Surface reconstruction of MIL-53(Fe) facilitating dynamic cavitation-catalysis interaction for sustained persulfate activation

Although metal-organic frameworks are promising activators for persulfate activation, their catalytic efficiency is hampered by the slow rate of the Fe 2+ /Fe 3+ redox cycle. Herein, we develop a novel hydrodynamic cavitation-MIL-53(Fe) synergistic system to overcome this limitation for efficient tetracycline degradation, and elucidate the underlying synergistic effect via a unique cavitation-catalysis interaction. The violent collapse of cavitation bubbles induces in situ surface reconstruction of MIL-53(Fe) at both structural and electronic levels, doubling its specific surface area, elevating the Fe 2+ /Fe 3+ ratio, and reducing the work function to 2.90 eV (from 3.37 eV). These modifications significantly promote electron transfer to persulfate, enabling rapid generation of reactive radicals. Concurrently, the porous MIL-53(Fe) skeleton acts as stable heterogeneous nucleation sites, intensifying the cavitation field by extending bubbles lifetime and expanding the cavitation cloud. This bidirectional synergy yielded a high synergy factor of 2.69, achieving 90.3% tetracycline removal within 45 min and high chemical oxygen demand removal from actual traditional Chinese medicine wastewater. The process performed robustly over a wide pH range (3–7) with minimal iron leaching. This work unveils a dynamic, cavitation-driven mechanism that regulates catalyst activity and redox cycling, offering a scalable, chemical-free strategy for intensifying sulfate radical-based advanced oxidation processes in actua l wastewater treatment.