CNFs@ZIF-8 hybrid nanofibers with ultrahigh adsorption capacity for malachite green: preparation and adsorption performance

The development of efficient adsorbents for removing toxic organic dyes from wastewater remains a critical challenge in environmental remediation. Herein, novel carbon nanofibers (CNFs) supported ZIF-8 hybrid composite (CNFs@ZIF-8) was synthesized via an in-situ growth method and evaluated for its malachite green (MG) adsorption performance. The composite exhibited a porous structure with a high specific surface area (1154.18 m 2 /g) and abundant functional groups, enabling exceptional adsorption capacity (2384.13 mg/g). Systematic studies revealed that the adsorption mechanism involved synergistic electrostatic interactions, π-π stacking, with the process fitting the Langmuir isotherm and pseudo-second-order kinetic models. Remarkably, CNFs@ZIF-8 demonstrated pH-responsive selectivity toward cationic dyes, achieving removal efficiencies of >90 % for MG, methylene blue (MB), and rhodamine B (RhB), while showing minimal affinity for anionic methyl orange (MO). Thermodynamic analysis confirmed the spontaneous (ΔG 0  < 0) and endothermic (ΔH 0  = 71.49 kJ/mol) nature of adsorption. The composite maintained structural stability over five regeneration cycles, highlighting its potential for sustainable wastewater treatment. This work provides a strategy to overcome the limitations of pure MOFs by integrating carbon substrates, offering a multifunctional adsorbent with scalable applications in addressing complex dye-polluted effluents.