Preparation of La-doped nanometer TiO2 and its application for NO removal on asphalt concrete

Abstract

La-doped TiO2 nanoparticle was prepared by ultrasonic assisted sol–gel method. Its crystalline phase, surface morphologic structure and optical property were characterised by X-ray diffraction (XRD), scanning electron microscope (SEM) and ultraviolet visible light spectroscope (UV–VIS). The photocatalytic activity of La-TiO2 was evaluated by the degradation of nitric oxide (NO) under visible or ultraviolet irradiation. The results indicate that the photocatalysts exist lattice distortion and grain refinement after the modification, which cause more reactive centres on the surface, lead to the red shift of absorption spectra and the increase of absorption in ultraviolet light region. It concludes that the modified sample with 0.5% dosage of La has the optimal photocatalytic activity. Next, the La-TiO2 nanoparticles were well dispersed in silica sol and then loaded on the surface of asphalt concrete specimens, and the specimen’s degradation performance of NO was tested by using the self-designed photocatalytic performance tester. The results demonstrate that the specimens present considerable photocatalytic activity under different conditions of light sources, and the NO degradation rates diminish gradually with the increase of NO concentration in the mixed gas and the flow velocity. Under ultraviolet light and visible light irradiation, the NO degradation rates are 39.37% and 19.7%, respectively.