MOF-derived hierarchical porous CeO2/TiO2 composite for highly efficient removal of high-concentration tetracycline by synergistic adsorption and photocatalysis

Abstract

Tetracycline (TC) contamination in aquatic environments poses significant risks owing to antibiotic resistance gene dissemination and ecotoxicity. Integrating adsorption with photocatalysis offers a promising strategy for pre-concentrating contaminants at photocatalytic adsorbent surfaces while enabling solar-driven mineralization. Herein, a novel hierarchical mesoporous CeO₂/TiO₂ composite was constructed by transforming a Ti-based metal–organic framework, MIL-125-NH₂ (NM), which serves as a highly efficient photocatalytic adsorbent for the treatment of high-concentration TC solutions. Remarkably, it delivered a high equilibrium adsorption capacity of 146.4 mg g⁻¹ for TC within 240 min, significantly outperforming pristine NM by approximately 9.3 times. Moreover, its removal efficiency can further attain 93.1% for the high-concentration TC solutions (50 mg L⁻¹) under simulated solar irradiation, and it remains above 80% after three successive cycles. The hierarchical porous structure enables a rapid TC preconcentration, while Ce–O–Ti heterointerfaces facilitate efficient charge separation and interfacial reactions. This work validates a facile MOF-templating approach for designing bifunctional composites that couple efficient adsorption with solar photocatalysis, offering significant potential for treating recalcitrant antibiotic pollutants in wastewater systems.