Effects of surface rheology and surface potential on foam stability

Wang, Jianlong, Nguyen, Anh V. and Farrokhpay, Saeed (2016) Effects of surface rheology and surface potential on foam stability. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 488 70-81. doi:10.1016/j.colsurfa.2015.10.016

Author Wang, Jianlong
Nguyen, Anh V.
Farrokhpay, Saeed
Title Effects of surface rheology and surface potential on foam stability
Journal name Colloids and Surfaces A: Physicochemical and Engineering Aspects   Check publisher's open access policy
ISSN 1873-4359
Publication date 2016-01-05
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.colsurfa.2015.10.016
Open Access Status Not Open Access
Volume 488
Start page 70
End page 81
Total pages 12
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Collection year 2016
Language eng
Formatted abstract
Here, we examine the collapse of standing aqueous foams stabilized by the anionic surfactant SDS, using DOH and sodium chloride (NaCl) respectively to produce different surface viscoelasticities and surface potentials in order to elucidate the roles of surface rheology and intermolecular forces in foam stability. Inspired from chemical kinetics, we proposed a model to quantify the foam collapse process and to compare the foam stability with two characteristic parameters: the foam half-life, τ , and the prefactor of foam collapse rate, n/τ. The presence of DOH in the SDS solutions can significantly increase the surface viscoelasticity and foam stability, despite the decreased surface potential caused by the displacement of SDS molecules by DOH molecules at the air–water interface. The correlation between surface viscoelasticity and foam stability is explained by the decrease in foam drainage and the increased liquid film stability. For SDS–NaCl mixtures with the same value of the mean ionic product (1 mM), an increased concentration of NaCl in the SDS solution reduces the surface potential and the Debye length because of the screening effect resulting from the binding of sodium counter ions to the sulfate head groups. The foam stability decreases because of the weakened repulsive interactions between the two interfaces of the liquid films, despite the presence of the same surface concentration of SDS molecules, as indicated by the same equilibrium surface tension. This paper highlights two different mechanisms that dominate foam stability.
Keyword Foam
Foam stability
Surface rheology
Surface potential
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Julius Kruttschnitt Mineral Research Centre Publications
School of Chemical Engineering Publications
Official 2016 Collection
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Citation counts: TR Web of Science Citation Count  Cited 5 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 4 times in Scopus Article | Citations
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