Designing NAZO@BC electrodes for enhanced elimination of hydrophilic organic pollutants in heterogeneous electro-Fenton system: Insights into the detoxification mediated by 1O2 and •OH

Hydrophilic organic pollutants (HLOPs) in effluents of wastewater treatment plants are more prevalent than hydrophobic counterparts, therefore development of upstream processes that can effectively enhance the removal of HLOPs can substantially enhance overall treatment performance. To bridge this gap, 3D electrodes made of biochar-supported Al-ZnO nanoparticles (NAZO@BC) applied in heterogeneous electro-Fenton (EF) system, abbreviated as NBE−EF system, is rationally designed for enhanced elimination of HLOPs in wastewater. Our analysis indicates the NBE−EF system results in an efficient THM elimination, 42.4 times greater than that of conventional EF system. MoS2 as an efficient cocatalyst plays an important role in the conversion from Fe(III) to Fe(II). Singlet oxygen (1O2) and hydroxyl radical (•OH) are identified as the primary reactive oxygen species (ROS) in the NBE−EF system. NAZO@BC electrodes could concentrate HLOPs on their surface and degrade it effectively, achieving also a self-cleaning effect. Effective elimination of four HLOPs, i.e., thiamethoxam (THM), dinotefuran (DIN), nitenpyram (NIT), and acetamiprid (ACE), demonstrated the high degradation performance of the NBE−EF system, even at neutral and alkaline conditions. This study provides a new approach for enhanced elimination of HLOPs in wastewater treatment and mechanical insights into degradation pathways and toxicity attenuation. [Display omitted] •THM removal in the EF system is 42.4 times enhanced by NAZO@BC electrodes.•NEB-EF plays an important role in HLOP removal at neutral and alkaline conditions.•NAZO@BC electrodes concentrate HLOPs on the surface and achieve self-cleaning effect.•1O2 and •OH play important roles in the degradation and detoxification of HLOPs.•Eight mechanisms possibly account for THM degradation in the NBE−EF system.