Geometric parameters influencing production of O/W emulsions using flat metallic membranes and scale-up

The influence of geometric parameters (e.g., tank dimensions, diameter and position of impeller, continuous phase height-to-tank diameter ratio and impeller-to-tank diameter ratio) on the droplet size of emulsions produced by membrane emulsification has been studied. Two flat metallic membranes with pore sizes of 5 μm and 50 μm were used to prepare oil-in-water (O/W) emulsions in stirred tanks. Results show that the influence of geometric parameters depends on the rotational speed of the impeller. Under optimal geometric conditions, it was possible to obtain emulsions with minimum droplet sizes of 45 μm and 105 μm and span values of 0.60 and 0.53 using membranes with pore sizes of 5 μm and 50 μm, respectively. Scale-up experiments were carried out with different tanks and impellers, while maintaining geometric similarity. Emulsions with the same droplet size distributions were obtained using the impeller tip speed as the scale-up criterion.