Foaming in Micellar Solutions: Effects of Surfactant, Salt, and Oil Concentrations

Foaming in products based on micellar solutions has considerable importance in various consumer applications, such as washing and cleaning. In this work, the effects of surfactant concentration, oil content, and salts containing mono-, di-, and trivalent counterions on foam formation and stability were studied. The foams were generated by employing the Blender Test. The presence of salts caused a significant reduction in foam volume. Effectiveness of the salts followed the sequence Al 3+ > Ca 2+ > Na + . However, the foam collapse rate was slower in the presence of salt. The rate of adsorption of surfactant molecules at the air–water interface was augmented by salt. Oil reduced the foam volume and its stability. The entering, spreading, and bridging coefficients were calculated. These coefficients qualitatively explained the stability of foam in the presence of oil.