Internal Structure, Hygroscopic and Reactive Properties of Mixed Sodium Methanesulfonate-Sodium Chloride Particles

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Physical Chemistry Chemical Physics. PCCP (Print)

DOI:https://doi.org/10.1039/c1cp20444k· OSTI ID:1018128

Liu, Ying; Minofar, Babak; Desyaterik, Yury; Dames, E. E.; Zhu, Zihua; Cain, Jeremy P.; Hopkins, Rebecca J.; Gilles, Marry K.; Wang, Hai; Jungwirth, Pavel; Laskin, Alexander

Internal structures, hygroscopic properties and heterogeneous reactivity of mixed CH3SO3Na/NaCl particles were investigated using a combination of computer modeling and experimental approaches. Surfactant properties of CH3SO3 ions and their surface accumulation in wet, deliquesced particles were assessed using molecular dynamics (MD) simulations and surface tension measurements. Internal structures of dry CH3SO3Na/NaCl particles were investigated using scanning electron microscopy (SEM) assisted with X-ray microanalysis mapping, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The combination of these techniques shows that dry CH3SO3Na/NaCl particles are composed of a NaCl core surrounded by a CH3SO3Na shell. Hygroscopic growth, deliquescence and efflorescence phase transitions of mixed CH3SO3Na/NaCl particles were determined and compared to those of pure NaCl particles. These results indicate that particles undergo a two step deliquescence transition: first at ~69% relative humidity (RH) the CH3SO3Na shell takes up water, and then at ~75% RH the NaCl core deliquesces. Reactive uptake coefficients for the particle HNO3 heterogeneous reaction were determined at different CH3SO3Na/NaCl mixing ratios and RH. The net reaction probability decreased notably with increasing CH3SO3Na and at lower RH.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1018128
• Report Number(s): PNNL-SA-77991; 40087; KP1704020
• Journal Information: Physical Chemistry Chemical Physics. PCCP (Print), Journal Name: Physical Chemistry Chemical Physics. PCCP (Print) Journal Issue: 25 Vol. 13; ISSN 1463-9076
• Country of Publication: United States
• Language: English

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Environmental Molecular Sciences Laboratory