Activated Empty Palm Fruit Bunch for the Adsorption of Heavy Metal Ions: Kinetics and Thermodynamics

Equilibrium, kinetic and thermodynamic study of the adsorption capacity of activated carbon prepared from empty palm fruit bunch was done using samples of electroplating process waste stream and waste vegetable oil with the focus being on copper, iron and zinc heavy metal ions contained in the samples. Activation was chemically done using sulphuric acid at 3M concentration with furnace temperature and time being 450 oC and 3 h respectively. The equilibrium adsorption data were analysed using the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich adsorption isotherms. Linear regression was used for comparing the best fit of the isotherms. The best fit to the adsorption data of the investigated heavy metal ions in both samples was found to be the Langmuir isotherm. The kinetics of the adsorption process was evaluated with the pseudo-second order kinetic model providing the best description of the adsorption kinetics in both samples. Thermodynamic parameters (ΔG0, ΔH0, ΔS0) were also calculated which together with other theoretical basis proved the adsorption mechanism in both samples to be physical. Results showed that adsorption was exothermic and spontaneous in both samples with ΔH0 for samples A and B calculated to be -1.14 x 10-2 KJ/mol and -1.68 x 10-3 KJ/mol respectively.