Novel bionanocomposite of grafted chitosan-phthalic anhydride/Co2O3 nanoparticles for efficient removal of brilliant green dye: Adsorption optimization using Box-Behnken design.

A novel bionanocomposite of grafted chitosan-phthalic anhydride/Co₂O₃ nanoparticles (CHT-PHT/Co₂O₃) was synthesized and used for the elimination of brilliant green (BG) dye from aquatic systems. The CHT-PHT/Co₂O₃ material underwent several instrumental characterizations including, XRD, BET, FTIR, FESEM-EDX, and pH_pzc examinations. The impact of the key uptake factors, namely A: CHT-PHT/Co₂O₃ dose, B: starting solution pH, and C: contact duration, on the effectiveness of BG removal, was mathematically optimized using the response surface methodology (RSM). The ideal conditions of the maximum BG elimination (96.05 %) according to the desirability function are as follows: A: CHT-PHT/Co₂O₃ dose (0.044 g); B: pH ~ 10; and C: contact duration (34.6 min). The analysis of adsorption kinetics and equilibrium demonstrates a strong fit to the pseudo-first-order model, and the Freundlich isotherm model confirms the occurrence of multilayer adsorption. The highest adsorption capacity of CHT-PHT/Co₂O₃ for BG was determined to be 425.09 mg/g at a temperature of 25 °C. This study highlights the development of a practical bionanocomposite adsorbent that has a favorable ability to absorb organic dyes from wastewater. The current work offers a sustainable and efficient method of reducing the environmental impact of industrial dye pollutants by utilizing the distinctive properties of CHT-PHT/Co₂O₃ bionanocomposite.