Adsorption of Methyl Orange onto Chitosan from Aqueous Solution

Chitosan was utilized as adsorbent to remove methyl orange (MO) from aqueous solution by adsorption. Batch experiments were conducted to study the effects of pH, initial concentration of adsorbate and temperature on dye adsorption. The kinetic data obtained from different batch experiments were analyzed using both pseudo first-order and pseudo second-order equations. The equilibrium adsorption data were analyzed by using the Freundlich and Langmuir models. The best results were achieved with the pseudo second-order kinetic model and with the Langmuir isotherm equilibrium model. The equilibrium adsorption capacity (qe) increases with increasing the initial concentration of dye and with decreasing pH. The values of qe were found to be slightly increased with increasing solution temperatures. The activation energy (Ea) of sorption kinetics was found to be 10.41 kJ/mol. Thermodynamic parameters such as change in free energy (△G), enthalpy (△H) and entropy (△S) were also discussed.