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Droplet Microfluidics
Microfluidics enable precise control of droplet dynamics that help the study of interfacial phenomena and of mass transfer processes, making it a valuable tool for research and industrial applications. Our research focuses mainly on formulation of single and double emulsions stabilised by surface-active agents (surfactants) [1,2] and colloidal particles. To investigate all steps of the life of a droplet, from growth to pinch off, we developed a unique experimental lab-on-a-chip platform. We also use machine and deep learning to support our research by processing and analysing our experimental dataset with novel methods [3,4].
[1] Kalli, M., Pico, P., Chagot, L., Kahouadji, L., Shin, S., Chergui, J., D. Juric, Matar, O. K., and Angeli, P. (2023). Effect of surfactants during drop formation in a microfluidic channel: a combined experimental and computational fluid dynamics approach. Journal of Fluid Mechanics, 961, A15.
[2] Kalli, M., Chagot, L., and Angeli, P. (2022). Comparison of surfactant mass transfer with drop formation times from dynamic interfacial tension measurements in microchannels. Journal of Colloid and Interface Science, 605, 204-213.
[3] Chagot, L., Quilodrán-Casas, C., Kalli, M., Kovalchuk, N. M., Simmons, M. J., Matar, O. K., Arcucci, R., and Angeli, P. (2022). Surfactant-laden droplet size prediction in a flow-focusing microchannel: a data-driven approach. Lab on a Chip, 22(20), 3848-3859.
[4] Gelado, S. H., Quilodrán-Casas, C., and Chagot, L. (2023). Enhancing Microdroplet Image Analysis with Deep Learning. Micromachines, 14(10), 1964
Interfacial Phenomena
Interfaces are ubiquitous in natural and technological processes and studying them enables the development of innovative materials, the improvement of current technologies, tackling challenges in energy and environmental science and guiding the development of eco-friendly practices.
Our research is focused on the experimental investigation of the adsorption behaviour of surface-active compounds, including single surfactants, surfactant mixtures and colloidal particles, at liquid/air, liquid/liquid, and liquid/solid interfaces. We also explore monomeric and self-assembled states of surfactants and particles at interfaces and in the bulk.
In our labs, we conduct measurements of equilibrium and dynamic surface tension, interfacial tension, and contact angle for simple and complex systems. Additionally, we create controlled monolayers and analyse their formation by measuring the surface pressure and the mean area occupied by the molecules. As part of our research focus, we actively investigate the phenomena of droplet spreading and coalescence [1,2].
[1] Kotsi, K., Dong, T., Kobayashi, T., McRobbie, I., Striolo, A., and Angeli, P. (2024). Synergistic effects between a non-ionic and an anionic surfactant on the micellization process and the adsorption at liquid/air surfaces. Soft Matter, 20(3), 523-534.
[2] Dong, T., Kotsi, K., Kobayashi, T., Moriarty, A., McRobbie, I., Striolo, A., and Angeli, P. (2023). Blooming of Emulsion Droplet During Evaporation. Bulletin of the American Physical Society.
Intensified Continuous Processing
We develop innovative intensified continuous flow processes in small channels often in combination with non-organic solvents. Our studies have considered recycling of metals such as platinum group metals, spent nuclear fuel reprocessing, separation of biomolecules for pharmaceuticals, as well as biofuels production. We combine experimental studies of hydrodynamics and mass transfer with computational fluid dynamics simulations [1]. We also consider the effects of the intensified units on the whole process through flowsheet modelling using sustainability metrics such as solvent usage [2].
We investigate in detail the interplay between hydrodynamics and mass transfer in small channels (micro to milli scale). The reduction in volume is compensated by the enhanced mass transfer. For the separations we are studying novel solvents such as ionic liquids and aqueous biphasic systems [3].
We also consider the scale up of the processes by increasing the size of single channels as well as the number of single channels operating in parallel (scale out). We study the effects of increasing channel sizes on flow characteristics. For scale out, we are developing models to guide the design of flow manifolds that ensure uniform conditions in all channels.
[1] Li, Q., and Angeli, P. (2017). Experimental and numerical hydrodynamic studies of ionic liquid-aqueous plug flow in small channels. Chemical Engineering Journal, 328, 717-736.
[2] Bascone, D., Angeli, P., and Fraga, E. S. (2019). A modelling approach for the comparison between intensified extraction in small channels and conventional solvent extraction technologies. Chemical Engineering Science, 203, 201–211.
[3] Phakoukaki, Y. V., O'Shaughnessy, P., and Angeli, P. (2024). Continuous plug flow extraction of L-tryptophan using ionic liquid-based aqueous biphasic systems in small channels. Separation and Purification Technology, 334, 125468.
Complex Fluids
We explore the flow behaviour and rheology of complex fluids and soft matter. Our studies aim at understanding the interplay between the rheological properties of non-Newtonian fluids and their behaviour in processing units, with a specific focus on colloidal suspensions, Pickering emulsions and bubble suspensions in Newtonian and viscoelastic media. We use advanced characterisation approaches and measurement techniques, including rheo-optics and combine the experiments with computational fluid dynamics simulations [1, 2].
[1] Mitrou, S., Migliozzi, S., Angeli, P., and Mazzei, L. (2023). Effect of polydispersity and bubble clustering on the steady shear viscosity of semidilute bubble suspensions in Newtonian media. Journal of Rheology, 67(3), 635-646.
[2] Migliozzi, S., Meridiano, G., Angeli, P., and Mazzei, L. (2020). Investigation of the swollen state of Carbopol molecules in non-aqueous solvents through rheological characterization. Soft Matter, 16(42), 9799-9815.