Enhancing the Foam Stability of Aqueous Solution with High Ethanol Concentration

Abstract

Ethanol is widely used in our daily life, including in ingredient liqueurs, medicines, cosmetics, and so on. Aqueous solutions containing high concentrations of ethanol are also used as hand sanitizers. Such sanitizers are discharged from a bottle as liquid, mist, gel, or foam. Foams are generally stabilized by the adsorption of a surfactant at the air/liquid interface; however, the stabilization of foams containing high concentrations of ethanol in aqueous solutions is very challenging. In this short review, we focus on the foam stability of an aqueous solution containing a high concentration of ethanol (60 vol.%) under the combined addition of an anionic surfactant, a long-chain alcohol, and an inorganic electrolyte. The key conclusion of this work is that the addition of these materials in the aqueous ethanol solution results in an increased surface viscosity, leading to an enhanced foam stability. This finding is expected to provide a new platform for formulating foam-type hand sanitizers with high concentrations of ethanol.

graphical abstract