J. Chem. Eng. Data lQ92, 37, 124-126
124
Lireek Letters novalent ions and trivalent ions were increasing in proportion to two powers of Co. ahM: separation factor (-) (7) aNaM became constant although each value of x , y, Co, p : denslty of dry membrane (g ~ m - ~ ) and Q o was changed. Superscripts (8) ( ~ ~ ~ ~ Q ~ - ~ ) ~ ( ( a ~ ~ Qwas ~ - constant ~Xueo giving sep the~ ) - ~ M: M"' ion average value of 0.34 between monovalent ions and bivalent n: valence of M"+ ion ions, and ( a A M ) & ( a A M k J 1 was a constant value of 1.06 -: In the membrane between monovalent ions. Subscripts Acknowledgment A: A+ ion We thank Dr. Takaaki Dohmaru of University of Osaka Prei: initiil M: M"+ ion fecture, for his helpful discussion. We also thank Tokuyama Neosepta: Neosepta cation exchange membrane Soda Co. Ltd. for supplying various kinds of Neosepta type other: Selemion or Nafion cation exchange membrane cation exchange membranes. 0: total ions Nomenclature Literature Cited a : concentration of NaOH solution (meq ~ m - ~ ) b: volume of NaOH solution (cm3) MiyoshI, H.; Yamagaml, M.; Kataoke, T. Chem. Express 1990.5, 717. Miyoshi, H.; Fukumoto, T.; Kataoka, T. Sep . Sci. Technol. 1988, 23, C: concentration of the total ions in solution (meq ~ m - ~ ) 585. c: concentration of each ion in solution (meq ~ m - ~ ) Miyoshi, H.; Kataoka. 1. S e p . Sci. Technol. 1989, 2 4 , 507. E,: exchange capacity per weight of dry membrane (meq g-') Mlzuianl, Y. J . Membr. Sci. 1990, 49, 121. Miyoshi, H.; Fukumoto. 1.; Kataoka, T. Desalinstlon 1983, 48, 43. KNaM:selectivity coefficient of M"' ions relative to Na' ions beWallace, R. W. J . Phys. Chem. 1984, 68, 2416. tween membrane and solution Cwlrko, E. H.; Carbonell, R. 0. J . Membr. Scl. 1990, 48, 155. m: amounts of each ion (meq) Yeager, H. L.; Steck, A. Anal. Chem. 1979, 51, 862. Am: value difference between mi,Mand mMor mi,Naand mNa Kollma, T.; Furusakl, S.; Takao, K.; Mivauchi. T. Can. J . Chem. €nu. " 1082. 60. 642. (me@ Manning, M. J.; Melshelmer, S. S. I d . Eng. Chem. Fundam. 1989, 0:concentration of total ions, that is, the exchange capacity per 22. 31 1. volume of dry membrane (meq ~ m - ~ ) Pekpoulos, J. H.; Kimura, Y.; IiJIma, T. J. Membr. Sci. 1988, 38, 39. Kagaku Kogaku Hen. Kagaku Kogaku Blnran; Maruzen: Tokyo, 9: concentration of each ion in membrane (meq ~ m - ~ ) 1988; p 614. v: volume of mixture solution with M"' ions and Na' Ions (cm3) J. H. Chemical Engineers' Handbook; Mcaaw-Hill: New York, Perry, W,: water content (-) 1963; pp 16-8. w: weight of dry membrane (9) x: dimensionless concentration of M"' ions in solution (-) Recehred for revlew June 3, 1991. Revised September 9, 1991. Accepted September 27, 1991. y: dimensionless concentration of M"' ions in membrane (-)
Thermodynamics of Binary Mixtures Containing Alkenes. 1. Excess Enthalpies of Some Alkenes and Polyenes -k n-Heptane or Cyclohexane Mixturest Barbara Pittau, Bruno Marongiu, and Siivla Porcedda Dipartimento di Scienze Chimiche, Universita'di, Cagliari, Via Ospedale 72, 09 124 Cagliari, Italy
A flow microcalorimeter had been used to measure the excess enthalpies, HE,as a function of concentration at atmospheric pressure and 298.15 K for some binary liquid mlxtures containing alkenes and polyenes with n-heptane or cyclohexane. The values of H E are small and positive: This behavior Is attributed to Interactions between the ?r electrons of the double bonds, on the analogy of x-?r interactions between the aromatic hydrocarbon molecules.
Introduction This work is part of a systematic study of the thermodynamic properties of liquid organic mixtures, the TOM-Project ( 7 - 4 ) with the purpose of characterizing the type and magnitude of * To whom correspondence should be addressed.
-This paper is a contribution to the TOM-Project (Kehiaian, 1977, 1985).
0021-9568/92/1737-0124$03.00/0
molecular interactions in binary liquid mixtures and to improve the group contribution models currently used to predict thermodynamic excess functions. A h g h there is a great industrial interest about the alkenes, their mixtures had been relatively little studied. Recently Woycicki ( 5 ) ,Letcher ( 6 ) ,and Ghassemi et ai. (7) have started a more systematic study about the excess enthalpies of the mixtures containing alkenes. I n order to verify and to complete the lieratwe data and to better characterize the behavior of the C==C group, we decide to measure, in a systematic way, H E for mixtures of alkenes: 2-hexene (cis), 2-hexene (trans), 3hexene (trans), 1-octene, ldecene, and 1,7-octadiene with n-heptane or cyclohexane.
Experimental Section The molar liquid phase molar excess enthalpy, H E ,was determined by means of a flow microcalorimeter (model 2277, LKB-Producter AB, Bromme, Sweden). The detailed description
0 1992 American Chemical Society
Journal of Chemical and EnglneeringData, Vol. 37,No. 7, 7992 125 Table I. Experimental Measurements of Liauid Density o p l ( g mol-')
eoo-
component cyclohexane n-heptane 2-hexene (cia) 2-hexene (trans) 3-hexene (trans) 1-octene 1-decene 1,7-octadiene
-
r
I
150-
this work 0.773 89 0.679 46 0.682 43 0.674 96 0.679 03 0.71085 0.736 94 0.727 08
lit. 0.773 85 0.679 48 0.687 00 0.677 00 0.677 00 0.71085 0.736 93 0.730 00
ref 13 13 13 13 13 13 13 13
Table 11. Experimental Molar Excess Enthalpies, HE, at 298.15 K for Binary Mixtures of Alkenes or Polyenes n -Heptane or Cyclohexane
+
HEI(J
mo -
I
\
HEI(J
mol-')
HE/(J
0.1304 0.2856
mol-l) xl x 1 2-Hexene (cis) x 2 n-Heptane 32.80.5454 72.7 0.8781 59.2 0.7058 62.7
0.1294 0.2838
30.0 50.7
0.1292 0.2835 0.3724
32.7 57.2 63.1
0.1144 0.2053 0.2053
13.2 19.6 20.2
x1
x1
+
mol-') 32.5
xl 2-Hexene (trans) + x2 n-Heptane 50-
0.5432 0.7040
56.6 47.1
x1 3-Hexene (trans)
0I
I
0.2
I 0.4
I
I
0.8
0.6 Xl
+
Flgure 1. Molar excess enthalpies, H E ,at 298.15 K of alkenes (1) n-heptane (2) mixtures vs x , , the mole fraction of alkene: 0, 1decene; 0 , 2-hexene (cis); A,3-hexene (trans); 0,2-hexene (trans); W, 1,7-octadiene.
of this apparatus and experimental procedure are described elsewhere (8). Full automatic burets (ABU, from Radiometer Copenhagen) were used to pump the liquid into the LKB unit: volume of cylinder 2.5 cm3. The accuracy of the buret calibration was 0.5%. All measurements were carried out at 298.15 f 0.10 K. The accuracy of the LKB bath temperature is 0.1 K. The reliabilities of the apparatus and procedure adopted were checked by performing HE measurements on the test system benzene cyclohexane. Our resutts differed by
H
9.26 H,
,c=c
/CH3 ‘CH3
CH3
8.89
CH3, >
,c=c
CH3
/CH3 ‘CH3
8.53
Similar conclusions can be reached for cyclohexane mixtures with the alkenes. H E is higher by about 100 J mol-‘ at the maximum than the corresponding values for n-heptane. That may be attributed to dispersive aliphatic-cycloaliphatic interactions. I n this connection, it is worth remembering that, for n-heptane cyclohexane, HE ( x , = 0.5) at 298.15 K is about 240 J mol-’ (72). A detailed interpretation of these results in terms of the DISQUAC group contribution model (4) will be presented separately.
+
Regktry No. cisQ-hexene, 7688-21-3; trans-2hexene, 4050-45-7; trans9hexene, 13269-52-8; 1,7octadlene, 3710-30-3; ldecene, 87205-9; loctene, 111-660 cyclohexane, 110-82-7;nheptane, 142-82-5.
Literature Cited (1) (2) (3) (4) (5) (6) (7) (8) (9) (IO) (11)
(12) (13)
Kehiaian, H. V. Ber. Bunsen-Ges. Phys. Chem. 1977, 81, 908. Kehialan. H. V. Pure Appl. Chem. 1985, 57, 15. Maronglu, B.; Kehiaian, H. V. Thennochlm. Acta 1987, 122, 9. Kehialan. H. V.; Maronglu, B. NuM Phase Equlllb. 1983, 40, 23. Woyclcki, W. J. Chem. Thermodyn. 1975, 7, 77. Letcher, T. M.; Baxter, R. C. J. Chem. Thermodyn. 1988, 20, 149. Ghasseml, M. K.; Grolier, J.-P. E.; Kehiaian, H. V. J. CMm. P h p . 1976, 73,925. Monk, P.; Wadso. L. Act8 Chem. Scero‘. 1968, 22. 1842. Marsh, K. N. I n t . DATA Ser., Sel. D8t8 MMures, Ser. A 1973, I , 2. Collin, J.; Lossing, F. P. J. Am. Chem. Soc. 1959, 81, 2064. Ferguson. L. N. The modern Structural Theory of Organic Chemlsfty; RenticeHall Inc.: Engiewood Cliffs, NJ, 1964. Helnz, A.; Uchtenthaler,L. Ber. Bunsen-Ges.Phys. Chem. 1977, 81, 921. Riddick, J. A.; Berger, W. B.; Sakano, T. K. Organlc Solvents. Phisicel Properties and Methods of Purification; John Wiley & Sons: New York. 1988.
Received for review June 24, 1991. Revised October 8, 1991. Accepted October 13, 1991. Thls work has been performed with the financial aM of Progetto finallzatto del CNRChimlca Flne 11”.
