Laboratory simulation for the aqueous OH-oxidation of methyl vinyl ketone and methacrolein: significance to the in-cloud SOA production

Abstract. Increasing evidence suggests that secondary organic aerosol (SOA) is formed through aqueous phase reactions in atmospheric clouds. In the present study, the aqueous oxidation of methyl vinyl ketone (MVK) and methacrolein (MACR) via OH radical were investigated, with an emphasis on the composition and variation of small-molecular-weight organic products. In addition, high-molecular-weight compounds (HMWs) were found, interpreted as the ion abundance and time evolution. Our results provide, for the first time to our knowledge, experimental evidence that aqueous OH-oxidation of MVK contributes to SOA formation. Further, a mechanism primarily involving radical processes was proposed to gain a basic understanding of these two reactions. Based on the assumed mechanism, a kinetic model was developed for comparison with the experimental results. The model reproduced the observed profiles of first-generation intermediates, but failed to simulate the kinetics of most organic acids mainly due to the lack of chemical kinetics parameters for HMWs. A sensitivity analysis was performed in terms of the effect of stoichiometric coefficients for precursors on oxalic acid yields and the result indicates that additional pathways involving HMWs chemistry might play an important role in the formation of oxalic acid. We suggest that further study is needed for better understanding the behavior of multi-functional products and their contribution to the oxalic acid formation.

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Laboratory simulation for the aqueous OH-oxidation of methyl vinyl ketone and methacrolein: significance to the in-cloud SOA production

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-15595-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 15595-15628

Author(s):

X. Zhang ◽

Z. M. Chen ◽

Y. Zhao

Keyword(s):

Oxalic Acid ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Laboratory Simulation ◽

Cloud Droplets ◽

Kinetics Parameters ◽

Methyl Vinyl ◽

Oh Reactions ◽

Radical Processes

Abstract. Increasing evidence suggests that secondary organic aerosol (SOA) is formed through aqueous phase reactions in atmospheric clouds. In the present study, the aqueous oxidation of methyl vinyl ketone (MVK) and methacrolein (MACR) via OH radical were investigated under conditions typical of cloud droplets, with an emphasis on the composition and variation of oxygenated organic products. In addition to the small products, high-molecular-weight compounds (HMCs) with an oligomer system was found, interpreted as the ion abundance and time evolution. We observed the SOA yields of 23.8% and 8.8% from MVK–OH and MACR–OH reactions, respectively, for the entire 7 h experiment. Our results provide, for the first time to our knowledge, experimental evidence that aqueous OH-oxidation of MVK contributes to SOA formation. Further, a mechanism primarily involving radical processes was proposed to gain a basic understanding of these two reactions. Based on the assumed mechanism, a specific box model was developed for comparison with the experimental results. The model reproduced the observed profiles of first-generation intermediates, but failed to simulate the kinetics of most organic acids mainly due to the lack of chemical kinetics parameters for HMCs. A sensitivity analysis was performed in terms of the effect of reaction branching ratios on oxalic acid yields and the result indicates that additional pathways involving HMCs chemistry might play an important role in the formation of oxalic acid. We suggest that corresponding experiments are needed for better understanding the behavior of multi-functional products and their contribution to the oxalic acid formation.

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Development of DNPH/HPLC method for the measurement of carbonyl compounds in the aqueous phase: applications to laboratory simulation and field measurement

Environmental Chemistry ◽

10.1071/en09057 ◽

2009 ◽

Vol 6 (5) ◽

pp. 389 ◽

Cited By ~ 30

Author(s):

Hongli Wang ◽

Xuan Zhang ◽

Zhongming Chen

Keyword(s):

Aqueous Phase ◽

Carbonyl Compounds ◽

Global Climate ◽

Water Solution ◽

Field Measurements ◽

Hplc Method ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Laboratory Simulation ◽

Methyl Vinyl

Environmental context. Carbonyl compounds, a class of oxygenated organic matter, are crucial participants in atmospheric processes. Recently, studies have shown that the aqueous-phase processes of carbonyls have an important contribution to the formation of secondary organic aerosol (SOA), which is considered to have a significant impact on global climate change and human health. We developed the classical DNPH/HPLC method to characterise the aqueous-phase carbonyls, especially methacrolein, methyl vinyl ketone, glyoxal, and methylglyoxal, which are important precursors of SOA, in order to better understand the pathways of SOA formation in the atmosphere. Abstract. The DNPH/HPLC method for characterising monocarbonyls and dicarbonyls in the aqueous phase has been developed. A series of experiments have been carried out using eight atmospheric ubiquitous carbonyl compounds as model dissolved compounds in both acetonitrile and water solution to obtain the optimal derivatisation and analysis qualifications. Compared with the analysis of carbonyls dissolved in acetonitrile, the influence of acidity on the derivatisation efficiency should be carefully considered in determining carbonyls in water and the optimal acidity is pH 2.0. We find that methyl vinyl ketone (MVK) transforms to crotonaldehyde during the derivatisation reaction. This transformation can be controlled to a minor degree by increasing the mixing ratio of DNPH to MVK up to 100 : 1. This improved method has been satisfactorily applied to laboratory simulations and field measurements for better understanding the carbonyl chemistry in the atmosphere.

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Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high-NO<sub>x</sub> conditions

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-10779-2011 ◽

2011 ◽

Vol 11 (21) ◽

pp. 10779-10790 ◽

Cited By ~ 77

Author(s):

M. M. Galloway ◽

A. J. Huisman ◽

L. D. Yee ◽

A. W. H. Chan ◽

C. L. Loza ◽

...

Keyword(s):

Secondary Production ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Total Production ◽

Production Term ◽

Methyl Vinyl ◽

Chemical Mechanisms ◽

Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.2. The first-generation yield of glyoxal from isoprene was determined to be 2.1 (±0.6)%. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 hydroxycarbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 hydroxycarbonyls is important for models that include the production of the small organic molecules from isoprene.

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Yields of oxidized volatile organic compounds during the OH radical initiated oxidation of isoprene, methyl vinyl ketone, and methacrolein under high–NO<sub>x</sub> conditions

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-10693-2011 ◽

2011 ◽

Vol 11 (4) ◽

pp. 10693-10720 ◽

Cited By ~ 3

Author(s):

M. M. Galloway ◽

A. J. Huisman ◽

L. D. Yee ◽

A. W. H. Chan ◽

C. L. Loza ◽

...

Keyword(s):

Secondary Production ◽

First Generation ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Chemical Mechanism ◽

Total Production ◽

Production Term ◽

Methyl Vinyl ◽

Chemical Mechanisms ◽

Master Chemical Mechanism

Abstract. We present first-generation and total production yields of glyoxal, methylglyoxal, glycolaldehyde, and hydroxyacetone from the oxidation of isoprene, methyl vinyl ketone (MVK), and methacrolein (MACR) with OH under high NOx conditions. Several of these first-generation yields are not included in commonly used chemical mechanisms, such as the Leeds Master Chemical Mechanism (MCM) v. 3.1. Inclusion of first-generation production of glyoxal, glycolaldehyde and hydroxyacetone from isoprene and methylglyoxal from MACR greatly improves performance of an MCM based model during the initial part of the experiments. In order to further improve performance of the MCM based model, higher generation glyoxal production was reduced by lowering the first-generation yield of glyoxal from C5 carbonyls. The results suggest that glyoxal production from reaction of OH with isoprene under high NOx conditions can be approximated by inclusion of a first-generation production term together with secondary production only via glycolaldehyde. Analogously, methylglyoxal production can be approximated by a first-generation production term from isoprene, and secondary production via MVK, MACR and hydroxyacetone. The first-generation yields reported here correspond to less than 5% of the total oxidized yield from isoprene and thus only have a small effect on the fate of isoprene. However, due to the abundance of isoprene, the combination of first-generation yields and reduced higher generation production of glyoxal from C5 carbonyls is important for models which include the production of the small organic molecules from isoprene.

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Aqueous-phase ozonolysis of methacrolein and methyl vinyl ketone: a potentially important source of atmospheric aqueous oxidants

Atmospheric Chemistry and Physics ◽

10.5194/acp-8-2255-2008 ◽

2008 ◽

Vol 8 (8) ◽

pp. 2255-2265 ◽

Cited By ~ 60

Author(s):

Z. M. Chen ◽

H. L. Wang ◽

L. H. Zhu ◽

C. X. Wang ◽

C. Y. Jie ◽

...

Keyword(s):

Aqueous Phase ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Oxidation Products ◽

Laboratory Simulation ◽

Aerosol Formation ◽

Methyl Vinyl ◽

Gas Phase Oxidation ◽

Acid Catalyzed ◽

Catalyzed Oxidation

Abstract. Recent studies indicate that isoprene and its gas-phase oxidation products could contribute a considerable amount of aerosol through aqueous-phase acid-catalyzed oxidation with hydrogen peroxide (H2O2), although the source of H2O2 is unclear. The present study revealed a potentially important route to the formation of aqueous oxidants, including H2O2, from the aqueous-phase ozonolysis of methacrolein (MAC) and methyl vinyl ketone (MVK). Laboratory simulation was used to perform the atmospheric aqueous-phase ozonolysis at different pHs and temperatures. Unexpectedly high molar yields of the products, including hydroxylmethyl hydroperoxide (HMHP), formaldehyde (HCHO) and methylglyoxal (MG), of both of these reaction systems have been seen. Moreover, these yields are almost independent of pH and temperature and are as follows: (i) for MAC–O3, 70.3±6.3% HMHP, 32.3±5.8% HCHO and 98.6±5.4% MG; and (ii) for MVK–O3, 68.9±9.7% HMHP, 13.3±5.8% HCHO and 75.4±7.9% MG. A yield of 24.2±3.6% pyruvic acid has been detected for MVK–O3. HMHP is unstable in the aqueous phase and can transform into H2O2 and HCHO with a yield of 100%. We suggest that the aqueous-phase ozonolysis of MAC and MVK can contribute a considerable amount of oxidants in a direct and indirect mode to the aqueous phase and that these compounds might be the main source of aqueous-phase oxidants. The formation of oxidants in the aqueous-phase ozonolysis of MAC and MVK can lead to substantial aerosol formation from the aqueous-phase acid-catalyzed reaction of H2O2 with MAC, even if there are no other sources of oxidants.

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Aqueous-phase ozonolysis of methacrolein and methyl vinyl ketone: a potentially important source of atmospheric aqueous oxidants

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-17599-2007 ◽

2007 ◽

Vol 7 (6) ◽

pp. 17599-17623

Author(s):

Z. M. Chen ◽

H. L. Wang ◽

L. H. Zhu ◽

C. X. Wang ◽

C. Y. Jie ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Aqueous Phase ◽

Pyruvic Acid ◽

Vinyl Ketone ◽

Methyl Vinyl Ketone ◽

Laboratory Simulation ◽

Methyl Vinyl ◽

Reaction Systems ◽

Acid Catalyzed ◽

Catalyzed Oxidation

Abstract. Recent studies indicate that isoprene could contribute a considerable amount of aerosol through aqueous-phase acid-catalyzed oxidation with hydrogen peroxide (H2O2), although the source of H2O2 is unclear. The present study revealed a potentially important route to the formation of aqueous oxidants, including H2O2, from the aqueous-phase ozonolysis of methacrolein (MAC) and methyl vinyl ketone (MVK). Laboratory simulation was used to perform the atmospheric aqueous-phase ozonolysis at different pHs and temperatures. Unexpectedly high molar yields of the products, including hydroxylmethyl hydroperoxide (HMHP), formaldehyde (HCHO) and methylglyoxyl (MG), of both of these reaction systems have been seen. Moreover, these yields are almost independent of pH and temperature and are as follows: (i) for MAC–O3, 70.3±6.3% HMHP, 32.3±5.8% HCHO and 98.6±5.4% MG; and (ii) for MVK–O3, 68.9±9.7% HMHP, 13.3±5.8% HCHO and 75.4±7.9% MG. A yield of 24.2±3.6% pyruvic acid has been detected for MVK–O3. HMHP is unstable in the aqueous phase and can transform into H2O2 and HCHO with a yield of 100%. We suggest that the aqueous-phase ozonolysis of MAC and MVK can contribute a considerable amount of oxidants in a direct and indirect mode to the aqueous phase and that these compounds might be the main source of aqueous-phase oxidants. The formation of oxidants in the aqueous-phase ozonolysis of MAC and MVK effectively confirms the formation of aerosols from the aqueous-phase acid-catalyzed reaction of H2O2 with isoprene, even if there are no other sources of oxidants.

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