Predicting NRTL binary interaction parameters from molecular simulations

Abstract

A predictive approach for calculating the binary interaction parameters ( τij) of the nonrandom two liquid (NRTL) local composition model is developed, combining molecular simulations with the two‐fluid theory. The binary interaction parameters are determined for the following three sets of model binary mixtures: water + methanol, methanol + methyl acrylate, and water + methyl acrylate. For each binary mixture, the interaction parameters are expressed in terms of molecular size and strength of interactions, which are in turn, calculated from molecular simulations. We show that the binary interaction parameters determined from simulations are in qualitative agreement with those estimated from regressing experimental data. The major factors that determine the binary interaction parameters are outlined based on simple thermodynamic arguments for each mixture. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2758–2769, 2018

Bridging two‐liquid theory with molecular simulations for electrolytes: An investigation of aqueous NaCl solution

“…To calculate the interaction parameters from molecular simulations, it is necessary to develop a framework that relates these parameters to molecular quantities. For that purpose, we extend the approach of Ravichandran et al to electrolytes. Specifically, three different fluid domains are separately constructed by solving the combinatorial problem of forming a molecular domain around a center species.…”

“…Preferential local interactions between the species are also considered in this construction. For consistency, terminologies of Chen et al and Ravichandran et al are closely followed in this work.…”

“…The molecular interpretation of the classical thermodynamic models can be achieved through the interaction parameters, which quantify the strength and nature of intermolecular forces. There have been a few attempts for identifying the binary interaction parameters of thermodynamic models for nonelectrolyte systems from molecular simulations . Recently, a novel methodology was proposed by Ravichandran et al for predicting the NRTL binary interaction parameters from molecular dynamics (MD) simulations.…”

“…There have been a few attempts for identifying the binary interaction parameters of thermodynamic models for nonelectrolyte systems from molecular simulations . Recently, a novel methodology was proposed by Ravichandran et al for predicting the NRTL binary interaction parameters from molecular dynamics (MD) simulations. This technique utilizes the framework of two‐fluid theory to relate the NRTL binary interaction parameters to molecular size and interaction strength, both of which were obtained from simulations.…”

“…It was also shown that the binary interaction parameters obtained using this approach could predict the phase equilibria behavior and the thermophysical properties of organic binary mixtures. In this work, we extend the previously proposed technique to aqueous uni‐univalent electrolyte solutions. Such an extension is nontrivial and requires the interpretation of molecular parameters that is consistent with the theoretical framework of the classical thermodynamic model.…”