Nitrogen oxide reduction and nitrate measurements on TiO2 photocatalytic pervious concrete pavement

Heterogeneous photocatalysis is considered one of the potential solutions for pollution remediation in which the natural decomposition process of harmful air pollutants is accelerated. This process make use of photocatalytic agents like nano titanium dioxide. Nano titanium dioxide (TiO2) has been found to have photocatalytic properties in which under UV light can oxidize and remove VOCs and NOx from the atmosphere. Therefore, the objective of this study is to evaluate the amount of nitrates released due to pervious photocatalytic concrete. To achieve this objective, samples were tested in the laboratory for photocatalytic Nitrogen Oxide (NOx) reduction efficiency according to the Japanese Industrial Standard (JIS). After testing, samples were washed with deionized water to collect the nitrates deposited on the surface. The collected nitrate concentration was measured using colorimetric method (cadmium reduction). In addition, a parametric study was conducted to examine the performance of pervious photocatalytic concrete under different environmental conditions. Results showed that photocatalytic pervious concrete is capable of purifying ambient air from NOx. In addition, a good agreement was obtained between the total amount of nitrogen compound eluted and the net amount of NOx removed under different mix design and environmental conditions. Results indicated that photocatalytic efficiency improved with the decrease in humidity, decrease in flow rate, and the increase in UV light intensity. © Chinese Society of Pavement Engineering