Influence of process parameters on droplet size distribution in SPG membrane emulsification and stability of prepared emulsion droplets

SPG membranes were used to prepare monodispersed O/W and W/O/W emulsions over a wide range of membrane wall shear stress (0.37–40 Pa), dispersed phase content (1–20 vol.%) and transmembrane pressure. Although the most uniform droplets were prepared at the membrane wall shear stress of 30 Pa, a monodispersed O/W emulsion can be even obtained at the wall shear stress of 0.37 Pa, corresponding to laminar flow regime of continuous phase inside the membrane tube. The minimum droplet size somewhat decreased with time, probably due to gradual activation of smaller pores. There was no significant difference in the size distribution curve of pure oil droplets of O/W emulsions and W/O drops of W/O/W emulsions, if they were both prepared under the same conditions. No significant change in droplet size distribution of prepared O/W emulsions was observed during the storage time of up to 159 days.