378 J. zyxwvutsr Chem. Eng. Data 1991, zyxwvu 36, 378-382 binary systems were identical with the values given earlier in Table IV. With use of zyxwvutsr the binary parameters of Table VI and eqs 3 and 4, the ternary parameters of eq 4 were obtained by Barker’s method. These parameter values are given in Table VI. No evidence was found for strong correlation between any of the parameters. The average deviation between calculated, P,, and measured, P, pressures was 0.09 kPa with a maximum deviation of 0.28 kPa. A plot of the pressure residuals, P,, - P,,, for the ternary system is given in Figure 4. On the basis of the parameter values given in Table VI, the P-x surface for the ternary system was calculated and is shown in Figure 5. The parameter C which appears in this figure is defined by (7) binary parameters for GE, eq 2 molar second virial coefficient for species i and j, ternary composition parameter, eq 7 ternary composition parameter, eq 1 ternary parameter for GE, eq 4 ternary parameter for GE, eq 4 ternary function for GE, eq 3 molar excess Gibbs free energy, kJ mol-‘ pressure, kPa vapor pressure of pure species i, kPa calculated total pressure, kPa measured total pressure, kPa universal gas constant, kJ mol-’ K-’ temperature, K saturated molar volume of pure liquid i, cm3 mol-‘ liquid-phase mole fraction of species i cm3 mol-’ 4 Greek Letters zyxwvu at,a,, OP .I overall mole fraction of species i in equilibrium cell binary parameters for GE, eq 2 binary parameter for GE, eq 2 weighting factor for ith data point, eq 5, kPa Reglstry No. n-Pentane, 109-66-0; methanol, 67-56-1; 2-butanol, 76- 92-2. Literature Cited (1) Bhethanabotla, V. R.; Campbell, S. W. Fluidphase €qu///b. 1991, 62. 239. (2) Gibbs, R. E.; Van Ness, H. C. Ind. €ng. Chem. Fundem. 1972, 17, 410. (3) Selected Values of Physkai and “dpmk V s of wo- carbons and Related Cm~u~s: API Project 4 4 Carnegie Press: Plltsburgh, PA, 1953. (4) Hales, J. L.; Ellender, J. H. J. Chem. Thennodyn. 1976. 8, 1177. (5) Polak, J.; Murakami, S.; Lam, V. T.; Pflug, H. D.; Benson, G. C. Can. J. Chem. 1970, 48, 2457. (6) Barker, J. A. Aust. J. Chem. 1953. 6, 207. (7) Tsonopoulos, C. AIChf J. 1974, 20, 263. (8) Abbott. M. M.: Van Ness, H. C. AICM J. 1975, 27, 62. (9) Abbott, M. M.; Floess, J. K.; Waish, G. E., Jr.; Van Ness, ti. C. AICM J. 1975, 21, 72. (10) Bemabe, D.; Romero-Marlnez. A.; Trejo, A. F/uidphase EquHb. 1968, 40, 279. (1 1) Wilsak, R. A.; Campbell, S. W.; Thodos, G. Fluid Phase fquilib. 1987, 33. 157. (12) Tenn, F. G.; Missen, R. W. Can. J. Chem. Eng. 1963, 47, 12. (13) TRC-Thermodynamic Tables-Hydrocarbons; Thermodynamlcs Re- search Center, The Texas ABM University System: College Station, TX, extant, June 30, 1974; p. k-1010 (loose-leaf zyxw data sheets). ( 14) TRC-Thermodynamic Tables-Nonhydrocarbons; Thermodynamics Research Center, The Texas ABM University System: College Statbn, TX, extant, December 31, 1976, p. k5000; June 30, 1965: p. k-5010 (loose-leaf data sheets). Received for review September 14, 1990. Accepted May 21, 1991. Thls work was supported, In part, by the University of South Florida Research and Creative Scholarship Grant Program under &ant No. RCS-25. S.T. was sup ported by a National Science Foundation REU Grant No. €ID-9000720, Liquid-Liquid Equilibria of the Water + Acetic Acid + Cyclohexyl Acetate Ternary A. Alp Sayar’ zyxwvutsrqp Faculty of Engineering, Marmara University, 8 1040 Gijztepe, Istanbul, Turkey Begr Tatll and Umur Dramur Department of Chemical Engineering, Faculty of Engineering, University of Istanbul, 34459 Istanbul, Turkey Liquid-liquid equilibrla for the water + acetic acid + cyclohexyl acetate system were measured at 298.16 f 0.20, 308.16 f 0.20, and 318.16 f 0.20 K. Tie-Hne compodtions were correlated by the reduced Eisen-Joffe equatlon. Reliability of data was ascertained through Othmw-Tobias plots. Mstribution coefflclents and separation factors were evaluated over the immiscibility region, and it Is concluded that the high-boillng solvent, cyciohexyi acetate, Is a suitable separatlng agent for dilute aqueous scetlc acid soiutlons. I n addition, the temperature dependence of solubility and tie-llne comporitlons Is lnrlgnlflcant from 298 to 318 K, except at very low acetic acid concentratlons. To whom correspondence should be addressed. 0021-9568/91/1736-0378$02.50/0 Introduction Major advantages of high-boiling separating agents for the extraction of acetic acid from its aqueous solutions have been recently reported ( 1-3). I t has also been predicted that cy- clohexyl acetate could be used as solvent (4). The objective of this study was to determine the experimental solubility and tie-line compositions of the water + acetic acid + cyclohexyl acetate ternary at 298.16 f 0.20, 308.16 i 0.20, and 318.16 f 0.20 K, at atmospheric pressure. Complete phase diagrams were obtained by evaluating together the solubility and the tie-line compositions for each temperature. In addition, the tie-line compositions were correlated by using the reduced Eisen-Joffe equation (5). Their thermodynamic con- sistency was ascertained by making Othmer-Tobias plots (6) and applying an independent material balance check. In order to determine the most suitable process temperature, free-solvent-based selectivity diagrams at 298.16, 308.16, and 0 1991 American Chemical Society