Measurement of Limiting Partition Coefficient in Progressive Freeze-Concentration

Abstract

The limiting partition coefficient is the partition coefficient of a solute at the ice-liquid interface observed at an infinitesimal advance rate of the ice front or infinite mass transfer rate at the interface in progressive freeze-concentration. A method to determine the limiting partition coefficient was proposed based on the concentration polarization model. Electrolytes were concentrated at various operating conditions in advance rate of the ice front (u) and stirring rate (N) in progressive freeze-concentration. The limiting partition coefficients (K0) of NaCl and KCl were obtained from the effective partition coefficients (K) observed under various operating conditions. From K experimentally de-termined, ln(1/K1) was calculated and plotted against u/N0.2. This plot showed a linear line, from which K0 was ob-tained by extrapolation to u/N0.2 → 0. The limiting partition coefficient was dependent both on the solute concentration and the chemical species of solute.