Fast-Track Remediation: N-Doped Carbon Derived from Banana Stem for Efficient Water Treatment

The present study tackles the critical issue of water pollution and wastewater management through the development of hierarchical porous nitrogen-doped carbon (HPNC) synthesized from banana plant stems—a renewable, cost-effective precursor. The resulting HPNC material demonstrates an exceptionally high surface area of 1978.8 m²/g and achieves a remarkable monolayer adsorption capacity of 1435.95 mg/g for methylene blue (MB), outperforming previously reported carbon-based adsorbents. Isotherm and kinetic analyses reveal a rapid adsorption process, reaching equilibrium within approximately 20 minutes, governed by both physisorption and chemisorption mechanisms, as evidenced by Dubinin–Radushkevich (D–R) isotherm and pseudo-second-order kinetic modeling. The adsorption kinetics are further influenced by intraparticle diffusion, liquid-film diffusion, and chemisorption pathways. Importantly, HPNC-800 maintains 80% of its adsorption efficiency even after eight regeneration cycles using 0.1 M HCl, indicating excellent reusability and structural stability. Beyond dye removal, HPNC-800 exhibits strong potential for pharmaceutical wastewater treatment, achieving removal efficiencies of 79.8% for ciprofloxacin (CPX) and 81.1% for cefixime (CFX) within 30 minutes. Moreover, real effluent treatment trials with industrial dye wastewater demonstrate a 97% removal rate within just 15 minutes, underscoring the material’s practical applicability and multifunctional performance in real-world remediation scenarios.