The performance of rotating membrane emulsification in the presence of baffles: Insights from flux experiments, microstructural analysis, and positron emission particle tracking

Abstract

Rotating Membrane Emulsification (RME) is a bottom-up emulsification technique developed to circumvent the significant energy requirements of conventional methods; however, its implementation has been hindered by low emulsion throughputs. This work presents a novel baffled-RME setup and investigates the potential improvement to emulsion throughput and droplet microstructure, whilst employing both surface-active and Pickering particle emulsifiers to assess whether any advantages are emulsifier-specific. Overall, baffle addition improves emulsion throughputs, however the droplet microstructure was positively influenced only when using surfactant-based emulsifiers. Positron Emission Particle Tracking (PEPT) was utilised to demonstrate that these advantages result from improved hydrodynamic conditions instigated by the break-up of streamlines, inducing higher turbulence near the membrane surface, and by increasing the transmembrane pressure drop and drag force through flow restrictions. Overall, by detailing the first baffled-RME setup and first application PEPT analysis to such equipment, this work lays the foundation for further optimisation of bottom-up emulsification approaches.