Photocatalytic concrete for NOx degradation: Influence factors and durability

The application of titanium dioxide (TiO 2 ) photocatalyst in concrete is considered a promising method to effective remove nitrogen oxide (NOx) pollutants. However, the influences of application ways on photocatalytic efficiency and catalyst durability should be concerned in detail for its large-scale application. This paper compared the photocatalytic NOx degradation efficiency and durability of conventional TiO 2 powder dispersed in cement mortar (TPC), TiO 2 supported aggregates mounted on cement mortar surface (TAS) and TiO 2 supported aggregates dispersed in cement mortar (TAD), with considering different environmental factors effects such as gas flow rate, NO initial concentration and relative humidity. The photocatalytic efficiency results show that the NOx removal efficiency of TAS is about 1.5 and 1.1 times higher than that of TPC and TAD, respectively, corresponding to the utilization efficiency of TiO 2 photocatalysts in TAS is ca. 10 and 16 times higher than in TPC and TAD, respectively. The surface abrasion test suggests that TAS has relatively low photocatalytic efficiency compared with TAD after polishing the sample surface by more than 2 mm, which depends on the mounted thickness of TiO 2 supported aggregates. The findings in this work can provide the basis for the application ways of TiO 2 supported aggregates in concrete by considering its photocatalytic efficiency, economic efficiency and catalytic durability.