Solubility of terephthalic acid (TPA) in subcritical water was measured as a function of the temperature from (349 to 547) K at a pressure of 10.0 MPa. A semi-batch flow apparatus was developed for the solubility measurement. N-methylpyrrolidone was used as a good solvent for collection of TPA saturated in subcritical water without deposition upon cooling. The solubility of TPA in water showed an exponential increase with increasing temperature from (1.25 ~10.5 at 349 K to 2.99 ~10.2 at 547 K). The aqueous solubility of TPA was found to be lower than those of m- and o-phthalic acids by one and three orders of magnitude, respectively. The Gibbs free energy of solution ( centsGsol) as well as the enthalpic and entropic components ( centsHsol and .T centsSsol) were calculated from the temperature dependence of the solubility. The thermodynamic analysis showed that the centsGsol gradually decreases with increasing temperature, as a result of the competition between a large increase in centsHsol and a large decrease in .T centsSsol. The centsGsol value decreased in the order of (p-phthalic acid) greater than (m-phthalic acid) greater than (ophthalic acid) due to a decrease in .T centsSsol, whereas the centsHsol showed a small variation among the three isomers.
Compounds
#
Formula
Name
1
C8H6O4
1,4-benzenedicarboxylic acid
2
H2O
water
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.