Highly efficient and cheap treatment of dye by graphene-doped TiO2 microspheres

Highly efficient dye wastewater treatment by photocatalytic catalysis commonly requires expensive catalysts, long degradation time and a complicated procedure. Here, we for the first time prepared cheap graphene-doped titanium dioxide microspheres with a simple procedure to degrade dye with high efficiency. When the catalyst concentration was 0.2 g·L−1, the photocatalysis degradation extent of methylene blue solution, methylene green solution and 1,9-dimethyl methylene blue solution reached 96.4, 85.9 and 98.7%, respectively. The results showed that the degradation reactions accorded with the Langmuir–Hinshelwood model, and the photocatalytic reactions belonged to a first-order reaction in the primary stage. Furthermore, different photocatalytic degradation mechanisms were proposed, which have not been found in other literature. This work opened a new route for simple preparation of cheap microspheres in photocatalytic dye wastewater treatment with high efficiency.