Sonochemical-assisted synthesis of α-Fe2O3 nanoparticles and their photocatalytic activity toward methylene blue and methyl orange dyes

In this work, a facile and low-cost sonochemical-assisted route accompanied by calcination is used for the synthesis of α-Fe2O3 nanoparticles using Fe(NO3)3·9H2O as iron precursor, oxalic acid and polyvinyl pyrrolidone (PVP) as fuel and surfactant. The as-synthesized α-Fe2O3 nanoparticles were characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), vibrating sample magnetometer (VSM) and transmission electron microscope (TEM) and the results confirmed the preparation of single phase of rhombohedral α-Fe2O3 nanoparticles with quasi-spherical shapes and ferromagnetic properties. The studies of photocatalytic degradation of rhombohedral α-Fe2O3 nanoparticles were performed using methylene blue (MB) and methyl orange (MO) dyes in aqueous solution under visible light irradiation. The effect of the important parameters such as pH solution, catalyst dose and contact time was investigated. Under optimum conditions, the efficiency of MB and MO degradation reaches to 93 and 88% for Fe-1 and 91 and 84% for Fe-2, respectively. In addition, the photodegradation of MB and MO dyes using the as-synthesized spherical α-Fe2O3 nanoparticles was evaluated using the pseudo-first-order kinetic model.