Dynamic membrane emulsification

The membrane emulsification can be considered as a case of microdevice emulsification process [17, 18] in which the porous membrane is used as microdevices. Membrane emulsification carried out in quiescent conditions is also referred to as static membrane emulsification, while membrane emulsification carried our in moving conditions (either the membrane, i.e., rotating module, or the phase, i.e., crossflow) is also referred to as dynamic membrane emulsification (Figure 21.2(b)). 

In the microfluid dynamics approaches the continuity and Navier-Stokes equation coupled with methodologies for tracking the disperse/continuous interface are used to describe the droplet formation in quiescent and crossflow continuous conditions. Ohta et al. [54] used a computational fluid dynamics (CFD) approach to analyze the single-droplet-formation process at an orifice under pressure pulse conditions (pulsed sieve-plate column). Abrahamse et al. [55] simulated the process of the droplet break-up in crossflow membrane emulsification using an equal computational fluid dynamics procedure. They calculated the minimum distance between two membrane pores as a function of crossflow velocity and pore size. This minimum distance is important to optimize the space between two pores on the membrane... 

Although the premix membrane emulsification can yield larger fluxes with respect to direct membrane emulsification neither methods using surface-energy minimization nor microfluid dynamics approaches have been until now reported on the theoretical treatment of the premix membrane emulsification. 

Van der Graaf S, Schroen CGPH, Van Der Sman RGM, Boom RM. 2004. Influence of dynamic interfacial tension on droplet formation during membrane emulsification. / Colloid Interface Sci 711 456-463. 

V. Schroder, O. Behrend, and H. Schubert Effect of Dynamic Interfacial Tension on the Emulsification Process Using Microporous Ceramic Membranes. J. Colloid Interface Sci. 202, 334 (1998). 

Aqueous molecular assemblies such as micelles and bilayer membranes are formed by the self-assembly of amphiphihc compounds (Figure 11.la, b) [10]. Aqueous micelles have been utihzed for a variety of apphcations in surfactant industry, including emulsification, washing, and extraction processes [11]. BUayer membranes are basic structural components of biomembranes, and their structures are maintained even in dilute aqueous media. This is in contrast to micelles that show dynamic equihbrium between aggregates and monomeric species. Thus bilayers are more stable and sophisticated self-assemblies, and they require suitable molecular design of the constituent amphiphiles. BUayer membranes and vesicles have wide-ranging applications, as exemphfied by drug dehvery [12], sensors [13], and bilayer-templated material synthesis [14]. 

Schroder, V., Behrend, O., and Schubert, H. (1998a). Effect of dynamic interfacial tension on the emulsification process using microporous, ceramic membranes. J. Coll. Interf. Sci. 202, 334-340. 

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