Grantee Research Project Results
2011 Progress Report: Chemistry of Secondary Organic Aerosol Formation from the Oxidation of Aromatic Hydrocarbons
EPA Grant Number: R833752Title: Chemistry of Secondary Organic Aerosol Formation from the Oxidation of Aromatic Hydrocarbons
Investigators: Ziemann, Paul J. , Arey, Janet , Atkinson, Roger
Institution: University of California - Riverside
EPA Project Officer: Chung, Serena
Project Period: October 1, 2007 through September 30, 2010 (Extended to March 31, 2012)
Project Period Covered by this Report: October 1, 2010 through September 30,2011
Project Amount: $514,464
RFA: Sources and Atmospheric Formation of Organic Particulate Matter (2007) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Particulate Matter , Air
Objective:
In this project we are developing a quantitative understanding of the kinetics, products, and mechanisms of secondary organic aerosol (SOA) formation from the photooxidation of aromatic hydrocarbons, and will provide this information to the scientific community in a form that can be readily incorporated into SOA modules used in air quality models for predicting atmospheric organic PM2.5 concentrations. These types of models are used widely to evaluate the potential effects of aerosols on global climate, air pollution and visibility, and human health, all of which are important problems confronting society.
Progress Summary:
In year 1 of this program, environmental chamber experiments were carried out to identify and quantify dicarbonyl products formed from reactions of OH radicals with toluene, o-, m- and p-xylene and 1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene. Gas-phase products were collected using denuders coated with XAD resin and O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) to derivatize carbonyl-containing products for GC/MS analysis. The 1,2-dicarbonyls glyoxal, methylglyoxal and biacetyl were observed, as were 8 of 9 possible unsaturated 1,4-dicarbonyl co-products. Compared to their potential co-product 1,2-dicarbonyls, unsaturated 1,4-diketones had similar formation yields, whereas all but one unsaturated 1,4-dialdehyde and keto-aldehyde had lower yields. These results provide new product yields from aromatic reactions that can be used as inputs to atmospheric models. In addition, the photolysis rate of 2-formylcinnamaldehyde was measured by monitoring its time dependent signal during the naphthalene-OH reaction using atmospheric pressure ionization mass spectrometry (API-MS). 2-Formylcinnamaldehyde is a major product of the OH radical-initiated reaction of naphthalene, the atmospherically most abundant polycyclic aromatic hydrocarbon, whose oxidation has been suggested as a possible source of SOA in urban atmospheres. Results were used with those from our earlier, 1997, study to determine a 2-formylcinnamaldehyde formation yield of 56%. Combined with other previously observed and quantified products, we now can account for ~92% of naphthalene reaction products under conditions where the NO2 concentration is greater than ~60 ppbv.
In year 2 of this project, the formation yields of glyoxal were measured from the OH radical-initiated reactions of naphthalene, 1-methylnaphthalene, 1,4-dimethylnaphthalene, acenaphthene and acenaphthylene, using solid phase microextraction (SPME) fibers pre-coated with PFBHA for collection of glyoxal and GC-FID for analysis. In the presence of NOx, glyoxal was observed as a first-generation product from these PAHs, with yields of 5%, 3%, 2%, 10-15% and <2%, respectively, and with a yield from naphthalene in the absence of NOx of 3%. Second-generation formation was obvious from the 1-methylnaphthalene, 1,4-dimethylnaphthalene and acenaphthene reactions. Simultaneous measurements of phthaldialdehyde from naphthalene, of 2-acetylbenzaldehyde from 1-methylnaphthalene and of 1,2-diacetylbenzene from 1,4-dimethylnaphthalene suggest that these aromatic dicarbonyls are co-products to glyoxal. The formation yields of glyoxal and methylglyoxal were measured from the gas-phase OH radical-initiated reactions of toluene, o-, m- and p-xylene, and 1,2,3-, 1,2,4- and 1,3,5-trimethylbenzene as a function of the NO2 concentration [(0.1-4) ppm]. Glyoxal and methylglyoxal were collected onto SPME fibers pre-coated with PFBHA and analyzed as their oximes by GC-FID. The glyoxal and methylglyoxal yields generally decrease with increasing NO2 concentration. However, for formation of glyoxal from 1,2,3-trimethylbenzene and of glyoxal and methylglyoxal from 1,2,4-trimethylbenzene, the yields were independent of the NO2 concentration within the experimental errors. These data allow, by a very short extrapolation, glyoxal and methylglyoxal yields appropriate for atmospheric conditions.
In years 2 and 3 of this project, 2-formylcinnamaldehyde formation from OH + naphthalene was investigated in the absence of NOx (using O3 + alkene to generate OH radicals) and in the presence of NOx at 0.1 and 1 ppm NOx. SPME fibers were used for sample collection, and our data show that 2-formylcinnamaldehyde is formed in the absence (as well as in the presence) of NOx, indicating that the OH-naphthalene adduct + O2 reaction forms 2-formylcinnamaldehyde. Based on our previous 2-formylcinnamaldehyde yield at ppm levels of NO2, the 2-formylcinnamaldehyde yields at 0.1 ppm NOx and in the absence of NOx are 43% and ~20%, respectively. In the absence of NO, RO2 + RO2 and RO2 + HO2 radical reactions will dominate and a lower yield of 2-formylcinnamaldehyde is expected if 2-formylcinnamaldehyde is formed from an alkoxy radical. Our data then suggest that the 2-formylcinnamaldehyde formation yield is not too dissimilar from the reactions of the OH-naphthalene adducts with O2 and NO2. We investigated the formation of unsaturated 1,4-dicarbonyls (and other products) from the OH radical-initiated reactions of furans (furan, 2- and 3-methylfuran and 2,3- and 2,5-dimethylfuran), using PFBHA-coated denuders, gas chromatography and API-MS. These studies are valuable for understanding the chemistry of aromatic reactions because the unsaturated 1,4-dicarbonyls formed from these furans are the same as those formed from aromatics, but are formed in higher yields and with fewer co-products so they can be used more easily to investigate the subsequent kinetics and products of the 1,4-unsaturated dicarbonyl reactions. We find that furan forms HC(O)CH=CHCHO, 2-methylfuran forms CH3C(O)CH=CHCHO, 3-methylfuran forms HC(O)C(CH3)=CHCHO, 2,3-dimethylfuran forms CH3C(O)C(CH3)=CHCHO, and 2,5-dimethylfuran forms CH3C(O)CH=CHC(O)CH3, with formation yields in the presence of NO of 82 ± 9%, 31 ± 5%, 38 ± 2%, 8 ± 2%, and 24 ± 3%, respectively. The formation yield of CH3C(O)CH=CHC(O)CH3 (mainly the cis-isomer) from OH + 2,5-dimethylfuran in the absence of NO also was measured, and determined to be 34 ± 4%. API-MS analyses showed the formation of additional products from all of the furans studied, which are attributed to (taking furan as an example) HC(O)CH=CHCOOH and/or the isomeric hydroxylactone. In addition, for OH + 2,5-dimethylfuran API-MS analyses showed the formation of a product attributed to the keto-ester CH3C(O)OCH=CHC(O)CH3. Using API-MS to monitor the 1,4-unsaturated dicarbonyls, the concentration-time dependence of the 1,4-unsaturated dicarbonyls has been studied from the five furans available; the results indicate that in our chambers with blacklamp irradiation, removal of the unsaturated 1,4-dicarbonyls is dominated by reaction with OH radicals, with OH radical reaction rate constants of (6 ± 2) ´ 10-11 cm3molecule-1s-1, and showing no evidence of rapid photolysis or wall loss rate of the unsaturated 1,4-dicarbonyls.
Future Activities:
We will re-determine the formation yields of unsaturated 1,4-dicarbonyls from the OH radical-initiated reactions of selected aromatic hydrocarbons using the PFBHA-coated denuder technique, by adding 2,5-hexanedione as an internal standard into the chamber after the reaction (the 2,5-hexanedione concentrations can be measured accurately by GC-FID without derivatization), as we have done in our recent OH + furans study. We also will conduct experiments to further investigate SOA formation from OH radical-initiated reactions of toluene, m-xylene, p-xylene, 1,3,5-trimethylbenzene, and nonylbenzene in the presence and absence of NOx. A major focus will be the role of oligomer formation, which will be probed via environmental chamber studies of these reactions in the presence of alkenes (which we know form hemiacetals in SOA) and solution studies of hemiacetal and peroxyhemiacetal formation from reactions of unsaturated carbonyls with alcohols, phenols, and hydroperoxides. Joint studies of SOA formation using real-time particle and gas mass spectrometric analysis also will be carried out to further investigate oligomer formation from unsaturated dicarbonyls. The experiments with nonylbenzene, which will form much less volatile products than the other aromatics, will allow us to investigate whether the reason that products of OH reactions with unsaturated 1,4-dicarbonyls do not form SOA is solely due to their volatility. If so, then they may form SOA if compounds are present with which they can form oligomers. Work also will continue on the preparation of a significant number of additional new manuscripts for publication.
Journal Articles on this Report : 8 Displayed | Download in RIS Format
Other project views: | All 34 publications | 16 publications in selected types | All 16 journal articles |
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Arey J, Obermeyer G, Aschmann SM, Chattopadhyay S, Cusick RD, Atkinson R. Dicarbonyl products of the OH radical-initiated reaction of a series of aromatic hydrocarbons. Environmental Science & Technology 2009;43(3):683-689. |
R833752 (2008) R833752 (2009) R833752 (2010) R833752 (2011) R833752 (Final) |
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Aschmann SM, Arey J, Atkinson R. Extent of H-atom abstraction from OH + p-cymene and upper limits to the formation of cresols from OH + m-xylene and OH + p-cymene. Atmospheric Environment 2010;44(32):3970-3975. |
R833752 (2010) R833752 (2011) R833752 (Final) |
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Aschmann SM, Arey J, Atkinson R. Reactions of OH radicals with C6-C10 cycloalkanes in the presence of NO:isomerization of C7-C10 cycloalkoxy radicals. Journal of Physical Chemistry A 2011;115(50):14452-14461. |
R833752 (2011) R833752 (Final) |
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Aschmann SM, Nishino N, Arey J, Atkinson R. Kinetics of the reactions of OH radicals with 2-and 3-methylfuran, 2,3-and 2,5-dimethylfuran, and E-and Z-3-hexene-2,5-dione, and products of OH + 2,5-dimethylfuran. Environmental Science & Technology 2011;45(5):1859-1865. |
R833752 (2010) R833752 (2011) R833752 (Final) |
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Nishino N, Arey J, Atkinson R. Formation and reactions of 2-formylcinnamaldehyde in the OH radical-initiated reaction of naphthalene. Environmental Science & Technology 2009;43(5):1349-1353. |
R833752 (2008) R833752 (2009) R833752 (2010) R833752 (2011) R833752 (Final) |
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Nishino N, Arey J, Atkinson R. Yields of glyoxal and ring-cleavage co-products from the OH radical-initiated reactions of naphthalene and selected alkylnaphthalenes. Environmental Science & Technology 2009;43(22):8554-8560. |
R833752 (2009) R833752 (2010) R833752 (2011) R833752 (Final) |
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Nishino N, Arey J, Atkinson R. Formation of nitro-products from the gas-phase OH radical-initiated reactions of toluene, naphthalene and biphenyl: effect of NO2 concentration (erratum). Environmental Science & Technology 2010;44(9):3644-3645. |
R833752 (2011) R833752 (Final) |
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Nishino N, Arey J, Atkinson R. Formation yields of glyoxal and methyglyoxal from the gas-phase OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes as a function of NO2 concentration. The Journal of Physical Chemistry A 2010;114(37):10140-10147. |
R833752 (2010) R833752 (2011) R833752 (Final) |
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Supplemental Keywords:
absorption, chemicals, environmental chemistry, global climate, oxidants, particulates, PAHs, regional and climate models, toxics, tropospheric, VOCRelevant Websites:
http://www.envisci.ucr.edu/faculty/arey.html Exithttp://www.envisci.ucr.edu/faculty/atkinson.html Exit
http://www.envisci.ucr.edu/faculty/ziemann.html Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.