Ascending air bubbles in solutions of surface-active molecules: Influence of desorption kinetics

We present and discuss experiments on bubble rise velocities performed in v arious solutions of surface-active molecules; we particularly focus our stu dy on the role of bulk-surface exchanges. For proteins, the vanishing desor ption limit (irreversible adsorption) can be achieved experimentally and me asurements are found in quantitative agreement with the stagnant cap model. The opposite limit of fast exchange rates is obtained by using short alcoh ols that turn out to slightly influence bubble velocities; a surface remobi lization at high concentrations has been evidenced with isopropyl alcohol.