Surface forces in thin foam films stabilised by non-ionic surfactants

Qu, Xuan, Wang, Liguang and Nguyen, Anh V. (2010). Surface forces in thin foam films stabilised by non-ionic surfactants. In: Chemeca: Australasian Conference on Chemical Engeering (2010). 40th Australasian Chemical Engineering Conference, Adelaide, SA, Australia, (1-12). 26 - 29 September 2010.

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Author Qu, Xuan
Wang, Liguang
Nguyen, Anh V.
Title of paper Surface forces in thin foam films stabilised by non-ionic surfactants
Conference name 40th Australasian Chemical Engineering Conference
Conference location Adelaide, SA, Australia
Conference dates 26 - 29 September 2010
Proceedings title Chemeca: Australasian Conference on Chemical Engeering (2010)
Place of Publication Barton, ACT, Australia
Publisher Engineers Australia
Publication Year 2010
Sub-type Fully published paper
ISBN 9780858259713
Start page 1
End page 12
Total pages 12
Collection year 2011
Language eng
Formatted Abstract/Summary
An improved understanding of the surface forces between air bubbles in aqueous solutions is of fundamental and practical importance in a number of areas, from biological and colloidal systems to fire foams and mineral froth systems. The thin film pressure balance (TFPB) technique was used to study the surface forces in thin foam films containing non-ionic surfactants of low molecular weight, such as methyl isobutyl carbinol and tetraethylene glycol monooctyl ether, with fixed 5 × 10-5M NaCl as the background electrolyte. Film thickness was measured interferometrically, and the constant thickness (H) obtained at the final film drainage stage was taken as a key parameter to assess surface forces. The experimental H values were compared with those predicted from the celebrated DLVO (Derjaguin–Landau–Verwey–Overbeek) theory, which considers only the contributions from electrostatic double-layer and van der Waals dispersion forces. In calculating the double-layer force, the ionic strength was determined from the electrolytic conductivity measurement of the film-forming solutions and the bubble surface potential was estimated from the ζ-potential measurement. It was found that the DLVO theory predicted a monotonic increase in H with increasing surfactant concentration, in stark contrast to the distinct peak-valley of the experimental curve. The DLVO theory also considerably over predicted H over a broad surfactant concentrate range. The discrepancy was attributed to the existence of additional non-DLVO attractive forces, whose strength was two orders of magnitudes higher than the van der Waals forces. Finally, the possible origins of these non-DLVO forces were discussed.
Keyword Thin film pressure balance
DLVO (Derjaguin–Landau–Verwey–Overbeek) theory
Q-Index Code E1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Conference also known as Chemeca 2010.

Document type: Conference Paper
Collections: School of Chemical Engineering Publications
Official 2011 Collection
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Created: Fri, 26 Nov 2010, 21:50:40 EST by Dr Liguang Wang on behalf of School of Chemical Engineering