June 1951
INDUSTRIAL AND ENGINEERING CHEMISTRY
were exhibited by the solutions containing 0% water; they were found to vary with temperature from -0.33 to 0.50%. Time has not permitted an investigation of additional properties which may lend themselves to the above-described type of correlation. However, it is felt that the following generalization may be made: Whenever lines of varying cornpositions of ternary systems on a graph with two variables as the coordinates are entirely or practically parallel, the method is applicable. Furthermore, cross plots can be attached to all three sides of one ternary diagram; this will permit the correlation of three physical properties of one ternary system, using one graph.
+
A
EXPERIMENTAL PROCEDURE
*
VAPORPRESSURE DETERMINATION.The experimental data were obtained by placing a solution of desired composition in a previously evacuated metal bomb, which was connected either to a mercury manometer (subatmospheric range) or a calibrated pressure gage (aboveatmospheric range). The bomb waa immersed in a constant-temperature bath, and determinations were made at steady-state conditions. The accuracy was found to be *2.4%. SPECIFICGRAVITYDETERMINATION.The specific gravities were determined by weighing the constituents into a glass
l433
cylinder containing a hydrometer and thermometer. The cylinder was enclosed in a transparent plastic case, reinforced to withstand pressure. The entire assembly was immersed in a constanttemperature bath prior to taking the readings. The average accuracy was *0.02y0. The ammonia and ammonium nitrate used in the determinations had a minimum purity of 99.95%. ACKNOWLEDGMENT
Acknowledgment and thanks are due to the Spencer Chemical Co. for the privilege of publishing these correlations. Special thanks are extended to the Technical Department and Research Section of the company for having determined physical property data required for this work. LITERATURE CITED
(1) Perry, J. H., ed., “Chemical Engineers’ Handbook,” 2nd ed.,p. 413,New York, McGraw-Hill Book Co., 1941. (2) Ibid., p. 2544. (3) Shultz, J. F., and Elmore, G. V., IND.ENQ. CEEM.,38, 296-8 (1946). (4)
Spencer Chemical Go., unpublished data, 1960.
RECEIVED November 24, 1950.
Ternarv Svstem FurfuralEthylene Glycol-Water J
d
J
d
JOSEPH B. CONWAY AND JOHN J. NORTON’ Villanova College, Villanova, Pa.
..
T h e present work was undertaken to evaluate the applicability of furfural toward the extraction of ethylene glycol from aqueous solutions, in terms of the ternary equilibrium and tie-line data for this system. The ternary equilibrium diagram for the system, furfural-ethylene glycol-water at 25’ C. is presented together with several tie lines. The tie-line data are correlated in terms of previously proposed methods. A comparison of equilibrium data, using previously published data for the two alcohol systems, indicates that furfural is a better extractive solvent for ethylene glycol than either n-amyl or n-hexyl alcohol.
L
ADDHA and Smith (6) investigated the extraction of ethylene glycol from aqueous solutions and considered some normal alcohols aa solvents. Ternary equilibrium data together with several tie lines were presented in an effort to evaluate the solvents considered. Data on n-amyl and n-hexyl alcohol indicated that these were poor extractive solvents for removing glycol from aqueous solutions. The distribution greatly favored the water phase, and n-amyl alcohol seemed to be better than n-hexyl alcohol. An approximate method for predicting distribution and selectivity in ternary liquid systems has been proposed by Conway ( 2 ) . This method is based on the physical properties of the components and makes it possible to determine approximately if good selectivity in a solvent will be obtained. This method was employed in evaluating the extraction of ethylene glycol from aqueous solutions. The prediction that amyl alcohol may be a better solvent for this extraction than n-hexyl alcohol is substantiated by the data of Idaddha and Smith (6). Further1
Present address, Panelyte Division, St. Regia Paper Co., Trenton, N. J.
more, the method proposed by Conway ( 9 ) was used to predict that furfural might be a good solvent for the extraction of glycol from water, better than either n-amyl or n-hexyl alcohol. The present work was undertaken to verify this prediction and to compare furfural as an extractive solvent for ethylene glycol with n-amyl and n-hexyl alcohol. MATERIALS
Laboratory-distilled water was used. Technical furfural (Quaker Oats Co.) was purified by fractionation in a small fractionating column. Purification was carried out a t 15 mm. of mercury and the first and last portions of the distillate were discarded. The purified product was clear and had a very faint straw-yellow color. Ethylene glycol (Eimer and Amend, refined ethylene glycol) had a specific gravity of 1.11 at 25’ C. PROCEDURE
All measurements were made at 25’ C., using the method discussed by Othmer, White, and Trueger (7‘). The furfural side of the curve was obtained by taking a dilute solution of glycol in furfural and titrating to turbidity with water. A measured quantity of glycol was added until the mixture was made homogeneous and it was then titrated to turbidity again with water. This process was repeated until the furfural side of the equilibrium curve was obtained. The water side of the equilibrium curve was determined in a similar manner. In determining the equilibrium curve each time a point on the binodal curve was obtained, its specific gravity was determined with a Chaino-matic Westphal balance. The specific gravity values for each side of the equilibrium curve were plotted against weight per cent glycol and used in establishing the tie lines. Tie-line data were obtained by making up mixtures .whose compositions fell within the two-phase area of the equilibnum curve. These mixtures were agitated, stoppered, and allowed
1434
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 43, No. 6
GLYCOL
A
0 I
E
b
Figure 1.
Equilibrium Diagram at 25" C. for FurfuralEthylene Glycol-Water S>-stem
to stand for 24 hours. The layers were then separated and their specific gravities \!-ere measured. The composition of each layer was determined by referring to the specific gravity plot for the appropriate layer. In this way, the extremities of the tie lines were determined. Care via8 taken to see that the point representing the original mixture fell on the line connecting the two points determined from the specific gravity plots. The equilibrium curve for the furfural-ethylene glycol-water system is shown in Figure 1. The data are presented in Table I. The tie-line data were analyzed hy the method of Othmer and Tobias (6) by plotting (1 - a ) / a vs. (1 - b ) / b 011 log-log paper, where a is the fraction of solvent in the solvent phase and b is
Figure 2.
Othmer axid Tobias Plot of Tie-Line Data
the fraction of diluent in the diluent phase. Figure 2 indicates that for the present data such a plot results in a straight line. This system then adds to the number of systems for which such a plot is obtained. The tie-line data were also correlated by the method suggested by Bachman ( 1 ) . -4plot of the ratio of the weight per cent water in the water layer to the weight per cent furfural in the furfural layer versus the weight per cent water in the nater layer gives a straight line. Figure 3 shows the tie-line data coirelated in this manner. The curves in Figure 4 give a comparison of the ability of the three solvents to extract glycol from water. The curves for am>-1and hexyl alcohol mere taken from Laddha and Smith ( 5 ) and are compared nith the curve for furfural plotted from the data presented in this paper. -4myl alcohol is shown to he a better solvent for glycol extraction than hexyl alcohol and furfural is better than either of these solventP. These facts are in
TABLE I. EQCILIBRIUhI
DATA FOR FURFURAL-&HYLESE GLYCOIr\~1.4TER S Y S T E M AT 25"
c
(Data in weight %)
Specific Gravity 1.1482 1.1436 1.1373 1.1317 1.1284 1.1276 1.1206 1,1205 1,1149 1,1117 1.1090 1.1037 1.1023
Furfural,
Glycol,
%
%
94.78 84.4 72.4 63.1 55.4 49.4 44.8 40.6 33.2 33.8 28.19 23.21 25.5 20.1 12.1 10.2 7.9 7.96 8.71 '3.18 10.1
1.0931 1 ,0778 1.0577 1.0134 1.0291 1.0405 1.0539 1,0574
TIE-LINE Glycol in Solvent Layer,
%
WT.% W A T E R
Figure 3.
IN W A T E R R I C H L A Y E R
Bachman Plot of Tie-Line Data
7.7 6.1 4.8
2.3
Water,
% 5.22 4.13 5.54 7.17 8.49 9.0 11.5 11.9 15.2 16.1 18.91 23.88 22.8 29.4 41.6 57.6 92.1 80.9 72.2 62.2 59,3
ii:45 22.0 29,74 36.2 41.6
43.7 47.5 51.6
50.1 52.9 52.9 51.7 50.6 46.3 32.2 ii:ii 19.15 28.1 30.6 DATA AT
25'
c. Glycol in Water Layer,
%
28.8 21.9 14.3 7.3
INDUSTRIAL AND ENGINEERING CHEMIST.RY
June 1951
1435
tractive solvent for glycol but, nevertheless, it is better than the solvents studied by the above authors. The values for the solubility of furfural in water and water in furfural reported herein compare favorably with the values reported by Griswold, Klecka, and West ( 4 ) . The equations presented by these authors, although applicable only over the temperature range 100" t o 200' F., were extrapolated t o 25" C. (77" F.) to calculate 8.54 weight % as the solubility of furfural in water and 5.46 weight, % as the solubility of water in furfural. These values are very close to the values reported in the present article. ACKNOWLEDGMENT
The authors would like to acknowledge the cooperation of the Quaker Oats Co. in furnishing the furfural used in this work. BIBLIOGRAPHY
WEIGHT FRACTION GLYCOL IN SOLVENT
Figure 4.
PHASE
Distribution of Glycol between Water and Solvent Phases A. B. C.
n-Hexyl alcohol as solvent rz-Amyl alcohol as solvent Furfural a s solvent
(1) Bachman, I., IND. ENG.CHEIM., ANAL.ED., 12, 38 (1940). (2) Conway, J. B., M.S. thesis, University of Cincinnati, 1947. (3) Elgin, J. C., Chem. & Met. Eny., 49, 110 (May 1942). (4) Griswold. J.. Klecka. M. E.. and West. R. V.. Jr.. Chem. E?m. Progress, 44, 839 (1944). ( 5 ) Laddha, G. S., and Smith, J. M., IND.ENG.CHEM.,40, 494 (1948).
(6) Othmer, D. F., and Tobias, P. E., Ibid., 34, 690 (1942). (7) Othmer, D. F., White, R. E., and Trueger, E., I b i d . , 33, 1240
agreement with the predictions made from the method proposed by Conway (9). Furfural is not to be considered a good ex-
(1941). RECEIVEDAugust 5 , 1950.
Solubility of Sucrose in Aqueous Glycerol and Propylene Glycol lMARY W. FEY, C. M. VEIL, AND J. B. SEGUR The Miner Laboratories, Chicago, I l l .
c
T h e use of glycerol or propylene glycol with sucrose in the preparation of pharmaceutical sirups makes it desirable to know the solubility of the sugar in aqueous dilutions of the two substances. The information will also be useful in the food and candy industries. Solubilities of sucrose were determined at 25" C., using aqueous glycerol or propylene glycol in concentrations ranging from 25 to practically 100% by weight as solvents. These data can serve as a guide for the avoidance of supersaturated sirups that are likely to deposit crystals.
THE
solubility of suerose in aqueous glycerol is of interest because of the wide use of glycerol in food and pharmaceutical sirups. Propylene glycol was also used to some extent in pharmaceutical sirups during the wartime shortage of glycerol. MATERIALS
Glycerol, redistilled in vacuo. The specific gravity of 1.2619 at 25"/25" C. showed the glycerol concentration to be 99.96% (2). Propylene glycol, commercial grade, redistilled in vacuo, the middle fraction used. The specific gravity was 1.0359 a t 25O/ 25" C. and the refractive index (ns5)was 1.4312. Huntress and Mulliken ( 3 ) give the specific gravity as 1.0354 at 23"/4" C. and the refractive index as 1.43162. The propylene glycol used was assumed to be approximately 99 to 100%. C.P. sucrose (specific rotation $66.5'). Distilled water.
Aqueous solutions of glycerol arid propylene glycol were made up on an analytical balance, and the specific gravity of each solution was taken. The values obtained for the glycerol solutions indicated that they were within 0.1% of the desired concentrations. Inasmuch as the specific gravity of propylene glycol solutions is not suitable for determining their concentrations, because i t is so near unity, they were assumed to be within the same limit of accuracy. The C.P. sucrose crystals were powdered and added to the solutions until saturation was attained.
TABLEI. SATURATEDSOLUTIONS OF SUCROSEIN AQUEOCS GLYCEROL AND PEOPYLENE GLYCOL AT 25" C.
Solvent Water Glycerol 25% 50%
75%
82.5%
::36%
Propylene glycol
Specific Gravity, 250/250 c. Sucrosesaturated Solvent solutions 1.0000 1.334ia 1.0609 1,1274 1.1956 1.2156 1.2492 1.2619
1 0200 1 0375 1 0419 62% 1 0437 75% 1 0396 1 0360 a From Bates (f). b Calculated from weight 25%
50%
E?%
na,b of
SucroseSaturated solutions 1 .4 6 0 i a
Sucrose Grams/ 100 MI. Solution 90.6a
1.3175 1.2963 1,2756 1.2751 1.2744 1,2758
1.4571 1 ,4564 1.4610 1.4640 1.4723 1.4796
78.2 58.0 32.4 25.5 12.6 7.2
1 1 1 1 1 1
1 1 1 1 1 1
75 62 39 24 4 2
2882 2223 1774 1233 0561 0437
4527 4440 4382 4330 4309 4331
7 2 4 5
8 0
per cent sucrose X specific gravity.
Siicrose, %,by
Welght 6 7 . 8Qa 59.4 44.8 25.4 20.0 9.9 5 7 58 42 33 21 4 1
8 7 5 8 5 9
