Abstract: The preparation of photocatalytic materials by loading TiO₂ on the surface of fly ash is a new way for high-value applications of fly ash.Loading TiO₂ on the surface of fly ash by demulsification method is a new attempt.Using fly ash modified with sodium dodecylbenzene sulfonate acted as the carrier,nano TiO₂ sol acted as the titanium source,NaOH used as the demulsifier,and urea acted as the nitrogen source,N-doped TiO₂/fly ash composite material was successfully synthesized in the reactor by the demulsification method.The products were characterized by scanning electron microscope (SEM),X-ray diffractometer (XRD),infrared spectrometer (FT-IR),and ultraviolet-visible diffuse reflectance spectrometer (UV-Vis DRS). The effect of photocatalytic materials on the visible light catalytic degradation of rhodamine B was tested.The results show that when the mass ratio of TiO₂ to fly ash is 1∶1 and the addition amount of urea is 0.5 g,the N-TiO₂/fly ash photocatalyst has a good degradation effect on rhodamine B under visible light. 96.98% of rhodamine B is degraded in 180 min and the degradation process conforms to the model of first-order kinetics reaction,it still has good stability and repeatability after 6 times of cycling utilization.This method provides a functional application scheme for high-value applications of fly ash and has a good application prospect.

Key words: nano TiO₂ sol, demulsification method, N-doped TiO₂/fly ash, visible light degradation, rhodamine B