New insights into enhanced catalytic degradation of sulfamethoxazole using Fe-Zn@biochar composite-activated periodate system: The combination of radical and non-radical pathways

In this study, a novel iron-zinc bimetal-loaded sludge biochar-based biochar (Fe-Zn@SBC) was prepared for efficient removal of sulfamethoxazole (SMX) from aquatic environments through the activation of periodate (Pl). The addition of bimetals resulted in a unique honeycomb-like microstructure within the biochar, significantly affecting its pore distribution, functional group intensity, and defect characteristics. The Fe-Zn@SBC catalyst demonstrated exceptional performance in activating PI across a wide range of pH conditions and exhibited robustness against interference from prevalent contaminants in water bodies. Quenching experiments, electron paramagnetic resonance (EPR) analysis, and electrochemical assessments indicated that the degradation of SMX primarily occurs through a radical pathway driven by superoxide radicals, alongside a non-radical pathway facilitated by electron transfer. The synergistic interaction between Fe-Zn@SBC and PI enhanced the degradation of SMX into various small molecular intermediates, thereby contributing to the safety of aquatic ecosystems. This research presents an innovative modification strategy for sludge biochar, providing an effective and environmentally sustainable approach to mitigating pollution from pharmaceutical active compounds (PhACs) in aquatic systems.