EquilibriumModeling, Kinetic, and Thermodynamic Studieson Adsorption of Pb(II) by a Hybrid Inorganic–Organic Material:Polyacrylamide Zirconium(IV) Iodate.

The sorption of Pb(II) onto polyacrylamidezirconium(IV) iodate,a hybrid inorganic–organic material, has been studied throughthe batch equilibrium technique. The experimental equilibrium datahave been analyzed using Langmuir, Freundlich, Temkin, and Dubinin–Radushkevichisotherm models. The accuracy of the fit of isotherm models to theexperimental equilibrium data was assessed using error analysis.TheTemkin model yields the best fit between experimental and simulateddata. The kinetic data obtained at different concentrations have beenanalyzed using pseudo-first-order, pseudo-second-order, and intraparticlediffusion models. The experimental data obey the pseudo-second-orderkinetic model. The plot of qtversus t1/2suggests that intraparticle diffusion isnot the sole rate-controlling step; some degree of boundary layerdiffusion is also involved. The calculated thermodynamic parametersΔG°, ΔH°,and ΔS° indicate that the adsorption ofPb(II) onto the sorbent is a spontaneous, endothermic, and physicalsorption process. [ABSTRACT FROM AUTHOR]