Controlling Nitrogen Oxide and Ultraviolet-A irradiance in ventilation duct system using TiO2 photocatalyst

Abstract

In this study, we verified the application of TiO2 photocatalysts on ventilation ducts used in buildings and their effects on reducing nitrogen oxide (NOx), which is a typical particulate matter precursor. The TiO2 photocatalyst produces a radical dioxide with a strong acid oxidation power through photochemical reactions with ultraviolet-A (UV-A) rays and removes NOx through oxidation. The removal experiment was conducted by applying TiO2 photocatalyst coatings inside the duct to comply with the conditions of the ISO 22197-1: 2007. In addition, changes in the NOx removal were confirmed through changes in the concentration of NOx and UV-A irradiance inside the duct. At approximately 100 min after switching on the UV-A lamp during the experiment conduced according to ISO 22197-1: 2007, the NOx concentration decreased to 0.053 ppm (by 94.87%). Moreover, it has been confirmed that the trend of reduction is proportional to the changes in UV-A irradiance and NOx concentration, that is, an increase in UV-A irradiance has a significant impact on the reduction of NOx concentration; NOx reduction increases as a secondary function due to an increase in the UV-A irradiance. Through this study, it is believed that NOx, a representative precursor material that generates particulate matter, can be removed through a building ventilation system using a TiO2 photocatalyst. © 2021 Elsevier Ltd