Ternary mutual diffusion coefficients of KCl-LaCl3-water mixtures from taylor dispersion profiles

Abstract

The Taylor dispersion (peak-broadening) method is used to measure ternary mutual diffusion coefficients at 25°C for fifteen different compositions of the system KCl−LaCl3-water at ionic strengths from 0.02 to 0.24 mol-dm−3. The diffusion coefficients are evaluated by least-squares analysis of the refractive index profiles across the dispersed solute peaks. Diffusing LaCl3 is found to cotransport significant amounts of KCl. Monte Carlo simulations are used to estimate the precision of ternary diffusion coefficients determined by the dispersion method. Tracer diffusion coefficients are also reported for La3+ ions in aqueous KCl solutions and for K+ ions in aqueous LaCl3 solutions.