Regression of NRTL parameters from ternary liquid-liquid equilibria using particle swarm optimization and discussions

Abstract

The particle swarm optimization (PSO) method was successfully used to regress the nonrandom two-liquid (NRTL) parameters from liquid-liquid equilibria (LLE) data and the resulting parameters had smaller root-mean square deviations (RMSD) compared with literature values. Analysis of the results reveals that multiple groups of parameters with sufficiently small RMSDs can be found for the same set of LLE data. The activities calculated using these parameters and their corresponding predicted mole fractions can be far beyond the reasonable range of activity, clearly demonstrating that the NRTL model does not represent the real activities of components with parameters regressed from LLE. In addit..