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

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.

Automated summary

This study presents a novel baffled-RME setup to improve emulsion throughput and droplet microstructure. It is found that baffle addition enhances hydrodynamic conditions, resulting in higher turbulence and increased transmembrane pressure drop and drag force, which positively influence the droplet microstructure. The use of surfactant-based emulsifiers further enhances these advantages. The study lays the foundation for further optimization of bottom-up emulsification approaches, and introduces the application of PEPT analysis to such equipment.