Fast and selective removal of Cr(VI) from aqueous solutions by a novel magnetic Cr(VI) ion-imprinted polymer

Abstract

In the present study, a novel magnetic Cr(VI) ion-imprinted polymer (MGOIIP) was prepared by a sol-gel process for fast and selective adsorption of Cr(VI) anions from aqueous solutions. In the synthesis process, 4-vinyl pyridine (4-VP) and 2-hydroxyethyl methacrylate (HEMA) were used as functional monomer and co-monomer; ethylene glycol dimethacrylate (EGDMA) and N,N-azoisobisbutyronitrile (AIBN) were used as cross-linker and initiator, respectively; acetone was selected as solvent. Fe3O4@SiO2 nanoparticles were introduced for separating adsorbents from the aqueous solution conveniently, and graphene oxide (GO) could prevent Fe3O4@SiO2 particles from aggregating. Some different techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to confirm the successful synthesis of ion-imprinted polymer on the surface of Fe3O4@SiO2/GO nanoparticles. The obtained magnetic ion-imprinted polymer has a high adsorption capacity (up to 311.95mg/g) for Cr(VI) anions at an optimal pH of 2.0, and the adsorption equilibrium can be reached within 3min. The adsorption process can be fitted well with Langmuir isotherm model and the pseudo-second-order kinetic model. Moreover, the results showed that MGOIIP has excellent selectivity and good regeneration ability. The prepared MGOIIP exhibited a satisfactory recovery for Cr(VI) anions in tap, river and lake water samples.