Kovalchuk, NM;
Roumpea, E;
Nowak, E;
Chinaud, M;
Angeli, P;
Simmons, MJH;
(2017)
Effect of surfactant on emulsification in microchannels.
Chemical Engineering Science
, 176
pp. 139-152.
10.1016/j.ces.2017.10.026.
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Abstract
Drop formation in a microfluidic flow-focusing device (cross-junction) was studied in absence and presence of one of two ionic surfactants. Four different flow regimes: squeezing, dripping, jetting, and threading were observed in line with existing literature. The effect of surfactant on the transition between flow regimes was shown to depend upon the value of critical micelle concentration and correlates with dynamic surface tension. Drop length in the channel increased as the ratio of flow rate of dispersed to continuous phase, φ increased. For drops smaller than the channel width, the increase was slow, proportional to φ 0.1 , yet was much faster, proportional to φ for larger drops. In contradiction to the expected stabilisation of drops by surfactant, surfactant-laden drops larger than the channel height coalesced inside the channel at a higher rate than surfactant-free drops. It is proposed that the coalescence is caused by the electrostatic attraction due to surfactant redistribution under the high shear stresses near the wall of the channel.
| Type: | Article |
|---|---|
| Title: | Effect of surfactant on emulsification in microchannels |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.ces.2017.10.026 |
| Publisher version: | https://doi.org/10.1016/j.ces.2017.10.026 |
| Language: | English |
| Additional information: | This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
| Keywords: | Microfluidic drop formation, Flow mapIonic surfactant, Dynamic interfacial tension, Critical micelle concentration, Coalescence |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10038850 |
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