471339 Aging Oil-Water Interfaces with Asphaltene Adsorption: Interface Rheology and Heterogeneity

Tuesday, November 15, 2016: 3:30 PM
Union Square 25 (Hilton San Francisco Union Square)
Chih-Cheng Chang1, Arash Nowbahar1, Vincent Mansard2, Jodi Mecca3, Adam Schmitt3, Tom Kalantar4, Tzu-Chi Kuo4 and Todd M. Squires2, (1)Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, (2)Chemical Engineering, University of California, Santa Barbara, Santa Barbara, CA, (3)Formulation Science, The Dow Chemical Company, Midland, MI, (4)Dow Chemical, Midland, MI

Water is often used in the production and processing of oil, but the water and oil must ultimately be separated. Such separations can be very challenging, because various surface-active materials naturally exist in crude oil that stabilize water-oil interfaces. Polycyclic aromatic hydrocarbons called asphaltenes are a broad class of surface-active compounds that adsorb at water-oil interfaces and stabilize such emulsions.
We use ferromagnetic microbuttons as interfacial rheological probes to probe the evolution of oil/water interfaces as asphaltenes adsorb, and the effect of chemical additives like ethylcellulose (EC) on the evolution of the mechanical properties of the interface. Oil/water interfaces progressively stiffen as asphaltenes adsorb; this process, however, can be prevented or reversed with the addition of EC.
To probe the mechanism behind these observations, we visualize the deformation (strain) field of the oil/water interface in response to the stresses imposed by the microbutton. Asphaltene-adsorbed oil/water interfaces show significant mechanical heterogeneity, with pronounced stiff and weak regions. EC affects these heterogeneous regions differently, suggesting various hypotheses for its action on asphaltene-stabilized interfaces.
Our study reveals the rich properties of water/asphaltene/oil interfaces, and highlights new tools to probe mechanically heterogeneous interfaces as they evolve in response to their local chemical environments.

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See more of this Session: Emulsions and Foams II
See more of this Group/Topical: Engineering Sciences and Fundamentals