Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants

Qu, Xuan, Wang, Liguang, Karakashev, Stoyan I. and Nguyen, Anh V. (2009) Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants. Journal of Colloid and Interface Science, 337 2: 538-547. doi:10.1016/j.jcis.2009.05.038

Author Qu, Xuan
Wang, Liguang
Karakashev, Stoyan I.
Nguyen, Anh V.
Title Anomalous thickness variation of the foam films stabilized by weak non-ionic surfactants
Journal name Journal of Colloid and Interface Science   Check publisher's open access policy
ISSN 0021-9797
Publication date 2009-09
Year available 2009
Sub-type Article (original research)
DOI 10.1016/j.jcis.2009.05.038
Volume 337
Issue 2
Start page 538
End page 547
Total pages 10
Editor v Wasan
Place of publication San Diego, CA, USA
Publisher Elsevier
Collection year 2010
Language eng
Subject 030603 Colloid and Surface Chemistry
970103 Expanding Knowledge in the Chemical Sciences
Abstract The constant thickness (H) of metastable free films of various non-ionic surfactant solutions was measured at surfactant concentrations less than the critical micelle concentrations or solubility limits with fixed 5 x 10(-5) M sodium chloride (NaCl) serving as the background electrolyte. The surfactants include n-pentanol, n-octanol, methyl isobutyl carbinol (MIBC), polypropylene glycol (PPG-400), tetraethylene glycol monooctyl ether (C8E4), and tetraethylene glycol monodecyl ether (C10E4). H was interferometrically measured. For each surfactant in this study, the H-versus-surfactant-concentration curve finds a peak at a concentration around 5 x 10(-6) -1 x 10(-5) M and a valley at a higher concentration. The measured H values were compared to those predicted from the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which considers solely the contribution from electrostatic double-layer repulsion with van der Waals attraction being neglected in the present work. In determining the double-layer repulsion, the ionic strength was determined from the electrolytic conductivity measurement of the film-forming solutions and the surface potential was estimated from the zeta-potential measurement of air bubbles. It was found that the DLVO theory failed to explain the thickness variance with surfactant concentration, implying that additional non-DLVO attractive forces might be required to explain the experimental results. Finally, the possible origins of these attractive forces were discussed. (C) 2009 Elsevier Inc. All rights reserved.
Keyword Surface Force
Flotation Frother
Foam Films
Hydrophobic Force
Dissolved Gas
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Chemical Engineering Publications
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Citation counts: TR Web of Science Citation Count  Cited 16 times in Thomson Reuters Web of Science Article | Citations
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Created: Thu, 03 Sep 2009, 07:44:06 EST by Mr Andrew Martlew on behalf of School of Chemical Engineering