Towards modelling the meniscus geometry and volume of capillary water between two contacting microspheres in moist air

Glasstetter, R.; Ricketts, C.I.; Wilhelm, J.G.

doi:10.1016/s0021-8502(05)80068-0

Cited by 7 publications

(3 citation statements)

References 1 publication

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“…Once a sufficient amount of liquid has condensed, the surface tension in the liquid will tend to bring the primary particles into a closer configuration to minimize the surface of the liquid phase (Glasstetter et al 1991). Our results also support this hypothesis by noting that the sulphuric acidcoated (θ can be assumed <90 • ), but not the fresh hydrophobic soot (θ can be assumed >90…”

Section: Mass-mobility Relationshipsupporting

confidence: 75%

Processing of Soot by Controlled Sulphuric Acid and Water Condensation—Mass and Mobility Relationship

Pagels

Khalizov

McMurry

et al. 2009

Aerosol Science and Technology

191

262

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. To simulate atmospheric processing, combustion soot agglomerates were altered by sulphuric acid vapor condensation, relative humidity (RH) cycling, and evaporation of the sulphuric acid and water by heating. Primary investigated properties were particle mobility size and mass. Secondary properties, derived from these, include effective density, fractal dimension, dynamic shape factor, and the mass fraction of condensed material. A transformation of the soot particles to more compact forms occurs as sulphuric acid and water condense onto fresh soot. The particle mass increases and initially the mobility diameter decreases, indicating restructuring of the soot core, likely due to surface tension forces. For a given soot source and condensing liquid, the degree of compaction depends strongly on the mass (or volume) fraction of condensed material. For water and sulphuric acid condensing on combustion soot, a mass increase of 2-3 times is needed for a transformation to spherical particles. In the limit of spherical particles without voids, the effective density then approaches the inherent material density, the fractal dimension approaches 3 and the dynamic shape factor approaches 1. Our results indicate that under typical atmospheric conditions, soot particles will be fully transformed to spherical droplets on a time scale of several hours. It is expected that the morphology changes and addition of soluble material to soot strongly affect the optical and hygroscopic properties of soot.

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Section: Mass-mobility Relationshipsupporting

confidence: 75%

Processing of Soot by Controlled Sulphuric Acid and Water Condensation—Mass and Mobility Relationship

Pagels

Khalizov

McMurry

et al. 2009

Aerosol Science and Technology

191

262

View full text Add to dashboard Cite

show abstract

“…The significant restructuring may indicate the presence of a subcooled liquid‐like PAH layer on the aggregate surface. For liquid coatings, the restructuring is described qualitatively as a sequence of three interconnected events [ Glasstetter et al ., ; Kütz and Schmidt‐Ott , ]. First, when a thin coat of a wetting liquid is formed on the aggregate surface, the molecules of the liquid replace the solid‐solid contact by a solid‐liquid contact in the meniscus between spherules, reducing the surface energy and enabling sliding and rolling of the monomers [ Kütz and Schmidt‐Ott , ].…”

Section: Resultsmentioning

confidence: 99%

An unexpected restructuring of combustion soot aggregates by subnanometer coatings of polycyclic aromatic hydrocarbons

Chen

Fan

Shaltout

et al. 2016

Geophysical Research Letters

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We investigated the effect of thin polycyclic aromatic hydrocarbon (PAH) coatings on the structure of soot aggregates. Soot aerosol from an inverted diffusion burner was size classified, thermally denuded, coated with six different PAHs, and then characterized using scanning electron microscopy, light scattering, and mass‐mobility measurements. Contrary to our expectation, significant restructuring was observed in the presence of subnanometer layers of pyrene, fluoranthene, and phenanthrene. These PAHs remained in subcooled liquid state in thin films, whereby the liquid layer acted as a lubricant, reducing the force required to initiate the restructuring. Thin layers of PAH of higher melting temperatures (perylene, anthracene, and triphenylene) presumably remained solid because these chemicals induced lesser structural changes. Our results suggest that some of the intrinsic PAH generated during incomplete combustion may induce significant restructuring of soot aggregates, even when present in small quantities, altering the properties and atmospheric impacts of combustion aerosols.

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“…In the case of liquid coatings, such as sulfuric acid and ozonolysis products of α-pinene , the force leading to compaction of agglomerates is the surface tension of the liquid that brings the primary particles into a closer configuration in order to minimize the surface of the liquid . Once the contact region between the solid surfaces is replaced by a contact of liquid to liquid, restructuring of the agglomerates occurs.…”

Section: Resultsmentioning

confidence: 99%

Effects of Coating of Dicarboxylic Acids on the Mass−Mobility Relationship of Soot Particles

Han

Khalizov

Wang

et al. 2009

Environ. Sci. Technol.

111

112

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Atandem differential mobility analyzer (TDMA) and a differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) have been employed to study morphology and hygroscopicity of soot aerosol internally mixed with dicarboxylic acids. The effective densities, fractal dimensions, and dynamic shape factors of soot particles before and after coating with succinic and glutaric acids are determined. Coating of soot with succinic acid results in a significant increase in the particle mobility diameter, mass, and effective density, but these properties recover to their initial values once succinic acid is removed by heating, suggesting that no restructuring of the soot core occurs. This conclusion is also supported from the observation of similar fractal dimensions and dynamic shape factors for fresh and coated/heated soot aggregates. Also, no change is observed when succinic acid-coated aggregates are cycled through elevated relative humidity (5% to 90% to 5% RH) below the succinic acid deliquescence point. When soot is coated with glutaric acid, the particle mass increases, but the mobility diameter shrinks by 10-40%. Cycling the soot aerosol coated with glutaric acid through elevated relative humidity leads to an additional mass increase, indicating that condensed water remains within the coating even at low RH. The fractal dimension of soot particles increases after coating and remains high when glutaric acid is removed by heating. The dynamic shape factor of glutaric acid-coated and heated soot is significantly lower than that of fresh soot, suggesting a significant restructuring of the soot agglomerates by glutaric acid. The results imply that internal mixing of soot aerosol during atmospheric aging leads to changes in hygroscopicity, morphology, and effective density, which likely modify their effects on direct and indirect climate forcing and deposition in the human respiratory system.

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Towards modelling the meniscus geometry and volume of capillary water between two contacting microspheres in moist air

Cited by 7 publications

References 1 publication

Processing of Soot by Controlled Sulphuric Acid and Water Condensation—Mass and Mobility Relationship

Processing of Soot by Controlled Sulphuric Acid and Water Condensation—Mass and Mobility Relationship

An unexpected restructuring of combustion soot aggregates by subnanometer coatings of polycyclic aromatic hydrocarbons

Effects of Coating of Dicarboxylic Acids on the Mass−Mobility Relationship of Soot Particles

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