The Surface Adsorption of Sodium Alkyl Sulfates from Dioxane-Water Mixtures

The surface adsorptions of three sodium alkyl sulfates (C12, C14, C16) from dioxane-water mixtures have been measured by using 35S-labeled surfactants; it has been found to decrease with an increase in the dioxane concentration. This decrease has been explained in terms of the following factors; (1) the variation in the standard chemical potential of the surfactant in the bulk phase, or the free energy of transfer, (2) the surface tension of the solution, and (3) the dielectric constant of the solvent. In a solvent containing more dioxane than 40wt.%, it has been shown, both by experiment and by theory, that these alkyl sulfates lose their surface activities.