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 C 4-C 8 DCA heterogeneous photooxidation catalysed by TiO 2 /Fe 2 O 3-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.

Atmospheric Chemistry of Oxalate: Insight Into the Role of Relative Humidity and Aerosol Acidity From High‐Resolution Observation

“…‐L. Zhang, Kawamura, Fu, et al., 2016; Y. L. Zhang, Kawamura, Cao, & Lee, 2016; Zhao et al., 2019) in the reaction of gas‐phase (Bao et al., 2012; Grgić et al., 2010; Mochizuki et al., 2017), heterogeneous‐phase (Aggarwal et al., 2012; Chang et al., 2019; Chen et al., 2019; Deshmukh Kawamura & Deb, 2016; Deshmukh, Kawamura, Lazaar, et al., 2016; Ervens et al., 2011; Fitzgerald et al., 2015; Hara et al., 2002; Hsieh et al., 2009; Kawamura et al., 2007; Knopf et al., 2010; Kunwar et al., 2016; Kunwar et al., 2019; Laskina et al., 2013; Levitt et al., 2007; Narukawa et al., 2003; Park & Cho, 2012; Pillar et al., 2015; Ponczek et al., 2019; Ren et al., 2019; Shen et al., 2013; Styler & Donaldson, 2012; Sullivan & Prather, 2007; Tang et al., 2016; Wang et al., 2010; Wang et al., 2015; Yang et al., 2009; Yao et al., 2002; Yao et al., 2003), and aqueous‐phase (Altieri et al., 2006; Bikkina, Kawamura, & Miyazaki, 2015; Bikkina, Kawamura, Imanishi, et al., 2015; Boreddy et al., 2017; Couvidat et al., 2013; Crahan et al., 2004; Ervens & Feingold, 2009; Kerminen et al., 1999; Kondo et al., 2007; Laongsri & Harrison, 2013; Lim et al., 2005; McNeill, 2015; Passananti et al., 2016; C. Pavuluri et al., 2015; Sorooshian, Lu, et al., 2007; Sorooshian, Ng, et al., 2007; Sorooshian et al., 2006; Tomaz et al., …”

Formation mechanisms of atmospheric nitrate and sulfate during the winter haze pollution periods in Beijing: gas-phase, heterogeneous and aqueous-phase chemistry

“…It has been acknowledged that the severe haze pollution is mainly ascribed to stagnant meteorological conditions with high atmospheric relative humidity (RH) and low mixed boundary layer height, strong emissions of primary gaseous pollutants, and rapid formation of secondary inorganic aerosols (SIAs, the sum of sulfate, nitrate and ammonium), especially sulfate and nitrate (Cheng et al, 2016;Guo et al, 2014;Huang et al, 2014). Some studies suggested that the contribution of SIAs to PM 2.5 was higher than 50 % during the most serious haze days (Quan et al, 2014;Xu et al, 2017;Zheng et al, 2015a).…”

Photochemical Degradation of Organic Matter in the Atmosphere

“…Mineral dust, the most abundantly emitted aerosol globally, has a photocatalytic effect that can trigger photoinduced het erogeneous chemistry of organic matter including carboxylic acids. [63] Deshmukh et al [64] reported that considerable frac tions of dicarboxylic acids and related compounds in coarse mode were related to mineral dust particles by their adsorption and photooxidation of biogenic and anthropogenic precursors via heterogeneous reactions on dust surface in the urban aero sols from central India. Ponczek et al [63] conducted laboratory experiments and found that the photochemistry of the selected dicarboxylic acids exhibited an even-odd alternation as for their heterogeneous reactivity, with evennumbered carbon diacids being less reactive than their oddnumbered homologous ones.…”

“…[63] Deshmukh et al [64] reported that considerable frac tions of dicarboxylic acids and related compounds in coarse mode were related to mineral dust particles by their adsorption and photooxidation of biogenic and anthropogenic precursors via heterogeneous reactions on dust surface in the urban aero sols from central India. Ponczek et al [63] conducted laboratory experiments and found that the photochemistry of the selected dicarboxylic acids exhibited an even-odd alternation as for their heterogeneous reactivity, with evennumbered carbon diacids being less reactive than their oddnumbered homologous ones. They proposed a general reaction mechanism (Scheme 3) for the heterogeneous photooxidation of C4-C8 diacids catalysed by TiO 2 /Fe 2 O 3 rich dust particles.…”

“…Their results showed that photoinduced reactions can happen on actual dust surfaces with coatings of organic matter, suggesting that photochemical processing on mineral dust surfaces should be considered as a potentially efficient pathway for modifying their surface prop erties affecting atmospheric processes, for instance, acting as cloud condensation (CCN) and ice forming nuclei (IN). [63] In contrast, photolysis of dustoxalate complexes is con sidered an important sink of oxalate, which is effective under clearsky sunlight conditions. [65] For instance, Zhou et al [65b] observed a decrease in the oxalate content by 20% during the degradation process in the early morning, consistent with a decrease in ironcontaining oxalate particles, and persuasively proved ironmediated photochemical decay of oxalate.…”