Is secondary organic aerosol yield governed by kinetic factors rather than equilibrium partitioning?

2018 ◽  
Vol 20 (1) ◽  
pp. 245-252 ◽  
Author(s):  
Chen Wang ◽  
Frank Wania ◽  
Kai-Uwe Goss
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Equilibrium Partitioning ◽  
Kinetic Processes ◽  
Atmospherically Relevant

The concept of differential SOA yield and a consideration of kinetic processes are important when modelling SOA formation under atmospherically relevant conditions.

scholarly journals α-Pinene secondary organic aerosol yields increase at higher relative humidity and low NO<sub><i>x</i></sub> conditions

2016 ◽  
Author(s):  
Lisa Stirnweis ◽  
Claudia Marcolli ◽  
Josef Dommen ◽  
Peter Barmet ◽  
Carla Frege ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Relative Humidity ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Liquid Water Content ◽  
Strong Increase ◽  
Chemical Compositions ◽  
Scanning Mobility Particle Sizer ◽  
Equilibrium Partitioning ◽  
Phase Partitioning

Abstract. Secondary organic aerosol (SOA) yields from the photooxidation of α-pinene were investigated in smog chamber (SC) experiments at low (23–29 %) and high (60–69 %) relative humidity (RH), various NOx/VOC ratios (0.04–3.8) and with different aerosol seed chemical compositions (acidic to neutralized sulfate-containing or hydrophobic organic). A combination of a scanning mobility particle sizer and an Aerodyne high resolution time-of-flight aerosol mass spectrometer was used to determine SOA mass concentration and chemical composition. We present wall-loss-corrected yields as a function of absorptive masses combining organics and the bound liquid water content. High RH increased SOA yields by up to six times (1.5–6.4) compared to low RH. The yields at low NOx/VOC ratios were in general higher compared to yields at high NOx/VOC ratios. This NOx dependence follows the same trend as seen in previous studies for α-pinene SOA. A novel approach of data evaluation using volatility distributions derived from experimental data served as basis for thermodynamic phase partitioning calculations of model mixtures in this study. These calculations predict liquid-liquid phase separation into organic-rich and electrolyte phases. At low NOx conditions, equilibrium partitioning between the gas and liquid phases can explain most of the increase in SOA yields at high RH. This is indicated by the model results, when in addition to the α-pinene photooxidation products described in the literature, more fragmented and oxidized organic compounds are added to the model mixtures. This increase is driven by both the increase in the absorptive mass due to the additional particulate water and the solution non-ideality described by the activity coefficients. In contrast, at high NOx, equilibrium partitioning alone could not explain the strong increase in the yields with increased RH. This suggests that other processes including the reactive uptake of semi-volatile species into the liquid phase may occur and be enhanced at higher RH, especially for compounds formed under high NOx conditions such as carbonyls.

scholarly journals Water diffusion in atmospherically relevant α-pinene secondary organic material

2015 ◽  
Vol 6 (8) ◽  
pp. 4876-4883 ◽  
Author(s):  
Hannah C. Price ◽  
Johan Mattsson ◽  
Yue Zhang ◽  
Allan K. Bertram ◽  
James F. Davies ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Organic Material ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Water Diffusion ◽  
Direct Measurements ◽  
Atmospherically Relevant

We report the first direct measurements of water diffusion coefficients in secondary organic aerosol.

Evidence for a kinetically controlled burying mechanism for growth of high viscosity secondary organic aerosol

2020 ◽  
Vol 22 (1) ◽  
pp. 66-83 ◽  
Author(s):  
Allison C. Vander Wall ◽  
Véronique Perraud ◽  
Lisa M. Wingen ◽  
Barbara J. Finlayson-Pitts
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
High Viscosity ◽  
Particle Formation ◽  
Organic Nitrates ◽  
Equilibrium Partitioning ◽  
Kinetically Controlled

The incorporation of organic nitrates into viscous secondary organic aerosol during particle formation is enhanced relative to expected equilibrium partitioning, and is best described by a kinetically controlled “burying” mechanism.

scholarly journals The SOA/VOC/NO<sub>x</sub> system: an explicit model of secondary organic aerosol formation

2007 ◽  
Vol 7 (21) ◽  
pp. 5599-5610 ◽  
Author(s):  
M. Camredon ◽  
B. Aumont ◽  
J. Lee-Taylor ◽  
S. Madronich
Keyword(s):  
Gas Phase ◽  
First Principles ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Current Understanding ◽  
Aerosol Formation ◽  
Explicit Model ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Atmospherically Relevant

Abstract. Our current understanding of secondary organic aerosol (SOA) formation is limited by our knowledge of gaseous secondary organics involved in gas/particle partitioning. The objective of this study is to explore (i) the potential for products of multiple oxidation steps contributing to SOA, and (ii) the evolution of the SOA/VOC/NOx system. We developed an explicit model based on the coupling of detailed gas-phase oxidation schemes with a thermodynamic condensation module. Such a model allows prediction of SOA mass and speciation on the basis of first principles. The SOA/VOC/NOx system is studied for the oxidation of 1-octene under atmospherically relevant concentrations. In this study, gaseous oxidation of octene is simulated to lead to SOA formation. Contributors to SOA formation are shown to be formed via multiple oxidation steps of the parent hydrocarbon. The behaviour of the SOA/VOC/NOx system simulated using the explicit model agrees with general tendencies observed during laboratory chamber experiments. This explicit modelling of SOA formation appears as a useful exploratory tool to (i) support interpretations of SOA formation observed in laboratory chamber experiments, (ii) give some insights on SOA formation under atmospherically relevant conditions and (iii) investigate implications for the regional/global lifetimes of the SOA.

scholarly journals Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low and high NO<sub>x</sub> conditions

2016 ◽  
Author(s):  
Emma L. D'Ambro ◽  
Ben H. Lee ◽  
Jiumeng Liu ◽  
John E. Shilling ◽  
Cassandra J. Gaston ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Molecular Composition ◽  
Photochemical Oxidation ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Equilibrium Partitioning ◽  
Group Contribution Methods

Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation formed in an environmental simulation chamber using dry neutral seed particles, thereby suppressing the role of acid catalyzed multiphase chemistry, at a variety of oxidant conditions. A high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and AEROsols (FIGAERO) allowed for the simultaneous online sampling of the gas and particle composition. Under high HO2 and low NO conditions, highly oxygenated (O : C ≥ 1) C5 compounds were major components (~ 50 %) of the SOA. The overall composition of the SOA evolved both as a function of time and as a function of input NO concentrations. As the level of input NO increased, organic nitrates increased in both the gas- and particle-phases, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence time scale (5.2 hours) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular weight compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, indicative of thermal decomposition of effectively lower volatility components, likely larger molecular weight oligomers. We use these insights from the laboratory and observations of the same SOA components made during the Southern Oxidant and Aerosol Study (SOAS) to assess the importance of isoprene photooxidation as a local SOA source.

scholarly journals Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NO<sub><i>x</i></sub> conditions

2017 ◽  
Vol 17 (1) ◽  
pp. 159-174 ◽  
Author(s):  
Emma L. D'Ambro ◽  
Ben H. Lee ◽  
Jiumeng Liu ◽  
John E. Shilling ◽  
Cassandra J. Gaston ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Molecular Composition ◽  
Photochemical Oxidation ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Equilibrium Partitioning ◽  
Group Contribution Methods

Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO2 and low-NO conditions, highly oxygenated (O : C  ≥  1) C5 compounds were major components (∼ 50 %) of SOA. The SOA composition and effective volatility evolved both as a function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, which is indicative of thermal decomposition of effectively lower-volatility components such as larger molecular weight oligomers.

scholarly journals The SOA/VOC/NOx system: an explicit model of secondary organic aerosol formation

2007 ◽  
Vol 7 (4) ◽  
pp. 11223-11256 ◽  
Author(s):  
M. Camredon ◽  
B. Aumont ◽  
J. Lee-Taylor ◽  
S. Madronich
Keyword(s):  
Gas Phase ◽  
First Principles ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Current Understanding ◽  
Aerosol Formation ◽  
Explicit Model ◽  
Phase Oxidation ◽  
Gas Phase Oxidation ◽  
Atmospherically Relevant

Abstract. Our current understanding of secondary organic aerosol (SOA) formation is limited by our knowledge of gaseous secondary organics involved in gas/particle partitioning. The objective of this study is to explore (i) the potential for products of multiple oxidation steps contributing to SOA, and (ii) the evolution of the SOA/VOC/NOx system. We developed an explicit model based on the coupling of detailed gas-phase oxidation schemes with a thermodynamic condensation module. Such a model allows prediction of SOA mass and speciation on the basis of first principles. The SOA/VOC/NOx system is studied for the oxidation of 1-octene under atmospherically relevant concentrations. In this study, gaseous oxidation of octene is simulated to lead to SOA formation. Contributors to SOA formation are shown to be formed via multiple oxidation steps of the parent hydrocarbon. The behaviour of the SOA/VOC/NOx system simulated using the explicit model agrees with general tendencies observed during laboratory chamber experiments. This explicit modelling of SOA formation appears as a useful exploratory tool to (i) support interpretations of SOA formation observed in laboratory chamber experiments, (ii) give some insights on SOA formation under atmospherically relevant conditions and (iii) investigate implications for the regional/global lifetimes of the SOA.

scholarly journals Secondary Organic Aerosol Formation from the Oxidation of Decamethylcyclopentasiloxane at Atmospherically Relevant OH Concentrations

2021 ◽  
Author(s):  
Sophia M. Charan ◽  
Yuanlong Huang ◽  
Reina S. Buenconsejo ◽  
Qi Li ◽  
David R. Cocker III ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Urban Areas ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Aerosol Formation ◽  
Yield Data ◽  
Mixing Ratios ◽  
Outdoor Concentration ◽  
Chemical Products ◽  
Atmospherically Relevant

Abstract. Decamethylcyclopentasiloxane (D5, C10H30O5Si5) is measured at ppt levels outdoors and ppb levels indoors. Primarily used in personal care products, its outdoor concentration is correlated to population density. Since understanding the aerosol formation potential of volatile chemical products is critical to understanding particulate matter in urban areas, the secondary organic aerosol yield of D5 was studied under a range of OH concentrations, OH exposures, NOx concentrations, and temperatures. The secondary organic aerosol (SOA) yield from the oxidation of D5 is extremely dependent on the OH concentration, and differing measurements of the SOA yield from the literature are resolved in this study. Here, we compare experimental results from environmental chambers and flow tube reactors. Generally, there are high SOA yields (> 68 %) at OH mixing ratios of 5 × 109 molec cm−3. At atmospherically relevant OH concentrations, the SOA yield is largely < 5 % and usually ~1 %. This is significantly lower than SOA yields used in emission and particulate matter inventories and demonstrates the necessity of OH concentrations similar to the ambient environment when extrapolating SOA yield data to the outdoor atmosphere.

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