Membrane emulsification is a technique which uses the pores of a microporous membrane to disperse one of two immiscible liquids, the disperse phase, into another liquid, the continuous phase, by applying pressure. The possible advantages of using this technique are that it is a low-shear, low-energy process capable, in theory, of producing an emulsion with a narrow droplet size. The main aim of this study was to provide a systematic analysis of membrane emulsification processes for the production of O/W emulsions using commercial available equipment and membranes. An experimental approach was adopted. Two methods of membrane emulsification were investigated. The first, dead-end membrane emulsification, used an adaptation of traditional membrane filtration equipment. Several membrane types were selected and investigated, including flat-sheet polymeric micro-and ultrafiltration membranes, and a ceramic microfiltration membrane. The second method, crossflow membrane emulsification, employed a hollow fibre ultrafiltration membrane. A standard emulsion formulation and experimental protocol for emulsion formation and characterisation was employed for all experimental work. Experimental investigations showed that O/W emulsions could be reproducibly produced with each membrane type, with emulsion characteristics related to membrane characteristics and operating conditions. For all membranes the results indicated that good quality emulsions with small droplet sizes and narrow size ranges were produced at slow disperse phase flowrates, usually at the lowest operating pressure possible, and moderate stirring at 600 rpm, or low crossflow velocities. An optimum set of operating conditions was most clearly identified for the polymeric microfiltration membranes. For comparison purposes, emulsions were produced using stirring only and by vortex mixing. Characterisation of the emulsions was undertaken using optical microscopy with image analysis and particle sizing techniques. Membrane characteristics were obtained using atomic force microscopy and scanning electron microscopy.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:636279 |
| Date | January 1998 |
| Creators | Collins, S. E. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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