Fabrication of well-defined electromagnetic Fe3O4/polyaniline hollow microspheres and their application in Pb2+ uptake

Well-defined superparamagnetic and conductive Fe3O4/polyaniline (PANI) hollow spheres were fabricated using positively charged polystyrene (PS) spheres as templates. The negatively charged Fe3O4 particles, which were decorated by citric acid, can be attached onto the surface of the PS spheres via electrostatic interaction. Subsequently, the PANI layer was coated onto the PS/Fe3O4 templates by in situ chemical oxidative polymerization. Finally, removal of the PS core by dissolving with tetrahydrofuran provided the electromagnetic hollow spheres. Morphologies and compositions of Fe3O4/PANI hollow spheres were investigated by using SEM, TEM, FTIR and XRD. Magnetic analysis demonstrates that the synthesized composite spheres possess the characteristic of superparamagnetism and the saturation magnetization value is 26.2 emu g−1. Batch adsorption shows that the Fe3O4/PANI hollow spheres exhibit high uptake property of Pb2+ in aqueous solution. The adsorption kinetics follows the mechanism of pseudo-second-order kinetics and the sorption agrees well with the Langmuir isotherm.