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Title: Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

Abstract

Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment andmore » climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1129356
Report Number(s):
PNNL-SA-99362
44638
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Geophysical Research. D. (Atmospheres), 119(6):3335-3351
Country of Publication:
United States
Language:
English
Subject:
Aerosols; Atmospheric Aging; Internally Mixed Organic/Nitrate particles; Environmental Molecular Sciences Laboratory

Citation Formats

Wang, Bingbing, and Laskin, Alexander. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts. United States: N. p., 2014. Web. doi:10.1002/2013JD021169.
Wang, Bingbing, & Laskin, Alexander. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts. United States. doi:10.1002/2013JD021169.
Wang, Bingbing, and Laskin, Alexander. Tue . "Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts". United States. doi:10.1002/2013JD021169.
@article{osti_1129356,
title = {Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts},
author = {Wang, Bingbing and Laskin, Alexander},
abstractNote = {Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.},
doi = {10.1002/2013JD021169},
journal = {Journal of Geophysical Research. D. (Atmospheres), 119(6):3335-3351},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 25 00:00:00 EDT 2014},
month = {Tue Mar 25 00:00:00 EDT 2014}
}
  • Atmospheric inorganic particles undergo complex heterogeneous reactions that change their physicochemical properties. Depletion of chloride in sea salt particles was reported in previous field studies and was attributed to the acid displacement of chlorides with inorganic acids, such as nitric and sulfuric acids [1-2]. Recently, we showed that NaCl can react with water soluble organic acids (WSOA) and release gaseous hydrochloric acid (HCl) resulting in formation of organic salts [3]. A similar mechanism is also applicable to mixed WSOA/nitrate particles where multi-phase reactions are driven by the volatility of nitric acid. Furthermore, secondary organic material, which is a complex mixturemore » of carboxylic acids, exhibits the same reactivity towards chlorides and nitrates. Here, we present a systematic study of reactions between atmospheric relevant WSOA, SOM, and inorganic salts including NaCl, NaNO3, and Ca(NO3)2 using complementary micro-spectroscopy analysis.« less
  • Distribution data and extraction mechanisms are reviewed for metal salt extraction by mixtures of water immiscible amines and organic acids in a diluent. Some new results from this laboratory were included to widen the scope of extractant components, provide more data on extraction of transition metal sulfates from concentrated solutions, and study the mutual effects of extraction and aqueous-phase acidity. An effort was made to present a matrix of the affecting parameters (extracted salt and extractant characteristics, aqueous-phase concentration and acidity, organic-phase concentration, temperature, etc.) and the distribution data (capacity and extraction selectivity and stoichiometry, the shape of the distributionmore » curve, and water coextraction). This data provides the tools required for tailoring extractants for many hydrometallurgical and waste management processes. In addition, it provides the basis for analysis of the mechanisms involved and of the species present in the organic phase.« less
  • A comprehensive discussion is provided for the complex system obtained on equilibrating an aqueous solution of a salt with an acid-base couple (ABC) extractant. These extractants were analyzed as a combination of a liquid cation exchanger and a liquid anion exchanger operating concurrently. The effect of the amine on the organic acid activity and the effect of the acid on the amine activity were compared to those of mineral bases and acids on single active component extractants. The available distribution and spectroscopic data, summarized in the previous article, are discussed.
  • A new field instrument is described that quantifies total particle phase organic nitrates. The instrument is based on the thermal dissociation laser induced fluorescence (TD-LIF) method that thermally converts nitrates to NO2 which is then detected by LIF. This instrument is unique in its ability to provide fast sensitive measurements of particle phase organic nitrates, without interference from inorganic nitrate. Here we use it to quantify organic nitrates in SOA generated from high-NOx photooxidation of limonene, a-pinene, D-3-carene, and tridecane. In these experiments the organic nitrate moiety is observed to be 6-15percent of the total SOA mass, depending on themore » organic precursor.« less