Modified chitosan flakes with glutaraldehyde and citric acid as a potential biosorbent for adsorption of Cd(II) from aqueous solution

This study investigated the adsorption of Cd(II) ions in aqueous solutions onto the chitosan flakes cross-linked with glutaraldehyde (Gch), and citric acid (CGch). The optimal conditions for these adsorptions process were found to be at pH 6 with contact time of 400 min for Gch and 350 min for CGch. The Cd(II) adsorption process on Gch and CGch well fitted to the pseudo-second-order model. The data obtained from the equilibrium experiment were analyzed using Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models. The results showed that the adsorption process was more effectively described by Langmuir model for Gch and Freundlich model for CGch. Calculated thermodynamic parameters, Delta G, Delta H, and Delta S of the processes showed that Cd(II) adsorption on Gch and CGch was spontaneous and endothermic process.