Surfactant in the gaseous phase I. Formation of foams and thin liquid films

A new possibility of obtaining foams and single thin liquid films by supplying a surfactant through the gaseous phase is presented. Argon saturated with vapors ofn-amyl orn-decyl alcohol was passed through the water phase and formation of the foam was measured as a function of time, gas flow rate, and volume of the water phase. Formation and properties of microscopic thin liquid films were measured as a function of the time of their contact with the surfactant vapors. Two possible mechanisms of foam formation by supplying surfactant via the gaseous phase are discussed. A theoretical model of surfactant dissolution is presented and its predictions are compared with the experimental results. It is shown that foam formation resulted mainly from dissolution of the surfactant vapors in the water phase.