Study on Dynamics and Thermodynamics for Removal of Ph(II) from Aqueous Solution by Ion-Imprinted Sorbent

The adsorption of lead onto the Pb(H) ion-imprinted sorbents has been dynamically and thermodynamically investigated by considering the influence of various parameters such as solution pH, contact time, initial concentration and temperature. The adsorption of Pb(II) increased with an increase of initial concentration. The optimal range of pH for Pb(II) adsorption is 5-7. First-order rate equation and pseudo second-order rate equations were applied to study adsorption kinetics. In comparison to first-order kinetic model, pseudo-second-order model described well the sorption kinetics of Pb(II) onto Pb(II) ion-imprinted sorbents from aqueous solution. The adsorption rate slightly increased with the increase of solution temperature. The Langmuir and Freundlich sorption models were employed to depict the isotherms and isotherm constants. Equilibrium modeling of the adsorption showed that the adsorption of Pb(II) ion-imprinted sorbents to the imprinted ion Pb(II) was fitted well to the Langmuir equation. From the results of the thermodynamic analysis, standard free energy change Delta G(0), standard enthalpy change Delta H(0), and standard entropy change Delta S(0) were determined. The positive value of Delta H(0) suggests that the interaction of Pb(II) adsorbed by Pb(II) ion-imprinted sorbents is endothermic. The negative value of Delta G(0) and positive value of Delta S(0) indicate that the adsorption reaction is spontaneous process.