Dye removal from aqueous solution by a novel dual cross-linked biocomposite obtained from mucilage of Plantago Psyllium and eggshell membrane

Abstract

In this study, a novel dual cross-linked biocomposite of Plantago Psyllium mucilage, eggshell membrane, and alginate was prepared and used for removal of cationic methylene blue and anionic methyl orange dyes from aqueous solution. The fabricated biocomposite was characterized by FeSEM, EDX, XRD, TGA, BET, and FTIR analyses. Parameters such as kinetics, isotherm, thermodynamics, regeneration, swelling, and the influence of contact time, dye concentration, adsorbent amount, and pH on the dye adsorption capacity were determined. The maximum adsorption capacities of biocomposite were obtained for 0.05 g of the adsorbent with an initial concentration of 10 ppm in pH equal to 11 and 3, about 5.45 and 3.25 mg/g for methylene blue and anionic methyl orange, respectively. The thermodynamic results showed that the adsorption of the dye processes are a spontaneous exothermic process. The results showed that the adsorption of the dyes follows the pseudo-second-order kinetic model and the isotherm of both the dyes fit the Freundlich model. The experimental breakthrough curves were analyzed using different dynamic models of Bohart-Adams, Thomas, and Yoon–Nelson. The continuous adsorption process of dyes by the synthesized adsorbent was shown an appropriate consistency with the dynamic models, and best fitted to the Thomas and Yoon–Nelson models.