Adsorption Equilibrium and Thermodynamic Studies of Copper (II) Ions from Aqueous Solutions by Oil Palm Leaves

Oil palm leaf powders (OPLP), an agricultural waste material, were used as new non-conventional and low-cost adsorbents for the removal of copper (II) ions from aqueous solution. Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, pH of the solution, initial metal ion concentrations and adsorbent dosage. Langmuir, Freundlich and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fit well with the Langmuir adsorption isotherm, indicating thereby the mono layer adsorption of the copper (II) ions. The monolayer sorption capacity of OPLP for copper (II) ions was found to be 11.22 mg/g at 30 °C. The thermodynamic parameters like standard free energy, standard enthalpy, and standard entropy changes for the adsorption of copper (II) ions have also been computed and discussed. The heat of adsorption [?H° = -39.84 kJ/mol] implied that the adsorption was exothermic in nature.