How does the Gibbs inequality condition affect the stability and detachment of floating spheres from the free surface of water?

Feng, Dong-xia and Nguyen, Anh V (2016) How does the Gibbs inequality condition affect the stability and detachment of floating spheres from the free surface of water?. Langmuir, 32 8: 1988-1995. doi:10.1021/acs.langmuir.5b04098


Author Feng, Dong-xia
Nguyen, Anh V
Title How does the Gibbs inequality condition affect the stability and detachment of floating spheres from the free surface of water?
Journal name Langmuir   Check publisher's open access policy
ISSN 1520-5827
0743-7463
Publication date 2016-02-02
Year available 2016
Sub-type Article (original research)
DOI 10.1021/acs.langmuir.5b04098
Open Access Status Not Open Access
Volume 32
Issue 8
Start page 1988
End page 1995
Total pages 8
Place of publication Washington DC, United States
Publisher American Chemical Society
Language eng
Formatted abstract
Floating objects on the air–water interfaces are central to a number of everyday activities, from walking on water by insects to flotation separation of valuable minerals using air bubbles. The available theories show that a fine sphere can float if the force of surface tension and buoyancies can support the sphere at the interface with an apical angle subtended by the circle of contact being larger than the contact angle. Here we show that the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, also plays a significant role in controlling the stability and detachment of floating spheres. Specifically, we truncated the spheres with different angles and used a force sensor device to measure the force of pushing the truncated spheres from the interface into water. We also developed a theoretical modeling to calculate the pushing force that in combination with experimental results shows different effects of the Gibbs inequality condition on the stability and detachment of the spheres from the water surface. For small angles of truncation, the Gibbs inequality condition does not affect the sphere detachment, and hence the classical theories on the floatability of spheres are valid. For large truncated angles, the Gibbs inequality condition determines the tenacity of the particle–meniscus contact and the stability and detachment of floating spheres. In this case, the classical theories on the floatability of spheres are no longer valid. A critical truncated angle for the transition from the classical to the Gibbs inequality regimes of detachment was also established. The outcomes of this research advance our understanding of the behavior of floating objects, in particular, the flotation separation of valuable minerals, which often contain various sharp edges of their crystal faces.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Chemical Engineering Publications
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