Fabrication of an efficient surface ion-imprinted polymer based on sandwich-like graphene oxide composite materials for fast and selective removal of lead ions

Abstract

An efficient surface Pb(Ⅱ) ion-imprinted polymer based on sandwich-like graphene oxide composite materials (GO-IIP) was synthesized and characterized for studying the morphology and adsorption properties. Effects of preparation and adsorption conditions including solvent type, molar ratio of functional monomer to crosslinking agent, initiator dosage, pH, adsorbent dosage, contact time, ions concentration on the Pb(Ⅱ) removal were studied. Adsorption equilibrium was reached within 30 min and the adsorption process followed pseudo-second-order kinetic and Langmuir adsorption isotherm models, indicating chemisorption was the rate-limiting step. The maximum adsorption capacity of Pb(Ⅱ) ion-imprinted polymer was as high as 40.02 mg g−1 at 25 ℃, which was much higher than that of the non-imprinted polymer (20.45 mg g−1). The selectivity coefficient of Pb / Zn, Pb / Cd, Pb / Co, Pb / Ni and Pb / Ca were 20.12, 14.26, 31.67, 25.65 and 81.29, respectively, further confirming the satisfactory selectivity of GO-IIP. In addition, the prepared adsorbent could be reused 5 times without significant reduction of the adsorption capacity. Furthermore, an XPS spectra analysis was successfully applied to exploring the possible adsorption mechanism between Pb(Ⅱ) and GO-IIP, indicating that nitrogen atom in the amide bond of the functional monomer was the main coordination atom.