| Summary: | In the last decade , the potential of reverse micelles to extract proteins from fermentation broths with considerable cost savings has become recognised. Reverse micelles are thermodynamically stable nano-size droplets stabilised by a monolayer of surfactant in an organic solvent. The succesful exploitation of this new technology for large scele protein separation requires a good understanding of the effect of various parameters on the physico-chemicalproperties of reverse micelle systems, and the thermodynamics and kinetics of protein transfer, and protein activity. This tehsis will present the experimental data obtained in examining certian aspects of this subject.The effect of various system parameters such as solvent type and structure, alt type and concentration, and surfactant concentration on water solubilisation, surfactant partitioning, protein forward and backward extraction, and the kinetics of protein dn water forward dna backward transfer were studied.An anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), and a-chymotrypsin. trypsin and cytochrome c were used as a model surfactant and protein perspectively. The water solubilisation, surfactant partitioning, andprotein forward and backward extraction were carried out using the phase transfer technique, while a non-dispersed stirred cell (NDSC) was used to evaluate the kinetics of protein and water transfer.The water solubilisation studies showed that water solubility in organic solvents, and water solubilisation in reverse micelle systems are governed by different mechanisms. Water solubility increases with increasing solvent polarity, whereas water solubilisation with increasing surfactant concentrattion however, can be regarded as being due to either an increase in the reverse micelle size, or a number or combination of both. Increasing water solubilisation with decreasing salt concentration was due to a decrease in the cation charge screening effect on surfactant head froups, and the extent of this effect with decreases with increasing hydration radius of the cation involved. Surfactant partitioning into the conjugate aqueous phase increases with an increases hydrophilic-hydrophobic balance (HLB) of the surfactant, and this is increased by decreasing solvent polarity and salt concentration and changing to salts with a larger hydration size. It also increases with increasing surfactant loading. The use of physico-chemical properties of teh solvent, as expressed in solvent polarity scales, and their correlation with water solubility, water solubilisation and surfactant partitioning showed that the solvent polarity scales could be grouped into categories: Group A: solubility parameter, dielectric constant and polarizability; Group B: log P, log Sw/o and molar volume, wh
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