The reduction in the entropy value upon the adsorption process is due to a lesser degree of freedom of the gas molecule, owing to minimum free space on the carbon surface. In addition, the magnitude of ΔHo denotes the type of CO2 adsorption process, whether it belongs to the physical adsorption or chemical adsorption. It has been reported that the magnitude of ΔHo for the physisorption reaction is < 20 kJ/mol, whilst for the chemical adsorption, the value is within 80-200 kJ/mol [32, 33].