Prediction Of Phase Equilibrium Of Aqueous Two-phase Systems Water + Poly(ethylene Glycol) + Salt

Liquid-liquid extraction by aqueous two-phase systems of the type polymer-salt has been increasing importance in the separation of biomolecules. The thermodynamic behavior of these systems is extremely difficult to model, due to the size differences between the smaller molecules and the polymer. Several activity coefficient models have been proposed, including the combinatorial and free volume effects in one term. This work uses the Elbro-FV model as the combinatorial-free volume contribution of the UNIFAC-Dortmund group contribution model. New group interaction energy parameters for this model have been determined using reported data on the systems water + poly(ethylene glycol) [PEG4000] + salt, where the salts were potassium phosphate and sodium sulfate.315427432Abrams, D.S., Prausnitz, J.M., Statistical thermodynamics of liquid mixtures: A new expression for the excess gibbs energy of partly or completely miscible systems (1975) AIChE J., 21, pp. 116-128Anderson, T.F., Abrams, D.S., Grens E.A. II, Evaluation of parameters for nonlinear thermodynamic models (1978) AIChE J., 24, pp. 20-29Aznar, M., Mattedi, S., Tavares, F.W., Castier, M., Silva Telles, A., A review of group contribution methods for the prediction of phase equilibria (1997) Latin American Applied Research, 27, pp. 1-24Bondi, A., (1968) Physical Properties of Molecular Crystals, Liquids and Glasses, , Wiley, New YorkDerr, E.L., Deal, C.H., Analytical solution of groups: Correlation of activity coefficients through structural group parameters (1969) Inst. Chem. Eng. Symp. Ser., 32, pp. 44-51Duarte, C.S.A., Equilíbrio líquido-líquido em sistemas contendo polímero e eletrólito: Água/polietileno-glicol/fosfato (1999) Scientific Report, FEQ/UNICAMP, , CampinasElbro, H.S., Fredenslund, Aa., Rasmussen, P., A new simple equation for the prediction of solvent activities in polymer solutions (1990) Macromolecules, 23, pp. 4707-4714Franco, T.T., Andrews, T.A., Asenjo, J.A., Use of chemically modified proteins to study the effect of a single protein characteristics in Aqueous two-phase systems. Effect of surface charge (1996) Biotech. Bioeng., 49, pp. 300-308Fredenslund, Aa., Jones, R.L., Prausnitz, J.M., Group contribution estimation of activity coefficients in nonideal solutions (1975) AIChE J., 21, pp. 1086-1099Fredenslund, Aa., Gmehling, J., Rasmussen, P., (1977) Vapor-liquid Equilibria Using UNIFAC, , Elsevier, AmsterdamGmehling, J., Li, J., Schiller, M., A modified UNIFAC model. 2. Present parameter matrix and results for different thermodynamic properties (1993) Ind. Eng. Chem. Res., 32, pp. 178-193Gmehling, J., Lohmann, J., Jakob, A., Li, J., Joh, R., A modified UNIFAC model. 3.Revision and extension (1998) Ind. Eng. Chem. Res., 37, pp. 4876-4882Grossi, F.R., Equilíbrio líquido-líquido em sistemas contendo polímero e eletrólito: Água/polietileno-glicol/sulfato (1999) Scientific Report, FEQ/UNICAMP, , CampinasKojima, K., Tochigi, K., (1979) Prediction of Vapor-liquid Equilibria by the ASOG Method, , Elsevier/ Kodansha, TokyoKontogeorgis, G.M., Fredenslund, Aa., Tassios, D.P., Simple activity coefficient model for the prediction of solvent activities in Polymer solutions (1993) Ind. Eng. Chem. Res., 32, pp. 362-372Kula, M.R., Trends and future prospects of aqueous two-phase extraction (1990) Bioseparation, 1, pp. 181-189Langmuir, I., The distribution and orientation of molecules (1925) 3rd Colloid Symposium Monograph, , The Chemical Catalog Co., Inc., New YorkNelder, J.A., Mead, R., A simplex method for function minimization (1965) Computer J., 7, pp. 308-313Ninni, L., Camargo, M.S., Meirelles, A.J.A., Water activity in poly(ethylene glycol) aqueous solutions (1999) Termochimica Acta, 328, pp. 169-176Niesen, V.G., Yesavage, V.F., Application of a maximum likelihood method using implicit constraints to determine equation of state parameters from binary phase behavior data (1989) Fluid Phase Equil., 50, pp. 249-266Renon, H., Prausnitz, J.M., Local compositions in thermodynamic excess functions for liquid mixtures (1968) AIChE J., 14, pp. 135-144Stragevitch, L., D'Ávila, S.G., Application of a generalized maximum likelihood method in the reduction of multicomponent phase equilibrium data (1997) Braz. J. Chem. Eng., 14, pp. 41-52Van Krevelen, D.W., (1990) Properties of Polymers: Their Correlation with Chemical Structure, Their Numerical Estimation and Prediction from Additive Group Contributions, , Elsevier, AmsterdamWeidlich, U., Gmehling, J., A modified UNIFAC model. 1. Prediction of VLE, hE and γ∞ (1987) Ind. Eng. Chem. Res., 26, pp. 1372-1381Wilson, G.M., Vapor-liquid equilibria. XI. A new expression for the excess free energy of mixing (1964) J. Am. Chem. Soc., 86, pp. 127-13