The membrane emulsification process—a review

Abstract

Membrane emulsification has received increasing attention over the last 10 years, with potential applications in many fields. In the membrane emulsification process, a liquid phase is pressed through the membrane pores to form droplets at the permeate side of a membrane; the droplets are then carried away by a continuous phase flowing across the membrane surface. Under specific conditions, monodispersed emulsions can be produced using this technique. The purpose of the present paper is to provide a review on the membrane emulsification process including: principles of membrane emulsification, influence of process parameters and industrial applications. Small-scale applications such as drug delivery systems, food emulsions, and the production of monodispersed microspheres are also included. Compared with conventional techniques for emulsification, membrane processes offer advantages such as control of average droplet diameter by average membrane pore size and lower energy input.

The impact of mass transfer and interfacial expansion rate on droplet size in membrane emulsification processes

“…The characteristic parameter used to discuss the effect of the flowing continuous phase is the wall shear stress. Previous studies have shown that the droplet size decreases as the wall shear stress increases [5,7,19]. One popular explanation of this phenomenon is that the flowing continuous phase creates the drag force that pulls the droplets away from the pore mouths after reaching a certain size [15].…”

“…The size of droplets when they detach from the membrane or micro-channel depends on the above mentioned process parameters, which have been evaluated by associating them to forces which act on the system [1,5,[15][16][17][18]. The relative magnitude of these forces change as the droplet increases in size and has been plotted in the literature [1,12,15].…”

“…For extensive and recent reviews on membrane emulsification consult Joscelyne and Trägårdh [4], Charcosset et al [5] and Gijsbertsen-Abrahamse et al [7]. Other authors have described droplet formation depending by considering the type of mechanisms causing the droplets to detach and or the systems sensitivity to operating conditions [8][9][10].…”

“…The droplet size to pore size ratio, has been found to range from approximately 3 to 15 [4,5] for oil-in-water emulsions and the size distributions have been in some cases mono-dispersed, but with others showing over 50% coefficient of variation [6]. Size and size distribution are the parameters of an emulsification system, which determines the products quality as fitness for its intended use, and thus are essential to control and predict.…”

Preparation of liposomes: A novel application of microengineered membranes–From laboratory scale to large scale

“…It involves mixing of two miscible liquids (the organic and aqueous phase) by injecting the organic phase through a microporous membrane into the aqueous phase. It is similar to membrane emulsification [7,8], which involves the injection of one liquid (the dispersed phase) into another immiscible liquid (the continuous phase) through a microporous membrane [9,10]. Micro-engineered membranes, which have a perfect hexagonal array of uniform pores, allow a much more uniform and controllable injection of lipid-containing organic phase into an aqueous phase.…”