Degradation of florfenicol in a flow-through electro-Fenton system enhanced by wood-derived block carbon (WBC) cathode

Abstract

The flow-through electro-Fenton (EF-T) reactor with WBC cathode was designed to remove florfenicol (FF). The activated WBC cathode was prepared by facile carbonization and activation methods, and featured high specific surface area, natural multi-channel structure, abundant oxygen-containing groups, good hydrophilicity, and excellent O2 reducing capacity. WBC cathode was located above Ti/Ru-IrO2 mesh anode. O2 evolved at the anode was carried to the inner wall of channel of WBC by the force of buoyancy and water flow, which increases oxygen source of H2O2 generation at the cathode. The flow-through system by using WBC electrode promote the mass transfer of O2 and FF. The production amount of H2O2 at activated WBC was 32.2 mg/L, which was almost twice as much as that at non-activated WBC (15.0 mg/L). FF removal ratio in EF-T system was 98%, which was much higher than that of traditional flow-by electro-Fenton (EF-B, 33%) or single electrooxidation system (EO, 16%). EF-T system has the lowest energy consumption (4.367 kWh/kg) among the three electrochemical systems. The cathodic adsorption, anodic electrooxidation, and EF reaction are responsible for the degradation of FF. After five consecutive cycle experiments, FF removal ratio was still 98%, indicating WBC has the good stability.