Highly efficient capture of reactive orange 16 dye from industrial wastewater using sodium tripolyphosphate crosslinked Chitosan-charcoal composite

Abstract

In this study, we developed a chitosan-charcoal composite (Cs–Ac) crosslinked with sodium tripolyphosphate (STPP) for the efficient removal of Reactive Orange 16 dye from aqueous solutions. The Cs–Ac composite was thoroughly characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and pH point of zero charge (pH_pzc) analysis to understand its physicochemical, structural, and morphological properties. The material was subjected to the adsorption of Reactive Orange 16 dye. The effects of the solution pH, adsorbent dose, contact time, temperature, and dye concentration were examined. The equilibrium data was described well by the Langmuir isotherm model with a coefficient of determination (R²) value of 0.9881. At near-neutral pH, with a contact time of only 60 min at room temperature, the material showed an adsorption capacity of 39.43 mg g^-1 which is much higher in contrast to all the previously reported materials. The adsorption performance of Cs–Ac for Reactive Orange 16 dye was evaluated by examining the effects of solution pH, adsorbent dose, contact time, temperature, and dye concentration. The equilibrium data were best described by the Langmuir isotherm model, indicating monolayer adsorption with a high coefficient of determination (R² = 0.9881). At near-neutral pH and a contact time of 60 minutes at room temperature, the Cs–Ac composite demonstrated an impressive adsorption capacity of 39.43 mg g⁻¹, significantly outperforming previously reported materials. The kinetics of uptake was well-defined by the pseudo-second-order model chemisorption model. Evaluation of the thermodynamic parameters revealed the spontaneous, endothermic and entropy-driven nature of adsorption. Cs–Ac exhibited excellent performance in capturing Reactive Orange 16 dye from aqueous solutions. Its high adsorption capacity, coupled with favorable kinetic and thermodynamic properties, makes it a promising material for water purification applications. Further studies could explore the regeneration and reuse of the composite, as well as its effectiveness in removing other pollutants from water.