Green synthesis of superparamagnetic magnetite nanoparticles: effect of natural surfactant and heat treatment on the magnetic properties

A facile and eco-friendly synthetic approach was employed to synthesize superparamagnetic magnetite (Fe3O4) nanoparticles with cubic lattice structure. Zucchini and pomegranate peel-extracts were used as natural stabilizer and surfactant. The X-ray diffraction patterns revealed that the green synthetic technique was successful in formation of highly distributed Fe3O4 nanoparticles using both of the above extracts. The infrared (IR) analysis further confirmed the phase formation and the binding of extracts with Fe3O4 nanoparticles. Based on UV–Vis analysis, the samples showed the characteristic of surface plasmon resonance in the presence of Fe3O4 nanoparticles. The as-synthesized samples were heated at 550 °C for 2 h. It was found that the particles however grew, their sizes remained in nanoscale regime, indicating their thermal stability. The VSM analysis indicated that the as-synthesized samples have a saturation magnetization of 21.4 emu/g (using zucchini peel extract) and 13.3 emu/g (using pomegranate peel extract), which increased respectively to 45.8 emu/g and 38.1 emu/g after the heating process. A negligible coercivity in the samples with the particle sizes of less than 10 nm suggests superparamagnetic behavior of the samples.