Fabrication of recoverable magnetic surface ion-imprinted polymer based on graphene oxide for fast and selective removal of lead ions from aqueous solution

Abstract

In this study, a novel Pb(II) ion-imprinted polymer based on magnetic laminar graphene oxide composite materials (MnFe2O4@SiO2/GO-IIP) was synthesized by surface ion-imprinted technique for the selective removal of lead ions from aqueous solutions. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and magnetic measurement system were used to characterize the structure and property of as-prepared adsorbents. The adsorption experiments exhibited the MnFe2O4@SiO2/GO-IIP possessed a good adsorption performance and the maximum adsorption capacity of Pb (II) ions reached 58.82 mg g-1. The adsorption could be accomplished within 30 min and the adsorbents could be separated quickly by a permanent magnet. The Langmuir adsorption isotherm and pseudo-second-order kinetic models were used to describe the adsorption procedure appropriately and the result proved that the chemisorption was the rate-limiting step. The selectivity coefficient of Pb (II)/Ni(II), Pb (II)/Zn(II), Pb (II)/Cd(II), Pb (II)/Co(II) were 25.37, 19.71, 33.07 and 45.7, respectively. In addition, the regeneration experiments confirmed the high stability and reproducibility of adsorbents. Lastly, X-ray photoelectron spectroscopy (XPS) proved the bonding mechanisms of the material and Pb(II) ions with a coordination N‒Pb bond.