Journal of Chemical and Engineering Data, Vol.56, No.5, 2119-2127, 2011
Novel Zwitterionic Inorganic-Organic Hybrids: Kinetic and Equilibrium Model Studies on Pb2+ Removal from Aqueous Solution
Pb2+ removal from aqueous solution using zwitterionic hybrid polymers as adsorbents was studied. Influence factors such as solution temperature, initial pH, adsorption time, and solution concentration on Pb2+ adsorption were investigated. Adsorption kinetics data were modeled using four two-parameter kinetic equations (i.e., Lagergren first-order and second-order, Ritchie modified second-order, and intraparticle diffusion models). It was indicated that Pb2+ adsorption on these zwitterionic hybrid polymers followed the Lagergren second-order kinetic model. Meanwhile, the equilibrium adsorption data were analyzed using four two-parameter isotherm equations (i.e., Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models). The results reveal that the adsorption of Pb2+ ions followed the Langmuir isotherm model. The thermodynamic parameters Delta G, Delta H, and Delta S for Pb2+ removal from aqueous solution were also calculated. The negative values of Delta G and the positive values of Delta H are evidence that Pb2+ adsorption on these zwitterionic hybrid polymers is spontaneous and an endothermic process in nature. Moreover, the zwitterionic hybrid polymers produced reveal relatively high desorption efficiency in 1.0 mol.dm(-3) aqueous HNO3 solution, indicating that they can be recycled in industrial processes. These findings suggest that the zwitterionic hybrid polymers are promising adsorbents for Pb2+ removal from contaminated water.