Photocatalytic Degradation of Methylene Blue from Aqueous Solutions by rGO/TiO2 Nanocomposites

Methylene blue (MB), as a typical pollutant in industrial dyestuff wastewater, has caused serious water pollution. Therefore, reduced graphene oxide (rGO)/TiO2 nanocomposites were synthetized by a simple hydrothermal technique and used as photocatalyst to degrade MB. It was illustrated when TiO2 nanoparticles were loaded 5wt.% rGO framework, nanocomposite had a huge specific surface area of 176.45 m(2) g(-1) and the average pore size of 4.25 nm. Effects of the rGO fraction in rGO/TiO2 photocatalyst, the rGO/TiO2 photocatalyst content, the initial pH, and the initial MB concentration on MB degradation efficiency were studied. The degradation efficiency about 98.18% was acquired at 5rGO/TiO2 content of 0.4 g L-1, pH = 6, MB concentration of 60 mg L-1. The degradation efficiency of 5rGO/TiO2 for MB was still as high as 86.24% after the tenth cycles, demonstrating rGO/TiO2 nanocomposites were useful for the practical application. The potential photocatalytic mechanism of rGO/TiO2 for MB degradation was immediate oxidative degradation procedure, and the combined action of O-2(center dot-), OH center dot and h(+) can contribute to the photocatalytic degradation of MB. Furthermore, the photocatalytic degradation kinetic of rGO/TiO2 for MB under UV irradiation was first-order model.

Automated summary

Reduced graphene oxide (rGO)/TiO2 nanocomposites, synthesized through a hydrothermal technique, were used as photocatalysts to effectively degrade methylene blue (MB) in industrial dyestuff wastewater. The degradation efficiency of the nanocomposites for MB was as high as 98.18% at 5wt.% rGO content, 0.4 g L-1 rGO/TiO2 content, pH 6, and 60 mg L-1 MB concentration. The photocatalytic degradation mechanism involved immediate oxidative degradation and the combined action of O-2(center dot-), OH(center dot), and h(+) species. The degradation kinetic of the nanocomposites for MB followed a first-order model under UV irradiation.