Vapour-liquid equilibrium for the acetone-methanol-inorganic salt system

Abstract

Isobaric VLE data were measured for the acetone-methanol binary system at 101.32 kPa and for the acetone-methanol-salt system at the same pressure at different salt concentrations using a modified Othmer equilibrium still. Both salts investigated in this work, KI and NaI, exhibited a salting-out effect on acetone. The experimental data for the salt-free system were correlated by Wilson, NRTL and UNIQUAC models. For the salt systems, the experimental data were correlated by the electrolytic NRTL model of Mock et al. [Mock, B., Evans, L.B. and Chen, C.C., 1986. AIChE J., 32: 1655–1664], the extended UNIQUAC equation of Sander et al. [Sander, B., Fredenslund, A. and Rasmussen, P., 1986. Chem. Eng. Sci., 41: 1171–1183], and the modified Wilson and NRTL models proposed by Tan [Tan, T.C., 1985. AIChe J., 31: 2083–2085; Tan, T.C., 1987. Chem. Eng. Res. Des., 65: 355–366; Tan, T.C., 1990. Trans. Ind. Eng. Chem., 68: 93–102]. The results were compared with the data predicted by the modified Wilson and NRTL models of Tan. The mean absolute deviations in vapour-phase mole fraction and bubble points for the salt-free system were about 0.002 and 0.02, respectively. The mean absolute deviations in vapour-phase mole fraction and bubble points for both salt systems, over 252 data points, were about 0.004 and 0.21, respectively, using the electrolytic NRTL model of Mock et al., 0.009 and 0.44 using the extended UNIQUAC model of Sander et al., 0.024 and 0.38 using Tan's modified Wilson model, and 0.019 and 0.15 using Tan's modified NRTL model. Both the modified Wilson and the NRTL models proposed by Tan predict the vapour composition of both salt systems with a mean absolute error of about 0.024-0.019, and the bubble points with a mean absolute error of about 0.56.