Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders
Agglomeration of hydrophobic powders using aqueous solutions is an important technology. The outcome is linked to the particle wettability, but the mechanisms are not well-understood. We present a fundamental study of the early stages of agglomeration. Drops of alcohol-water mixtures were deposited...
| Main Authors: | , , |
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| Format: | Journal Article |
| Published: |
Elsevier BV
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/54414 |
| _version_ | 1848759365675253760 |
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| author | Whitby, C. Bian, X. Sedev, Rossen |
| author_facet | Whitby, C. Bian, X. Sedev, Rossen |
| author_sort | Whitby, C. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | Agglomeration of hydrophobic powders using aqueous solutions is an important technology. The outcome is linked to the particle wettability, but the mechanisms are not well-understood. We present a fundamental study of the early stages of agglomeration. Drops of alcohol-water mixtures were deposited onto three hydrophobic powders: hydrophobised glass beads (spherical, 90-106 µm), coal dust (angular shape, 90-106 µm) and molybdenite powder (angular shape, 1-20 µm). Their wettability was manipulated through the surface tension of the liquid, which was varied by the alcohol-water ratio. On coarse powders (glass beads and coal dust) the droplet either penetrates into the porous bed (at low surface tensions and contact angles), or sits on top and evaporates (at higher surface tensions and contact angles). Particles spontaneously coat drops of intermediate surface tension. The coating slows evaporation and remains as a dry agglomerate after evaporation. Drops that do not penetrate into the fine powder beds (molybdenite) spontaneously roll away, even when deposited carefully. The reason is that the powder surface behaves like a superhydrophobic one. Rolling drops collect hydrophobic particles along their path. After rolling, the partially coated drop evaporates in the same way as on coarser powders. |
| first_indexed | 2025-11-14T09:58:44Z |
| format | Journal Article |
| id | curtin-20.500.11937-54414 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:58:44Z |
| publishDate | 2013 |
| publisher | Elsevier BV |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-544142017-11-03T01:55:33Z Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders Whitby, C. Bian, X. Sedev, Rossen Agglomeration of hydrophobic powders using aqueous solutions is an important technology. The outcome is linked to the particle wettability, but the mechanisms are not well-understood. We present a fundamental study of the early stages of agglomeration. Drops of alcohol-water mixtures were deposited onto three hydrophobic powders: hydrophobised glass beads (spherical, 90-106 µm), coal dust (angular shape, 90-106 µm) and molybdenite powder (angular shape, 1-20 µm). Their wettability was manipulated through the surface tension of the liquid, which was varied by the alcohol-water ratio. On coarse powders (glass beads and coal dust) the droplet either penetrates into the porous bed (at low surface tensions and contact angles), or sits on top and evaporates (at higher surface tensions and contact angles). Particles spontaneously coat drops of intermediate surface tension. The coating slows evaporation and remains as a dry agglomerate after evaporation. Drops that do not penetrate into the fine powder beds (molybdenite) spontaneously roll away, even when deposited carefully. The reason is that the powder surface behaves like a superhydrophobic one. Rolling drops collect hydrophobic particles along their path. After rolling, the partially coated drop evaporates in the same way as on coarser powders. 2013 Journal Article http://hdl.handle.net/20.500.11937/54414 10.1016/j.colsurfa.2013.07.041 Elsevier BV restricted |
| spellingShingle | Whitby, C. Bian, X. Sedev, Rossen Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title | Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title_full | Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title_fullStr | Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title_full_unstemmed | Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title_short | Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| title_sort | rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders |
| url | http://hdl.handle.net/20.500.11937/54414 |