Less is more: Unstable foams clean better than stable foams - Kölner UniversitätsPublikationsServer

Schad, Tamara, Preisig, Natalie, Blunk, Dirk ORCID: 0000-0001-6365-0404, Piening, Heinrich, Drenckhan, Wiebke and Stubenrauch, Cosima (2021). Less is more: Unstable foams clean better than stable foams. J. Colloid Interface Sci., 590. S. 311 - 321. SAN DIEGO: ACADEMIC PRESS INC ELSEVIER SCIENCE. ISSN 1095-7103

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DOI:10.1016/j.jcis.2021.01.048

Abstract

Hypothesis: Foamed surfactant solutions can clean surfaces! We hypothesise that the cleaning efficiency depends on the liquid fraction and on the stability of the foam. We also hypothesise that the cleaning efficiency is the better the smaller the average bubble size is. Experiments: The double syringe technique was used to generate foams with varying liquid fractions but the same, very small bubble sizes with and without perfluorohexane in the gas phase. We performed cleaning tests in which the foams were applied to glass substrates contaminated with a fluorescent oil. Findings: We found that unstable foams clean better than stable foams. Three cleaning mechanisms were identified: (1) imbibition at low liquid fractions, (2) wiping, i.e., shifting of the contact line between oil, foam and glass, at all liquid fractions, and (3) drainage at high liquid fractions. The change of the liquid fraction and of the foam stability lead to different combinations of these mechanisms and thus to different cleaning results. CO 2021 Elsevier Inc. All rights reserved.

Item Type:

Journal Article

Creators:

Creators	Email	ORCID	ORCID Put Code
Schad, Tamara	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Preisig, Natalie	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Blunk, Dirk	UNSPECIFIED	orcid.org/0000-0001-6365-0404	UNSPECIFIED
Piening, Heinrich	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Drenckhan, Wiebke	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED
Stubenrauch, Cosima	UNSPECIFIED	UNSPECIFIED	UNSPECIFIED