Solar-enhanced bio-electro-Fenton driven by sediment microbial fuel cell for ametryn degradation in simulated seawater

In marine aquaculture areas, herbicides have been used to inhibit the wild growth of seaweed, which may seriously affect the ecological environment and food safety. Here the commonly applied ametryn was used as the representative pollutant, and solar enhanced bio-electro-Fenton driven in situ by sediment microbial fuel cell (SMFC) was proposed to degrade ametryn in simulated seawater. SMFC with γ-FeOOH-coated carbon felt cathode was operated under the simulated solar light (γ-FeOOH-SMFC), where two-electron oxygen reduction and activation of H₂O₂ occurred to promote the production of hydroxyl radicals at the cathode. Hydroxyl radicals, photo-generated holes, and anodic microorganism worked together to degrade ametryn with an initial concentration of 2 mg/L in the self-driven system. The removal efficiency of ametryn in γ-FeOOH-SMFC was 98.7 % during the operation period of 49 days, which was 6 times higher than that under natural degradation condition. When γ-FeOOH-SMFC was in the steady phase, oxidative species were continuously and efficiently generated. The maximum power density (P_max) of γ-FeOOH-SMFC was 44.6 W/m³. According to the intermediate products of ametryn degradation in γ-FeOOH-SMFC, four possible pathways of ametryn degradation were proposed. This study provides an effective, cost-saving, and in situ treatment for refractory organics in seawater.