Comparing the Different Methods Used in the Determination of Thermodynamic Parameters Using Adsorption of Pb(II) on to Chicken Feather as an Example

Abstract

Background: Thermodynamic parameters are important in determining the feasibility and spontaneity of an adsorption process. They are also vital in estimating adsorptive mechanisms (i.e., physiosorption, ion exchange or chemisorption). Accurate calculation of these thermodynamic parameters is highly dependent on the equilibrium constant KC. Many authors make use of constants obtained from various isotherm models, partition constant and distribution coefficient in calculating the thermodynamic parameters especially the Gibbs free energy. According to the provisions of the International Union of Pure and Applied Chemistry, the standard equilibrium constant (K°) for calculating Gibbs free energy change (ΔG°) must be a dimensionless parameter. Results: In this work various methods have been employed in determining the thermodynamic parameters. Fourier Transform Infra-red Spectroscopy (FTIR) analysis confirmed the presence of carboxyl, hydroxyl, amino and sulphur-containing functional groups in chicken feathers. There were no substantial variations in the chicken feather spectra before and after biosorption as confirmed by FTIR Spectroscopy spectroscopy which can be an indication of the possible reuse of chicken feather. Conclusion: Negative values of ΔG show a spontaneous process with spontaneity increasing with temperature. Finally, scanning electron microscope images of the chicken feather were found to have rough and uneven surfaces.