Seed-assisted secondary growth of a Polyethyleneimine-functionalized ZIF-8 Nanofibrous membrane for selective adsorption of anionic dyes

The selective removal of dyes from wastewater remains a critical challenge due to the structural complexity and persistence of dye molecules. In this work, a polyethyleneimine (PEI)-functionalized ZIF-8 hybrid nanofibrous membrane was fabricated via a seed-assisted secondary growth strategy, aiming to achieve high selectivity toward anionic dyes. Synergistic interactions between the porous metal-organic framework (MOF) grown on the surface and the polymer functional groups enable efficient and selective adsorption of anionic dyes. Adsorption experiments demonstrated that the hybrid membrane exhibited high adsorption capacities for anionic dyes, reaching 506.48 and 929.30 mg·g −1 for Congo red (CR) and methyl orange (MO), respectively. In contrast, significantly lower adsorption capacities were observed for cationic dyes (rhodamine B, RhB and methylene blue, MB). Moreover, the membrane maintained strong selectivity toward anionic dyes in mixed dye systems containing all four dyes and retained over 80 % removal efficiency for CR and MO after ten consecutive adsorption–desorption cycles. Additionally, the membrane exhibits superhydrophilicity, excellent water stability, enhanced mechanical properties, and antibacterial activity, highlighting its potential for advanced wastewater treatment, particularly in the remediation of dye effluents. This work also provides valuable insights into the practical application of MOF-based composite materials.