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Enhanced photocatalytic degradation of methylene blue by TiO2-rGO binary nanocomposites

The accelerated development of the dye industry in recent years contributes to an overload of wastewater, which has a negative influence on human health and aquatic ecosystems [1]. Methylene blue (MB) is a commonly used cationic dye and is very harmful to human health above a certain concentration due to its toxicity. In addition, MB is difficult to biodegrade because of its chemical persistence. Nowadays, treatment methods such as biological, physical, and chemical have been used to remove dye wastewater. However, those methods have some drawbacks like high cost as well as toxic by-products. Therefore, advanced oxidation processes, like heterogeneous photocatalytic degradation can be used as a more appropriate method for MB removal from wastewater [2], [3]. In this research, the binary TiO2-rGO nanocomposite catalyst was successfully synthesized as a mixture of pure TiO2 particles and reduced graphene oxide (rGO). The graphene oxide (GO) was synthesized by Hummer's method using natural graphite flakes (particle size ≤ 50 µm) as a precursor. The binary TiO2-rGO nanocomposite has been self-assembled through one- pot hydrothermal synthesis followed by a calcination treatment. The structural and morphological analysis of the synthesized nanocomposites have been performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FTIR). Photocatalytic experiments under ultraviolet (UV) and solar-like irradiation were performed in order to evaluate the efficiency of the synthesized catalysts. Further, the influence of rGO concentration on TiO2 performance for photodegradation of the MB dye was determined. It was found that the photodegradation of MB was increased as irradiation time for both sources of irradiation increased. The obtained results showed that the photocatalytic activity was increased as rGO concentration increased in the prepared nanocomposite, which can be attributed to the synergistic effect of the incorporation of rGO with TiO2.

TiO2-rGO, photocatalysis, methylene blue

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