Equilibrium, Kinetics and Thermodynamic Studies on the Removal of Safranin-O from Waste Water Using Activated Carbons Derived from Coconut Shell and Pineapple Peel

This work is aimed at comparing the adsorption capacities of the activated carbons derived from coconut shell and pineapple peels using Safranin-O as adsorbate. Physical activation method was employed to generate the activated carbons using phosphoric acid (H3 PO4) as activating agent. Batch adsorption experiment was employed for the adsorption process. Effects of experimental factors such as adsorbent dosage, inititial Safranin-O dye concentration, pH and contact time on the adsorption process were examined. The results showed that the adsorption capacities were dependent on these factors. Langmuir and Freundlich Isotherms Models were applied and the results indicated that both models fitted well with the observed data but Freundlich Model fitted better. Pseudo first and second order kinetic models were also applied to describe the adsorption kinetic, only the second order model fitted well with the experimental data. Thermodynamic parameters such as enthalpy change (？H), Gibb’s free energy change (？G) and entropy change (？S) were evaluated using Van’t Hoff equations, both the free energy and enthalpy change were found to be negative indicating the feasibility and exorthermic nature of the adsorption process respectively. While the entropy change was found to be positive indicating that the degree of dispersion in the adsorption process increased with increase in temperature, Based on the results obtained from this research work, the activated carbon derived from coconut shell (CSAC) showed better adsorbent when compared with the one derived from pineapple peel (PPAC) as CSAC recorded the highest percentage of Safranin-O dye removal from waste water under all the experimental conditions