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Heterogeneous photochemistry of dicarboxylic acids on mineral dust
Abstract Dicarboxylic acids have low volatilities and hence are present mostly in the particulate phase, including the surface of dust particles. Mineral dust, globally the most emitted aerosol, has photocatalytic properties that can initiate photo-induced heterogeneous chemistry of organic compounds, which is still poorly characterized. We investigated the photochemistry of five dicarboxylic acids (DCA) i.e., succinic (butanedioic) acid, glutaric (pentanedioic) acid, adipic (hexanedioic) acid, pimelic (heptanedioic) acid and suberic (octanedioic) acid on Arizona test dust (ATD) particles upon UV-A light irradiation (0–1.4 mW cm−2). Gas-phase products were monitored by a high-resolution proton-transfer-reaction mass spectrometer (PTR-ToF-MS), and surface sorbed products were extracted and analyzed by ultra-high-performance liquid chromatography coupled to a heated electrospray ionization high-resolution mass spectrometer (UHPLC-HESI-HRMS). Monoacids and aldehydes were the main observed and quantified gaseous products. In contrast, shorter chain DCA and highly oxygenated products were found at the surface of the dust particles. Interestingly, the photochemistry of these DCAs presented an even-odd alternation concerning their heterogeneous reactivity, with odd-numbered carbon diacids being more reactive than their even-numbered homologous ones. We present and discuss a reaction mechanism for the C4–C8 DCA heterogeneous photooxidation catalysed by TiO2/Fe2O3-rich dust particles. Our results suggest that photochemical processing on dust surfaces should be regarded as a possible efficient pathway for altering their surface properties impacting ice nucleation and cloud condensation properties.
Highlights Dicarboxylic acids are photochemically active on mineral dust. Monoacids and aldehydes were the main observed and quantified gaseous products. Shorter chain DCA and highly oxygenated products were found at the surface. This photochemistry presented an even-odd alternation. Photochemical processing on dust surfaces alters their surface properties.
Heterogeneous photochemistry of dicarboxylic acids on mineral dust
Abstract Dicarboxylic acids have low volatilities and hence are present mostly in the particulate phase, including the surface of dust particles. Mineral dust, globally the most emitted aerosol, has photocatalytic properties that can initiate photo-induced heterogeneous chemistry of organic compounds, which is still poorly characterized. We investigated the photochemistry of five dicarboxylic acids (DCA) i.e., succinic (butanedioic) acid, glutaric (pentanedioic) acid, adipic (hexanedioic) acid, pimelic (heptanedioic) acid and suberic (octanedioic) acid on Arizona test dust (ATD) particles upon UV-A light irradiation (0–1.4 mW cm−2). Gas-phase products were monitored by a high-resolution proton-transfer-reaction mass spectrometer (PTR-ToF-MS), and surface sorbed products were extracted and analyzed by ultra-high-performance liquid chromatography coupled to a heated electrospray ionization high-resolution mass spectrometer (UHPLC-HESI-HRMS). Monoacids and aldehydes were the main observed and quantified gaseous products. In contrast, shorter chain DCA and highly oxygenated products were found at the surface of the dust particles. Interestingly, the photochemistry of these DCAs presented an even-odd alternation concerning their heterogeneous reactivity, with odd-numbered carbon diacids being more reactive than their even-numbered homologous ones. We present and discuss a reaction mechanism for the C4–C8 DCA heterogeneous photooxidation catalysed by TiO2/Fe2O3-rich dust particles. Our results suggest that photochemical processing on dust surfaces should be regarded as a possible efficient pathway for altering their surface properties impacting ice nucleation and cloud condensation properties.
Highlights Dicarboxylic acids are photochemically active on mineral dust. Monoacids and aldehydes were the main observed and quantified gaseous products. Shorter chain DCA and highly oxygenated products were found at the surface. This photochemistry presented an even-odd alternation. Photochemical processing on dust surfaces alters their surface properties.
Heterogeneous photochemistry of dicarboxylic acids on mineral dust
Ponczek, Milena (Autor:in) / Hayeck, Nathalie (Autor:in) / Emmelin, Corinne (Autor:in) / George, Christian (Autor:in)
Atmospheric Environment ; 212 ; 262-271
16.05.2019
10 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Electrochemical synthesis of dicarboxylic acids
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