g-C 3 N 4 /TiO 2 Composite Photocatalyst and Its Application to Asphalt for NO Removal

Automobile exhaust emission has become one of the environmental problems that cannot be ignored. In order to improve the photocatalytic activity of titanium dioxide (TiO2), graphitic carbon nitride (g-C3N4)/TiO2 was prepared, and its bonding state and morphology were analyzed by microscopic characterizations. The nitric oxide (NO) removal efficiency of g-C3N4/TiO2 was higher than that of g-C3N4 and TiO2. This was attributed to the formation of a heterojunction between g-C3N4 and TiO2 which accelerated the separation and transfer of photoinduced carriers. Because the results showed that the micropores produced by demulsification of emulsified asphalt were beneficial to the improvement of photocatalytic performance, emulsified asphalt was chosen as the carrier of g-C3N4/TiO2 photocatalysts to study the influence of different application forms on photocatalytic performance of asphalt specimens. Furthermore, it was found that both the specimens with spraying photocatalyst aqueous solution and the specimens with spreading powder had a good NO removal effect. However, with the increase of photocatalyst content, the NO removal efficiency of sprayed specimen was higher than that of the spreading specimen due to the good dispersion of the photocatalyst in the spraying solution.