Facile preparation of hierarchical porous MOF-based hollow carbon nanofiber mats using a polymer-blend electrospinning strategy for efficient adsorption of ciprofloxacin

A novel hierarchical porous metal-organic framework (MOF)-based hollow carbon nanofiber mat (CNFM) was prepared through a facile electrospinning process followed by carbonization. Two immiscible polymers, polyacrylonitrile/polymethyl methacrylate (PAN/PMMA), and porous zeolitic imidazolate framework-8 (ZIF-8) particles were selected as components for the electrospinning suspension. The resulting PPZ-CNFM-1–2–2 (PAN:PMMA:ZIF-8 = 1:2:2, mass ratio) exhibited a hollow tubular structure with uniformly distributed dense hollow-spheres on the tube walls. The obtained CNFM possessed a high Brunauer-Emmett-Teller specific surface area (S_BET) of 1696 m²/g and total pore volume of 2.74 cm³/g, which are comparable to those achieved by traditional physical or chemical activation methods. This MOF-based CNFM demonstrated excellent adsorption performance towards ciprofloxacin (CIP), exhibiting a high static adsorption capacity of approximately 600 mg/g and achieving adsorption equilibrium withing only 1 h. The exceptional adsorption capacity can be attributed to its high S_BET and abundant pores that accommodate CIP molecules, while the rapid adsorption rate is facilitated by the presence of hollow-sphere and hollow tubular structures in the carbon nanofibers. Furthermore, the study revealed the significant contributions of pore-filling effect during the adsorption process. Fixed-bed experiments confirmed that this MOF-based hollow CNFM holds great potential for large-scale applications in purifying CIP-contaminated water.