Investigation on Parameters Affecting the Effectiveness of Photocatalytic Functional Coatings to Degrade NO: TiO₂ Amount on Surface, Illumination, and Substrate Roughness

Abstract

This paper deals with the degradation of NO by photocatalytic oxidation using TiO 2 -based coatings. Tests are conducted at a laboratory scale through an experimental setup inspired from ISO 22197-1 standard. Various parameters are explored to evaluate their influence on photocatalysis efficiency: TiO 2 dry matter content applied to the surface, nature of the substrate, and illumination conditions (UV and visible light). This article points out the different behaviors between three kinds of substrates which are common building materials: normalized mortar, denser mortar, and commercial wood. The illumination conditions are of great importance in the photocatalytic process with experiments under UV light showing the best results. However, a significant decrease in NO concentration under visible light is also observed provided that the TiO 2 dry matter content on the surface is high enough. The nature of the substrate plays an important role in the photocatalytic activity with rougher substrates being more efficient to degrade NO. However, limiting the roughness of the substrate seems to be of utmost interest to obtain the highest exposed surface area and thus the optimal photocatalytic efficiency. A higher roughness promotes the surface contact between TiO 2 and NO but does not necessarily increase the photochemical oxidation.

In situ NO abatement by photocatalysis—study under continuous NO injection in a 10-m3 experimental chamber

“…This quantity was controlled and determined by weighing the recipient containing the TiO 2 dispersion and the brush before and after coating each plasterboard sample. The targeted value of 3 g/m² of photocatalytic product on the surface was chosen according to previous research work carried out by the same authors (Hot, Topalov et al 2017). Finally, each photocatalytic plasterboard sample was mounted on the walls inside the experimental chamber.…”

“…Visible and UV light intensity were measured under a combination of natural and artificial lighting. More details can be found in Hot, Topalov et al (2017).The lowest mean UV intensity was 50 mW/m² and the highest was 260 mW/m², depending on the room location and aspect. These values were slightly lower than the ones obtained in the experimental chamber.…”

“…Studies on the use of semi-conductors such as TiO 2 or ZnO are abundant in the literature (Fujishima et al 2008;Yu & Brouwers 2009;Lin et al 2013;Zhong & Haghighat 2015;Ren et al 2017). Most experimental studies have been performed under laboratory conditions at different reactor scales (Horgnies et al 2015;Toro et al 2016a;Ifang et al 2014;Horgnies et al 2012;Ren et al 2017;Martinez et al 2011;Hot, Topalov et al 2017;Hernández Rodríguez et al 2016;Hüsken et al 2009;Aïssa et al 2011). Often, photocatalytic oxidation (PCO) efficiency is estimated using international standards and recommendations (ISO 22197-1 2016; CEN/TS 16980-1 2016).…”

Development of Multifunctional Coatings for Protecting Stones and Lime Mortars of the Architectural Heritage

“…Photocatalysts have been also applied on surfaces of building materials as active coatings (Nath et al 2013;Hot et al 2017;Yang et al 2018;Veltri et al 2019). Photocatalytic oxidation of dirt compounds by TiO 2 is widely known but its effectiveness is confined under UV radiation (Khan et al 2014;Khalid et al 2017).…”

In situ investigation of NOᵪ photocatalytic degradation: Case study in an open space office in Manchester, UK

“…Redox reactions were then promoted to decompose NO x . Such process has been well documented in the literature [24,[34][35][36] . DtoxGuard R Int coating was also used in a previous study, in which it was applied to the walls (a surface of 9.3 m 2 was covered) in a 10-m 3 experimental chamber.…”