Development of a novel low-cost adsorbent Chitosan@EDTA@Cellulose composite to effectively remove Methyl Orange dye from wastewater: Experimental and theoretical investigation.

Methyl Orange, a toxic and persistent azo dye, poses significant environmental challenges in aquatic ecosystems. This study investigates the efficiency of a novel Chitosan@EDTA@Cellulose composite, synthesized by linking shrimp-derived chitosan and cactus-derived cellulose using EDTA as a linking agent. Comprehensive characterization techniques, including Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller surface area analysis, were employed. Under optimal conditions (pH 5, 50 mg/L dye concentration, 55 min, 0.1 g adsorbent), the composite achieved a maximum adsorption capacity of 55.87 mg/g, significantly outperforming chitosan (7.29 mg/g) and cellulose (5.69 mg/g). Adsorption followed the pseudo-second-order kinetic model and the Langmuir isotherm model, with thermodynamic analysis confirming a spontaneous and endothermic process. Competitive adsorption tests demonstrated >90 % removal efficiency despite the presence of interfering ions, attributed to the chelating properties of EDTA and the synergistic effect of the composite structure. Reusability tests showed a slight efficiency decline from 97.8 % to 81.86 % after four cycles. Box-Behnken Design optimization identified adsorbent mass, pH, and dye concentration as key factors in removal efficiency. Density Functional Theory analysis clarified the functional group interactions driving adsorption. These findings underscore the composite's potential as an effective and eco-friendly adsorbent for Methyl Orange removal.