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

We present and discuss experiments on bubble rise velocities performed in various solutions of surface-active molecules; we particularly focus our study on the role of bulk-surface exchanges. For proteins, the vanishing desorption limit (irreversible adsorption) can be achieved experimentally and measurements are found in quantitative agreement with the stagnant cap model. The opposite limit of fast exchange rates is obtained by using short alcohols that turn out to slightly influence bubble velocities; a surface remobilization at high concentrations has been evidenced with isopropyl alcohol. Received 16 November 1999 and Received in final form 24 March 2000