Adsorption of lead by modified Eucalyptus camaldulensis barks: equilibrium, kinetic and thermodynamic studies

In order to remove lead ions from aqueous solutions, the potential use of a modified form of Eucalyptus camaldulensis bark (ECB) through acrylic acid grafting (EAA) was investigated through several methods. On one hand, the adsorbent was characterized by Fourier Transformed Infrared Spectroscopy (FTIR), X-Ray diffraction (XRD) and bohemian method. The bulk density and the zero-charge point (p zch ) were also determined. The results showed that EAA is rich in COOH and OH groups and p zchis acid . The remove of Pb (II) is highly dependent on the solution pH, which increases with increasing of the pH of the solution while the adsorption capacity increases with the increasing of initial metal concentration and the weight of the adsorbent. The adsorption rate of Pb 2+ decreases with the increasing of temperature. On the other hand, the kinetic measurements using Lagergen pseudo-first order model, pseudo-second order model and diffusion intra particle model have explained that the process is fast following the pseudo-second order model. The studies of adsorption equilibrium, using several isotherm models such as Freundlich, Langmuir, Temkin, Elovich, Dubinin-Ra- dushkevich (DR) and Redlich-Peterson, have shown that the adsorption of lead ions by EAA obeys Langmuir model and the maximum adsorption amount of EAA is 82 mg/g at 25°C. Finally, various thermodynamic parameters indicate that the adsorption process is spontaneous and exothermic.