Analytical solution of groups

UNIFAC andASOG Development. Pertinent equations of the UNIQUAC functional-group activity coefficient (UNIFAC) model for prediction of activity coefficients including example calculations are available (162). Much of the background of UNIFAC involves another QSAR technique, the analytical solution of groups (ASOG) method (163). 

Tochigi, K., Minami, S., Kojima, K. Prediction of vapour-liquid equilibria with chemical reaction by analytical solutions of groups./. Chem. Eng. Jpn. 1977, 10, 349-354. 

When experimental equilibrium data on nonideal mixtures are not available, methods such as those based on Derr and Deal s analytical solution of groups (ASOG) [28] or the UNIFAC correlation (discussed in Example 3.4) may be used. Activity-coefficient estimation methods are also available in various thermodynamic-data packages, such as Chemshare. Further discussion may be found in Prausnitz [3] and in Reid, Prausnitz, and Sherwood [1]. 

Activity coefficients, which play a central role in chemical thermodynamics, are usually obtained from the analysis of phase equilibrium measurements. However, with shifts in the chemical industry and the use of combinatorial chemistry, new chemicals are being introduced for which the needed phase equilibrium data may not be available. Therefore, predictive methods for estimating activity coefficients and phase behavior are needed. Group contribution methods, such as the ASOG [analytical solution of groups... 

The UNIFAC-FV and Entropic-FV models are not the only extensions of UNIFAC to polymers. Similar models have been presented by Iwai and Arai ° ° and by Choi etal. ° Choi s model is not based on UNIFAC but on ASOG. ASOG (Analytical Solution of Groups) is a predictive GC method for calculating activities, similar to UNIFAC, but which has not experienced the widespread use of UNIFAC. It is mostly employed in Japan. Besides this difference, the models of Aral and Choi contain an FV, which is different from that of Equation 16.49. These two models have been applied with success for some polymer-solvent systems but not for LEE. 

Predicted Compositions during Mixed Solvent Evaporation from Resin Solutions Using the Analytical Solutions of Groups Method... 

In the analytical solution of groups (ASOG) method of Derr and Deal [14], the four postulates of Wilson and Deal are implemented. The activity coefficient due to molecular size differences is given by the Flory-Huggins equation, Equation (4.414), and the group activity coefficient is given by the Wilson equation. 

The analytical-solution-of-groups (ASOG) method was developed by Derr and Deal17 and Wilson,72 and a compilation of parameters has been prepared by Kojima and Tochigi.41 In this method, the activity coefficient of component / in a mixture is computed as follows... 

E. L. Derr and C. H. Deal Analytical Solutions of Groups Correlation of Activity Coefficients through Structural Groups Parameters, Inst. Chem. Eng. Symp. Ser. (Institute of Chemical Engineers, London) 32(3) 40 (1969). 

The two most developed group contribution methods are the ASOG (Analytical Solution Of Groups) and UNIFAC (UNIquac Functional-group Activity Coefficient) " models, both of which are the subjects of books. We will consider only the UNIFAC model here. UNIFAC is based on the UNIQUAC model of Sec. 9.5. This model, you will remember, has a combinatorial term that depends on the volume and surface area of each molecule, and a residual term that is a result of the energies of interaction between the molecules. In UNIQUAC the combinatorial term was evaluated using group contributions to compute the size parameters, whereas the residual term had two adjustable parameters for each binary system that were to be fit to experimental data. 

Derr, E. L. and C. H. Deal, Jr. 1969 (September 8-10). Analytical solutions of groups. Correlation of activity coefficients through structural group parameters. Paper read at Proceedings of the International Symposium on Distillation, Brighton, England. 

The first group contribution method for the prediction of VLE (activity coefficients) was the so-called analytical solution of groups (ASOG) method [50, 51], developed within Shell. The ASOG method uses the Wilson model to describe the concentration dependence of the group activity coefficients required in the solution of groups concept. 

Correa, A., Comesana, J., Sereno, A. (1994). Use of analytical solutions of groups (ASOG) contribution method to predict water activity in solutions of sugars, polyols and urea. International Journal of Food Science and Technology, 29, 331-338. 

Several methods of group contributions have been developed Analytical Solution of Groups (ASOG) [WIL 62], Universal Quasichemical... 

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