Fe₃O₄@Polypyrrole Microspheres with High Magnetization and Superparamagnetism for Efficient and Fast Removal of Pb(II) Ions

Core-shell structured Fe₃O₄@PPy microspheres are synthesized successfully through a facile polyol reduction method in combination with a modified Stöber method. We show that the as-prepared Fe₃O₄@PPy microspheres with high saturation magnetization, superparamagnetism, and good dispersibility have a high efficient adsorption capacity for high efficient removal of Pb(II) ions of up to 391.71 mg g–1 and a fast adsorption equilibrium time of 20 min. Furthermore, the lead-adsorbed Fe₃O₄@PPy microspheres can be rapidly separated from solution because of the excellent superparamagnetic properties. The composite Fe₃O₄@PPy microspheres are characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The adsorption data from our experiments show that the adsorption process fits well with the pseudosecond- order kinetic model and the adsorption isotherm follows the Langmuir isotherm model. The thermodynamic studies show that the adsorption of Pb(II) on Fe₃O₄@PPy microspheres is an endothermic and spontaneous process. Comprehensive comparison among adsorbents for the removal of Pb(II) ions that literature reported, reusability, high adsorption efficiency, fast adsorption equilibrium, and rapid magnetic separation make these Fe₃O₄@PPy microspheres very promising application for removal of Pb(II) ions from contaminated water.