Hydrodynamic properties and mass transfer characteristics of electrochemical flow-through cells of the confined wall—jet type

The hydrodynamic properties and mass transfer characteristics of confined wall—jet electrochemical flow-through cells have been investigated for an electrochemically and chemically reversible, uncomplicated electrode reaction. Numerical as well as experimental results are presented. The approximate analytical solution for the stationary Sherwood number of a cell with a disk working electrode with radius R is: 〈Shj〉anal=0.924Re13d(d/b)23(d/R)23Sc12 This relation is valid only when the diffusion boundary layer is small, creeping flow is assumed and the contribution of the impingement area to the signal can be neglected. Numerical correlations give the following solution for the mass transfer at a disk working electrode for Red values between 10 and 180; 1000 ⩽ Sc ⩽ 2000; 2 ⩽ R/d ⩽ 16.7 and 0.083 ⩽ b/d ⩽ 0.67 (reproduction of the solute at the auxiliary electrode is accounted for): 〈Shd〉num = 0.82Re0.36d(d/b)0.63(d/R)23Sc13 For experimental verification a hydrodynamically optimized cell has been developed with a gold working electrode and a glassy carbon auxiliary electrode. For 10−3M potassium hexacyanoferrate(II) in 1 M potassium nitrate, the experimental results deviated less than 15% from the numerical solution when 8 ⩽ Red ⩽ 78; 0.083 ⩽ b/d ⩽ 0.67; Sc=1400 and R/d = 16.7.