Equilibrium Modeling, Kinetic, and Thermodynamic Studies on Adsorption of Pb(II) by a Hybrid Inorganic-Organic Material: Polyacrylarnide Zirconium(IV) Iodate

The sorption of Pb(II) onto polyacrylamide zirconium(IV) iodate, a hybrid inorganic organic material, has been studied through the batch equilibrium technique. The experimental equilibrium data have been analyzed using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models. The accuracy of the fit of isotherm models to the experimental equilibrium data was assessed using error analysis.The Temkin model yields the best fit between experimental and simulated data. The kinetic data obtained at different concentrations have been analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The experimental data obey the pseudo-second-order kinetic model. The plot of q(t) versus t(1/2) suggests that intraparticle diffusion is not the sole rate-controlling step; some degree of boundary layer diffusion is also involved. The calculated thermodynamic parameters Delta G degrees, Delta H degrees, and Delta S degrees indicate that the adsorption of Pb(II) onto the sorbent is a spontaneous, endothermic, and physical sorption process.