Chitosan as an eco-green activator of mesoporous carbon synthesis for methylene blue adsorbent in water

Spherical mesoporous carbon was synthesized via in situ formation of ZIF-8/chitosan composites using acetic acid as the solvent. ZIF-8 acted as a morphology template, while chitosan functioned as an eco-friendly activator that enhanced pore formation and surface development during carbonization. Varying the chitosan content revealed that 60% provided the optimal structure, yielding mesoporous carbon with a high surface area of 749.7 m² g⁻¹ and an adsorption capacity of 294.1 mg g⁻¹ for methylene blue. Adsorption followed the Langmuir and pseudo-second-order models, governed by boundary-layer diffusion, with an enthalpy change of 25.4 kJ mol⁻¹ indicating endothermic physical interaction. This study demonstrates a simple and green approach for producing mesoporous carbon with enhanced dye-removal efficiency, highlighting chitosan’s potential as a sustainable activator for advanced carbon materials.