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Abstract
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Carboxylic acids are commercially compounds and are used in industrially relevant separation
processes. They are used in a variety of fields, such as production of nylon, biodegradable plastics,
pharmaceuticals and so on [1]. In order to design for the separation, removal and purification of acids,
knowledge of the phase equilibra are necessary.
Molecular simulation using advanced sampling techniques has become a popular way to study the phase
behavior of model systems. Since Gibbs ensemble Monte Carlo (GEMC) method was put forward by A. Z.
Panagiotopoullos, it has become one of the most widely used molecular simulation methods due to its strong
operability and high accuracy [2].
In this work, configurational- bias Monte Carlo simulations were carried out in the NVT Gibbs ensemble
to generate phase equilibrium data for propionic acid systems. The TraPPE-UA force field [3] developed
by Kamath and co-works, was used. This force fields was divided in pairwise additive non-bonded
interactions and bonded terms for pairs of atoms separated by one, two, or three bonds. The non-bond
interactions comprised Lennard-Jones (LJ) 12-6 and Coulomb interactions. The LJ parameters for all
interactions are determined with the standard Lorentz-Berthelot combining rules [4]. Monte Carlo
simulation carried out with MCCCS-Towhee code in order to calculate the data presented here. Pure
component saturated vapor pressure and densities were measured for propionic acid. Results showed good
agreement with the experimental data.
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