Effect of contact angle and contact angle hysteresis on the floatability of spheres at the air-water interface

Feng, Dong-xia and Nguyen, Anh V. (2017) Effect of contact angle and contact angle hysteresis on the floatability of spheres at the air-water interface. Advances in Colloid and Interface Science, 248 69-84. doi:10.1016/j.cis.2017.07.031


Author Feng, Dong-xia
Nguyen, Anh V.
Title Effect of contact angle and contact angle hysteresis on the floatability of spheres at the air-water interface
Journal name Advances in Colloid and Interface Science   Check publisher's open access policy
ISSN 0001-8686
1873-3727
Publication date 2017-07-28
Year available 2017
Sub-type Article (original research)
DOI 10.1016/j.cis.2017.07.031
Open Access Status Not yet assessed
Volume 248
Start page 69
End page 84
Total pages 16
Place of publication Amsterdam, 1043 NX Netherlands
Publisher Elsevier BV
Language eng
Abstract The floatability of solid particles on the water surface governs many natural phenomena and industrial processes including film flotation and froth flotation separation of coal and valuable minerals. For many years, the contact angle (CA) has been postulated as the key factor in determining the particle floatability. Indeed, the maximum force (tenacity) supporting the flotation of fine spheres was conjectured to occur when the apical angle of the contact circle is equal to the contact angle. In this paper, the model predictions are reviewed and compared with experimental results. It is shown that CA can be affected by many physical and chemical factors such as surface roughness and chemical heterogeneity and can have a range of values known as the CA hysteresis. This multiple-valued CA invalidates the available theories on the floatability of spheres. Even the intuitive replacement of CA by the advancing (maximum) CA in the classical theories can be wrong. A few new examples are also reviewed and analyzed to demonstrate the significance of CA variation in controlling the particle floatability. They include the pinning of the contact line at the sharp edge, known as the Gibbs inequality condition, and the nearby interaction among floating particles, known as lateral inter-particle interaction. It is concluded that our quantitative understanding of the floatability of real particles being irregular and heterogeneous both morphologically and chemically is still far from being satisfactory. (C) 2017 Elsevier B.V. All rights reserved.
Keyword Contact angle hysteresis
Detachment
Gas-liquid interface
Lateral interaction
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID DP150100395
Institutional Status UQ

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