Phase Equilibrium Study in Supercritical Fluid Extraction of Ethanol to Octane Mixture Using CO2

R Davarnejad; K.M.  Kassim; A Zainal; Suhairi A. Sata

R Davarnejad School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia
K.M. Kassim School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia
A Zainal School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia
Suhairi A. Sata School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia

Keywords: activity coefficient, CO2 solvent, ethanol and octane, phase equilibria, regular solution theory, supercritical extraction

Abstract

Solubility data was measured for carbon dioxide with ethanol and octane using a phase equilibrium loading re-circulating high-pressure type apparatus at a pressure up to 100.75 bar and a temperature of 348.15K for ethanol and octane mixture involved with 25% ethanol and 75% octane. Experimental data was compared with the calculated regular solution theory data. A procedure is employed to each phase by applying activity coefficient expressions based on regular solution theory. Calculations along these lines are described and the physical bases for applying this method under the relevant conditions are discussed. The regular solution theory approach has been found to be encouraging for the prediction of phase equilibria solubilities though the interaction parameters must be regarded as pressure dependent.

References

1. Benmekki, E.H., and Mansoori, G.A. (1987). “Phase equilibrium calculations of highly polar systems,” Fluid Phase Equilibria, 32, 139-149.
2. Browarzik, D. (2004). “Phase-equilibrium calculations for n-alkane + alkanol systems using continuous thermodynamics,” Fluid Phase Equilibria, 217, 125-135.
3. Davarnejad, R., Kassim, K.M., Zainal, A., and Suhairi, A.S. (2008a). “Mutual solubility study for 94.2:5.8 of ethanol to octane with supercritical carbon dioxide solvent,” J. Chinese Institute of Chemical Engineers, 39, 343-352.
4. Davarnejad, R. Kassim, K.M., Zainal, A., and Suhairi, A.S. (2008b). “Supercritical fluid extraction of carotenoid from microalgae with projected thermodynamic models,” Int. J. Engineering, 21, 117-126.
5. Francis, A.W. (1954). “Ternary systems of liquid carbon dioxide,” J. Phys. and Chem., 58, 1099-1114.
6. Fredenslund, A., Gmehling, J., and Rasussen, P. (1977). Vapor-Liquid Equilibria Using UNIFAC. Elsevier, Amesterdam-Oxford- New York.
7. Goral, M., Maczynski, A., Bok, A., Oracz, P., and Skrzecs, A. (1998). Vapor-Liquid Equilibria. Vol. 3, Alcohols + Aliphatic Hhydrocarbons. Thermodynamic Data Center, Warszawa.
8. Guggenheim, E.A. (1952). Mixtures. Oxford University Press, UK.
9. Gupta, S.K., Lesslie, R.D., and King, A.D. (1973). “Solubility of alcohols in compressed gases. A comparison of vapor-phase interactions of alcohols and homomorphic compounds with various gases. I. Ethanol in compressed helium, hydrogen, argon, methane, ethylene, ethane, carbon dioxide and nitrous oxide,” J. Phys. Chem., 77, 2011-2015.
10. Hildebrand, J.H. and Scott, R.L. (1964). The Solubility of Nonelectrolytes. Dover Publications, New York.
11. Hildebrand, J.H., Prausnitz, J.M., and Scott, R.L. (1970). Regular and Related Solutions, The Solubility of Gases, Liquids and Solids. Van Nostrand Reinhold, New York.
12. Kassim, K.M., and Davarnejad, R. (2006, November 13-15). Mutual solubilities prediction for some oils derivatives with supercritical and slightly subcritical carbon dioxide solvent. First International Conference on Environment. Park Royal Hotel, Malaysia.
13. Kassim, K.M., and Davarnejad, R. (2006, December 19-21). Supercritical fluid extraction of carbon dioxide solvent used with different ratios of ethanol/octane systems. 20th Symposium of Malaysian Chemical Engineers, UITM University, Kuala Lumpur, Malaysia.
14. Kassim, K.M., Davarnejad, R., and Zainal, A. (2008). “Phase equilibrium studying for the supercritical fluid extraction process using carbon dioxide solvent with 1.35 mole ratio of octane to ethanol mixture,” Chem. Eng. J., 140, 173-182.
15. King, M.B., Alderson, D.A., Fallah, F.H., Kassim, K.M., Kassim, D.M., Sheldon, J.R,. and Mahmud, R.S. (1983). Chemical Engineering at Supercritical Fluid Conditions. Chapter 1. In: Paulaitis, M.E., Penninger, J.M.L., Gray, R.D. Jr., and Davidson, P. editors. Ann Arbor Science, Ann Arbor, MI.
16. King, M.B., Kassim, K.M., Bott, T.R., Sheldon, J.R., and Mahmud, R.S. (1984). “Prediction of mutual solubilities of heavy components with supercritical and slightly subcritical solvents: The role of equations of state and some applications of a simple expanded lattice model at subcritical temperatures,” Ber. Bunsenges Phys. Chem., 88, 812- 820.
17. King, M.B. (1969). Phase Equilibrium in Mixtures. Pergamon Press, UK. Pires, A.P., Mohamed, R.S., Mansoori, G.A. (2001). “An equation of state for property prediction of alcohol-hydrocarbon and water-hydrocarbon systems,” J. Petrol. Sci. & Eng., 32, 103-114.
18. Schneider, G., Alwani, Z., Horvath, E., and Frank, U. (1967). “Phase equilibriums and critical phenomena in binary mixed systems to 1500 bars carbon dioxide with n-octane, n-undecane, n-tridecane, and n-hexadecane,” Chem. Ing. Tech., 39, 649-656.
19. Smith, J.M., and Van Ness, H.C. (1987). Introduction to Chemical Engineering Thermodynamics. 4th ed. McGraw-Hill, New York. 294.
20. Wang, L.S., Lang, Z.X., and Guo, T.M. (1996). “Measurement and correlation of the diffusion coefficients of carbon dioxide in liquid hydrocarbons under elevated pressures,” Fluid Phase Equilibria, 117, 364.