Selective Removal of Lead(II) from Aqueous Solution by an Ion-Imprinted Silica Sorbent Functionalized with Chelating N-Donor Atoms

摘要

A Pb(II)-imprinted silica sorbent functionalized with chelating N-donor atoms for the selective removal of Pb(II) ion from aqueous solution had been synthesized by hydrothermal assisted surface imprinting technique. This sorbent was characterized by Fourier transmission infrared spectra, scanning electron microscopy and N2 adsorption. The results revealed that the Pb(II)-imprinted silica sorbent had high adsorption capacity (61.9 mg/g for Pb(II)), fast adsorption equilibrium rate within 30 min, wide pH range (3.5 to 6.5) for constant adsorption capacity, high selectivity and good regeneration performance. Compared with Lang- muir, Freundlich and Dubinin-Radushkevich isotherm models, the best interpretation for the experimental data was given by the Langmuir isotherm. Its adsorption kinetics was better represented by pseudo-second-order rate equation in comparison to pseudo-first-order, Elovich and intraparticle diffusion models. The thermodynamic results showed that the adsorption of Pb(II) onto the imprinted silica sorbent was a spontaneous and endothermic process with further increase the degree of freedom at the solid-solution interface. Thus, this Pb(II)-imprinted silica sorbent is believed to be a favorable and useful material for the selective removal of Pb(II) from aqueous solution.