Green Synthesis of Magnetite (Fe 3 O 4 ) Nanoparticles Using Azadirachta indica Leaf Extract and Their Characterization

Magnetite (Fe3O4) nanoparticles (NPs) were prepared through green synthesis route using Azadirachta indica leaf extract that acted as an efficient stabilizer and capping agent of the NPs. Two types of magnetite NPs were synthesized using 5 and 10 mL Azadirachta indica leaf extract of the same concentration. The X-ray diffraction (XRD) analysis showed that the particles were crystalline with cubic inverse spinel structure and the crystallite size was found to be about 5.73 nm and 6.34 nm, respectively. The surface morphology of the NPs was investigated by field emission scanning electron microscopy (FESEM) which showed that NPs were spherical in shape. The Fourier transform infrared spectroscopy (FT-IR) analysis showed that the capping agents of the NPs contained the functional groups alcohol, alkane, amine, alkyne, etc. The thermal stability of Fe3O4 NPs was investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC showed endothermic and exothermic peaks. The percentage of weight loss was about 55% and 40%, respectively, as found from TGA. The NPs were superparamagnetic in nature with zero coercivity and zero reminance magnetization which was observed using a vibrating sample magnetometer (VSM). On the treatment of aqueous solutions of ferrous and ferric salts in alkaline medium with Azadirachta indica leaf extract, the rapid formation of stable iron oxide nanoparticles (Fe3O4-NPs) is observed to occur. The average crystallite size was determined by Scherer formula which showed that the crystallite size of the NPs gets increased with the increasing amount of Azadirachta indica extract used. Which support and show a good agreement with XRD and VSM analysis.