Influence of the emulsion formulation in premix emulsification using packed beds

Premix emulsification was investigated using packed beds consisting of micron-sized glass beads, a system that avoids fouling issues, unlike traditional premix membrane emulsification. The effects of emulsion formulation were investigated, most notably the viscosity and the surfactant. The droplet size was reduced by increased shear stress in the emulsion. This was stronger at low viscosity ratios than at high ratios. As expected the flux was proportional to the overall emulsion viscosity, and emulsions with small droplet size (Sauter mean droplet diameter <5. μm) could still be produced at up to 60% of dispersed phase provided that sufficient surfactant was available. More uniform emulsions (span≈0.75) were produced with Tween-20 (nonionic) and SDS (anionic) as surfactants than with CTAB (a cationic surfactant), possibly due to a combination of a low equilibrium interfacial tension and electrostatic attractions with the glass surface.Scaling relations were proposed taking into account all investigated product properties that can describe the droplet size successfully.