Coalescence of bubbles in aqueous mixed surfactant–alcohol systems

Coalescence of gas bubbles in aqueous solutions of surfactant–alcohol mixtures has importance in many scientific and engineering applications. This article reports studies on coalescence of air bubbles in aqueous solutions of sodium dodecyl sulphate, cetyltrimethylammonium bromide, ethanol and butanol. Adsorption of surface active molecules at the air/water interface, which plays a crucial role in coalescence, was studied by measuring the surface tension of the aqueous solutions. The results on coalescence time were analysed using the film drainage and stochastic theories of coalescence. Seven film drainage models were employed to predict the coalescence time. The parameters of the stochastic model were analysed based upon the physicochemical properties of the systems.