Kinetics of Compositional Ripening in Emulsions Stabilized with Nonionic Surfactants

Abstract

The rates of solubilization of single n-decane/squalane drops were measured in solutions of the pure nonionic surfactant C12E8 containing different amounts of solubilized decane at 22°C. Solubilization of squalane was negligible for these conditions. The results showed that mass-transfer rates of decane were controlled by interfacial phenomena, not by diffusion in the micellar solution, when transfer was either from drop to solution or vice versa. Good agreement with experimental data was obtained by using a model which assumed that the decane/squalane drops were ideal solutions. This model based on interface-controlled mass transfer was extended to describe the behavior of mixed emulsions stabilized with nonionic surfactants. Predictions of time variation of drop sizes for a particular mixed emulsion studied by B. P. Binks et al. [Langmuir14, 5402 (1998)] were in better agreement with the experimental data than those of the authors' model based on diffusion control.