Thermodynamics of carbohydrate surfactant containing systems

Abstract

The skillful combination of carbohydrate surfactant–water–oily component–cosurfactant is successful in obtaining microemulsion states for the solubilization of comparable amounts of materials as dissimilar as oil and water into a single, thermodynamically stable, liquid phase. This paper focused on theoretical study of the phase behavior of the corresponding binary and ternary subsystems and the quaternary system. The phase equilibrium calculations based on the Koningsveld–Kleintjens model. Applying the Koningsveld–Kleintjens model the essential features of phase behavior, including two- and three-phase equilibria, in the ternary system can be calculated. The calculation results are in good quantitative agreement with the experimental observations. Not unexpectedly, it turned out to be impossible to model the quaternary systems, and with these theoretical frameworks it was even impossible to form the correct three-phase equilibria, especially the microemulsion phase. The quantitatively correct composition of the middle phase microemulsion cannot be modeled, whereas the composition of excess water-rich and of the oil-rich phase can be predicted. Taking into account the partially ordering of the system by a special entropy contribution or the screening of the enthalpy repulsion between water and oil do not lead to an improvement of the modeling results.