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Issue 6, 2012
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A microfluidic method to study demulsification kinetics

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Abstract

We present the results of experiments studying droplet coalescence in a dense layer of emulsion droplets using microfluidic circuits. The microfluidic structure allows direct observation of collisions and coalescence events between oil droplets dispersed in water. The coalescence rate of a flowing hexadecane-in-water emulsion was measured as a function of the droplet velocity and droplet concentration from image sequences measured with a high-speed camera. A trajectory analysis of colliding droplet pairs allows evaluation of the film drainage profile and coalescence time tc. The coalescence times obtained for thousands of droplet pairs enable us to calculate coalescence time distributions for each set of experimental parameters, which are the mean droplet approach velocity 〈v0〉, the mean dispersed phase fraction 〈ϕ〉 and the mean hydraulic diameter of a droplet pair 〈dp〉. The expected value Etc of the coalescence time distributions scales as Etc ∝ 〈v0−0.105±0.043dp0.562±0.287, but is independent of ϕ. We discuss the potential of the procedure for the prediction of emulsion stability in industrial applications.

Graphical abstract: A microfluidic method to study demulsification kinetics

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Publication details

The article was received on 26 Sep 2011, accepted on 12 Dec 2011 and first published on 03 Jan 2012


Article type: Paper
DOI: 10.1039/C2LC20930F
Lab Chip, 2012,12, 1060-1070

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    A microfluidic method to study demulsification kinetics

    T. Krebs, K. Schroen and R. Boom, Lab Chip, 2012, 12, 1060
    DOI: 10.1039/C2LC20930F

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