Date of Award
Master of Science in Chemical Engineering - (M.S.)
Chemical Engineering and Chemistry
Dimitrios P. Tassios
Hung T. Chen
The feasibility of developing a method of correlation and prediction, for mixtures of two solvents containing a dissolved salt has been studied. The procedure consisted of arriving at the interaction parameters for the three binary systems (solvent 1-solvent 2, solvent 1-salt, solvent 2-salt) and using these to calculate the ternary results. Attempts to generate interaction parameters for the solvent-salt binaries by means of the Wilson equation were unsuccessful, whereas, use of the NRTL equation resulted in a very good fit of the binary data.
In correlating the ternary results, it became necessary to redefine the liquid phase mole fractions and activity coefficients for the binary and ternary systems, by the assumption of full dissociation of the salt in solution. A further assumption led to a simplification of the procedure and an improvement of the results for some of the ternary systems: for certain binaries in which the activity coefficient of the solvent did not deviate from unity by more than 10%, the parameters were assumed to equal 0.0 and the binary to behave ideal.
A study was made of the effect of α12 on the ternary fit. Prediction of the ternary behavior from binary data appears possible but additional experimental data is needed for the development of guidelines for the choice of the appropriate value of α for the solvent-solvent binary.
For the system MeOH-H2O-LiCl the results are better than those of the Broul and Hala correlation. Good results were also obtained for MeOH-H2O-potassium acetate and MeOH-H2O-CaCl2. The Johnson and Furter equation fails to correlate the potassium acetate system. For two additional systems of questionable experimental accuracy, erroneous predictions were made.
The method of correlation is easier to apply than the Broul and Hala technique. All other methods of correlation - Broul and Hala excepted - have dealt only with systems saturated with salt. The method presented here can be applied for any salt concentration. The method can be applied to either isobaric or isothermal data.
Bekerman, Enrique M., "Prediction and correlation of the salt-effect in vapor-liquid equilibrium" (1976). Theses. 2119.