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Remediation and Control Technologies
Unexpectedly high levels of organic compounds released by indoor photocatalytic paints Adrien Gandolfo, Sylvain R. A. Marque, Brice Temime-Roussel, Rachel Gemayel, Henri Wortham, Delphine Truffier-Boutry, Vincent Bartolomei, and Sasho Gligorovski Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.8b03865 • Publication Date (Web): 06 Sep 2018 Downloaded from http://pubs.acs.org on September 9, 2018
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Environmental Science & Technology
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Unexpectedly high levels of organic compounds
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released by indoor photocatalytic paints
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Adrien Gandolfo*1, Sylvain Marque2, Brice Temime-Roussel1, Rachel Gemayel1§, Henri
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Wortham1, Delphine Truffier-Boutry3, Vincent Bartolomei3, Sasho Gligorovski*1,4
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Aix Marseille Univ, CNRS, LCE, UMR 7376, 13331, Marseille, France
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Aix Marseille Univ, CNRS, ICR, UMR 7273, 13297, Marseille, France
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Grenoble Alpes Univ, CEA, L2N, 38054 Grenoble, France
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State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510 640, China
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Present adress : Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, UMR 5256, IRCELYON, Villeurbanne, France
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Corresponding authors*:
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Sasho Gligorovski
[email protected] 21
Adrien Gandolfo
[email protected] 1 ACS Paragon Plus Environment
Environmental Science & Technology
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ABSTRACT
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Photocatalytic paints based on titanium dioxide (TiO2) nanoparticles represent a promising
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treatment technology for cleaning the air at our dwellings. A few studies have shown that
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instead of elimination of harmful indoor air pollutants the production of carbonyl compounds
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occurs from the photocatalytic paints.
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Herein, we report unexpectedly high concentrations of volatile organic compounds (VOCs)
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released upon irradiation of photocatalytic paints which are meant to clean the air at our
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dwellings. The concentrations of the VOCs were measured continuously and on-line by PTR-
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ToF-MS (Proton Transfer Reaction – Time of Flight - Mass Spectrometry) connected to a
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well-established flow tube photoreactor. The PTR-ToF-MS analysis revealed the presence of
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52 ions in the mass range between 20 and 490 amu, among which 43 have been identified. In
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particular very high emission rates were estimated of two relevant indoor air pollutants,
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formaldehyde and acetaldehyde as 355 µg h-1 and 257 µg h-1 for 1 m2, respectively. We
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suggest a detailed reaction mechanism responsible for the production of these harmful indoor
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air pollutants (formaldehyde and acetaldehyde, among the others). The hydroxyl radicals
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(OH) formed upon activation of TiO2, react with the organic constituent (butyl acrylate and
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vinyl acetate) of the paint binder lead to generation of an important number of organic
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compounds. We demonstrate that the TiO2 quantity and the organic content of the binder is of
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paramount importance with respect to the formation of VOCs, which should be considered for
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future optimization of this air remediation technology based on TiO2 nanoparticles.
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Environmental Science & Technology
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TOC GRAPHICS
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KEYWORDS Volatile organic compounds, formaldehyde, indoor air, photocatalysis, PTR-
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ToF-MS
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Introduction
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Considering that in the developed world people spend most of their time indoors, the risks to
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health may be greater due to exposure to air pollution indoors than outdoors 1. The air
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exchange rate is the main removal pathway of airborne pollutants in the indoor environments
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considerably the air exchange rates in order to save the energy consumption, which in turn
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implies higher levels of air pollutants
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paints based on titanium dioxide nanoparticles anatase crystalline form (TiO2), have been
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suggested as an alternative air treatment technology. The global photocatalyst market size was
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estimated at 1.65 billion USD in 2016 and it is expected to reach 4.58 billion of USD by
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2025, according to a new report by Grand View Research, Inc5. The market of indoor
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photocatalytic paints makes an important contribution to it. For example, the leaders on EU
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market, EVONIC and KEIM, recently launched new commercial indoor photocatalytic
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paints5.
. However, the modern low energy buildings are airtight with a tendency to decrease
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. To improve the indoor air quality, photocatalytic
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Environmental Science & Technology
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When TiO2, is irradiated with photons carrying energy equal or in excess of its band gap (λ
