Effects of monovalent anions and cations on drainage and lifetime of foam films at different interface approach speeds

Firouzi, Mahshid and Nguyen, Anh V. (2014) Effects of monovalent anions and cations on drainage and lifetime of foam films at different interface approach speeds. Advanced Powder Technology, 25 4: 1212-1219. doi:10.1016/j.apt.2014.06.004


Author Firouzi, Mahshid
Nguyen, Anh V.
Title Effects of monovalent anions and cations on drainage and lifetime of foam films at different interface approach speeds
Journal name Advanced Powder Technology   Check publisher's open access policy
ISSN 0921-8831
1568-5527
Publication date 2014-07
Year available 2014
Sub-type Fully published paper
DOI 10.1016/j.apt.2014.06.004
Open Access Status
Volume 25
Issue 4
Start page 1212
End page 1219
Total pages 8
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2015
Language eng
Formatted abstract
Ions of inorganic salts are known to affect bubble coalescence via ion size, charge density and polarizability. In this paper, a systematic study of the effect of monovalent anions (F-, Cl-, Br- and I-) and cations (Li+, Na+ and K+) on the lifetime of liquid films between two bubble surfaces is carried out by applying the thin film interferometry method. To mimic realistic conditions of bubble coalescence in a bubble column, drainage and stability of saline water films driven by different interface approach speeds (10-300μm/s) using a nano-pump was investigated. The results show significant effects of interface approach speed on transient film thickness and radius, film stability and rupture, and lifetime of saline water films. The experiments also indicate that there is a critical approach speed of 35μm/s for pure deionised water above which the water films instantly coalesce, i.e., no water film can be obtained. High interface approach speed creates corrugation on saline water film surfaces, which rapidly increases the rates of film radial expansion and drainage, and shortens the film lifetime. There is a critical salt concentration above which the saline water film lifetime abruptly increases. This critical concentration is independent of the interface approach speeds of 10-300μm/s. Our experimental results show a decreasing trend of film lifetime with increasing the size of either the cation or anion (NaF>LiCl>NaCl>NaBr>NaI). The order of the critical concentrations is the opposite of the order of lifetimes. The experimental results highlight the ion-specific effect of salt ions on the water structure and hence the behavior of saline liquid films. These results are relevant to a number of chemical engineering processes taking place in saline water, including mineral separation by flotation using air bubbles in saline water.
Keyword Saline water
Liquid film
Bubble coalescence
Ion-specificity
Critical concentration
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Fully published paper
Collections: School of Chemical Engineering Publications
Official 2015 Collection
 
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