A Study on the Evaluation Methods of Nitrogen Oxide Removal Performance of Photocatalytic Concrete for Outdoor Applications

Abstract

In Korea, the issue of particulate matter pollution is growing, and many solutions are being developed to deal with it. Photocatalytic technology has been found to be helpful in removing precursors such as nitrogen oxides that cause particulate matter. In a microcosm setup, ISO 22197-1 has been successfully used to quantify the removal of nitrogen oxides from the specimen to which the photocatalyst is applied. However, owing to a lack of suitable tools, on-site measurement of real-scale efficacy is difficult. Depending on the substrate and surrounding circumstances at the application location, the photocatalyst may function at varying levels. Additionally, the expected photocatalytic effect may differ depending on the ambient air quality and sunlight irradiation intensity. This article describes two approaches for studying outdoor concrete photocatalysis. Standard gas measurement and dual-reactor measurement are the recommended evaluation approaches. The standard gas measurement method was found useful for assessing the applied photocatalyst itself as an outcome of field assessment. The performance of photocatalysts at different sites was found to be mutually exclusive and comparable. Over 180 min, on a building roof deck, the NO removal by the standard gas method was 0.68 ppm, whereas, at two shaded locations, the removal amount was 0.51 ppm (side wall) and 0.24 ppm (underpass) for 300 min. The dual reactor measurement approach, on the other hand, was discovered to be one of the most suitable methods for assessing how much of an improvement there has been in the air quality in areas where photocatalysts have been placed.