First electrochemical Couette-Taylor reactor for studying the influence of transport phenomena on electrochemical kinetics

Abstract

This study presents the first electrochemical Couette-Taylor reactor (eCTR). It was implemented with 20 large electrodes exposed to the same hydrodynamics from Taylor numbers (Ta) of 144 to 28,800. The limiting currents (IL) recorded with hexacyanoferrate (III/II) at different concentrations and at different Ta were used to calculate the Nernst diffusive layer thickness (δN, ranged from 14.6 to 423 µm). Two hydrodynamic regimes were identified: the wavy (Ta from 144 to 1,440) and the turbulent (Ta > 2,200) vortex flows which corresponded to the correlations δN∝Ta-0.44 and δN∝Ta-0.70, respectively. The second correlation confirmed the theoretical equation established by Gabe & Robinson for turbulent flow. In contrast, the wavy vortex flow cannot be approached by the laminar or turbulent hypothesis. Dimensionless correlations gave comparable results between the eCTR and rotating cylinder electrodes under turbulent vortex flow and confirmed the specific behavior of the Couette-Taylor wavy vortex flow.