Effect of Different Adding Methods of Nano-TiO₂ on Photocatalytic Degradation of Automobile Exhaust on Asphalt Mixture

Abstract

As to photocatalytic degradation of automobile exhaust by TiO₂ nanomaterials loaded on asphalt mixtures, the paper investigated that the effect of different adding processes of nano-TiO₂ on the photocatalytic degradation efficiency on asphalt mixture. First, the nano-TiO₂ was modified by surface modification, and its hydrophilicity was changed to lipophilicity. Then, the study discussed the effects of nano-TiO₂ adding processes and asphalt mixture types in the form of filler (dry processes) and in the form of asphalt additive (wet processes) on photocatalytic performance, through photocatalytic performance test. The test results show that: the degradation efficiency of porous asphalt mixture was 12% higher than that of dense gradation asphalt mixture, because contact area between photocatalyst and UV light in porous asphalt mixture was higher. The photocatalytic degradation efficiency of dry processes was about 33%, which was higher than about 22% of being added into the asphalt mixture using wet processes. When dry processes was employed, the photocatalytic degradation efficiency increased with the nano-TiO₂ increasing, and reached the maximum of 35%, and then decreased. Through analysis, dry processes had a unique advantage that nano-TiO₂ and mineral powder homogeneously mixed, hindered the agglomeration of Nano-particles, which makes it better in the dispersion, and thus exhibits better photocatalytic performance.