for solvent blends may be obtained from vapor pressure observations or from computational schemes such as NRTL , UNIFAC , and others.
The specific retention volume, Vg0, glass transition temperature, Tg; adsorption enthalpy, IHa; the sorption enthalpy, IH1S; sorption free energy, IG1S; sorption entropy, IS1S; the weight fraction activity coefficients
of solute probes at infinite dilution, a|1a, partial molar enthalpy of solute probes at infinite dilution, IH1a; and Flory-Huggins interaction parameters, I12a; between polymer and solvents were determined in the temperature range of 493-343 K for poly(ABM) and 473-343 K for poly(ABM%41-coAN)-poly(ABM%71-coAN).
of a species in a solution represents the relation between the real fugacity and the fugacity corresponding to an ideal solution (calculated via Lewis-Randall rule).
These solvent heats of vaporization values, derived from the experimentally determined activity coefficients
, can be compared with the ones estimated employing the Watson model  as a kind of consistency test, in order to check the goodness of the experimental data.
Accurate measurement of activity coefficients
at infinite dilution by inert gas stripping and gas chromatography.
Hence, the VLE model itself is valid at low acid gas partial pressures even though the parameters of the activity coefficient
model were not fitted in this range (Kundu, 2004).
Knowing parameters of interaction, let us determine activity coefficient
of sulfur in crude ferronickel [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII.
The mean activity coefficients
calculated by eq (1) from these smoothed values of E and the values of E[degrees] given in table 1 are summarized in table 3.
Depending on specific retention volumes, V 0, of probes the w ht activity coefficients
of solute probes at infinite dilution, 1[?
Thus, activity coefficient
for single component in membrane (State I) is
By obtaining the weight fraction activity coefficient
, O1 , the partial molar free energy, DG1, and the average partial molar enthalpy, DH1 values can be calculated from following relations, respectively at infinite dilution [31-33].
i], T) is the activity coefficient
of species i as function of liquid composition [x.