Equilibrium, kinetics and thermodynamics of Cadmium (II) biosorption on to composite chitosan biosorbent

A composite chitosan biosorbent (CCB) was prepared by coating chitosan onto ceramic alumina. The uptake capacity of CCB for Cadmium (II) was studied under equilibrium conditions in the temperature range 298-318 K. The sorbent was characterized by high temperature, pyrolysis, porosimetry, FTIR, SEM, EDAX and XRD analyses. The adsorption capacity of the biosorbent is investigated as a function of initial pH, contact time, initial concentration of adsorbate, amount of biomass and temperature. The data were analyzed using different kinetic and isotherm models. Pseudo-second-order model and Elovich equation provided a better representation of the experimental data. Among the adsorption isotherm models, Langmuir model gave a better fit of the equilibrium data. The calculated thermodynamic parameters showed that the biosorption of Cd(II) ions is feasible, spontaneous and endothermic in nature. Experimental results indicated that the CCB beads appear to be a promising biosorbent material for the removal of Cd(II) ions from aqueous media.