Study on Degradation of Lignin by TiO2-based Photocatalyst Doped with Carbon Dots

The carbon dots were prepared by the microwave method, and then the TiO2 doped with carbon dots was successfully synthesized by the hydrothermal method. Its structure was investigated using TEM, XRD and XPS. The catalyst was applied to the degradation of lignin base solution (50 mg of lignin in 30 mL of sodium hydroxide solution pH = 12) under ultraviolet light. It was found that when the mass ratio of carbon point to TiO2 was 1.5:1, the dosage of catalyst was 0.75 g/L, and the degradation time was 6 h, the degradation rate could reach more than 45%. The degradation rate of more than 40% could be maintained after seven cycles, indicating that the catalyst had good photocatalytic cycle stability. The degradation products were analyzed by GC-MS, and the main products were n-butyl acetate, butyl phthalate and alkanes with long carbon chains.