Modified NRTL Equation in Predicting Liquid – Liquid Equilibria

Abstract

The present work deals with fitting literature
data of liquid – liquid equilibria and to obtain a
new correlation for non-randomness parameter?
suitable to use in NRTL activity coefficient
model.
New simple correlation is proposed for
modifying the original three-parameter NRTL
activity coefficient model to make it a true twoparameter
model. The performance of the
proposed expression is compared with the original
three-parameter NRTL activity coefficient model,
in correlating LLE data of binary systems, as well
as in predicting binary systems from infinitedilution
activity coefficients and ternary systems
from binary data.
To ensure the results had physical significance,
the obtained parameters were used to predict the
infinite activity coefficients. Properties at infinite
dilution are of interest as they usually indicate the
maximum non-ideality of the system.
The model was successfully applied to
correlate liquid - liquid equilibria, and low
temperature activity coefficients. A large database
of data was collected for the investigation and it
covers a wide range of composition, temperature
and pressures. It was found that the proposed form
of non-randomness parameter gave the best
results.