Comparison of Nernst–Planck equations and Miller's LN approximations for countercurrent electrolysis in a thin porous membrane

Abstract

Two models which describe the transport of electrolytes in a porous membrane during countercurrent electrolysis are compared with experimental results. One model is based on Nernst–Planck equations and the other is based on Miller's LN approximations. The comparison was made in the ternary system NaCl + HCl + H₂O at a total concentration of 0.01 mol dm^–3. Both models give errors of approximately the same order of magnitude, and they both predict the behaviour of the system fairly accurately. The errors are surprisingly high compared with the errors in the transport quantities. This is thought to be due to the accumulation of small errors in the integration over the membrane.