Ionic mass transfer on fixed disk and conical electrodes under streaming solutions-III. A second experimental approach and kinetic application

J.C Bazán,S.L Marchiano,A.J Arvía

doi:10.1016/0013-4686(67)80119-1

J.C Bazán, S.L Marchiano + Show 1 more

Open Access

https://doi.org/10.1016/0013-4686(67)80119-1

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Journal: Electrochimica Acta	Publication Date: Jul 1, 1967
Citations: 17	License type: cc-by

Affiliation: Universidad Nacional de La Plata

Abstract

The rate of ionic mass transfer on fixed disk electrodes under streaming solutions was studied avoiding as far as possible any wall effect on the mass-transfer rate. Nickel electrodes, previously activated, and platinum and graphite electrodes with solutions of potassium ferro- and ferricyanide in sodium hydroxide were used. The geometry of the cell and other variables of the system were conveniently changed. The experimental rate equation agrees with that found by solving the Navier-Stokes and Fick's differential equations, for results with activated nickel electrodes, the fluid velocity being properly defined.Results obtained with platinum and graphite electrodes present a deviation from those equations, a fact which is interpreted in terms of an electrochemical reaction with intermediate kinetics. The kinetic parameters of the corresponding electrochemical reactions are evaluated.

Highlights

THE THEORETICAL rate equation, deduced in Part I,l indicates that the maximum rate of mass transfer, under convective-diffusion control in laminar flow, increases with the square root of the fluid velocity
It is interesting to study the ionic mass-transfer rate in circumstances similar to those already described,[2] but in a different type of electrolysis cell, where the incidence of the streaming solution is such that it takes place as if the influence of the counter-electrode wall on the process occurring in the working electrode were absent
Activated nickel electrodes Current/voltage curves obtained with these electrodes show no appreciable activation polarization in the electrochemical reaction, as already established.[8]

Summary

INTRODUCTION

THE THEORETICAL rate equation, deduced in Part I,l indicates that the maximum rate of mass transfer, under convective-diffusion control in laminar flow, increases with the square root of the fluid velocity. It is interesting to study the ionic mass-transfer rate in circumstances similar to those already described,[2] but in a different type of electrolysis cell, where the incidence of the streaming solution is such that it takes place as if the influence of the counter-electrode wall on the process occurring in the working electrode were absent. This is equivalent to assuming that the velocity protie has a uniform distribution. The electrolysis cell was assembled with the rest of the hydrodynamical circuit which comprised a glassrotatory pump driven by a regulated ac motor, a flowmeter and a storage container, kept at a constant temperature in a thermostat

Working conditions

RESULTS

Platinum electrodes

Graphite electrodes

DISCUSSION