Studies of concentrated surfactant solutions using the maximum bubble pressure method

An analysis of the adsorption process during the deadtime period in maximum bubble pressure experiments is performed. The adsorption dynamics is calculated for the actual surface area increase of a bubble in a surfactant solution, which depends on characteristic system parameters such as the length and diameter of the capillary and the surfactant's concentration and adsorption activity. Under certain conditions, the calculations yield extreme adsorption behavior. In particular, a sharp adsorption minimum is predicted in the initial period of the deadtime interval. This effect can be relevant for the interpretation of bubble pressure results for concentrated surfactant solutions, when the initial adsorption of the surfactant is significant. Tn this case, the experimental results should be presented as a function of the effective total time (deadtime plus lifetime) rather than the effective lifetime. (C) 2000 Elsevier Science B.V. All rights reserved.