TERNARY DIFFUSION-COEFFICIENTS FOR THE ILL-CONDITIONED SYSTEMS KCL-KI-H2O AND NACL-NAI-H2O MEASURED BY A 2-DETECTOR TAYLOR DISPERSION METHOD

The ternary mutual diffusion coefficients of KCl-Kl-H2O and NaCl-Nal-H2O are measured at 25-degrees-C by the Taylor dispersion (peak-broadening) method. The broadened distribution of injected solution samples is followed by monitoring the changes in both the refractive index and the electrical conductivity as the samples flow out of the dispersion tube. Resolving the diffusion of the dissolved salts by refractive-index detection alone is difficult because they diffuse at nearly identical rates. Ca. an order of magnitude improvement in the precision of the measured diffusion coefficients is obtained by analysing the combined conductivity and refractive-index data.