Preparation and properties of hierarchically self-assembled iron oxide nanosheets with specific removal performance of lead ions

Hieratically self-assembled iron oxide nanosheets have directly been synthesized by a facile chemical co-precipitation method without any template at the presence of poly(ethylene glycol) (PEG) through the self-assemble behavior of PEG-coated iron oxide nanoparticles. These iron oxide nanosheets were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–vis spectroscopy (UV–vis), thermogravimetric analyzer (TGA), Zeta Potential and vibrating sample magnetometer (VSM). The results proved the nanosheet structure and the stability in broad concentration range of salt and at broad pH values. The application of these nanosheets in heavy metal removal has also been investigated. The results indicated that these iron oxide nanosheets could adsorb lead ions in aqueous solution even at neutral environment and show high adsorption capacity of 336 mg g⁻¹, which is higher than that of other reported adsorbents. The adsorption behavior well fitted Langmuir isotherm modal and followed pseudo-second-order kinetics. This research provided a platform for the application of self-assembled nanosheet structure in Pb²⁺ removal with high adsorption efficiencies compared with those traditional 2D and 3D materials that were complicated and energy cost in preparation. (paper)