Photocatalytic NO abatement by cement blocks covered with Fe-TiO2 and surface hardening agents: Impacts of Fe-TiO2 contents of coating solutions

Abstract

In this study, the photocatalytic activity of commercial TiO2 particles (R996) in promoting the oxidation of NO under visible light irradiation at 50% relative humidity was enhanced by the temperature-regulated chemical vapor deposition of Fe-oxide (0.4 wt%) and post-annealing (375 degrees C, 2 h). Fe-TiO2@SHA/cement block samples were prepared by dispersing the modified TiO2 particles (Fe-TiO2) on cement blocks using a surface hardening agent (SHA) as a binder. The Fe-TiO2@SHA/cement blocks exhibited higher photocatalytic activity in promoting the conversion of NO into NO3- than the particulate counterparts. The Fe-TiO2@SHA/cement blocks exhibited dissimilar patterns in terms of the changes in NO removal as a function of the reaction time in the early stage of the reaction (0-150 min) depending on the Fe-TiO2 contents. The removal of NO increased gradually as the reaction time increased with lower Fe-TiO2 contents, whereas a gradual decrease in NO removal as a function of the reaction time was observed with higher Fe-TiO2 contents. The dependence of the response on the Fe-TiO2 contents was attributed to the dissimilar Fe-TiO2 structures formed on the cement blocks due to variations in the viscosity of the Fe-TiO2 coating solutions with different Fe-TiO2 contents.