-oxides plate as anode, and a 3D air-diffusion cathode (graphite felt + carbon cloth-PTFE), where hydrogen peroxide (H2O2) is generated by the oxygen reduction reaction (ORR). The ozone (O-3) gas, externally produced, was injected directly into the electrolyte flow pipeline to favor the mixing of O-3 + H2O2 and thus promote the formation of hydroxyl radicals (%OH) to mineralize LVN. The influence of current density (j), volumetric electrolyte flow rate (Q), and initial concentration of LVN on the mineralization efficiency was systematically analyzed. The best E-peroxone trial achieved 63% mineralization of LVN (initially having 20 mg L-1 TOC in 0.05 M Na2SO4 at pH 3), with current efficiency and electrolytic energy consumption of 9.2% and 0.27 kWh (gTOC)(-1), respectively, for the electrolysis performed at j = 20 mA cm(-2) and Q = 2.0 L min(-1). The processes of ozonation and anodic oxidation with simultaneous formation of H2O2 (AO-H2O2) were also performed and compared with the E-peroxone method. Oxalic, oxamic, and tartaric acids were determined throughout the electrolysis and identified as the main final products of LVN mineralization.

Automated summary

This study focused on the degradation of antibiotic levofloxacin (LVN) using the electro-peroxone (E-peroxone) process in a lab-scale flow plant operated in recirculation mode. The research found that the E-peroxone method achieved 63% mineralization of LVN under specific conditions, with factors such as current density, volumetric electrolyte flow rate, and initial concentration of LVN influencing the mineralization efficiency. Oxalic, oxamic, and tartaric acids were identified as the main final products of LVN mineralization during the electrolysis process.