A New Gibbs Energy Model for Obtaining Thermophysical Properties of Aqueous Electrolyte Solutions
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In this paper, a new Gibbs energy model is proposed to study the thermophysical properties of aqueous electrolyte solutions at various temperatures. The proposed model assumes that the electrolytes completely dissociate in solution. The model also has two temperature-independent adjustable parameters that were regressed using experimental values of the mean ionic activity coefficients (MIAC) for 87 electrolyte solutions at 298.15 K. Results from the proposed model for the MIAC were compared with those obtained from the E-Wilson, E-NRTL, Pitzer and the E-UNIQUAC models, and the adjustable model parameters were used directly to predict the osmotic coefficients at this temperature. The results showed that the proposed model can accurately correlate the MIAC and predict the osmotic coefficients of the aqueous electrolyte solutions better on the average than the other models studied in this work at 298.15 K. Also, the proposed model was examined to study the osmotic coefficient and vapor pressure for a number of aqueous electrolyte solutions at high temperatures. It should be stated that in order to calculate the osmotic coefficients for the electrolyte solutions, the regressed values of parameters obtained for the vapor pressure at high temperatures were used directly. The results obtained for the osmotic coefficients and vapor pressures of electrolyte solutions indicate that good agreement is attained between the experimental data and the results of the proposed model. In order to unequivocally compare the results, the same experimental data and same minimization procedure were used for all of the studied models.
KeywordsElectrolyte solution Local composition Gibbs energy Thermophysical properties
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- 1.Debye, P., Hückel, E.H.: The theory of electrolytes. I. Lowering of freezing point and related phenomena. Phys. Zeit. 24, 185–206 (1923) Google Scholar
- 13.Pazuki, G.R., Taghikhani, V., Vossoughi, M.: Study of VLE phase behavior and correlating the thermophysical properties of polymer solutions using a local composition based model. J. Appl. Polymer Sci. (2009, in press) Google Scholar
- 14.Robinson, R.A., Stokes, R.H.: Electrolyte Solutions, 2nd edn. Butterworth, London (1970) Google Scholar
- 15.Zaytsev, I.D., Aseyev, G.G.: Properties of Aqueous Solutions of Electrolytes, 1st edn. CRC Press, Boca Raton (1992) Google Scholar
- 16.Prausnitz, J.M., Lichtenthaler, R.N., de Azevedo, E.G.: Molecular Thermodynamics of Fluid Phase Equilibria, 3rd edn. Prentice Hall, Englewood Cliffs (1999) Google Scholar
- 17.Vargaftik, N.B., Vinogradov, Y.K., Yargin, V.S.: Handbook of Physical Properties of Liquids and Gases (Pure Substances and Mixtures), 3rd augmented and revised edn. Begell House, New York (1996) Google Scholar