Photocatalytic activity of biosynthesized α-Fe2O3 nanoparticles for the degradation of methylene blue and methyl orange dyes

Abstract

Hematite (α-Fe2O3) nanoparticles (NPs) was biosynthesized using Vernonia amygdalina (V. amygdalina) leaves extract and Fe(NO3)3.9H2O precursor and characterized using X-ray diffraction (XRD), Ultraviolet–visible (UV-Vis), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) techniques. Moreover, the photocatalytic activity of synthesized sample calcined at 550 and 650 °C for the degradation of methyl orange (MO) and methylene blue (MB) dyes was studied and results indicated good catalytic activity towards MB at natural pH and efficient degradation at alkaline pH under sunlight irradiation. However, MO was efficiently degraded only in the presence of a small amount of H2O2 oxidant and that this disparity in photodegradation between the two dyes at similar experimental parameters could be due to difference in their molecular structure stability and HOMO-LUMO energy gap compared to VB-CB positions of catalyst α-Fe2O3 NPs.