Use of the BET adsorption isotherm equation to examine styrene adsolubilization by nonionic surfactants at the water-silica interface.

A modified BET adsorption isotherm equation was used to explain adsolubilization at the water-silica interface, producing a method for understanding adsolubilization that is independent of admicelle structure. The two constants k1 and k2 provide a measure of the surfactant-solute and solute-solute interactions, respectively. As predicted, k1 changed with various factors including surfactant structure, the presence and quantity of added lipophilic linker and hexane. On the other hand, k2 was fairly constant for all examined systems having the same solute. Commonly used partition coefficients can be easily related to the model and adsolubilization isotherms may be reproduced by the developed equation. Inferences about solute distribution at the interface and its location within the admicelle may be extracted from the results. The model is useful in explaining trends in adsolubilization and in predicting adsolubilization behavior for similar systems.