Fast liquid–liquid dispersion for low volumina in an active micromixer — AI-based investigation

Abstract

Miniaturized equipment offers many benefits for mixing and liquid–liquid dispersion processes, such as fast and controllable mixing, high surface-to-volume ratio, and lower specific energy consumption. Rapidly changing product mixtures, as can be found in cosmetics industry, require special knowledge of the performance of the mixing and emulsification processes. Here, the droplet size distribution (DSD) is important to define the quality, consistency, and stability of the product and is often regarded as a critical quality attribute. In this work, a modified microstructured annular gear pump is examined as an active mixer for emulsification processes. The active micromixer has the benefit that the mixing power can be freely adjusted, independently of the volumetric flow rate, which enables performance investigation of the DSD based on the specific energy dissipation rate. Important process parameters, such as volumetric flow rate (0.5 to 1.5 mL$\cdot$min^-1), rotor speed (6000 to 12000 min^-1) , and mass fraction of the dispersed phase (10 to 18.4 w% of the oil phase) are examined to investigate their effects on the DSD. For this, an AI-based image recognition is used for emulsion characterization. This methodology provides real-time monitoring and the opportunity to define operation ranges for rapid optimization of rotor, housing, geometry of mixing devices, and further process conditions such as volumetric flow rate for liquid–liquid mixing.