An
extension of the PPC-SAFT equation of state to treat strong
electrolyte aqueous solutions is presented. It is capable of describing
the behavior of such systems up to 473 K with a good precision and
without requiring temperature-dependent model parameters. Long-range
Coulombic interactions are taken into account using the mean spherical
approximation (MSA) for a primitive model of the electrolyte solution,
and the effect of solvation is described using short-range ion–water
interactions mediated through association sites. Pairing between anions
and cations is also treated through site–site interactions.
A Born term is added to describe the change of dielectric constant
resulting from solvation. A single ion-specific, temperature-independent
model parameters are used, for 20 alkali-halide aqueous solutions.
The Pauling ionic diameters are used for all terms (hard sphere, MSA,
and Born). The dispersion energy of the ions is considered negligible.
In the resulting ePPC-SAFT model, only the water–ion association
energy is considered as an adjustable parameter. The results show
coherent energy density behavior with respect to ionic size. The approach
allows the calculation of the mean ionic activity coefficient, density,
or vapor pressure of the aqueous solutions over a wide range of temperatures
and molalities (298–573 K and 0–6 m). Moreover, salting out of carbon dioxide and methane in saline
water can also be predicted accurately. A discussion of the changes
in ion hydration at different salinity is also presented taking advantage
of the model proposed that explicitly includes ion–water site–site
interactions.
New isobaric vapor−liquid equilibria data were measured for N,N-dimethyl-1-butanamine + n-hexane, n-heptane, 1-propanol, 1-butanol, or 1-pentanol and N,N-dimethyl-1-octanamine + n-heptane or 1-butanol binary mixtures. The boiling temperatures of both pure amines were also investigated. For this, an ebulliometer based on Cottrell's apparatus was used. Thus, 180 new mixture data points displayed on 35 isobars were obtained in a pressure range from (29.84 to 99.83) kPa and in the full composition range. The experiments were compared with the Group contribution polar perturbed chain statistical associating fluid theory (GC-PPC-SAFT) equation of state predictions for pure amines and the mixtures containing an alkane. In the case of the systems containing an alkanol, the binary interaction parameters needed to be fitted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.