MOF-derived Fe-Cu doped biochar composites for synchronous adsorption, electro-Fenton oxidation and in-situ...

Adsorption as an uncomplicated and effective water purification strategy, faced inherent limitations in pollutant mineralization and adsorbent regeneration, while conventional electro-Fenton (EF) struggles with inefficient removal of low-concentration contaminants and narrow pH applicability. To address these challenges, we developed a bifunctional MOF-derived Fe-Cu@biochar composite, which synergistically coupled adsorption with heterogeneous EF (hetero-EF) oxidation for enhanced antibiotics removal and green adsorbent regeneration. The biochar substrate engineered with mesoporous structure and large specific surface area, stabilized Fe-Cu dual sites through coordination bonds while providing abundant oxygen functional groups for rapid tetracycline (TC) adsorption (192.3 mg·g⁻¹) via electrostatic and coordination interaction. Crucially, the key lied in the Fe-Cu dual sites bridging the adsorption of H₂O₂ (Fe-O-O-Cu), and the polarization of the O-O bond significantly lowered the H₂O₂ adsorption energy, accelerating its dissociation into radical (^•OH and O₂^•-) and non-radical migration paths (¹O₂). This synchronous adsorption-oxidation-regeneration process achieved > 99% TC removal within 20 min at pH 3 ∼ 9 with energy consumption 70.8% lower than the non-adsorption enriched system. Its performance was further validated in a continuous flow system and cyclic experiments, maintaining 98.5% TC removal over 300 min, which was unlike conventional adsorbents that rapidly lost 58% capacity after 60 min. This work provides a paradigm for atomic-level modulation of dual-site catalysts, enabling synchronous adsorption-oxidation processes for deep and sustainable pollutant remediation.