Foaming of nonionic surfactant solutions: Effect of surfactant concentration and temperature

Foaming of solutions of the nonionic surfactant, octoxynol 9, was investigated in the concentration range of 0.010 to 5.00% and in the temperature range of 7–37 C, well below the cloud point of 65 C, by measuring the height and stability of foams generated by pouring thin streams of surfactant solutions into a glass column. All foams were fast-thinning. Their height increased monotonically with surfactant concentration. The rate of change of foam height with log surfactant concentration underwent no change at the CMC of 0.018%, but was four times lower above 0.146% than below 0.146%. Foams at lower temperatures generally thinned somewhat more slowly and were stronger or more cohesive and more stable than foams generated at higher temperatures by surfactant solutions of comparable concentrations. Oxidative degradation reduced foam height somewhat. Octoxynol 9 and sodium lauryl sulfate, rated as a good foamer, produced foams of comparable volume and stability.