Electrochemistry in the presence of convective flow generated by acoustic streaming from a focused ultrasonic source.

Limiting currents for the reduction of hexacyanoferrate-(III), i(lim), in aqueous solutions have been recorded in the presence of convective flow generated by a focused acoustic source with its main axis placed normal to the surface of a circular Au electrode embedded in a coplanar Teflon shroud. The results obtained could be fitted to a formula of the type -i(lim) = a(Uz(ss))b, where Uz(ss) is the axial velocity of the fluid along the center line of the lens evaluated at the focal point using computer simulation routines developed by Kamakura and co-workers (Kamakura, T.; Matsuda, K; Kumamoto, Y.; Breazeale, M. A. J. Acoust. Soc. Am. 1995, 97, 2740-2746). The fit yielded a value of b approximately 0.5 in agreement with that of rotating disk and impinging jet electrodes.