Adsorption of food dyes onto chitosan: Optimization process and kinetic

Adsorption of food dyes acid blue 9 and food yellow 3 onto chitosan was optimized. Chitosan was obtained from shrimp wastes and characterized. A full factorial design was used to analyze the effects of pH, stirring rate and contact time in adsorption capacity. In the optimal conditions, adsorption kinetics was studied and the experimental data were fitted with three kinetic models. The produced chitosan showed good characteristics for dye adsorption. The optimal conditions were: pH 3, 150 rpm and 60 min for acid blue 9 and pH 3, 50 rpm and 60 min for food yellow 3. In these conditions, the adsorption capacities values were 210 mg g−1 and 295 mg g−1 for acid blue 9 and food yellow 3, respectively. The Elovich kinetic model was the best fit for experimental data and it showed the chemical nature of dyes adsorption onto chitosan.