MEASUREMENTS OF THE ULTRASOUND-DIFFUSION AT AN ELECTRODE AND ITS PRACTICAL APPLICATION

Under the action of ultrasound (I up to 2 W/cm**2) quasi-stationary current voltage curves were obtained, from which the densities of the exchange, the diffusion-limited currents and the transfer coefficient were calculated. The acceleration of diffusion with ultrasound was attributed to surface cavitation involving pulsating bubbles surrounded by microstreaming. At higher sound intensities a limiting current due to cavitation saturation was observed. In order to explain this saturation effect a Langmuir kinetic for the enrichment and the depletion of cavitation bubbles beyond the threshold intensity was proposed. In the case of acoustic resonance (h equals n lambda /2) standing waves are generated in the solution. At the pressure loops the sound action has then a maximum.