It has relatively been difficult to accurately correlate
and predict
vapor–liquid equilibrium (VLE) data for the strongly associating
system containing the carboxyl acid due to its monomer undergoing
partial dimerization and even higher polymerization in the vapor and
liquid phases. Herein, this paper reports that the formation state
for the associating component mainly has been the existence of dimer
in the vapor and liquid phases through the geometric structures of
ethanoic acid investigated theoretically with density functional theory
(DFT), and the VLE data for the associating ternary system ethanal
+ ethanol + ethanoic acid and the three constituent binary systems
were measured using a recirculating still at 101.325 kPa. Marek’s
chemical theory was considered due to the associating species as the
dimer existence in the both phases. The three experimental binary
data sets were independently correlated using nonrandom two-liquid
(NRTL), Wilson, and universal quasichemical activity coefficient (UNIQUAC)
model, respectively, and the binary parameters were applied to predict
the VLE data for ternary system without any additional adjustment.
By comparison with the measured values, the ternary equilibrium values
predicted agreed well with the measured values in this way. The thermodynamic
consistency of the experimental VLE data was checked out by means
of the Wisniak’s L–W test for the binary systems and the Wisniak–Tamir’s
modification of McDermott–Ellis test for the ternary system,
respectively.
