Abstract
Multicomponent diffusion experiments for three concentrations in the H2O-SmCl3-NdCl3 ternary system and for a single concentration in the H2O-SmCl3-NdCl3-PrCl3 quaternary system were carried out with the positionscanning spectrophotometer and the diffusion coefficients were determined using the extended Boltzmann method. Binary diffusion coefficients for the H2O-SmCl3 and H2O-NdCl3 systems were also measured. They were nearly the same as each other, slightly increasing as the solute concentration increased from 0.1 to 1.0kmol/m3. Reliability of the measured multicomponent diffusion coefficients was supported by the fact that they satisfied Onsager''s reciprocal relation. Cross diffusion coefficients were between 20 and 50 percent of the main terms and cannot be neglected, even from the engineering viewpoint. The large cross diffusion coefficients were due to the electrostatic interaction among the constituent ions and the observed multicomponent diffusion coefficients could be estimated fairly well by the method of Wendt at low concentrations. Improvement in the estimation of the multicomponent diffusion coefficients by the method of Miller was pronounced, especially at higher concentrations.
