Photocatalytic Oxidation of NOx under Visible Light on Asphalt-Pavement Surface

This work examines the potential use of heterogeneous photocatalysis as an innovative oxidation technology. The aim is to demonstrate that this technology can reduce the damaging effects of vehicle emissions by using nitrogen doped (N-doped) TiO2 as a photocatalyst immobilized above the asphalt road surface. In the study, the photocatalytic effectiveness and durability of N-doped TiO2 photocatalytic asphalt road material were assessed in both the laboratory and the field using direct and indirect measurement. The experimental results show that under visible light irradiation, N-doped TiO2 asphalt road material has a higher activity compared with pure TiO2 asphalt road material. The decontamination rate for NOx is approximately 27.6, 24.6, 16.3, and 13.8% under irradiation at light wavelengths of 330-420, 430-530, 470-570 and 590-680 nm, respectively. Results of the field test and prediction models suggest that the service life of N-doped TiO2 asphalt road material is approximately 13 months. (C) 2017 American Society of Civil Engineers.