Facile fabrication of electrospun hybrid nanofibers integrated cellulose, chitosan with ZIF-8 for efficient remediation of copper ions

Abstract

To removal copper ions (Cu²⁺) from wastewater, structurally stable microcrystalline cellulose (MCC)/chitosan (CS)/zeolitic imidazole framework-8 (ZIF-8) hybrid nanofibers were fabricated by mixing electrospinning (MCC/CS/ZIF-8) and in-situ grown of ZIF-8 on electrospun nanofibers (I-MCC/CS/ZIF-8). The microstructure, porosity, thermal stability, crystal structure, surface wettability, chemical groups of hybrid nanofibers as well as their adsorption performance, isotherms, and kinetics were characterized and analyzed. The rhombohedral ZIF-8 at the optimum synthesis ratio was evenly bounded to nanofibers, corresponding to an average diameter of 775.81 nm. The introduction of ZIF-8 effectively improved the thermal stability of biomass polysaccharide nanofibers, maintained beneficial hydrophilicity (25.08°), increased their specific surface area by 16.51 times, and provided abundant potential active sites for Cu²⁺ adsorption. The adsorption performance of I-MCC/CS/ZIF-8 was superior to that of MCC/CS/ZIF-8, achieving the maximum Cu²⁺ adsorption capacity of 204.08 mg g⁻¹ at pH = 5, which conformed to both the Langmuir model and the pseudo-second-order kinetic model. The enhanced mechanism for Cu²⁺ adsorption can be attributed to the sufficient channels of porous network and the strong hydrogen bonding facilitating physical adsorption, as well as the effective chemical adsorption resulting from the rapid growth of ultrathin lamellar copper oxide‑zinc oxide heterojunctions with nanoflower-like shapes.