Cross-flow membrane emulsification

Cross-flow membrane emulsification (see Section 15.6.1 and Figure 15.9)... 

Droplet sizes and important proeess parameters The properties of the membrane are very important in this process. The membrane should have a relatively narrow pore size distribution, just as with cross-flow membrane emulsification, and it should be wetted by the phase that should be the continuous phase. 

A few food products have been on the market using cross-flow membrane emulsification. The method can make emulsions that have small droplets with a narrow size distribution. Thus, it is possible to make sauces with lower oil content than with conventional emulsification techniques. The technique of cross-flow emulsification is clearly the best developed process for small-scale, high-value applications it is an attractive process. 

FIGURE 6.26 Schematic representation of cross-flow membrane emulsification. 

Gijsbertsen-Abrahamse AJ, van der Padt A, and Boom RM. Stams of cross-flow membrane emulsification and outlook for industrial appUcation. J. Membr. Sci. 2004 230 149-159. 

The effects of flow rate(s), monodispersity, energy input, and ease of parallelization are evaluated to indicate the potential of microfluidic techniques for large-scale application. Cross-flow membrane emulsification will be used as benchmark technology as it is already available and relatively easy to scale up by using several membranes in series or in parallel. Table 1 shows a summary of various effects of which more detailed information is given in the remainder of this section. 

A few devices have been proposed that resemble cross-flow membrane emulsification, where a phase is induced to disperse through the small openings of a membrane in a flow of continuous phase [3]. Such processes are more energy efficient than conventional approaches such as colloid mills and homogenizers [142]. A microstructured analogue of membrane emulsification was presented by de... 

A.f. Abrahamse, R. van Lierop, R.G.M. van der Sman, A. van der Padt, R.M. Boom, Analysis of droplet formation and interactions during cross-flow membrane emulsification, /. Membr. Sci., 2002, 204, 125-137. 

A second, new class of processes is that of membrane and micro-channel emulsification. A to-be-dispersed phase is here pushed through pores of a membrane or through micro-engineered micron-scale channels. At the pore or channel mouth, droplets are formed. These droplets can spontaneously detach from the pore or channel mouth (interfacial tension driven snap-off), due to the distortion of the droplet shape when it is still attached to the mouth. At higher fluxes or with channel mouths not giving a strong shape distortion, droplets are sheared off by a cross-flowing continuous phase. 

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