Adsorption of copper solution on chitosan beads adsorbent

Abstract

The use of waste as an adsorbent for removal of copper from aqueous solution was investigated due to its low cost value. Chitosan which was derived from crustacean shells was used in this study. The adsorption experiment was carried out at various parameters such as temperature (30-50 °C), pH (2-6), initial concentration (25-250 mg/L) and contact time. The maximum adsorption capacities of copper on chitosan beads were found to be 91.74 mg/g. The experimental data were analyzed using Langmuir and Freundlich isotherm model. Freundlich isotherm model fits the experimental data better than Langmuir isotherm. Kinetic studies showed that the adsorption followed pseudo-second-order kinetic model compare to pseudo-first-order kinetic model. Thermodynamic parameters such as free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) change were computed to predict the nature of the adsorption process based on Van’t Hoff equation. The negative value of free energy (∆G°), indicates the spontaneous process while the negative value of enthalpy (∆H°) and entropy (∆S°) which is -22.13 kJ/mol and -0.067 kJ/mol indicates that the process was an exothermic and more favorable at lower temperature. The value of Arrhenius activation energy, Ea which is 16.86 kJ/mol indicates that the process was physisorption mechanism.