Evaluation of the NO x Reduction Performance of Mortars Containing Zeolite/Activated Red Clay Coated with a TiO 2 Photocatalyst.

Globally, there is a growing concern about air pollution due to rapid industrialization and urbanization. Therefore, in this study, an experimental study was conducted to evaluate the performance of reducing nitrogen oxides, a precursor to fine dust, in mortars coated with a titanium dioxide (TiO ₂ ) photocatalyst, which has the effect of decomposing pollutants. In particular, in this study, zeolite and activated red clay were used as cement substitutes to improve the fine dust reduction performance of the TiO ₂ photocatalyst. A total of 14 different mixtures were designed, considering the substitution rates of zeolite and activated red clay (30%, 40%, and 50%) and the cement-fine aggregate ratio (1:2 and 1:3) as experimental variables. A TiO ₂ photocatalyst was employed in this study to evaluate the NO _x reduction performance. As zeolite and activated red clay were added, the compressive strength and flexural strength of the mortars decreased by 15% to 60%, while the absorption rate increased by 5% to 16%. The NO _x reduction efficiency of up to 67.4% was confirmed in the H50-3 specimen with the TiO ₂ catalyst. The NO _x reduction performance of mortars with the TiO ₂ photocatalyst sprayed on their surface improved as the substitution ratio of zeolite and activated red clay increased. Additionally, it was confirmed that the NO _x reduction effect of specimens using activated red clay was superior to those using zeolite. Therefore, through this study, it was confirmed that the NO _x reduction performance of the TiO ₂ photocatalyst can be improved when zeolite and activated red clay are used as cement substitutes.