Functionalized magnetic Fe3O4 nanoparticles for removal of heavy metal ions from aqueous solutions

Abstract

Fe3O4 nanoparticles (MNP) were coated with 3-aminopropyltriethoxy-silane (APTES), resulting in anchoring of primary amine groups on the surface of the particles, then four kinds of novel magnetic adsorbents (Fe3O4@SiO2-NH-HCGs) were formed by grafting of different heterocyclic groups (HCG) on amino groups via substitution reaction. These Fe3O4@SiO2-NH-HCGs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and energy disperse spectroscopy (EDS). The results confirmed the formation of Fe3O4@SiO2-NH-HCGs nanoparticles and the Fe3O4 core possessed superparamagnetism. Batch experiments were performed to evaluate adsorption conditions of Cu2+, Hg2+, Pb2+ and Cd2+. Under normal temperature and neutral condition, just 20 min, the removal efficiency of any Fe3O4@SiO2-NH-HCGs is more than 96%. In addition, these Fe3O4@SiO2-NH-HCGs have good stability and reusability. Their removal efficiency has no obvious decrease after being used seven times. After the experiments were finished, Fe3O4@SiO2-NH-HCGs were conveniently separated via an external magnetic field due to superparamagnetism. These results indicate that these Fe3O4@SiO2-NH-HCGs are potentially attractive materials for the removal of heavy metal ions from industrial wastewater.