Kinetics And Thermodynamic Studies Of Biosorption Of Cadmium (II) From Aqueous Solution Onto Sweet Potato Skin (Sps)

摘要

Thebiosorption of Cadmium onto Sweet Potato Skin (SPS) from aqueous solution were investigated in this study. The amount of Cd(II) adsorbed was found to be dependent on the pH of the solution, contact time and initial concentration of Cd(II). The equilibrium data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) Isotherm equation. The Freundlich Isotherm model fits the experimental data than the others. The values of the separation factors (R_L) are in the range of 0.2-0.7 which indicates favourable biosorption. Results also showed that the pseudo-second order equation provided the best model for the biosorption process. Various thermodynamic parameters such as ΔH°, ΔG° and ΔS° were evaluated. A positive value of ΔH°, indicates the endothermic nature of the process. The negative values of the Gibbs free energy at all the temperature showed that the adsorption process was spontaneous and the positive value of ΔS° reflects good affinity of Cadmium ions towards the biosorbent.