Kinetic and Isotherm Studies of Al (III) Ions Removal from Aqueous Solution by Adsorption onto Coula edulis Nut Shell Activated Carbon

Abstract

The adsorption of Al (III) ions onto coula edulis activated carbon was performed at using batch protocol. The eexperiments were accomplished as function of several parameters such as: pH (2-4), initial concentration (159.1-1006.6 mg/L), contact time (10-120 min.), and temperature (25-60 °C). The adsorption capacity of Al (III) ions increased when pH, initial concentration and / or contact time increased and decreased when temperature increased. The adsorption data was fitted by Langmuir isotherm model rather than Freundlich isotherm model. Kinetic study revealed an adsorption process following the pseudo-second order model. Thermodynamic parameters gave negative value of enthalpy change, which corresponded to an exothermic process and negative value of entropy change which indicated a more ordered distribution of Al (III) ions in solid phase rather than in liquid phase. The free energy change was found positive in all the studied temperatures range. The effectively of the reaction is supported by supplementary energy produced by agitation.