Fabrication of bimetallic metal organic frameworks functionalized electrospun polyacrylonitrile nanofibers for efficient and selective removal of ciprofloxacin: performance and mechanism

Fluoroquinolones residues pose direct threats to the ecological system and human health, hence it is important to effectively remove them from aqueous environment. In this work, a composite of bimetallic ZnCo-metal organic framework (MOF) functionalized electrospun polyacrylonitrile (PAN) nanofibers (ZnCoMOF@PAN) was prepared using room-temperature in situ growth approach for efficient adsorption of ciprofloxacin (CIP). The ZnCoMOF@PAN revealed well-defined crystallinity and exceptional BET surface area (1267.87 m 2 /g). The systematic adsorption studies (kinetics, isotherms, and thermodynamics) showed that the CIP adsorption process was spontaneous and the adsorption isotherms obeyed the Freundlich model, and the pseudo-second-order kinetics model could be well fitted to the adsorption behavior. Remarkably, the maximum adsorption capacity of ZnCoMOF@PAN to CIP can reach 872.32 mg/g, which is significantly higher than that of other reported adsorbents. In addition, the adsorption of CIP onto ZnCoMOF@PAN was dominated by a synergistic effect of multiple interactions: electrostatic attraction, hydrogen bonding, complexation, π-π stacking, and hydrophobic effects. Furthermore, the composite exhibited excellent adsorption selectivity, maintaining over 90% removal efficiency for CIP in various real water matrices. After 5 consecutive adsorption-desorption cycles, it still retained more than 90% of its original removal efficiency, demonstrating great potential for practical application in wastewater treatment.