Photodegradation of methylene blue using magnetically reduced graphene oxide bismuth oxybromide composite

Abstract

A magnetically reduced graphene oxide–bismuth oxybromide (MRGO–BiOBr) composite was successfully synthesized and found to possess magnetic, adsorptive and photocatalytic properties. The synthesized composite have been characterized by Fourier transform infrared spectroscopy (FT-IR), X-Ray Diffraction (X-RD), Scanning electron microscopy (SEM) and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). Presence of FeO bond stretching vibrations and bromo compounds have been confirmed using FT-IR and the diffraction peaks of the composite obtained from X-RD showed a combination of peaks of both MRGO and BiOBr. SEM images further confirmed the presence of minute flakes of BiOBr scattered onto the surface of MRGO. Reduction in band gap energy from 2.76eV for pure BiOBr to 1.91eV for the composite was determined using UV–vis DRS. Photocatalytic degradation of Methylene Blue dye under visible light irradiation (150W Tungsten filament lamp) was examined using MRGO–BiOBr and around 96.84% of dye of 50ppm was degraded in 2h. Kinetic studies were done by splitting the kinetic data into 2 regions at 30min of irradiation and using the Langmuir–Hinshelwood (L–H) model to determine the rate constants. The composite was found to be easily separable in the presence of a magnet and on regeneration, studies showed no significant decrease in the photocatalytic activity of the composite even after 3 runs.