Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols

Robert F. Hansen; Evan Z. Dalton; Rebecca B. Abney; Mark H. Engelhard; Gerardo Castillo Valdes; Sarah D. Burton; Rosalie K. Chu; Daniel P. Veghte; Swarup China; Yaroslav Losovyj; John B. Cliff; Jonathan D. Raff

doi:10.1021/acsearthspacechem.3c00111

Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols

Robert F. Hansen, Evan Z. Dalton, Rebecca B. Abney, Mark H. Engelhard, Gerardo Castillo Valdes, Sarah D. Burton, Rosalie K. Chu, Daniel P. Veghte, Swarup China, Yaroslav Losovyj, John B. Cliff, Jonathan D. Raff

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Organic nitrate ester compounds (RONO₂) are an important sink for nitrogen oxides (NO_x ≡ NO + NO₂) that impact ozone and organic aerosol formation in the lower atmosphere. While RONO₂ formation from gas phase oxidation chemistry and heterogeneous reactions involving reactive uptake of NO₃ into organic aerosols is well documented, in situ bulk-aqueous-phase production of RONO₂ within organic aerosols has not been explored as extensively. Here, we provide evidence that RONO₂ species are produced during aqueous phase reactions of nitronium (NO₂⁺) with humic and fulvic acids, which are used as surrogates for aerosol organic matter. X-ray photoelectron spectroscopy (XPS) and high-resolution mass spectrometry were used to characterize nitrogen functional groups and changes in bulk chemical composition during nitration reactions. Correlations between the organic N abundance in reacted humic and fulvic acids and functional group abundance measured by solid-state ¹³C NMR indicate that NO₂⁺ targets the lipid fraction of the organic matter. Fourier transform infrared spectroscopy (FTIR) analysis of model lipid compounds shows that the reaction of NO₂⁺ with terminal alcohols (ROH) and alkenes is a source of stable RONO₂ compounds. Further, the low-pH environment of most nitrate aerosols is expected to enhance the total terminal ROH pool through acid-catalyzed ester hydrolysis within the lipid-like fraction of natural organic matter. Our findings demonstrate that multiphase oxidation of organic matter by NO₂⁺, along with air-particle partitioning of products from gas-phase chemistry, may be an important source of particle-phase organic nitrates.

Original language	English
Pages (from-to)	1727-1738
Number of pages	12
Journal	ACS Earth and Space Chemistry
Volume	7
Issue number	9
DOIs	https://doi.org/10.1021/acsearthspacechem.3c00111
State	Published - Sep 21 2023
Externally published	Yes

Funding

We are grateful to the National Science Foundation for supporting this research (CHE-1609752 and CHE-2305078) and EZD (Graduate Research Fellowship Program, 2019286041). RBA was supported by a grant from the United States Department of Energy (DE-SC0014443). A portion of this research was performed on a project award DOI: 10.46936/sthm.proj.2015.48892/60005738 from the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science User Facility sponsored by the Biological and Environmental Research program under Contract No. DE-AC05-76RL01830. We also thank Dr. Nancy Washton for expertise and assistance with the solid state C NMR measurements at EMSL. Lastly, we are grateful to an anonymous reviewer whose comments contributed to improving this manuscript. 13

Keywords

atmospheric chemistry
humic-like substances
nitronium
organic nitrate
secondary organic aerosols

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10.1021/acsearthspacechem.3c00111

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Hansen, R. F., Dalton, E. Z., Abney, R. B., Engelhard, M. H., Castillo Valdes, G., Burton, S. D., Chu, R. K., Veghte, D. P., China, S., Losovyj, Y., Cliff, J. B., & Raff, J. D. (2023). Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols. ACS Earth and Space Chemistry, 7(9), 1727-1738. https://doi.org/10.1021/acsearthspacechem.3c00111

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title = "Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols",

abstract = "Organic nitrate ester compounds (RONO2) are an important sink for nitrogen oxides (NOx ≡ NO + NO2) that impact ozone and organic aerosol formation in the lower atmosphere. While RONO2 formation from gas phase oxidation chemistry and heterogeneous reactions involving reactive uptake of NO3 into organic aerosols is well documented, in situ bulk-aqueous-phase production of RONO2 within organic aerosols has not been explored as extensively. Here, we provide evidence that RONO2 species are produced during aqueous phase reactions of nitronium (NO2+) with humic and fulvic acids, which are used as surrogates for aerosol organic matter. X-ray photoelectron spectroscopy (XPS) and high-resolution mass spectrometry were used to characterize nitrogen functional groups and changes in bulk chemical composition during nitration reactions. Correlations between the organic N abundance in reacted humic and fulvic acids and functional group abundance measured by solid-state 13C NMR indicate that NO2+ targets the lipid fraction of the organic matter. Fourier transform infrared spectroscopy (FTIR) analysis of model lipid compounds shows that the reaction of NO2+ with terminal alcohols (ROH) and alkenes is a source of stable RONO2 compounds. Further, the low-pH environment of most nitrate aerosols is expected to enhance the total terminal ROH pool through acid-catalyzed ester hydrolysis within the lipid-like fraction of natural organic matter. Our findings demonstrate that multiphase oxidation of organic matter by NO2+, along with air-particle partitioning of products from gas-phase chemistry, may be an important source of particle-phase organic nitrates.",

keywords = "atmospheric chemistry, humic-like substances, nitronium, organic nitrate, secondary organic aerosols",

author = "Hansen, {Robert F.} and Dalton, {Evan Z.} and Abney, {Rebecca B.} and Engelhard, {Mark H.} and {Castillo Valdes}, Gerardo and Burton, {Sarah D.} and Chu, {Rosalie K.} and Veghte, {Daniel P.} and Swarup China and Yaroslav Losovyj and Cliff, {John B.} and Raff, {Jonathan D.}",

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doi = "10.1021/acsearthspacechem.3c00111",

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Hansen, RF, Dalton, EZ, Abney, RB, Engelhard, MH, Castillo Valdes, G, Burton, SD, Chu, RK, Veghte, DP, China, S, Losovyj, Y, Cliff, JB & Raff, JD 2023, 'Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols', ACS Earth and Space Chemistry, vol. 7, no. 9, pp. 1727-1738. https://doi.org/10.1021/acsearthspacechem.3c00111

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T1 - Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols

AU - Hansen, Robert F.

AU - Dalton, Evan Z.

AU - Abney, Rebecca B.

AU - Engelhard, Mark H.

AU - Castillo Valdes, Gerardo

AU - Burton, Sarah D.

AU - Chu, Rosalie K.

AU - Veghte, Daniel P.

AU - China, Swarup

AU - Losovyj, Yaroslav

AU - Cliff, John B.

AU - Raff, Jonathan D.

PY - 2023/9/21

Y1 - 2023/9/21

N2 - Organic nitrate ester compounds (RONO2) are an important sink for nitrogen oxides (NOx ≡ NO + NO2) that impact ozone and organic aerosol formation in the lower atmosphere. While RONO2 formation from gas phase oxidation chemistry and heterogeneous reactions involving reactive uptake of NO3 into organic aerosols is well documented, in situ bulk-aqueous-phase production of RONO2 within organic aerosols has not been explored as extensively. Here, we provide evidence that RONO2 species are produced during aqueous phase reactions of nitronium (NO2+) with humic and fulvic acids, which are used as surrogates for aerosol organic matter. X-ray photoelectron spectroscopy (XPS) and high-resolution mass spectrometry were used to characterize nitrogen functional groups and changes in bulk chemical composition during nitration reactions. Correlations between the organic N abundance in reacted humic and fulvic acids and functional group abundance measured by solid-state 13C NMR indicate that NO2+ targets the lipid fraction of the organic matter. Fourier transform infrared spectroscopy (FTIR) analysis of model lipid compounds shows that the reaction of NO2+ with terminal alcohols (ROH) and alkenes is a source of stable RONO2 compounds. Further, the low-pH environment of most nitrate aerosols is expected to enhance the total terminal ROH pool through acid-catalyzed ester hydrolysis within the lipid-like fraction of natural organic matter. Our findings demonstrate that multiphase oxidation of organic matter by NO2+, along with air-particle partitioning of products from gas-phase chemistry, may be an important source of particle-phase organic nitrates.

AB - Organic nitrate ester compounds (RONO2) are an important sink for nitrogen oxides (NOx ≡ NO + NO2) that impact ozone and organic aerosol formation in the lower atmosphere. While RONO2 formation from gas phase oxidation chemistry and heterogeneous reactions involving reactive uptake of NO3 into organic aerosols is well documented, in situ bulk-aqueous-phase production of RONO2 within organic aerosols has not been explored as extensively. Here, we provide evidence that RONO2 species are produced during aqueous phase reactions of nitronium (NO2+) with humic and fulvic acids, which are used as surrogates for aerosol organic matter. X-ray photoelectron spectroscopy (XPS) and high-resolution mass spectrometry were used to characterize nitrogen functional groups and changes in bulk chemical composition during nitration reactions. Correlations between the organic N abundance in reacted humic and fulvic acids and functional group abundance measured by solid-state 13C NMR indicate that NO2+ targets the lipid fraction of the organic matter. Fourier transform infrared spectroscopy (FTIR) analysis of model lipid compounds shows that the reaction of NO2+ with terminal alcohols (ROH) and alkenes is a source of stable RONO2 compounds. Further, the low-pH environment of most nitrate aerosols is expected to enhance the total terminal ROH pool through acid-catalyzed ester hydrolysis within the lipid-like fraction of natural organic matter. Our findings demonstrate that multiphase oxidation of organic matter by NO2+, along with air-particle partitioning of products from gas-phase chemistry, may be an important source of particle-phase organic nitrates.

KW - atmospheric chemistry

KW - humic-like substances

KW - nitronium

KW - organic nitrate

KW - secondary organic aerosols

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JF - ACS Earth and Space Chemistry

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ER -

Reaction of Organic Matter with Nitronium Ion as a Source of Organic Nitrate Esters in Proxies for Organic Aerosols

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