scholarly journals Chemical aging of ambient organic aerosol from heterogeneous reaction with hydroxyl radicals

2008 ◽  
Vol 35 (13) ◽  
Author(s):  
I. J. George ◽  
J. Slowik ◽  
J. P. D. Abbatt
Keyword(s):  
Hydroxyl Radicals ◽  
Heterogeneous Reaction ◽  
Organic Aerosol ◽  
Chemical Aging

scholarly journals Multi-generation chemical aging of <i>α</i>-pinene ozonolysis products by reactions with OH

2018 ◽  
Vol 18 (5) ◽  
pp. 3589-3601 ◽  
Author(s):  
Ningxin Wang ◽  
Evangelia Kostenidou ◽  
Neil M. Donahue ◽  
Spyros N. Pandis
Keyword(s):  
Hydroxyl Radicals ◽  
Atomic Oxygen ◽  
First Generation ◽  
Organic Aerosol ◽  
Product Distribution ◽  
Smog Chamber ◽  
Experimental Conditions ◽  
Chemical Aging ◽  
Significant Difference ◽  
Volatile Organic

Abstract. Secondary organic aerosol (SOA) formation from volatile organic compounds (VOCs) in the atmosphere can be thought of as a succession of oxidation steps. The production of later-generation SOA via continued oxidation of the first-generation products is defined as chemical aging. This study investigates aging in the α-pinene ozonolysis system with hydroxyl radicals (OH) through smog chamber experiments. The first-generation α-pinene ozonolysis products were allowed to react further with OH formed via HONO photolysis. After an equivalent of 2–4 days of typical atmospheric oxidation conditions, homogeneous OH oxidation of the α-pinene ozonolysis products resulted in a 20–40 % net increase in the SOA for the experimental conditions used in this work. A more oxygenated product distribution was observed after aging based on the increase in aerosol atomic oxygen-to-carbon ratio (O : C) by up to 0.04. Experiments performed at intermediate relative humidity (RH) of 50 % showed no significant difference in additional SOA formation during aging compared to those performed at a low RH of less than 20 %.

scholarly journals Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation

2014 ◽  
Vol 14 (21) ◽  
pp. 28919-28947
Author(s):  
A. Tasoglou ◽  
S. N. Pandis
Keyword(s):  
Relative Humidity ◽  
Hydroxyl Radicals ◽  
Secondary Organic Aerosol ◽  
Uv Light ◽  
Organic Aerosol ◽  
Average Density ◽  
Mass Yield ◽  
Chemical Aging ◽  
High Concentrations ◽  
Subsequent Chemical

Abstract. The secondary organic aerosol (SOA) production during the oxidation of β-caryophyllene by ozone (O3) and hydroxyl radicals (OH) and the subsequent chemical aging of the products during reactions with OH were investigated. Experiments were conducted with ozone, hydroxyl radicals at low NOx (zero added NOx) and at high NOx (100s of ppb). The SOA mass yield at 10 μg m−3 of organic aerosol is 26% for the ozonolysis, 20% for the reaction with OH at low NOx and 38% at high NOx. Parameterizations of the fresh SOA yields have been developed. The average fresh SOA atomic O : C ratio varied from 0.24 to 0.33 depending on the oxidant and the NOx level. The chemical aging of the produced β-caryophyllene SOA was studied by exposing the fresh SOA to high concentrations (107 molecules cm−3) of hydroxyl radicals for several hours. These additional reactions increased the SOA concentration by 15–40% and the O : C by approximately 25%. It was found that the exposure to UV-light has no effect on the β-caryophyllene SOA. Experiments suggested that there was a significant impact of the relative humidity in the chemical aging of the SOA. We quantified the evaporation rates of β-caryophyllene SOA by using a thermodenuder. The corresponding volatility distributions and the effective vaporization enthalpies were estimated. An average density of 1.06 ± 0.1 g cm−3 of the β-caryophyllene SOA was estimated.

scholarly journals Formation and chemical aging of secondary organic aerosol during the β-caryophyllene oxidation

2015 ◽  
Vol 15 (11) ◽  
pp. 6035-6046 ◽  
Author(s):  
A. Tasoglou ◽  
S. N. Pandis
Keyword(s):  
Hydroxyl Radicals ◽  
Secondary Organic Aerosol ◽  
Uv Light ◽  
Organic Aerosol ◽  
Average Density ◽  
Chemical Aging ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Dry Conditions ◽  
High Concentrations

Abstract. The secondary organic aerosol (SOA) production during the oxidation of β-caryophyllene by ozone (O3) and hydroxyl radicals (OH) and the subsequent chemical aging of the products during reactions with OH were investigated. Experiments were conducted with ozone and with hydroxyl radicals at low NOx (zero added NOx) and at high NOx (hundreds of parts per billion). The SOA mass yield at 10 μg m−3 of organic aerosol was 27% for the ozonolysis, 20% for the reaction with OH at low NOx, and 38% at high NOx under dry conditions, 20 °C, and ozone excess. Parameterizations of the fresh SOA yields have been developed. The average fresh SOA atomic O : C ratio varied from 0.24 to 0.34 depending on the oxidant and the NOx level, while the H : C ratio was close to 1.5 for all systems examined. An average density of 1.06 ± 0.1 μg m−3 of the β-caryophyllene SOA was estimated. The exposure to UV light had no effect on the β-caryophyllene SOA concentration and aerosol mass spectrometer (AMS) measurements. The chemical aging of the β-caryophyllene SOA produced was studied by exposing the fresh SOA to high concentrations (107 molecules cm−3) of OH for several hours. These additional reactions increased the SOA concentration by 15–40% and O : C by approximately 25%. A limited number of experiments suggested that there was a significant impact of the relative humidity on the chemical aging of the SOA. The evaporation rates of β-caryophyllene SOA were quantified by using a thermodenuder allowing us to estimate the corresponding volatility distributions and effective vaporization enthalpies.

scholarly journals Multi-generation Chemical Aging of α-Pinene Ozonolysis Products by Reactions with OH

2017 ◽  
Author(s):  
Ningxin Wang ◽  
Evangelia Kostenidou ◽  
Neil M. Donahue ◽  
Spyros N. Pandis
Keyword(s):  
Hydroxyl Radicals ◽  
Atomic Oxygen ◽  
First Generation ◽  
Organic Aerosol ◽  
Product Distribution ◽  
Smog Chamber ◽  
Experimental Conditions ◽  
Chemical Aging ◽  
Significant Difference ◽  
Volatile Organic

Abstract. Secondary organic aerosol (SOA) formation from volatile organic compounds (VOCs) in the atmosphere can be thought of as a succession of oxidation steps. The production of later-generation SOA via continued oxidation of the first-generation products is defined as chemical aging. This study investigates aging in the α-pinene ozonolysis system with hydroxyl radicals (OH) through smog chamber experiments. The first-generation α-pinene ozonolysis products were allowed to react further with OH formed via HONO photolysis. After an equivalent of 2–4 days' of typical atmospheric oxidation conditions, homogeneous OH oxidation of the α-pinene ozonolysis products resulted in a 20–40 % net increase of the SOA for the experimental conditions used in this work. A more oxygenated product distribution was observed after aging based on the increase in aerosol atomic oxygen to carbon ratio (O : C) by up to 0.04. Experiments performed at intermediate relative humidity (RH) of 50 % showed no significant difference in additional SOA formation during aging compared to those performed at low RH of less than 20 %.

scholarly journals Volatility and hygroscopicity of aging secondary organic aerosol in a smog chamber

2011 ◽  
Vol 11 (3) ◽  
pp. 7423-7467 ◽  
Author(s):  
T. Tritscher ◽  
J. Dommen ◽  
P. F. DeCarlo ◽  
P. B. Barmet ◽  
A. P. Praplan ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Physical Parameters ◽  
Oh Radicals ◽  
Smog Chamber ◽  
Chemical Aging ◽  
Aerosol Mass ◽  
Gas Phase Oxidation ◽  
Substantial Change

Abstract. The evolution of secondary organic aerosols (SOA) during (photo-)chemical aging processes was investigated in a smog chamber. SOA from 10–40 ppb α-pinene was formed during ozonolysis followed by aging with OH radicals. The particles' volatility and hygroscopicity (expressed as volume fraction remaining (VFR) and hygroscopicity parameter κ) were measured with a volatility and hygroscopicity tandem differential mobility analyzer (V/H-TDMA). These measurements were used as sensitive physical parameters to reveal the possible mechanisms responsible for the chemical changes in the SOA composition during aging: A change of VFR and/or κ during processing of atmospheric aerosol may occur either by addition of SOA mass (by condensation) or by an exchange of molecules in the SOA by other molecules with different properties. The former process increases the SOA mass by definition, while the latter keeps the SOA mass roughly constant and may occur either by heterogeneous reactions on the surface of the SOA particles, by homogeneous reactions like oligomerization or by an evaporation – gas-phase oxidation – recondensation cycle. Thus, when there is a substantial change in the aerosol mass with time, the condensation mechanism may be assumed to be dominant, while, when the mass stays roughly constant the exchange mechanism is likely to be dominant, a process termed ripening here. Depending on the phase of the experiment, an O3 mediated condensation, O3 mediated ripening, OH mediated condensation, and OH mediated ripening could be distinguished. During the O3 mediated condensation the particles volatility decreased (increasing VFR) while the hygroscopicity increased. Thereafter, in the course of O3 mediated ripening volatility continued to decrease, but hygroscopicity stayed roughly constant. After exposing the SOA to OH radicals an OH mediated condensation started with a significant increase of SOA mass. Concurrently, hygroscopicity and volatility increased. This phase was then followed by an OH mediated ripening with a decrease of volatility.

scholarly journals Volatility and lifetime against OH heterogeneous reaction of ambient Isoprene Epoxydiols-Derived Secondary Organic Aerosol (IEPOX-SOA)

2016 ◽  
Author(s):  
Weiwei Hu ◽  
Brett B. Palm ◽  
Douglas A. Day ◽  
Pedro Campuzano-Jost ◽  
Jordan E. Krechmer ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Heterogeneous Reaction ◽  
Ambient Air ◽  
Organic Aerosol ◽  
Amazon Forest ◽  
Reaction Products ◽  
Ambient Conditions ◽  
Forested Areas ◽  
Humidity Dependence

Abstract. Isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) can contribute substantially to organic aerosol (OA) concentrations in forested areas under low NO conditions, hence significantly influencing the regional and global OA budgets, accounting for example for 16–36 % of the submicron OA in the SE US summer. Particle evaporation measurements from a thermodenuder show that the volatility of ambient IEPOX-SOA is lower than that of bulk OA and also much lower than that of known monomer IEPOX-SOA tracer species, indicating that IEPOX-SOA likely exists mostly as oligomers in the aerosol phase. The OH aging process of ambient IEPOX-SOA was investigated with an oxidation flow reactor (OFR). New IEPOX-SOA formation in the reactor was negligible, as the OFR cannot accelerate processes such as aerosol uptake and reactions that do not scale with OH. Simulation results indicate that adding ~ 100 µg m−3 of pure H2SO4 to the ambient air allows to efficiently form IEPOX-SOA in the reactor. The heterogeneous reaction rate coefficient of ambient IEPOX-SOA with OH radical (kOH) was estimated as 4.0 ± 2.0 × 10−13 cm3 molec−1 s−1, which is equivalent to more than a 2-week lifetime. A similar kOH was found for measurements of OH oxidation of ambient Amazon forest air in an OFR. At higher OH exposures in the reactor (> 1 × 1012 molec. cm−3 s), the mass loss of IEPOX-SOA due to heterogeneous reaction was mainly due to revolatilization of fragmented reaction products. We report for the first time OH reactive uptake coefficients (γOH = 0.59 ± 0.33 in SE US and γOH = 0.68 ± 0.38 in Amazon) for SOA under ambient conditions. A relative humidity dependence of kOH and γOH was observed, consistent with surface area-limited OH uptake. No decrease of kOH was observed as OH concentrations increased. These observation of physicochemical properties of IEPOX-SOA can help to constrain OA impact on air quality and climate.

The role of alkoxy radicals in the heterogeneous reaction of two structural isomers of dimethylsuccinic acid

2015 ◽  
Vol 17 (38) ◽  
pp. 25309-25321 ◽  
Author(s):  
Chiu Tung Cheng ◽  
Man Nin Chan ◽  
Kevin R. Wilson
Keyword(s):  
Molecular Weight ◽  
Hydroxyl Radicals ◽  
Heterogeneous Reaction ◽  
Methyl Groups ◽  
Structural Isomers ◽  
Alkoxy Radicals ◽  
Weight Growth ◽  
Bond Scission

The heterogeneous reaction of hydroxyl radicals with two isomers of dimethylsuccinic acid is used to explore how the location of branched methyl groups controls C–C bond scission and molecular weight growth reactions.

scholarly journals Appearance of strong absorbers and fluorophores in limonene-O3secondary organic aerosol due to NH4+-mediated chemical aging over long time scales

2010 ◽  
Vol 115 (D5) ◽  
Author(s):  
David L. Bones ◽  
Dana K. Henricksen ◽  
Stephen A. Mang ◽  
Michael Gonsior ◽  
Adam P. Bateman ◽  
...  
Keyword(s):  
Time Scales ◽  
Organic Aerosol ◽  
Chemical Aging ◽  
Long Time

scholarly journals Gas uptake and chemical aging of semisolid organic aerosol particles

2011 ◽  
Vol 108 (27) ◽  
pp. 11003-11008 ◽  
Author(s):  
M. Shiraiwa ◽  
M. Ammann ◽  
T. Koop ◽  
U. Poschl
Keyword(s):  
Aerosol Particles ◽  
Organic Aerosol ◽  
Chemical Aging ◽  
Gas Uptake
Sign in / Sign up

Export Citation Format

Share Document