Aqueous-phase story of isoprene – A mini-review and reaction with HONO

The oxidation of dissolved sulfur dioxide, sulfur(IV), by oxygen proceeds through the involvement of sulfoxy radicals among which sulfate radical anion is the main chain carrier. When organics are present, they inhibit the oxidation of sulfur(IV) via scavenging of SO4− radicals. In contrast to previous studies, which were limited mostly to aliphatic compounds, this paper presents the results of the effect of 13 new volatile organic compounds (VOCs) including aromatic and heterocyclic on uncatalyzed sulfur(IV) autoxidation at pH 8.2 and 25°C. In all cases, the kinetics was first order in the presence and absence of VOCs and experimental rate law was Eq. (1). trueright−d[normalSfalse( IV false)]/normaldt=k obs []normalSfalse( IV false)=ko[]normalSfalse( IV false)/{}1+Bfalse[ Inh false]where −d[S(IV)]/dt is the rate of sulfur(IV) disappearance, kobs is the first‐order rate constant in the presence of inhibitor, ko is the first‐order rate constant in the absence of inhibitor, [S(IV)] is concentration of sulfur(IV) at time, t, and B is an inhibition parameter. VOCs cause inhibition by scavenging sulfate radical anions, which propagate the autoxidation chain. An analysis of B (Eq. (1)) and kinh (Eq. (2)) values for 21 aliphatic, aromatic, acyclic, and heterocyclic organic compounds showed that these to be related by Eq. (3) for a subgroup and Eq. (4) for b subgroup. trueright SO 4−+ VOC 0.33em⟶k inh 0.33em SO 42−+ VOC a subgroup (benzamide, 2,2‐dimethyl‐1‐propanol, 1‐hexanol, methanol, ethanol, 1‐propanol, 2‐ propanol, 1‐butanol, 2‐butanol, ethylene glycol, rebaudioside A) truerightB=()0.87±0.21×10−30.16emk inh b subgroup (o‐toluic acid, m‐toluic acid, p‐toluic acid, 4‐hydroxybenzoic acid, 1‐heptanol, glycerol, sucralose, acesuifame K, glycine, 3‐pentanol) truerightB=()1.2±0.3×10−30.16emk inh

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“…and its rearranged form Eq. , which are same as reported previously

\begin{matrix} true \\ right k_{obs} = k_{0} / ({}, 1 + B ([], Inh)) \end{matrix}

\begin{matrix} true \\ right 1 / k_{obs} = 1 / k_{0} + B ([], Inh) / k_{0} \end{matrix}

…”

Section: Resultssupporting

confidence: 87%

“…SO 3 − , SO 4 − , and SO 5 − as intermediates as discussed later. The autoxidation of sulfur(IV) is strongly inhibited by organics due to scavenging of SO 4 − radicals (1) .…”

Section: Introductionmentioning

confidence: 99%

Inhibition of Aquated Sulfur Dioxide Autoxidation by Aliphatic, Acyclic, Aromatic, and Heterocyclic Volatile Organic Compounds

Meena

Dhayal

Rathore

et al. 2017

Int J of Chemical Kinetics

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“…Other studies suggested that ISO-SOA formation yields under high-NO x conditions with acidified and non-acidified sulfate aerosol decreased with an increase in relative humidity while simultaneously the yield of organosulfates was enhanced (Zhang et al, 2011;Lewandowski et al, 2015). The latter observation can be explained by transformation of isoprene propagated by sulfate/sulfite radical anions in the aqueous particle phase or on the aqueous surface of aerosol particles (Zhang et al, 2011;Rudzinski et al, 2016;Szmigielski, 2016). The results obtained from the chamber experiments have been in agree-ment with recent model approaches when reactive uptake to aqueous aerosol is used rather than a reversible partitioning approach (Pye et al, 2013;Marais et al, 2016).…”

Section: Introductionmentioning

confidence: 96%

Chemical composition of isoprene SOA under acidic and non-acidic conditions: effect of relative humidity

et al. 2018

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The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies; however, few measurements have been conducted on individual aerosol compounds. The focus of this study has been the examination of the effect of acidity and relative humidity on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of nitrogen oxide (NO x ). A detailed characterization of SOA at the molecular level was also investigated. Experiments were conducted in a 14.5 m 3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from gas chromatography-mass spectrometry of silylated derivatives in electron impact and chemical ionization modes, ultra-high performance liquid chromatography/electrospray ionization/time-of-flight highresolution mass spectrometry, and collision-induced dissociation in the negative ionization modes, we characterized not only typical isoprene products but also new oxygenated compounds. A series of nitroxy-organosulfates (NOSs) were tentatively identified on the basis of high-resolution mass spectra. Under acidic conditions, the major identified compounds include 2-methyltetrols (2MT), 2-methylglyceric acid (2mGA), and 2MT-OS. Other products identified include epoxydiols, mono-and dicarboxylic acids, other organic sulfates, and nitroxy-and nitrosoxy-OS. The contribution of SOA products from isoprene oxidation to PM 2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. Methyltetrols, 2mGA, and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of relative humidity on SOA formation was modest in non-acidic-seed experiments and stronger under acidic seed aerosol. Total secondary organic carbon decreased with increasing relative humidity under both acidic and non-acidic conditions. While the yields of some of the specific organic compounds decreased with increasing relative humidity, others varied in an indeterminate manner from changes in the relative humidity.

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“…Isoprene organosulfates were also reported to occur in the aqueous-phase through the photooxidation or dark reactions of isoprene in aqueous solutions containing sulfate and sulfite moieties (Rudzinski et al, 2004(Rudzinski et al, , 2009Noziere et al, 2010). A detailed mechanism of this transformation has been tentatively proposed based on chain reactions propagated by sulfate and sulfite radical anions (Rudzinski et al, 2009) and confirmed by mass spectrometric 10 studies (Szmigielski, 2016). The acid-catalyzed formation of 2-methyltetrols was also suggested in aqueous phase oxidation of ISO with H2O2 (Claeys et al, 2004b).…”

mentioning

confidence: 92%

Chemical composition of isoprene SOA under acidic and non-acidic conditions: Effect of relative humidity

Nestorowicz¹,

Jaoui²,

Rudziński³

et al. 2018

Preprint

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Abstract. The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies, however few measurements have been conducted on individual aerosol compounds. While the focus of this study 10 has been the examination of the effect of acidity and RH on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of NOx, a detailed characterization of SOA at the molecular level have been also conducted. Experiments were conducted in a 14.5 m 3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from GCMS of silylated derivatives in EI and CI modes, and UPLC/ESI/QTOF HRMS, and collision-induced dissociation in the positive and negative ionization modes, we characterized not only 15 typical isoprene products, but also new oxygenated compounds. The analysis showed the presence of methylthreonic acids (mTr) and methyltartaric acids (mTA), proposed recently by our groups as isoprene aging SOA markers. Furthermore, a series of organosulfates (OSs) were tentatively identified including 2mTr-OS, 2mTA-OS and 2mTA nitroxy-OS. Under acidic conditions, the major identified compounds include 2-methyltetrols (2mT), 2-methylglyceric acid (2mGA) and 2mT-OS. Other products identified include epoxydiols, mono-and dicarboxylic acids, OSs, and nitroxy-and 20 nitrosoxy-OSs. The contribution of SOA products from isoprene oxidation to PM2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. mTs, mGA and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of RH on SOA formation was modest in non-acidic seed experiments. Total SOC decreased with increasing RH. The yields of most compounds decreased, but the concentrations of 2mTA, IEPOX-OS, 2mGA-OS and 2mTr-OS increased with increasing RH. Some components followed this pattern while other were more 25 abundant in non-acidic experiments or behaved in a mixed way, depending on RH.

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Aqueous-phase story of isoprene – A mini-review and reaction with HONO

Cited by 20 publications

References 78 publications

Inhibition of Aquated Sulfur Dioxide Autoxidation by Aliphatic, Acyclic, Aromatic, and Heterocyclic Volatile Organic Compounds

Inhibition of Aquated Sulfur Dioxide Autoxidation by Aliphatic, Acyclic, Aromatic, and Heterocyclic Volatile Organic Compounds

Chemical composition of isoprene SOA under acidic and non-acidic conditions: effect of relative humidity

Chemical composition of isoprene SOA under acidic and non-acidic conditions: Effect of relative humidity

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