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2 Polish Journal of Chemistry

2 2006

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VLE in (C6H14 + C16H34) Mixture. Prediction with Elbro Free Volume Method

Wilczura-Wachnik H., Pawłowski T.

Polish Journal of Chemistry

2006

Vol. 80, nr 1

107-116

The main purpose of thisworkwas a search for the dependence of VLE prediction quality on the kind of chosen n-alkanemodel system. The activities and total vapour pressure for (n-C6H14 + n-C16H34) mixture at 293.15 K, 313.15 K and 333.15 K were successfully predicted with Elbro free volume method using three sets of UNIQUAC Aij interaction parameters: (1) Aij obtained with the semi-empirical quantum mechanical method AM1 (Austin Model 1) for (n-C6H14 + n-C16H34) system, (2) Aij adjusted to (n-C6H14 + n-C16H34) VLE experimental data, (3) Aij obtained with the CFF (Consistent Force Field) method for the chosen (n-alkane + n-alkane) model system. The predicted curves were compared with experimental data. It has been found that when sizes of the solvent molecule and a chosen segment in the second long chain molecule are comparable to the model system size then the UNIQUAC interaction parameters obtained with molecular mechanics quantitatively describe the real intermolecular forces in n-hexane + n-hexadecane system.

Vapor-Liquid (VLE) and Liquid-Liquid (LLE) Phase Equilibria Calculations for Polystyrene + Methylcyclohexane and Polystyrene + Cyclohexane Solutions

Wilczura-Wachnik H., Jonsdottir S.

Polish Journal of Chemistry

2006

Vol. 80, nr 1

65-79

This paper presents the vapor-liquid (VLE) and liquid-liquid (LLE) phase equilibria predictions for polystyrene in two theta solvents: cyclohexane andmethylcyclohexane.VLE calculations were performed with the Elbro free volume method and a modified version of the PC-SAFT method, as well as with three UNIFAC type group contribution models: Entropic Free Volume + UNIFAC VLE 1coeff., Entropic Free Volume + UNIFAC VLE 2coeff., and Oishi-Prausnitz + UNIFAC VLE 2coeff. Solvent activities were calculated for the polystyrene + cyclohexane and polystyrene + methylcyclohexane solutions, and compared with experimental data. LLE predictions were performed with PC-SAFT method and compared with experimental data. The obtained results show that the PC-SAFTmethod gave themost accurate predictions for bothVLE as well as LLE for the systems studied.