Stirred membrane emulsification

Emulsification devices where the membrane is immersed in a stirred vessel containing the continuous phase, so as to obtain a batch emulsification device operating in deadend emulsification mode, have also been developed (Figure 21.13). Both flat-sheet and tubular membranes are used. In this membrane emulsification device, the continuous phase kept in motion creates the shear stress at the membrane surface that detaches the forming droplets. In a different operation mode, that is, when the continuous phase is not stirred, droplet formation in quiescent conditions is obtained. 

FIGURE 32.9 Schematic diagram of different emulsification processes to produce gel particles (a) mechanical stirring (b) static mixing (c) membrane emulsification and (d) microchannel emulsification. 

H. Okochi, M. Nakano, Comparative study of two preparation methods of W/O/W emulsions stirring and membrane emulsification, Chem. Pharm. Bull. 1997, 45, 1323. 

Both direct and premix emulsification can be obtained with a continuous phase flowing along the membrane surface (i.e., crossflow, stirring) (Figure 21.2(b)). However, it is important to distinguish between the droplet-formation mechanism and the macroscopic operation procedure. In other terms, often, in the literature, the... 

Figure 21.13 Emulsification devices where the membrane is immersed in a stirred vessel containing the continuous phase. Transmembrane pressure applied from (a) external or shell side, and (b) internal or lumen side.

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