Influence of dissolved atmospheric gases on the spontaneous emulsification of alkane-ethanol-water systems

We previously showed that the amount of oils dispersed in an aqueous phase, and their kinetic stability, could be enhanced when the dissolved atmospheric gases were removed from the system. Here we studied the effect of the removal of dissolved atmospheric gases on the formation and kinetic stability of oil droplets dispersed by the spontaneous emulsification (the Ouzo effect) for the ternary systems of ethanol, alkane, and water. The hydrocarbons studied were decane (C10), undecane (C11), dodecane (C12), tetradecane (C14), and hexadecane (C16). Our findings show that (1) the amount of oils dispersed to the aqueous phase was greater for the degassed samples than for the control (nondegassed) counterparts, (2) the variation in the size from sample to sample of the oil droplets dispersed, measured by dynamic light scattering (DLS), was much narrower for the degassed mixtures than for the control counterparts, and (3) the size of the oil droplets dispersed decreased with the molecular weight of the oil for the control mixtures, whereas it was largely independent of the molecular weight of the oil for the degassed mixtures. Our results suggest that the nature of nucleation during the spontaneous emulsification process may have changed after the removal of dissolved atmospheric gases, becoming more homogeneous in nature than that in the control samples.