Predictions of thermodynamic properties at infinite dilution of aqueous organic species at high temperatures via functional group additivity

In this study, a functional group additivity scheme was used for correlation of the partial molar volumes, V20, compressibilities, κ20, heat capacities, CP,20, hydration enthalpies, ΔhydH20, and hydration Gibbs energies, ΔhydG20, at infinite dilution of aqueous organic electrolytes and non-electrolytes. The results were used for predicting the chemical potentials of these solutes. At present, the groups included are C (hydrocarbon), H (hydrocarbon), COOH, CONH2, NH2, OH, COO−, NH3+, and an amino acid functional group. An equation of state based on the Fluctuation Solution Theory was employed which allows predictions for numerous acyclic organic compounds composed of these functional groups to 623 K and 100 MPa. Although the uncertainty normally associated with a group additivity scheme is larger than the experimental uncertainty at ambient conditions, at high temperatures and pressures the two uncertainties become comparable. The functional group contributions were based on almost 1400 experimental points and are reported as a function of solvent density and temperature.