Performance Evaluation of Nitrogen Oxide Removal by Air Purification Blocks with Titanium Dioxide

Abstract

This study evaluated the nitrogen oxide (NOx) removal efficiency by air purification concrete blocks with titanium dioxide (TiO2). The concrete in themixtures had a 30% water:cement ratio, to which TiO2 was added at 0%, 5%, and 10% of cement weight. The compressive strength reduction rateand removal efficiency of NOx were investigated. The result of the compressive strength test in the study indicated that addition rate of TiO2 did notlead to signifcant effect. In terms of the average removal efficiency of NOx, mix No. 1 using a TiO2 mixing ratio of 0% had a removal efficiencyof 0.57% on average; thus, the removal effect was not significant. For the other samples prepared by mixing, the average removal efficiencies for mixNo. 2 (5% TiO2) were 58.86% and 62.05% for normal and washing surface treatments, respectively, and those of sample No. 3 (10% TiO2) were59.94% and 67.61%. mixs No. 4 (5%) and No. 5 (10%), in which TiO2 diluted with distilled water was sprayed onto the block surface, had an averageNOx removal efficiency of 61.72% and 68.48%, respectively. In terms of NOx removal efficiency, Mixs No. 3 and No. 5 with 10% TiO2 were betterthan Mixs No. 2 and No. 4 with 5% TiO2. In addition, analyzing the NOx removal efficiency results from the fixing method, it was capable to applymixing (washing) and the diluted spray methods. Therefore, it was found that the diluted spray method applied in this study can be employed in anymanufacture of air purification concrete blocks.