Enhanced antibiotic removal via magnetic Ni@ZIF-8 composite nanotubes: Synergistic adsorption, facile recovery and adsorption mechanism

The integration of metal–organic framework (MOF) materials with magnetic cores not only serves as an effective adsorbent but also facilitates the recovery post-adsorption. In this study, we synthesized Ni@ZIF-8 composite nanotubes by introducing ZIF-8 onto the surface of Ni nanotubes, which were used as adsorbents for antibiotic removal. The Ni@ZIF-8 composite nanotubes exhibited high-efficiency and recyclable antibiotic adsorption, with the maximum adsorption capacities for tetracycline (TC) and cefixime (CFX) reaching 770.2 and 428.2 mg·g −1 , respectively. The Ni nanotubes, acting as magnetic cores, facilitated magnetic recovery after adsorption. Furthermore, the introduction of ZIF-8 not only increased the surface roughness of the composite but also incorporated a significant number of functional groups. The pseudo-second-order model, Langmuir model and intra-particle diffusion models provided better fits to the isotherm and kinetic data of the two antibiotics. Density functional theory (DFT) calculations results indicate that the π-π interactions dominate the adsorption process of both TC and CFX onto ZIF-8. And the electrostatic potential (ESP) calculations and interaction analysis indicate that the Ni atom enhances the adsorption behavior through π-π interactions between the benzene ring or carbonyl group of the two antibiotics and the imidazole of ZIF-8. This research offers a novel approach for the removal of antibiotics from contaminated water and environmental remediation using magnetic core-MOF composite materials.