Abstract:

Mixed aqueous-and-oil foams have been widely used in various industrial fields such as food, oil production and cosmetics. However, most reports on mixed aqueous-and-oil foams have focused on their formation and stability, and few reports on their drainage behavior. In this work, dodecane and kerosene were used as the oil phase, respectively, which were then mixed with water in a certain proportion, and finally 0.125% anionic surfactant sodium dodecyl sulfate （SDS） was added to prepare mixed aqueous-and-oil foam. The foam volume, half-life, apparent viscosity, microscopic foam structure, and the changes of conductivity, drainage volume, drainage rate and bubble size during free drainage were studied to find the rule and influence mechanism for the physical properties of mixed aqueous-and-oil foam during drainage. It was found that the mixed aqueous-and-oil foams with various oil-water volume ratios （1∶9-5∶5） exhibited shear thinning as non-Newtonian fluids. Compared with corresponding aqueous foam, the mixed aqueous-and-oil foam had poor comprehensive performance of foaming but strong liquid-carrying ability. With the increase of oil-water volume ratio, the drainage rate of mixed aqueous-and-oil foam decreased and the liquid-carrying ability increased. The drainage behavior of mixed aqueous-and-oil foam could be divided into three stages, the rapid drainage stage dominated by gravity, the slow drainage stage dominated by the viscosity of continuous phase, and the oil-droplet-blocked drainage stage.

Key words: mixed aqueous-and-oil foam, microstructure, drainage mechanism, drainage rate