Hydrodynamic effects in maximum bubble pressure tensiometry

Maximum bubble pressure tensiometry (MBPT) is one of very few techniques that can characterize the dynamics of surfactant transport at a liquid–gas interface at timescales below 1 ms. It involves the periodic formation and pinch-off of bubbles at the orifice of a capillary tube immersed in a liquid. To avoid dealing with the hydrodynamic complexity of the interface evolution, often ill-founded assumptions have been made to extract material parameters from an analysis of the experimental data, which then resulted in large systematic errors. In this manuscript, we propose an alternative, hydrodynamically consistent analysis procedure of MBPT data. It is based on a combination of high-speed imaging of the bubble expansion process and a one-dimensional numerical model for surfactant transport based on mixed kinetics. For validation we consider aqueous solutions of the well-characterized surfactant sodium dodecyl sulfate (SDS) and achieved good agreement with the scarce literature data of the adsorption rate constant.