The mechanism and oxidation efficiency of bio-electro-Fenton system with Fe@Fe2O3/ACF composite cathode

Abstract

A novel microbial fuel cell (MFC) system coupled with electro-Fenton (EF) in a two-chamber was constructed using a Fe@Fe2O3/ACF composite cathode to simultaneously degrade swine wastewater (SW) and rhodamine B (RhB) in both anode and cathode chambers. After 24 h, the removal rates were 85.2 ± 3.3%, 75.1 ± 3.1% and 60.5 ± 2.8% for BOD5, COD and TOC in the anode, respectively, the cathodic RhB removal efficiency was 95.0 ± 3.5% at RhB 10 mg/L, external resistance 120 Ω, air flow rate 0.3 L/min, anodic pH 10 and cathodic pH 3. Meanwhile, the maximum power density, current density, voltage were 16.7 W/m3, 36 A/m3, 900 mV, respectively. Finally, it was validated by trapping experiments and electron spin resonance (ESR) that hydroxyl radical (OH) was the main reactive oxidizing specie, thereby the electron transfer mechanism and the degradation pathway of RhB were put forward. The integrated bio-electro-Fenton (BEF) was verified to be long-term stability, and might be a promising eco-friendly technique for refractory wastewater treatment.