Electrical Conductance and Viscosity of Concentrated H2SO4/H2O Binary Systems at Low Temperatures:  Correlation with Phase Transitions

Das, Avijit; Dev, S.; Shangpliang, H.; Nonglait, K. L.; Ismail, K.

doi:10.1021/jp9618136

Cited by 24 publications

(23 citation statements)

References 40 publications

(75 reference statements)

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“…B2) suggest that the particles observed under dry conditions consisted of oxalic acid dihydrate or non-stoichiometric hydrates containing about two water molecules per oxalic acid molecule. This is consistent with earlier studies suggesting that the tendency of aqueous acids to form glasses is most pronounced at compositions that correspond to stable hydrates (e.g., amorphous sulfuric acid monohydrate; Kanno and Itoi, 1984;Das et al, 1997;Tomikawa and Kanno, 1998;Koop, 2004). Besides hydration also dimer formation and surface kinetic effects could possibly play a role in making OA particles less volatile than glutaric acid particles (surface vs. bulk accommodation, adsorption & desorption rate coefficients, etc.…”

Section: Particle Composition and Stabilitysupporting

confidence: 91%

Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

et al. 2009

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Abstract. Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we present a conceptual framework for the interaction of amorphous aerosol particles with water vapor, outlining characteristic features and differences in comparison to crystalline particles. We used a hygroscopicity tandem differential mobility analyzer (H-TDMA) to characterize the hydration and dehydration of crystalline ammonium sulfate, amorphous oxalic acid and amorphous levoglucosan particles (diameter ∼100 nm, relative humidity 5-95% at 298 K). The experimental data and accompanying Köhler model calculations provide new insights into particle microstructure, surface adsorption, bulk absorption, phase transitions and hygroscopic growth. The results of these and related investigations lead to the following conclusions:(1) Many organic substances, including carboxylic acids, carbohydrates and proteins, tend to form amorphous rather than crystalline phases upon drying of aqueous solution droplets. Depending on viscosity and microstructure, the amorphous phases can be classified as glasses, rubbers, gels or viscous liquids.(2) Amorphous organic substances tend to absorb water vapor and undergo gradual deliquescence and hygroscopic growth at lower relative humidity than their crystalline counterparts.(3) In the course of hydration and dehydration, certain organic substances can form rubber-or gel-like structures Correspondence to: U. Pöschl (u.poschl@mpic.de) (supramolecular networks) and undergo transitions between swollen and collapsed network structures.(4) Organic gels or (semi-)solid amorphous shells (glassy, rubbery, ultra-viscous) with low molecular diffusivity can kinetically limit the uptake and release of water and may influence the hygroscopic growth and activation of aerosol particles as cloud condensation nuclei (CCN) and ice nuclei (IN). Moreover, (semi-)solid amorphous phases may influence the uptake of gaseous photo-oxidants and the chemical transformation and aging of atmospheric aerosols.(5) The shape and porosity of amorphous and crystalline particles formed upon dehydration of aqueous solution droplets depend on chemical composition and drying conditions. The apparent volume void fractions of particles with highly porous structures can range up to ∼50% or more (xerogels, aerogels).(6) For efficient description of water uptake and phase transitions of aerosol particles, we propose not to limit the terms deliquescence and efflorescence to equilibrium phase transitions of crystalline substances. Instead we propose generalized definitions according to which amorphous and crystalline components can undergo gradual or prompt, partial or full deliquescence or efflorescence.We suggest that (semi-)solid amorphous phases may be important not only in the upper atmosphere as suggested in recent studies of glass formation at low temperatures. Depending on relative humidity, (semi-)solid phases and moisture-induced glass transitions may also play a role in gas-particle intera...

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Section: Particle Composition and Stabilitysupporting

confidence: 91%

Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

et al. 2009

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Section: Particle Composition and Stabilitysupporting

confidence: 91%

Amorphous and crystalline aerosol particles interacting with water vapor – Part 1: Microstructure, phase transitions, hygroscopic growth and kinetic limitations

Mikhailov¹,

Vlasenko²,

Martin³

et al. 2009

Preprint

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Abstract. Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we outline characteristic features and differences in the interaction of amorphous and crystalline aerosol particles with water vapor. Using a hygroscopicity tandem differential mobility analyzer (H-TDMA), we performed hydration, dehydration and cyclic hydration&dehydration experiments with aerosol particles composed of levoglucosan, oxalic acid and ammonium sulfate (diameters ~100–200 nm, relative uncertainties <0.4%, relative humidities <5% to 95% at 298 K). The measurements and accompanying Köhler model calculations provide new insights into particle microstructure, surface adsorption, bulk absorption, phase transitions and hygroscopic growth. The results of these and related investigations lead to the following main conclusions: 1. Many organic substances (including carboxylic acids, carbohydrates and proteins) tend to form amorphous rather than crystalline phases upon drying of aqueous solution droplets. Depending on viscosity and microstructure, the amorphous phases can be classified as glasses, rubbers, gels or viscous liquids. 2. Amorphous organic substances tend to absorb water vapor and undergo gradual deliquescence and hygroscopic growth at much lower relative humidity than their crystalline counterparts. 3. In the course of hydration and dehydration, certain organic substances can form rubber- or gel-like structures (supra-molecular networks) and undergo stepwise transitions between swollen and collapsed network structures. 4. Organic gels or (semi-)solid amorphous shells (glassy, rubbery, ultra-viscous) with low molecular diffusivity can kinetically limit the uptake and release of water by submicron aerosol particles on (multi-)second time scales, which may influence the hygroscopic growth and activation of aerosol particles as cloud condensation nuclei (CCN) and ice nuclei (IN). 5. The shape and porosity of amorphous and crystalline particles formed upon dehydration of aqueous solution droplets depend on chemical composition and drying conditions. The apparent volume void fractions of particles with highly porous structures can range up to ~50% or more (xerogels, aerogels). Void fractions as well as residual water in dried aerosol particles that are not water-free (due to kinetic limitations of drying or stable hydrate formation) should be taken into account in Köhler model calculations of hygroscopic growth and CCN activation. 6. For efficient description of water uptake and phase transitions of amorphous and crystalline organic and inorganic aerosol particles and particle components, we propose not to limit the terms deliquescence and efflorescence to equilibrium phase transitions of crystalline substances interacting with water vapor. Instead we propose the following generalized definitions: Deliquescence is the transformation of a (semi-)solid substance into a liquid aqueous solution, whereby water is absorbed from the gas phase ("liquefaction upon humidification/hydration"). Efflorescence is the transformation of a substance from a liquid aqueous solution into a (semi-)solid phase, whereby water is evaporated ("solidification upon drying/dehydration"). According to these definitions, individual components as well as entire aerosol particles can undergo gradual or prompt, partial or full deliquescence or efflorescence.

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“…For a given composition, the computed value is expected to be very close to since it represents the ideal glass transition temperature which should be independent of the transport property. 162 Das et al 107 found that the values of and are in fact close to one another over the explored concentration range Their investigations have also highlighted correlations between the viscosityconcentration curves and the phase diagram of the system.…”

Section: (Ii) Power-law Equations For Viscosity and Electrical Conducmentioning

confidence: 90%

“…Concerning the system studied in the subambient region, between 200 and 300 K, Das et al 107 have found that a power-law type equation [158][159][160] based on the mode coupling theory of relaxation in supercooled liquids 161 is better than a Vogel-Tammann-Fulcher type equation 108 to describe the temperature dependence of the electrical conductivity and the viscosity .…”

Section: (Ii) Power-law Equations For Viscosity and Electrical Conducmentioning

confidence: 99%

Thermodynamic and Transport Properties of Bridging Electrolyte-Water Systems

Abraham

2002

Modern Aspects of Electrochemistry

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Electrical Conductance and Viscosity of Concentrated H₂SO₄/H₂O Binary Systems at Low Temperatures: Correlation with Phase Transitions

Cited by 24 publications

References 40 publications

Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

Amorphous and crystalline aerosol particles interacting with water vapor – Part 1: Microstructure, phase transitions, hygroscopic growth and kinetic limitations

Thermodynamic and Transport Properties of Bridging Electrolyte-Water Systems

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