Using a novel gas diffusion electrode based on PL6 carbon modified with benzophenone for efficient H2O2 electrogeneration and degradation of ciprofloxacin

The present study reports the development and application of a gas diffusion electrode (GDE) based on Printex L6 carbon modified with 2.0% benzophenone-3,3 ',4,4 '-tetracarboxylic dianhydride (PL6C/2.0%BTDA) for the efficient electrogeneration of hydrogen peroxide (H2O2) and degradation of ciprofloxacin (CIP) using different advanced oxidation processes (AOPs). The modified GDE was studied under different current densities and 25 mA cm-2 was found to be the most efficient current density, since the application of the modified GDE at this current density yielded higher amounts of H2O2, greater kinetic constant and lower energy consumption compared to unmodified GDE. Based on these results, the modified GDE was used for the degradation of CIP in alkaline solutions using different AOPs, including anodic oxidation (AO), UVC photolysis, and processes based on H2O2 electrogeneration (AO/e-H2O2/UVC and AO/e-H2O2). The AO/e-H2O2/UVC technique was found to be the most efficient among the AOPs investigated; the application of this technique led to the complete removal of CIP (75 mu mol L-1) in 20 min of treatment, apart from yielding the highest kinetic constant rate and lower electrical energy per order (2.1 kWh m- 3 order-1). The oxidation by-products generated during CIP degradation via AO/e-H2O2/UVC were successfully identified and a pathway for CIP degradation was proposed.