n - PATh :.: Process and Product Applied Thermodynamics research ...

Modeling
previous work, dealing with the phase diagram of xenon in lighter alkanes (C1 to C4) and
perfluoroalkanes (C1 to C2), also using the SAFT-VR, they showed that while the
behaviour of xenon correlated strongly with that of the n-alkanes (the experimental phase
diagrams and excess volumes could be described accurately using simple Lorentz-
Berthelot combining rules to determine the cross interaction parameters), for xenon in nperfluoroalkanes
the existing experimental data could only be reproduced by introducing a
binary interaction parameter (Filipe et al., 2000 and McCabe et al., 2001). The energetic
binary interaction parameter used by the authors was the same that they used in an earlier
study of alkane + perfluoroalkanes binary mixtures (McCabe et al., 2001), equal to 0.92.
They stated that although this was not the best value and a slight improvement would be
possible if the parameter were fitted to the specific system, they preferred to use the
parameters in a transferable way giving importance to the predictive capability of the
equation instead of look for the accuracy of the results given by the model.
In this work a similar study were carried out using the soft-SAFT EoS to describe
solubility data for xenon and radon in perfluoroalkanes. Both solutes and solvents were
modelled as non associating molecules and any kind of interaction was admitted between
them. As in the work of Filipe et al. (2000) only the energetic parameter had to be included
to correctly describe experimental data. It was adjusted for each mixture and is listed in
Table III.6.
Table III.6. Adjusted Binary Parameters for the Solubility of Xenon and Radon in Fluorinated
Compounds and AADs of the Calculations by the Soft-SAFT EOS with Respect to Experimental
Data
Solvent η ξ AAD (%)
C6F14
Xenon
1 0.870 3
C7F16 1 0.860 2
C8F18 1
Radon
0.860 1
C6F14 1 0.825 7
C8F18 1 0.825 4
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