Calculation of diffusion coefficients in ternary systems from diaphragm cell experiments

Abstract

Using a generalized least square procedure, a method is developed to estimate diffusion coefficients, Dij, from concentration measurements made in a set of experiments of varying duration but with the same initial conditions. The method requires neither approximations nor restrictions in the flow equations. The Dij and their errors are calculated simultaneously with the adjustment of the weighted observables - concentrations of the two solute components and time. A procedure is described to insure convergence in a given experimental set. The effect of the duration of the longest experiment, and errors in the observables on the estimated values of Dij and their errors, are investigated. Application of the method to available data yielded values for Dij in agreement with those previously calculated by more involved procedures.