Production of emulsions using microporous, ceramic membranes

Emulsification with membranes is a new technology for producing emulsions. The apparent shear stress is low compared with that in conventional emulsification systems, because the droplets of the disperse phase are produced in a different way. The disperse phase is pressed through the pores of a membrane into the continuous phase flowing alongside the membrane surface, where droplets form. Droplet formation and detachment from membrane pores depend on various process parameters (e.g. transmembrane pressure, shear stress of the continuous phase acting on the membrane surface), membrane material and structure. Emulsification results for o/w emulsions produced using ceramic membranes are presented in terms of droplet size and disperse phase flux as a function of the main parameters of the process, e.g. dynamic interfacial tension of the emulsifier, transmembrane pressure and wall shear stress. Experimental results show that shear stress at the membrane surface is very low. Shear stress does not have to exceed 30 Pa. This is approximately 10 times less than that for droplet disruption in laminar flow. The membrane emulsification process is therefore advantageous with respect to shear-sensitive ingredients. Furthermore it is less energy consuming than conventional emulsifying systems. (C) 1999 Elsevier Science B.V. All rights reserved.