Kinetics, Isotherm and Thermodynamic Properties of the Basement Complex of Clay Deposit in Ire-Ekiti Southwestern Nigeria for Heavy Metals Removal

Abstract

Raw kaolinite clay collected from Ire-Ekiti, Ekiti State, Nigeria, was used to adsorb some heavy metals (Pb, Cr, Ni and Cu) from their aqueous solution through batch experiments. Adsorption studies were performed at the different temperatures, concentration and time to determine the kinetics, isotherm and thermodynamic properties of the adsorption processes. The adsorption thermodynamic properties showed that sorption of Cu, Cr and Ni on the raw clay was exothermic, while adsorption of Pb was endothermic. The negative values of ?G for Pb adsorption revealed the feasibility and spontaneity of the adsorption process while the positive ?G values for Cu, Cr and Ni sorption showed non-spontaneity of the adsorption process. Langmuir, Freundlich and Elovich isotherms were applied to explicate the nature of adsorption process, while Pseudo-first-order (PFO), Pseudo-second-order and Elovich kinetics were applied to literarily determine the adsorbate-adsorbent interaction. Pseudo-second-order kinetics was the best fitting kinetics for adsorption of the metals on the raw clay.

Keywords

• adsorption, heavy metal removal, kinetic isotherms, kaolinite, ire-ekiti