Premix membrane emulsification

In the early 1990s, Nakashima et al. [2] introduced membrane technology in emulsions preparation by a direct emulsification method, whereas, in the late 1990s, Suzuki et al. used premix membrane emulsification to obtain production rates higher than other membrane emulsification methods [11]. 

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. 

Table 21.2 List of most common membranes used in premix membrane emulsification. ... 

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. 

Premix membrane emulsification is a powerful technique, especially where the system does not induce internal fouling of the membrane used, and where high volume fractions of the dispersed phase are required. This probably limits the applications mostly to (fine) chemicals production, but one may expect a few applications in the food industry as well. 

Altenbach-Rehm, J.P., Schubert, H., Suzuki, K. (2002). Premix membrane emulsification by hydrophilic and hydrophobic PTFE membranes for manufacture of O/W emulsions with a narrow drop size distribution. Chem-Ing-Tech 74(5), 587-588. 

Li N, and Sakaki K, Performance of an emulsion enzyme membrane reactor combined with premix membrane emulsification for lipase-catalyzed resolution of enantiomers, J. Mem. Sci. 2008 314 183-192. 

Altenbach-Rehm, J., Suzuki, K., and Schubert H., Production of O/W-Emulsions with Narrow Droplet Size Distribution by Repeated Premix Membrane Emulsification, Proceedings of the third World Congress on Emulsions, Lyon, France, September 24-27, 2002, 6 pp. 

Vladisavljevic, G.T., Shimizu, M., and Nakashima, T., Preparation of monodisperse multiple emulsions at high production rates by multi-stage premix membrane emulsification, J. Membr. Set, 244 (1-2), 97-106, 2004. 

In premix membrane emulsification, emulsion premixes are pressed through the membrane pores. A phase inversion while passing the membrane is induced if the membrane surface is wetted by the droplet phase of the premix. Thus emulsions of high disperse phase fractions, even above 80%, can be produced at a throughput of up to several tons per square meter of membrane surface per hour. A narrow droplet size distribution requires a low number (2-3) of recirculations through the membrane. The mean droplet size is about twice the pore size [51]. 

Figure20.9 Processing applications ofmembrane emulsification rotating membranes [53, 54, 56] and premix membrane emulsification [49, 51, 57],...

Premix membrane emulsification was developed by Suzuki [4j. In this process, an emulsion premix containing large droplets instead of the pure disperse phase is... 

Figure 13.8 Schematic illustration of premix membrane emulsification.

For premix membrane emulsification, the factors influencing the emulsification results are the transmembrane pressure, repeated processing and the pore size of the membrane. Furthermore the composition of the emulsion, like disperse and continuous phase viscosity, emulsifier and emulsifier concentration have also an influence on the emulsification results [28-31]. 

Figure 13.9 Droplet size distributions in premix membrane emulsification at different transmembrane pressure differences.

Figure 13.14 shows the premix membrane emulsification flux for different process and product parameters. The product flux (Ap = 12bar, dp = 0.8 pm, one pass) decreases from 28m m h to 5m m h with increasing dispersed phase concentration from 30% to 80%. 

The flux in premix membrane emulsification is approximately ten times higher than the flux of conventional membrane emulsification, as measured for example by Schroder [8] considering membranes with similar mean pore diameters. 

Figure 13.14 Flux in premix membrane emulsification for different process and product parameters (Ap=12bar, dp = 0.8pm, one pass).

From the present point of view, premix membrane emulsification is the technique of choice for producing emulsions with high dispersed phase fractions at reasonable flux (see Figure 13.14) [32]. 

G.G. Badolato, G. Krug, H.P. Schuch-matm, H. Schubert, Premix Membrane Emulsification Hi ier Flux and Fligher Dispersed Phase Concentration in Membrane Process, Congres Mondial de I Emulsion, Lyon, 2006. 

TABLE 6.2 Premix membrane emulsification investigations currently reported... 

Altenbach-Rehm J, Suzuki K, Schubert H. 2002b. Production of OAV-emulsions with narrow droplet size distribution by repeated premix membrane emulsification. In Proceedings of the 3rd World Congress on Emulsions. Lyon. 

Ribeiro HS, Rico LG, Badolato GG, Schubert H. 2005. Production of OAV emulsions containing astaxanthin by repeated Premix membrane emulsification. J Food Sd 70(2) E117-123. 

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