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 m2 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 O2∙-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${O}_{2}^{\bullet -}$$\end{document}, OH∙\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${OH}^{\bullet }$$\end{document} 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.