The Surface Tension of Aqueous Solutions Saturated with Triacetin–Tributyrin Mixtures

Abstract
The surface tension of aqueous solutions saturated with triacetin–tributyrin mixtures was measured in order to study the phase equilibria among an adsorbed monolayer (m), an aqueous solution (w), and an oily mixture (1). The variation in the surface tension, γ, of saturated aqueous solutions with an increase in the number of moles, mt, of the added mixtures depended on the mole fractions, x2, of tributyrin in the mixtures; the γ value remained unchanged in the case of x2=0.0027, decreased in the case of x2>0.0027, and increased in the case of x22w. The characteristics of these curves were explained thermodynamically on the basis of the assumption that triacetin and tributyrin form a regular mixture in a monolayer as well as in a liquid.