Photocatalytic concrete pavements: Laboratory investigation of NO oxidation rate under varied environmental conditions

• Bench-scale study evaluated removal of NO in air by photocatalytic pavements.
• Study confirmed correlation between NO oxidation rate and environmental variables.
• Study found that pavement moisture content has an effect on NO oxidation rate.
• Slab surface temperature was found to be significant in NO oxidation.

Concrete pavements containing TiO2 can be used for air pollution control by oxidizing NOX under UV-bearing sunlight. This study employed a bench-scale photoreactor to estimate NO oxidation rates for varied environmental conditions. Rates correlated positively with NO inlet concentration and irradiance and negatively with relative humidity. No correlation occurred with flow rate. A decrease in slab moisture (previously unstudied) positively correlated with NO oxidation rate at 0–2% loss of saturated mass, but negatively correlated at losses greater that 2%. Although prior researchers deemed temperature insignificant, data indicated a positive correlation. Overall, rates ranged from 9.8 to 64 nmol·m−2·s−1.