Coalescence-induced phase separation of an oil in water emulsion under controlled shear and temperature conditions

• Published in: Chemical engineering research & design 2022-06, Vol.182, p.517-524
• Main Authors: Nadeem, Hannan, Vigil, R. Dennis, Samuel, Amanda, Sarkar, Avik, Yeoh, Thean, Olsen, Michael G.
• Format: Article
• Language: English
• Subjects: Coagulation; Couette flow; Droplet coalescence; Emulsions; Eötvös number; Galilei number; Membrane separation; Oil-in-water emulsion; Packaging design; Parameters; Phase separation; Shear strain; Stability; Strain rate; Temperature
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2022.04.024

Phase separation behavior was investigated in an oil-in-water type emulsion. A Couette flow cell was utilized for the phase separation experiments. The emulsion was tested for a range of shear strain rates of 10.5 s−1 to 62.8 s−1 and a temperature range of 25–35 ℃, both of which are much milder than the corresponding conditions used to manufacture the emulsion (~1000 s−1 and 51 ℃), to identify the onset of phase separation due to droplet coagulation. The onset of phase separation is dependent on the shear strain rate and the temperature, such that the onset of phase separation is detected at earlier times as either shear strain rate or temperature increase. Some experimental conditions resulted in no phase separation during the observation period. The results of these experiments can be organized by using two dimensionless parameters, namely the Eötvös and Galilei numbers. Specifically, a phase separation regime map was constructed using these dimensionless parameters, and this map features a linear boundary that demarcates a region for which emulsion remains stable and a region in which an emulsion can be expected to undergo phase separation. These results can potentially be used to characterize the stability of similar emulsions and to aid design, manufacture, packaging, and storage of similar products that have phase separation risk. [Display omitted] •Taylor Couette flow is used as a shearing mechanism to judge emulsion stability.•Study investigates different shear and temperature conditions for phase separation.•Phase separation time decreases with both increasing shear rate and temperature.•Stability dependence can be predicted by Eötvös and Galilei numbers.•Developed method is used to evaluate robustness of emulsion manufacture process.