Green Synthesis of Magnetite Nanostructures from Naturally Available Iron Sands via Sonochemical Method
Herein, we report the green synthesis of magnetite (Fe3O4) nanostructures (including flower-like nanosheets and cube-like particles) with large surface areas ranging from 127 to 318 m2 g−1 from naturally available iron sands using a facile sonochemical method, with the assistance of polyethylene glycol (PEG 6000). The X-ray diffraction (XRD) results reveal that the Fe3O4 nanostructures obtained from these iron sands are of good purity and crystallinity and are polycrystalline with an inverse cubic spinel structure. The increased addition of PEG 6000 from 5 to 25% v/v is found to result in larger crystallite size and improved crystallinity. Furthermore, the Fe3O4 nanostructures synthesized by our proposed method have a tendency to form flower-like structures composed of thin nanosheets when the amount of PEG 6000 is low (5-10% v/v), although their morphology gradually changes to cube-like particles at 15% PEG, before finally being converted to spherical nanoparticles with relatively good dispersity at high PEG contents (above 15%). More importantly, the specific surface area of the obtained Fe3O4 nanostructures decreases with increased addition of PEG due to the increased agglomeration of the particles. The magnetic properties characterization of the as-prepared Fe3O4 samples via vibrating sample magnetometer revealed that they exhibit superparamagnetism at room temperature and that their saturation magnetization values are strongly affected by the crystallite size of the Fe3O4 phase as Fe3O4 nanoparticles with larger crystallite size exhibit higher saturation magnetization (Ms) values. The presented work may encourage the use of naturally available resources rather than laboratory-made chemical reagents for the synthesis of iron oxide and other metal oxide nanostructures in the future.