Coaxial Electrospun ZIF-8@PAN Nanofiber Membranes for Tetracycline and Doxycycline Adsorption in Wastewater

Abstract

In this study, polyacrylonitrile (PAN) nanofibers functionalized with ZIF-8 (ZIF-8@PAN), exhibiting a core-shell structure, are produced via coaxial electrospinning for removing tetracycline (TC) and doxycycline (DC). This approach aims to enhance the recoverability and stability of metal-organic framework (MOF)-based adsorbents while effectively minimizing the embedding of ZIF-8 within the polymer in blend electrospinning. It is found that the highest removal efficiencies for TC and DC, obtained with 5% (w/v) ZIF-8 (PZ-5), are 72.2% and 94.1%. The maximum adsorption capacities are 83.4 and 150.2 mg g⁻¹, respectively. Kinetics, isotherms, and thermodynamic studies indicated adsorption is endothermic and conformed to pseudo-second-order kinetic and Sips models. Mechanisms such as electrostatic attraction, coordination bonding, hydrogen bonding, and π–π stacking are primarily responsible. DFT calculations revealed PZ-5 exhibited superior adsorption performance for DC compared to TC. Additionally, PZ-5 showed good resistance to various ions and exhibited high antibiotic removal efficiency in real water. It also exhibited excellent stability and reusability after three cycles. The ZIF-8@PAN nanofiber membrane developed in this study offers a novel approach for the efficient, stable, and easy separation of antibiotic from wastewater, as well as offers new insights into the application of MOF-based materials in environmental remediation.