Equilibrium Isotherm, Kinetic and Thermodynamic Study on Removal of Methylene Blue Dye from Aqueous Solution by using Corn cob Activated Carbon

Abstract

The adsorption performance of corn cob based activated carbon (CCAC), for adsorptive removal of methylene blue dye from aqueous solution, has been investigated by batch experiments. Batch studies have been performed to describe the impact of parameters such as pH, adsorbent dose, initial dye concentration, temperature and contact time on the removal of the dye. The maximum removal percentage (approximately 99%) was observed when used 2.5 g L^-1 of CCAC, 200 mg L^-1 of initial MB concentration at initial pH 6.97, and contact time of 90 min. The experimental data were analysed by the Langmuir and Freundlich isotherm models. The monolayer adsorption capacity of CCAC was found to be 119.04 mg g^-1 by using Langmuir isotherm model. The calculation of the thermodynamic parameters such as Gibbs free energy, entropy and enthalpy changes of the on- going adsorption process indicated the feasibility and endothermic nature of MB adsorption. Pseudo- first- and second- order kinetic models have been applied to the experimental data and pseudo- second- order kinetics was found to describe the adsorption of the dye (methylene blue) on the adsorbent.