%0 Journal Article %T Effect of Gas Permeability and Solubility on Foam %A Rouhollah Farajzadeh %A Sebastian Vincent-Bonnieu %A Nacera Bourada Bourada %J Journal of Soft Matter %D 2014 %R 10.1155/2014/145352 %X We perform a study on the influence of gas permeability and solubility on the drainage and stability of foam stabilized with an anionic surfactant. Our study compares the foam stability for four pure gases and two gas mixtures while previous works only compared two pure gases. Drainage and foam-volume-decay rates are calculated from the experimental data and analysed. We find good agreement with existing theory as the foam stability is strongly influenced by the properties of the gas phase, in particular its solubility in the aqueous phase (measured by Henry¡¯s solubility constant, ) and permeability (measured by foam-film permeability coefficient, ). The foam volume decreases considerably with increasing . Moreover, we observe that foams are more stable when a less soluble gas is added to a more soluble gas. Our analysis confirms theories linking drainage, stability, and coarsening rate. Finally, we introduce a new formulation for the foaming index that considers gas solubility and permeability. 1. Introduction Aqueous foams are dispersions of a gas in a surfactant solution (containing water, surfactant, and possibly electrolyte or particles) [1¨C3]. Similar to the liquid phase, the gas phase might consist of more than a single component. For instance, when foam is applied in petroleum industry for improving the oil production, the gases are often mixtures of a number of gases. Another example includes direct utilization of the flue gas (mixture of N2, CO2, and ¡¯s) in several applications, which aims at reducing costs of separation of CO2 from flue gas. Foam can be characterized by physicochemical properties of its constitutive components, such as bubble shape and size, liquid fraction, and film thickness [1, 2, 4]. The properties of both phases (and the components in the phases) control the dynamics of foam behaviour and eventually affect foam longevity. While many studies have shown the impact of the components of the aqueous phase on foam stability [1, 4¨C9], the effect of type and composition of the gaseous phase has received less attention. Foam stability is controlled by three main factors: drainage, coarsening, and bubble coalescence. Coarsening refers to the growth of the average bubble size. Two processes are responsible for the changes in degree of dispersion of gas bubbles in foam: (i) the diffusion of gas through the lamellae and (ii) collapse of liquid lamellae and subsequent coalescence of contiguous gas bubbles. Pressure difference between bubbles of unequal size induces gas transfer from small to larger bubbles [10¨C13]. The ability of gas %U http://www.hindawi.com/journals/jsmat/2014/145352/