Multi-competitor directed defect engineering in UiO-66: achieving hierarchical porosity and unsaturated sites for high-efficiency fluoroquinolone remediation

Abstract

The escalating prevalence of fluoroquinolone antibiotics, such as levofloxacin (LVX), in aquatic environments necessitates advanced adsorbents for efficient remediation. Herein, we report a defect-engineered zirconium-based metal–organic framework (UiO-66) synergistically modified via a mixed-competitor strategy involving heterometallic doping (Zn²⁺) and ligand/solvent modulation (acetic acid/H₂O) to enhance LVX adsorption. The introduction of competitive species induced hierarchical porosity (meso/microporous) and unsaturated Zr/Zn sites, achieving a 4.5-fold increase in surface area (1132 m² g⁻¹) compared to pristine UiO-66. Adsorption experiments demonstrated exceptional LVX uptake (63.51 mg g⁻¹), governed by coordination, hydrogen bonding, electrostatic attraction and π–π interactions. Kinetic and isotherm analyses revealed chemisorption-dominated monolayer adsorption, while pH studies highlighted electrostatic and defect-mediated synergies. On this basis, the great potential of the multi-competing species mediated defect engineering strategy is further demonstrated by adjusting the temperature to afford an even higher adsorption capacity (87.37 mg g⁻¹), and the potential of the modified material in practical application is also analysed. This work establishes a novel paradigm for engineering MOF defects through multi-competitor interactions, offering a sustainable solution for antibiotic removal.