J. Chem. Eng. Data 1989, 3 4 , 195-197
2400-
P PC P' V
0 THIS WORK, DENSITOMETER THIS WORK .]MTL BALANCE 0 CREEK 0 METCALFEIRABY
pressure critical pressure scaled pressure, (Pc - P ) / P c total volume of equilibrium cell liquid-phase mole fraction vapor-phase mole fraction general experimental variable critical composition (mole fraction)
X
Y Y &-
3n 2300-
0 Z C
0
oo
0
w'
2
v)
v)
Greek Letters
0
0
E
0
a,@, v
0
Y
m
PL PV
scaling-law parameters (critical indices) interfacial tension uncertainty in measured variable Y liquid-phase density vapor-phase density critical density liquid-phase density minus vapor-phase density general "order parameter"
W
a:
n
tY I
2200-
0
%
0
Pc
- 3 *
AP
0
4
Registry No. C02, 124-38-9; tetradecane, 629-59-4.
0
2100-fl
0 I
,
,
,
,
l
,
,
,
,
I
#
#
#
J
l
Literature Cited
L
(1) Hsu, Jack J. C.; Nagarajan, N.; Robinson, Jr., R. L. J : Chem. Eng. Data 1985, 30,485. (2) Nagarajan, N.; Robinson, Jr., R. L. J . Chem. Eng. Data 1988, 37, 168. (3) Nagarajan, N.; Robinson, Jr., R. L. J . Chem. Eng. Data 1987, 32, 369. (4) Bufkin. B. L. Personal communication, Oklahoma State University, Stillwater, OK, 1985. (5) Anderson, J. M.; Barrick, M. W.; Robinson, Jr., R. L. J . Chem. Eng. Data 1986, 31, 172. (6) Pollack, N. R.; Enick, R. M.; Mangone. D.J.; Morsi. B. I. SFEReserwir Eng. l 9 8 & May9533. (7) Creek, J. L., Personal communication, Chevron Oil Field Research Co.. La Habra, CA, 1985. (8) Metcalfe. R. S.; Raby, J. Personal communication, Amoco Production Co., Tulsa, OK, 1984. (9) Wichterle, I.; Chappelear, P. S.; Kobayashi, R . J. Comput. Phys. 1971. 7 . 606. --(IO) Charoensombut-amon, T.; Martin, R. J.; Kobayashi, R. FlUM Phase Euuilib 1986. 31 . 89. (11) Wegner, F. J: Phys. Rev. 1972, 85, 4529. (12) Nagarajan, N.; Kumar, A,; Gopal! E. S. R.; Greer, S. C. J. Phys. Chem. 1980, 84, 2883. (13) LeGuiilore, J. C.; ZinnJustin, J. Phys. Rev. 8 1980, 27,3976. (14) Levek-Sengers, J. M. H.; Greer. W. L.; Sengers, J. V. J. Phys. Chem. Ref. Data 1976, 5, 1.
Figure 4. Comparison of phase density measurements.
ment with Metcalfe and Raby at 2200 psia. For vapor densities, the present results agree very well with Creek's data at 2285 psia and above (differences less than 0.002 g/cm3), with larger differences at lower pressures. The estimated uncertainty in our material balance densities is 0.005 g/cm3 ( 0.8 %). Two separate runs were made, which generally deviate in opposite directions from our densitometer results. The average of the two material balance runs differs by no more than 0.002 g/cm3 from the densitometer results. Probably the major conclusion to be drawn from the above analyses is that various investigators are likely to produce saturated-phase densities that are consistent to no better than about 1% . N
. . .
Glossary
A,, B,, GI
parameters in eq Al-A4
fL
volume fraction liquid in equilibrium cell total mass in equilibrium cell mass of liquid in' equilibrium cell mass of vapor in equilibrium cell
m mL
mv
195
Received for review August 8, 1988. Accepted October 26, 1988. Financial support for this work was furnished by the following organizations: Amoco Production Research Co., ARC0 Oil and Gas Co., Chevron Oil Field Research Co., Marathon Oil Co., Mobil Research and Development Corp., Shell Development Co.. Sohio Petroleum Co., Sun Exploration and Production Co., and Texaco, Inc.
Vapor-Liquid Equilibria in Binary Systems Containing Ethanol with Hexamethyldisiloxane and Dimethyl Sulfoxide Barbara Kaczmarek and Ateksander Radecki Department of Physical Chemistry, Medical Academy, 80-4 16 Wafisk, Poland
Reagents
Results of the experimental determination of isobaric vapor-liquid equiilbrium data for the binary systems hexamethyldisiioxane (HMDS) with ethanol and ethanol with dlmethyl sulfoxide (DMSO) are reported. This work is a continuation of studles on phase equilibria in binary systems ( 1-6 ). 0021-9568/89/1734-0195$01.50/0
Hexamethyldisiloxane (HMDS) was supplied by CIECH, Gliwice. After purification it had bp 100.8-101 OC, dm4= 0.7634 g ~ m -and ~ , n2OO= 1.3777. Dimethyl sulfoxide had bp 189.0 OC, dZo4= 1.008 g ~ m - ~ , and nzo0= 1.4779. Ethanol boiled at 78.3 OC and had d204=
0
1989 American Chemical Society
196 Journal of Chemical and Engineering Data, Vol. 34, No. 2, 7989
Table I. Experimental Liquid-Vapor Equilibria under a Pressure of 14.665 kPa and Values of HMDS and DMSO Mole Fraction in Vapor Calculated from the Redlich-Kister Ethanol and DMSO Equation in the Systems HMDS Ethanol
+
+
HMDS + Ethanol HMDS mole fraction vapor calcd exutl liauid 0.2026 0.210 0.080 0.2492 0.260 0.100 0.2830 0.300 0.115 0.3250 0.340 0.135 0.3602 0.375 0.155 0.3869 0.385 0.190 0.3980 0.395 0.205 0.4050 0.400 0.235 0.4100 0.407 0.350 0.4116 0.410 0.410 0.4119 0.415 0.465 0.4178 0.420 0.545 0.4186 0.435 0.660 0.4401 0.450 0.775 0.5368 0.550 0.900 0.5950 0.590 0.930 0.7063 0.700 0.960
temv. K 306.65 305.65 305.15 304.65 304.15 303.65 303.40 303.15 303.05 302.65 302.90 303.05 303.65 304.15 306.90 308.65 311.90
314
310
306
0
exptl 0.010 0.016 0.025 0.036 0.050 0.060 0.130 0.210
Ok
0.2
0.6
0.0
Figure 1. Isobaric vapor-liqukl equilibrium diagram at the system HMDS 4- ethanol. liquid 0.4875 0.5975 0.6400 0.7100 0.7625 0.8050 0.8500 0.9000
1IKI
7.0
b.lDS
-’
vauor calcd 0.0018 0.0145 0.0222 0.0342 0.0489 0.0672 0.1225 0.2321
t
318
DMSO + Ethanol DMSO mole fraction temp, K 328.95 337.65 339.90 343.95 349.65 354.65 364.65 373.89
TLKI
14.67
kPa for
t
0.7894 g ~ m and - n20D ~ = 1.3614. Measurements
A relationship between the boiling point and cpmposition of a system was determined by using a modified Swigtoslawski ebulliometer (7, 8). Under isobaric conditions the temperature was held constant to within f0.05 K. The composition of the liquid and condensate was determined on the basis of the refractive index measurements by using previously prepared calibration graphs. Results and Conclusions
Results of the measurements are listed in Table I. They were used to construct liquid-vapor plots shown in Figures 1 and 2. The system ethanol HMDS exhibited strong positive deviations from ideal behavior. Under the pressure of 14.67 kPa an azeotrope is formed; it boils at 302.12 K with mole fraction of ethanol = 0.590. The DMSO ethanol system turned out to be a zeotropic one; for classification and terminology of vapor-liquid diagrams see Brostow (9).The boiling point range is 309.25-399.35K. There are large differences in the composition of the liquid and vapor phases. Thermodynamic verification of the experimental data was performed by using bi-, tri-, and tetraparametric Redlich-Kister equations (70):
0
+
+
Q=
GE
= xlx2; RT
n
A,(xl
I= 1
- x2)*’
(1)
where Q is often called the thermodynamic potential, GE is the excess Gibbs function, x, is the mole fraction of the ith com-
02
-
0.4
0.6
0.8
m
‘DMSO
Figure 2. Isobaric vapor-liquid equilibrium diagram at 14.67 kPa for the system dimethyl sulfoxide ethanol.
+
ponent, A,’s are constants, R is the gas constant, and Tis the absolute temperature in K. Activity coefficients, y1 and y2,of components 1 and 2 of the liquid phase were calculated from experimental data as
0 = x 1 In y1 + x 2 In y2
(2)
where In y, =
Pvl(01
P , O X l
and
In y2 =
Pv 2(02 -
(3)
P2OX*
The vapor pressure of the pure component, P o , was calculated from the Antoine equation ( l l ):
Journal of Chemical and Engineering Data, Vol. 34, No. 2, 1989 197
log P o = A
- B/(C +
T)
where A , 6,and C are constants. As the A , B , and C constants for DMSO are not known, they were calculated from the values of critical temperatures (72). Fugacities (a1 and (a, of the components were calculated under consideration of the second virial coefficient
Table 11. Constants Ai in the Redlich-Kister Equation and Mean Quadratic Error (RM(y)) no. numerical Daram values RM(v)
HMDS + Ethanol 2
AI A2 A1 A2 A3 A1 A2 A3 A,
3
In
(a,
=
In p, =
(Bl
-
V , ) ( P - PO) RT
(B,
-
V d P - PO) RT
+
4
+
= = = =
1.9634 0.1929 2.1505
4
Ai A2 A3 A,
,
= -0.4736 = 2.1401 = 0.1247 = -0.4973 = 0.3908
F , = 0.1445 F , = 0.073
- 0.1385T;' - 0.0121T;3 ( 6 ) + 0.5T;' - 0 . 0 9 7 T ~-~0.0073T;8
- 0.33T;'
+ 0.46T;l
(7) T, = T/T,
and
w = log ( P o / P , )
-
1
(8)
Partial pressure, P o , which occurs in the evaluation of the acentric coefficient w , was calculated for T = 0.7Tc. The value of Bl,, was calculated from the following combining rules (14): TCi,?= (TciTc2)1'2 and
w1,2 =
+02 2 w1
(9)
0.02991
+ Ethanol
= -0.0657
0.0089
= -8.6288 = 17.2393 = -18.1993
Theoretical values of y1and y2 in these expressions were follow from differention of eq 1 as In 71 =
where
0.0348
0.2140
DMSO where y 1 and y 2 are mole fractions of the components in the vapor phase, V1 and V, are molar volumes of the components, and P is the total pressure. The second virial coefficients, 6 and B,, of components 1 and 2 as well as Bl,, for the mixture were calculated by the Pitzer-Curl method (73)from
0.0302
~2~
+
+
(A1 A,(3x, - ~ 2 ) - x,) X (5x1 - x , ) A , ( x , - X2)'(7Xj -x2) ...) (12a)
+
In y2 = x 12 ( A - A * ( 3 x 2 - x 1) - A g(x - x 2 ) X ( 5 x 2 - x , ) - A , ( x l - x2)2(7x2- x , )
+
+ ...)
(12b)
The mean quadratic error was assumed as a measure of the agreement between the theoretical and experimental results: RMW) =
[(CW - Ycalcd)2)/~11'2 i=1
(13)
RMW) values in the bi-, tri-, and tetraparametric equations were juxtaposed with the values of the constants in these equations in Table 11. As can be seen in the tables, the agreement between the calculated and experimental mole fractions in the vapor phase is entirely satisfactory. This is both for the HMDS-containing azeotropic system and for the DMSO-containing zeotropic system. Reglstry No. HMDS, 107-46-0; DMSO, 67-68-5; EtOH, 64-17-5.
Literature Cited
P
Critical values V, T , and P , (volume, temperature, and pressure, respectively) for HMDS were taken from the article by Dickinson (75) whereas the T , value for the alcohol from Timmermans (76).The remaining critical values were calculated as described by Reid (77). The activity coefficients calculated from the experimental data enable one to find constants A , in the Redlich-Kister equation. To find these constants, a program was developed that utilized orthogonal polynomials. Having found the constants in the Redlich-Kister equation, the theoretical composition of the vapor phase, y 1 and y,, was determined as
Yl"
p lox1Y 1
P2OXZY2
PPl
p P2
= - and y2aw = -
and listed in Table I.
(11)
Radecki, A.; Kaczmarek, B. J. Chem. Eng. Data 1975. 20, 376. Radecki, A.; Kaczmarek, B.; Grzybowski, J. Inz. Chem. 1975, 5 , 861. Radecki, A,; Kaczmarek, B. J. Chem. Eng. Data 1980, 25, 230. Kaczmarek, B.; Radecki, A. Pol. J. Chem. 1978, 52, 431. Kazcmarek, B. Poi. J. Chem. 1983, 57, 617. Kaczmarek, B. I n z . Chem. 1983, 4 , 497. Swigtoslawski, W. Azeotropy and Polyazeotropy ; PWN, Macmillan: Warsaw, New York, 1963. Brzostowski, W. Bull. Acad. Polon. Ser. Chim. 1980, 8 , 291. Brostow, W. Science of Materials; Wiley: New York, 1979; Section 6.7. Rediich, 0.; Kister, A. T. Ind. Eng. Chem. 1948, 4 0 , 341. Boublik, T.; Fried, V.; Hala. E. The Vapor Pressures of Pure Substances; Amsterdam, London, New York, 1973. Zwolitiski, B. J.; Krgglewski, A. Rocz. Chem. 1961, 35, 1041. Pitzer, K. S.;Curl, R. F. J. J . Am. Chem. SOC. 1957, 79, 2369. Malanowski, S. RBwnowaga Ciecz-Para ; PWN: Warszawa, 1974. Dickinson, E.; Mc Lure, I. A. J. Chem. SOC.,faraday Trans. 1 1974, 7 0 , 2313. Timmermans, J. Physlco -Chemical Constants of Pure Organic Compounds ; Eisevier: Amsterdam, 1965. Reid, R. C.; Sherwood, T. K. The Properties of Gases and Liquids; Mc Graw-Hili: New York, 1966. Received for review May 16, 1968. Accepted December 20, 1988.
