Effective utilization of crustacean shells for preparing chitosan composite beads: applications in ameliorating the biosorption of an endocrine disrupting heavy metal

The study focuses on the removal of toxic hexavalent chromium (Cr(VI)) ions using fabricated chitosan composite beads (CCBs) using the shrimp shell waste and physically activated fish scales. The optimal parameters influencing biosorption were found to be pH 3.0, temperature 303 K, initial Cr(VI) concentration 100 mg/L after 150 min in batch experiments and the results showed 0.5 g CCBs adsorbed 99.86% Cr(VI). The Cr(VI) biosorption was confirmed using Fourier transform infrared spectroscopy analyses. The equilibrium data were fit into different isotherms such as Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich (D-R) models to elucidate Cr(VI) biosorption onto CCBs. The equilibrium results suggested that the biosorption was a physical process. The maximum adsorption capacity (qe) of CCBs was 28.9 mg/g and the pseudo-second-order kinetics best described the adsorption kinetics. Furthermore, the feasibility of CCBs regeneration using suitable treatment demonstrated desorption of Cr(VI) ions economically.