Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Destabilization of water-oil emulsion by drop interface deformation
Submission Author:
Marcio CARVALHO , RJ , Brazil
Co-Authors:
Talita Botti, Anthony Hutin, Marcio CARVALHO
Presenter: Talita Botti
doi://10.26678/ABCM.COBEM2023.COB2023-1759
Abstract
Emulsion formation and stabilization have been widely studied over the last years. The ability to stabilize emulsion is important in many applications, such as food, pharmaceutical, and cosmetics industries among others. However, sometimes due to a natural stabilizing component, undesired stabilization is obtained, as occurs in the oil industry, for example. In this case, the main interest is the destabilization of emulsions through the coalescence of drops and consequently phase separation, which is the purpose of this study. Hence, better understanding of the role of droplet deformation regarding the stability of water-in-oil (w/o) emulsions can allow the development of more efficient separation strategies. For this, stable w/o emulsions were prepared with Mili-Q water and a nonionic surfactant (Span 80) dissolved in mineral oil (Primol 352), varying the surfactant concentration, all above the critical micelle concentration (CMC). It was observed that the coalescence process is directly influenced by the structure formed at the drop interface due to the adsorption of the surfactant. This structure has been studied microscopically (using the optical microscope) and it was observed the appearance of small water droplets formed at the interface by spontaneous emulsification. We found that the emergence rate of these microdroplets is directly related to the surfactant concentration. As the surfactant concentration increases, faster the spontaneous emulsification process occurs, which confirms the results obtained with the interfacial rheology. Finally, a new method to promote emulsion destabilization by imposing a perturbation of the interfacial film by flowing the drops through constricted capillaries was proposed and tested. In this method, the flow through a constricted microchannel was used to deform the drop, increasing its interfacial area, and creating a strong shear stress to disturb the drop interface. The results showed that depending on the surfactant concentration the cleaning of the microdroplets interface formed along the drops is efficient allowing a rapid phase separation after production.
Keywords
Emulsion, emulsion stability, Interfacial phenomena
