Optimized adsorptive removal of organics from wastewaters using SAC-CNTs@ chitosan biogenic-composite: Modeling insight.

A novel SAC-CNTs@CS biogenic- composite, synthesized from sunflower seed-derived activated carbon, carbon nanotubes, and chitosan, was developed for eco-friendly tertiary treatment of real Abu Rawash wastewater (ARW), Egypt. The composite was characterized using FTIR, XRD, TGA, BET, and SEM, confirming its surface functionality and high adsorption capacity. It achieved maximum COD and TOC removal efficiencies of 97.18 % and 92.5 %, respectively, under optimized conditions. Response Surface Methodology (RSM) demonstrated strong predictive power (R2 = 0.9682 for COD and 0.9811 for TOC). Kinetic modeling revealed that COD followed a pseudo-second-order (PSO) mechanism, while TOC adhered to the Elovich model, indicating chemisorption and film diffusion as the dominant mechanisms. The composite exhibited excellent regeneration and reusability. This study underscores the potential of sunflower-based biosorbents as low-cost, sustainable materials for advanced wastewater treatment and highlights the necessity of tertiary treatment in ARW due to residual chemical pollutants in secondary-treated effluent.