Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols

Joshua P. Darr; Shannon Q. Davis; Yohei Kohno; Kevin McKenna; Paul Morales

doi:10.1016/j.jaerosci.2014.08.002

Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols

Joshua P. Darr, Shannon Q. Davis, Yohei Kohno, Kevin McKenna, Paul Morales

Chemistry

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

14 Scopus citations

Abstract

The hygroscopic properties of sodium sulfate, Na₂SO₄; sodium chloride, NaCl; and their mixed aerosols are monitored using a flow-cell apparatus and Fourier-transform infrared spectroscopy. While Na₂SO₄ exhibits the typical water uptake for an inorganic salt, spectra of NaCl and mixed NaCl-Na₂SO₄ aerosols reveal water content below the deliquescence relative humidity. This is explained on the basis of two different morphologies for NaCl and Na₂SO₄. While Na₂SO₄ can be described by a simple crystalline solid, NaCl contains pockets that trap water. The NaCl-Na₂SO₄ mixtures contain a combination of these two structural motifs, weighted by the relative amounts of the NaCl and Na₂SO₄ components. This makes NaCl-Na₂SO₄ mixtures an interesting candidate for exploring the effects of morphology on atmospherically relevant properties in a systematic fashion. Additionally, the formation of metastable Na₂SO₄ (III) is confirmed using Raman spectroscopy, though its effects on the hygroscopicity of NaCl-Na₂SO₄ mixtures are believed to be minimal.

Original language	English (US)
Pages (from-to)	158-167
Number of pages	10
Journal	Journal of Aerosol Science
Volume	77
DOIs	https://doi.org/10.1016/j.jaerosci.2014.08.002
State	Published - Nov 1 2014

Keywords

Hygroscopicity
Infrared spectroscopy
Metastable phase
Morphology
Sodium chloride aerosol
Sodium sulfate aerosol

ASJC Scopus subject areas

Environmental Engineering
Pollution
Mechanical Engineering
Fluid Flow and Transfer Processes
Atmospheric Science

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10.1016/j.jaerosci.2014.08.002

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title = "Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols",

abstract = "The hygroscopic properties of sodium sulfate, Na2SO4; sodium chloride, NaCl; and their mixed aerosols are monitored using a flow-cell apparatus and Fourier-transform infrared spectroscopy. While Na2SO4 exhibits the typical water uptake for an inorganic salt, spectra of NaCl and mixed NaCl-Na2SO4 aerosols reveal water content below the deliquescence relative humidity. This is explained on the basis of two different morphologies for NaCl and Na2SO4. While Na2SO4 can be described by a simple crystalline solid, NaCl contains pockets that trap water. The NaCl-Na2SO4 mixtures contain a combination of these two structural motifs, weighted by the relative amounts of the NaCl and Na2SO4 components. This makes NaCl-Na2SO4 mixtures an interesting candidate for exploring the effects of morphology on atmospherically relevant properties in a systematic fashion. Additionally, the formation of metastable Na2SO4 (III) is confirmed using Raman spectroscopy, though its effects on the hygroscopicity of NaCl-Na2SO4 mixtures are believed to be minimal.",

keywords = "Hygroscopicity, Infrared spectroscopy, Metastable phase, Morphology, Sodium chloride aerosol, Sodium sulfate aerosol",

author = "Darr, {Joshua P.} and Davis, {Shannon Q.} and Yohei Kohno and Kevin McKenna and Paul Morales",

note = "Funding Information: This work was funded by internal funding from the University of Nebraska at Omaha . The authors gratefully acknowledge Alan Gift for his assistance in acquiring the Raman spectra. Publisher Copyright: {\textcopyright} 2014 Elsevier Ltd.",

year = "2014",

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doi = "10.1016/j.jaerosci.2014.08.002",

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AU - Darr, Joshua P.

AU - Davis, Shannon Q.

AU - Kohno, Yohei

AU - McKenna, Kevin

AU - Morales, Paul

N1 - Funding Information: This work was funded by internal funding from the University of Nebraska at Omaha . The authors gratefully acknowledge Alan Gift for his assistance in acquiring the Raman spectra. Publisher Copyright: © 2014 Elsevier Ltd.

PY - 2014/11/1

Y1 - 2014/11/1

N2 - The hygroscopic properties of sodium sulfate, Na2SO4; sodium chloride, NaCl; and their mixed aerosols are monitored using a flow-cell apparatus and Fourier-transform infrared spectroscopy. While Na2SO4 exhibits the typical water uptake for an inorganic salt, spectra of NaCl and mixed NaCl-Na2SO4 aerosols reveal water content below the deliquescence relative humidity. This is explained on the basis of two different morphologies for NaCl and Na2SO4. While Na2SO4 can be described by a simple crystalline solid, NaCl contains pockets that trap water. The NaCl-Na2SO4 mixtures contain a combination of these two structural motifs, weighted by the relative amounts of the NaCl and Na2SO4 components. This makes NaCl-Na2SO4 mixtures an interesting candidate for exploring the effects of morphology on atmospherically relevant properties in a systematic fashion. Additionally, the formation of metastable Na2SO4 (III) is confirmed using Raman spectroscopy, though its effects on the hygroscopicity of NaCl-Na2SO4 mixtures are believed to be minimal.

AB - The hygroscopic properties of sodium sulfate, Na2SO4; sodium chloride, NaCl; and their mixed aerosols are monitored using a flow-cell apparatus and Fourier-transform infrared spectroscopy. While Na2SO4 exhibits the typical water uptake for an inorganic salt, spectra of NaCl and mixed NaCl-Na2SO4 aerosols reveal water content below the deliquescence relative humidity. This is explained on the basis of two different morphologies for NaCl and Na2SO4. While Na2SO4 can be described by a simple crystalline solid, NaCl contains pockets that trap water. The NaCl-Na2SO4 mixtures contain a combination of these two structural motifs, weighted by the relative amounts of the NaCl and Na2SO4 components. This makes NaCl-Na2SO4 mixtures an interesting candidate for exploring the effects of morphology on atmospherically relevant properties in a systematic fashion. Additionally, the formation of metastable Na2SO4 (III) is confirmed using Raman spectroscopy, though its effects on the hygroscopicity of NaCl-Na2SO4 mixtures are believed to be minimal.

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KW - Infrared spectroscopy

KW - Metastable phase

KW - Morphology

KW - Sodium chloride aerosol

KW - Sodium sulfate aerosol

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Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols

Abstract

Keywords

ASJC Scopus subject areas

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