Membrane Emulsification Processes

Considerable progress has been achieved in understanding the technology from the experimental point of view, with the establishment of many empirical correlations. On the other hand, their theoretical interpretation by means of reliable models is not accordingly advanced. The first model devoted to membrane emulsification, based on a torque balance, was proposed in 1998 by Peng and Williams [13], that is, ten years later the first experimental work was published, and still nowadays, a theoretical study aiming at a specific description of the premix membrane emulsification process is not available. 

In this section, an analysis of the experimental observations and empirical correlations related to membrane emulsification processes will be illustrated. The theoretical bases that support these results and predict membrane emulsification performance will be discussed in the next section. 

C. Charcosset, I. Limayem, H. Fessi.The membrane emulsification process - a review,/. Chem. Technol. Biotechnol. 2004, 79, 209. 

Schuchmann HP (2008) Membrane emulsification processes and characterisation methods. In Gilell C, Ferrando M, Lopez F (eds) Monitoring and visualizing membrane-based processes. Wiley-VHC, Weinheim (in press) (ISBN 3-527-32006-7)... 

In membrane emulsification processes, one phase (future disperse phase) is usually pressed through the pores of a membrane into the other phase (continuous phase) [3]. A different approach is the disruption of large droplets by pushing an emulsion premix through the pores of a membrane [4]. Furthermore, special shapes of the pore outlet of microcharmel modules allow the production of small droplets due to a special detachment mechanism [5-7]. 

Membrane emulsification processes can be directly visualized by microscope as vell as by the use of high-speed cameras. In this case, information can be obtained about droplet disruption [10, 11] and fouling of the membrane. An indirect characterization method is the (inline) measurement of the emulsion characteristics. The emulsion is mainly characterized by its droplet size and droplet size distribution [2]. These infiuence important product characteristics like structure, mouthfeel, color and appearance, texture and viscosity [12, 13]. 

Figure 13.5 Droplet formation by direct membrane emulsification process.

Charcosset C, Limayem I, Fessi H. 2004. The membrane emulsification process— A review. J Chem Technol Biotechnol 79 209-218. 

Rayner M, Tragardh G, Tragardh C. 2005. The impact of mass transfer and interfacial expansion rate on droplet size in membrane emulsification processes. Colloids Surf A 266 1-17. 

The next chapter by G. T. Vladisavljevic and R. A. Williams is a comprehensive and systematic review of new techniques of preparation of multiple emulsions, emulsions, and microparticles. The authors envisage the ways to form multiple droplets by using membrane emulsification processes and microchan-nel and microcapUlary devices. They also pay special attention to the preparation of solid microparticles via a double emulsion emulsification method using membrane emulsification and microfiuidic devices. 

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