Photocatalytic degradation of vehicle exhausts on asphalt pavement by TiO2/rubber composite structure

In order to improve the efficiency and durability of semiconductor photocatalyst for degrading vehicle exhausts, a highly active degradation micro-unit was designed by crosslinking nano-TiO2 to the surface of fine crumb rubber with coupling agent. The dependence of degradation efficiency of NO2 on preparation parameters and test conditions were studied. Laboratory tests showed that the degradation rate of NO2 could reach 90% under the appropriate test environment such as initial NO2 concentration of 20 mg/m3, a mercury lamp with illumination of 1000 lx, temperature of 25 °C, relative humidity of 50% and rubber powder of 80 mesh. Tunnel tests showed that the concentration of NO2 in test section was 0.1-0.3 mg/m3 lower than those of contrast sections and the degradation rate reached 60% in 1 h. Since a three-dimensional contact area among nano-TiO2, exhausts, moisture and light was formed on the surface of rubber powders, the proposed technology is expected to provide a new way for greatly improving the degradation efficiency of vehicle exhaust by asphalt pavements.