Stability of cellular foam generated from amphoteric surfactant aqueous solution.

Experiments were carried out to investigate the stability of cellular foam generated from an amphoteric surfactant aqueous solution in a standard bubble column. A typical growth and collapse process were found, and the cellular foam became stable with increasing pH of the solution under both acidic and basic conditions. The critical film thickness calculated from the thinning equation, the well-known Reynolds equation, was between 100 to 400 nm. Of particular note is that the cellular foam was not observed at pH=7 of the liquid.