Condensed-Matter Physics & Materials Science Seminar

"Bounds for the electric potential of water-oil interfaces"

Presented by Mihail Popescu, Ian Wark Research Institute, Univ. of South Australia, Adelaide, Australia

Thursday, July 26, 2012, 1:30 pm — Small Seminar Room, Bldg. 510

The value of the electric potential (or that of the closely related "zeta"-potential [1]) of a liquid-liquid interface is a crucial parameter for the stability of emulsions, extensively used in the food, cosmetics, or pharmaceutical industries. Because liquid-fluid (i.e., liquid or gas)
interfaces are deformable, determining their surface-potential using classic methods designed for solid particles, such as electrophoresis, remains a challenging task. In this work we exploit the spontaneously occurring cascade partial coalescence [2] of a drop of heptol (toluene - n-heptane mixture) rising through water
(electrolyte) with a water (electrolyte) - heptol quasi-planar interface, process in which a stable drop emerges as the final state. We discuss how lower- and upper-bounds for the absolute value of the surface potential of these
interfaces can be inferred within the limits of the classic DLVO theory [1].

1. Derjaguin, B. V., Churaev, N. V., and Muller, V. M., "Surface Forces" (Consultants Bureau, New York, 1987).
2. Blanchette, F. and Bigioni, T. P., "Partial coalescence of drops at liquid interfaces", Nat. Phys. 2, 254 (2006).

Hosted by: Antonio Checco

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