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

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

Research output: Contribution to journalArticle

9 Citations (Scopus)

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 languageEnglish (US)
Pages (from-to)158-167
Number of pages10
JournalJournal of Aerosol Science
Volume77
DOIs
StatePublished - Nov 1 2014

Fingerprint

Sodium sulfate
Sodium chloride
sodium chloride
Aerosols
Sodium Chloride
sodium
aerosol
sulfate
hygroscopicity
inorganic salt
water uptake
Raman spectroscopy
FTIR spectroscopy
relative humidity
Water
water content
Water content
Fourier transform infrared spectroscopy
Atmospheric humidity
Salts

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

Cite this

Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols. / Darr, Joshua P.; Davis, Shannon Q.; Kohno, Yohei; McKenna, Kevin; Morales, Paul.

In: Journal of Aerosol Science, Vol. 77, 01.11.2014, p. 158-167.

Research output: Contribution to journalArticle

Darr, Joshua P. ; Davis, Shannon Q. ; Kohno, Yohei ; McKenna, Kevin ; Morales, Paul. / Morphological effects on the hygroscopic properties of sodium chloride-sodium sulfate aerosols. In: Journal of Aerosol Science. 2014 ; Vol. 77. pp. 158-167.
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