engleski

Correlation of experimental data and prediction of vapour-liquid equilibria in the methyl ethyl ketone + polystyrene system

This study belongs to a series of continuing studies of vapour-liquid equilibria (VLE) in diluted polymer + solvent systems. Earlier we investigated polystyrene (PS) + toluene [1], poly(methyl methacrylate) + acetone [1] or + butan-2-one [3], poly(acrylic acid) + water [1], including previous measurements of VLE in solutions of co- and terpolymers of octadecyl acrylate and octadecyl methacrylate with styrene and 1-vinyl-2-pyrrolidone [4], [5]. The present paper brings new experimental data on VLE in the PS + butan-2-one system determined under isothermal conditions at 323.15, 333.15, and 343.15 K. Measurements were carried out with use of an all-glass microebulliometer with circulation of the liquid phase for the dynamic measurement of total pressure over liquid solutions. This ebulliometer was improved with every new study, and the last modification is described in detail in [3]. The obtained experimental data were correlated using the UNIQUAC-FV model [7], [3], as it better describes a polymer–solvent system than the UNIQUAC [6] due to the application free–volume contribution, calculated by means of the Flory expression. The UNIQUAC-FV energy parameters A12 and A21 have been estimated from the experimental solvent activity data for the temperature range 323.15–343.15 K. These parameters were used to predict activities and activity coefficients at infinite dilution for the three isotherms. Activities were well predicted, and parameters within the 20 K temperature range are practically independent of temperature. We validated the experimental data by predicting VLE, using the known predictive GC-Flory EoS [8] and the Entropic-FV models [9]. In order to compare our data with other available sources, we correlated all published data for the PS + butan-2-one system determined by different methods [6] using the UNIQUAC-FV model. In addition, we predicted the activities of butan-2-one in mixtures with PS using the GC-Flory EoS and the Entropic-FV models. All estimated parameters were plotted against temperature, together with parameters obtained from the correlation of our data at 323.15–343.15 K. For that purpose, mean temperature (333.15 K) represents well all three isotherms and perfectly agrees with all other data. Parameters A12 and A21 are found to be proportional to temperature over a large temperature range. It can be concluded that data for the methyl ethyl ketone + polystyrene system were successfully correlated using the UNIQUAC-FV model and they complete published data sets. The GC-Flory EoS and the Entropic-FV models were tested against the obtained experimental data and both can be used to predict VLE in the studied system. However, the GC-Flory EoS was slightly better at predicting activity coefficients at infinite dilution. References [1] J. Pavlíček, G. Bogdanić, I. Wichterle, Chem. & Biochem. Eng. Q. 29 (2015) 1–4. [2] J. Pavlíček, G. Bogdanić, I. Wichterle, Fluid Phase Equilib. 358 (2013) 301–303. [3] J. Pavlíček, G. Bogdanić, I. Wichterle, Chem. Biochem. Eng. Q. 28 (2014) 447–450. [4] J. Pavlíček, G. Bogdanić, I. Wichterle, Fluid Phase Equilib. 297 (2010) 142–148. [5] G. Bogdanić, I. Wichterle, J. Chem. Eng. Data 56 (2011) 1080–1083. [6] W. Hao, H.S. Elbro, P. Alessi, Polymer Solution Data Collection. 1: Vapor–Liquid Equilibrium, Chemistry Data Series XVI, Part 1, DECHEMA: Frankfurt/M., 1992. [7] A. Jonquières, L. Perrin, S. Arnold, P. Lochon, J. Membrane Sci. 150 (1998) 125–141. [8] G. Bogdanić, A. Fredenslund, Ind. Eng. Chem. Res., 33 (1994) 1331–1340. [9] G.M. Kontogeorgis, A. Fredenslund, D.P. Tassios, Ind. Eng. Chem. Res. 32 (1993) 362–372. This study was partly supported by the Czech Science Foundation (Grant No. 15-19542S).

experimental data; polymer–solvent system; vapour–liquid equilibrium

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