Kinetics of phenanthrene dissolution into water in the presence of nonionic surfactants.

The apparent liquid saturation concentration of phenanthrene and the observed mass transfer coefficient in a completely mixed batch system were quantified as a function of surfactant concentration for four commercially available nonionic surfactants and two synthetic, nonionic glycolipids under development for possible commercial application. A mathematical model was developed to describe the dissolution process in the presence of these nonionic surfactants. The model accounts for diffusional transport of phenanthrene in the aqueous phase and transport of phenanthrene-saturated micelles across the hydrodynamic boundary layer. For the surfactants investigated and the experimental apparatus used, the observed mass transfer coefficients for phenanthrene dissolution into water were in the range of 0.01-0.025 cm/min in the presence of surfactant micelles as compared to 0.1 cm/min without surfactant. Although surfactants decrease the observed mass transfer coefficient relative to water alone, the influence of surfactants on phenanthrene solubilization results in an overall increase in phenanthrene dissolution rates.