Constant vapour pressure evaporation from a fragrance emulsion-effect of solubility of surfactant in the fragrance compound

The algebraic system to extract information from phase diagrams was used to establish some of the conditions for an emulsion to evaporate under constant vapour pressure. The model system for the calculations was an emulsion characterized by virtually no solubility in water by either the surfactant or the fragrance and the same condition for the water in the oil. The surfactant and the fragrance, on the other hand, were assumed to be mutually completely soluble and this solution was presupposed to be close to ideal. The results showed a surprisingly strong dependence of the times for evaporation under constant vapour pressure on the surfactant concentration in the oil phase, at which the two-phase equilibrium between the aqueous and the oil phases is replaced by a three-phase equilibrium: aqueous phase, oil phase and liquid crystal phase. The lower this concentration, the more extended the times for evaporation under constant vapour pressure. Copyright (C) 2008 John Wiley & Sons, Ltd.