AN OSCILLATING BUBBLE TECHNIQUE TO DETERMINE SURFACTANT MASS-TRANSFERKINETICS

In this paper, an oscillating bubble method is introduced as a spheric al analog of the longitudinal wave method. In the longitudinal wave me thod, amplitude ratios and phase angles between surface tension variat ions at two locations on the interface are related to the surfactant m ass transfer kinetics. In the analogous oscillating bubble method, by forcing small-amplitude radial perturbations about an equilibrium base state, and measuring the phase angle between the bubble radius and th e gas phase pressure, the surfactant diffusion and sorption kinetics c an be determined. In this communication, data are presented for n-deca nol at the aqueous-gas interface. The phase angle is measured as a fun ction of bulk concentration and forcing frequency. By minimizing the e rror between theoretical and experimental phase angle profiles, the di ffusivity and desorption coefficients of n-decanol are obtained.