Author : Y. Hannachi and T.Boubaker

The adsorption characteristics of Pb(II) ions using the Tunisian bentonite were investigated. Experimental parameters affecting the adsorption process such as pH, contact time, adsorbent dosage and temperature were studied. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were applied to describe the biosorption isotherms. The adsorption capacity of bentonite for Pb(II) ions was found to be 36.23 mg/g. From the D–R isotherm model, the mean free energy was calculated as 11. kJ/mol, indicating that the adsorption of Pb(II) ions was taken place by ion-exchange process. The calculated thermodynamic parameters showed that the adsorption of Pb(II) ions onto bentonite was feasible, spontaneous and exothermic in nature. Kinetics data were best described by pseudo-second- order model. Infrared (IR) spectra of the bentonite sample showed that the positions and shapes of the fundamental vibrations of the OH and Si–O groups were influenced by the adsorbed Pb(II) cations. The X-ray diffraction (XRD) spectra indicated that the Pb(II) adsorption onto the bentonite samples led to changes in unit cell dimensions and symmetry of the parent bentonite.

Keywords: Bentonite, ion-exchange, Langmuir isotherm, pseudo-second- order model, mass transfer analysis, Thermodynamic, (IR) spectra, (XRD) spectra.

Article published in International Journal of Current  Engineering  and Technology, Vol.3,No.1 (March- 2013)