Sol-gel derived ion-imprinted silica-supported organic-inorganic hybrid sorbent for selective removal of lead(II) from aqueous solution

The current paper presents a novel Pb(II) ion-imprinted silica-supported organic-inorganic hybrid sorbent functionalized with Schiff base by coupling a surface imprinting technique with a sol-gel process for the selective removal of Pb(II) ions from aqueous solution. Fourier transmission infrared spectroscopy, scanning electron microscopy, N-2 adsorption-desorption isotherms and thermogravimetric analysis were used to characterize the Pb(II)-imprinted hybrid sorbent. The adsorption equilibrium was finished with 30 min. The experiment value of maximum adsorption capacity was found to be 54.9 mg g(-1). There were not significantly influence on the adsorption capacity of Pb(II) in the range of pH 3.5-6.5. The equilibrium data were fitted very well to the Langmuir isotherm model and pseudo-first-order kinetics model. Under competitive adsorption conditions, the Pb(II)-imprinted hybrid sorbent was 3.09, 4.73, 3.34 and 4.96 times more selective than the corresponding non-imprinted sorbent for the systems of Pb(II)/Cu(II), Pb(II)/Cd(II), Pb(II)/Ni(II) and Pb(II)/Zn(II), respectively. The thermodynamic results demonstrated that the adsorption of Pb(II) onto the Pb(II)-imprinted hybrid sorbent took place by a spontaneous and endothermic process with further increase in the degree of freedom at the solid-solution interface.