INDUSTRIAL AND ENGINEERING CHEMISTRY
December 1949
ACKNOWLEDGMENT
The authors wish t o express their thanks to A. E. Sobel of t h e Brooklyn Jewish Hospital for his helpful comments in the preparation of this manuscript.
2853
(16) Govindarajan, S. V., and Banerjee, B. N., I n d i a n J . V e t . Scd., 10, 336-45 (1940). (17) Marcus, J. K., J.B i d . Chem., 80,9 (1928). (18) Moore, T., Vitamins and Hormones, 3,12-15 (1945). (19) National Oil Products Co., British Patents 589,273 (June 16, 1947), 690,090 (July 8,1947). (20) Olcott, H. S., Oil & SOUP,18,77-80 (1941) (21) Oser, B. L., Melnick, D., and Pader, M., IND.ENG. CHEIM., ANAL.ED., 15, 717 (1943). (22) Oser, B. L., Melnick, D., Pader, M., Roth, R., and Oser, M., Ibid.. 17. 559 (1945). (23) Parker, W.'E., Neish, A. C., and McFarlane, W. D., Can. J . Research, 19B, 17-23 (1941). (24) Polskin, L. J., Ph.D. thesis, Rutgers University, 1940. (25) Sandell, E., Farm. Reuu, 45, 697-711 (1946). (26) Slanete, C. A.. and Scharf, A. J., J . Nutrition, 30, 239 (1945). (27) Sobel, A. E., and Werbin, H., IND.ENG.CHEM.,ANAL.ED., 18, 570 (1946). (28) Sobel, A. E., and Werbin, H., A n a l . Chem., 19, 107 (1947). (29) Stern, M. H., Robeson, C. D., Weisler, L., and Baxter, J. G., J. Am. Chem. Soc., 69,689-74 (1947). (30) Thurman, B. H., U. S. Patent 2,201,062 (May 14, 1940). (31) U. 8. Pharmacopoeia XIII, p. 718 1947. (32) U. S. Rubber Co., British Patent 560,958 (April 28, 1944). I
LITERATURE CITED
(1) Adelsberg, D., N. Y . S t a t e J . Med., 44,606 (1944). (2) Bessey, 0. A,, Lowry, 0. H., Brock, M. J., and Lopes, J. A., J . Biol. Chem., 169, 681 (1945). (3) Bisceglie, V., Boll. SOC. ital. biol. sper., 22, 1116-18 (1948). (4) Bolomey, R. A , , J . Biol. Chem., 169, 323-9 (1947). (5) Buxton, L. O., IND. ENG.CHEM.,39,225-32 (1947). (6) Ibid., 39, 1171-4 (1947). (7) Buxton, L. O., U. S. Patent 2,396,681 (March 19, 1946). (8) Buxton, L. O., and Dryden, C. E., Ibid., 2,426,486 (Aug. 26, 1947). (9) Caspe, S., and Hadjopoules, L. G., Am. J . Pharm., 110, 533-8 (1938). (10) Duboulos, P., and Hedde, M. F., Trav. membres SOC. ehim. biol., 24, 1137 (1942). (11) Dubouloe, P., Hedde, M. F., and Rousset, F., Compt. rend. soc. b i d , 137, 457-8 (1943). (12) Embree, N. D., Ann. Rev. Biochem., 17,323 (1947). (13) Feigenbaum, J., Nature, 157,770 (1946). (14) Fiedler, H., Fette u.Seifen, 45, 638-40 (1938). (15) Foy, J. R., and Morgareidge, K., A n a l . Chem., 20,304 (1948).
RECEIVEDJuly 26, 1948. Presented before the Division of Biologioab CEEMICALSOCIBTT, Chemistry a t the 113th Meeting of the AMERICAN Chicago, Ill.
Svstem Water-DiethvlarnineJ
Toluene
J
USE IN TESTING EXTRACTION COLUMNS W. E. WEHNl AND N. W. FRANKE2 Coal Research Laboratory, Carnegie Institute of Technology, Pittsburgh, P a . T h e system water-diethylamine-toluene is proposed for use in testing the efficiency of extraction columns. The use of this system allows more accurate calculation of HT or H p than most of the systems for which materials and distribution data are commonly available. Data and graphs both for the distribution coefficient and for the ternary diagram are included. Distribution data are given at three temperatures, 19.9', 24.4', and 29.9"C., and ternary data at 24t.4' C. Results of testing a glass extraction column 6 feet long and 4 inches in inside diameter packed with 5 feet of 0.5-inch Berl saddles are shown to illustrate the use of these data.
*
T
HE eficiency of a column used for liquid-liquid extraction is usually determined by operating the column with a pair of immiscible solvents and a solute whose equilibrium relationships are known. The amount of solute transferred from one solvent to the other is determined, and then the efficiency of the column is calculated either in terms of the height of a transfer unit, HT,or height equivalent to a theoretical stage, H p . D a t a are available for many two-phase three-component systems, and many of them have been used in evaluating these efficiencies. Most of the systems used, however, have high solute concentration in one phase compared to the other or large changes in the distribution coefficient for small changes in solute concentration, both of which make accurate calculation of the 1 Present address, Inspection Department, Associated Factory Mutual Fire Insurance Company, Cleveland, Ohio. * Present address, Gulf Research and Development Company, Hermarville, Pa.
column efficiency difficult. I n some systems the solute lacks a distinctive physical property, which makes analysis difficult. The use of a system having a high concentration of solute in one phase does not always allow the determination of the amount of material transferred from the rich phase. This occurs when the amount of solute needed to saturate the poor phase is close to the experimental error in the analysis of t h e solute in the rich phase, Hence, all efficiency calculations for such systems must be based on the solute transferred to the poor phase, and no material balance. is possible. Large changes in the distribution coefficient for small changes in solute concentration make t h e calculation of the number of equivalent stages (3) or transfer units (1) a n involved procedurc compared t o the simple methods available for calculating these if the ideal distribution law holds. Lack of some easily determined chemical property of the solute, such as acidic or basic groups, necessitates the use of physical properties of the solutions t o determine the solute concentration. These, in general, are less satisfactory than simple titration for t h e solute. Many of the systems which have been used have other drawbacks such as high cost, high inflammability, corrosiveness, chemical instability, undesirable physiological effects, or unavailability, which make their use inconvenient or hazardous, The system water-diethylamine-toluene proposed here h a s solubility relationships and chemical properties such that most of these difficulties do not appear. EXPERIMENTAL
The materials used for this investigation were toluene (Eimer & Amend "tested purity"), diethylamine (Sharples Chemicals, Inc.), and distilled water. An experiment made using nitration,
INDUSTRIAL A N D ENGINEERING CHEMISTRY
2854
Vol. 41, No. I 2
wibh a probable error of h0.01 in t'he value of CIT/CT for values of CW between 0.200 and 1.000 and temperatures from 20" to 30" C, The lines of Figure 1 are calculated from this equatioo and are valid only within the limited range. Published values (4, 5) for distribution coeficients in this system are limited to concentration8 below those for which the above equation applies Measurements in the lower concentration range were in substantial agreement with the published values and indicated that the lines of Figure 1 curve upward for values of CW less than 0.2. Tables II and I11 give data for tjhe ternarj diagram at 24.4" C. Table TI conta,ins selected values on a smooth solubility curve which repre,, Rents the results of 25 so1ubilit.y determinatione covering the entire two-phase range. Table IT1 contains experimental values for the conjugate line which passes through the intersections of line@ dram-n from the ends of the tie lines into and parallel to the sides of the reflected ternary d i e gram (Figure 2). Two tie lines on the ternary diagram were run in duplicate to check their precision. These appear on the conjugate line iu Figure 2 as the points a t ahout, 41 and 53 weighi Coefficient as a Function of Concentration of Figure 1. DistributionDiethylamine in Water diethylamine. A plot of C v t ~ CT . is included as Figure 3 The graphical determination of column eEciencizP In so Ear as the data deviate only slightly IS based on this plot grade toluene (Pittsburgh Coke and Chemical Compaiiy) and tap water gave the same results, indicating that these data can be from straight lines out nf the origin and l - h ~bolvents are -iffi used with the materials available for large scale tests. The distribution coefficient for solutions containing from about 2 to 10 weight % diethylamine was determined by placing mixtures of these materials in flasks, which were in turn placed in a constant temperature water bath, 10.1 ' C., until temperature equilibrium was reached. The flasks were then removed and shaken thoroughly, after which they were replaced in the bath This procedure was followed ah least three times, and then samples of both phases were taken and analyzed for diethvlamine by titration with 0.1 N hydrochloric acid u&ng mcthyl red indicator That equilibrium was attained was shown by analysis of a sccond set of samples after further shaking. The solubility curve for the ternary diagram was determinea by the synthetic method (67, taking care that the heat of solutiori was dissipated before the final reading was taken. The tie line8 were fixed by joining points on the solubility curve having diethylamine concentrations corresponding to phases in cquilibrium. The diethylamine content $.as calculated from titration and density measurenients made on both phases of thornugblv shaken samples.
4'
RESU&Tb AND DISCUSSION
Distribution data, m listed in Table I, can be represrrited b) the equation: CFI /CT =
Q.725
+ (Cw - 5.310)
I--0.897 f. 0.04731
i
- 0.000ti80ta)
OF DIETHYLAMINE BETWEEN T o ~ ~ s w a : TABLEI. DISTRIBUTION A ~ T DWLTER i, * c, CW CT L'W/CT
19.9 19.9 19.9 19.9 24.4 24.4 24.4 24.4 24.4 29.9 29.9 29.9 29.9
0.270 0.550 0.745 1.048 0.055 0.210 0.328 0.564 0.800 0.187 0.484 0.625 0,900
0.146 0.310 0.425 0.628 0.034 0.142 0,228
0,398 0.584 0.159 0.422 0.556 0.807
1.86 1.77 1.75 1.67 1.62
1.45 1.48 1.42 1.38 1.18 1.15 1.13 1.12
Figure 2.
'I'ernary Dingram for System
Water-Diethylamine-Toluene at 24.4" C.
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
December 1949
2855
TABL Iv. ~ EXTRACTION IN LARGE GLASSCOLUMN4 C = 0.000 gram mole/liter C = 0.184 gram mole /litel C = 0.455 gram mde/liter C = 0.293 gram mole/litr~
Inlet toluene Outlet toluene Inlet water Outlet water Toluene rate Water rate
0.475 liter /min. 0.615 liter /min. 25' C.
t
(&)ow
=
VLw
-=
K wa
7.4 feet
0 Column was 4.50 inches in outside diameter and 4.00 inches in inside diameter, packed with 6.00 feet of 0.5-inch Berl saddles.
a2
a4
CMJtUJTRATcLl Q tx3iiuwt.E
IN
-
ID MQES
PER L
~
R
Figure 3. Equilibrium Concentration of Diethylamine in Water us. Concentration of Diethylamine in Toluene ciently immiscible, the ,graphical procedures may be replaced by numerical calculations, using the formulas given in Table IV. The use of simplified equations with the water-diethylaminetoluene system in the 2 to 10% concentration range will introduce no error larger than 2% in the amount of diethylamine transferred in a given column, if the value chosen for C ~ / C T is the average of the values for the rich and lean ends of the column i ~ calculated 8 from the equation given. Unfortunately, the distribution coefficient is somewhat aensitive to temperature, so that equipment tested with this system must be held near a constant temperature during an extraction. This system was used t o test a large glass extraction column constructed for a pilot plant study of the recovery of organic acids produced by the direct oxidation of bituminous coal.
-
TABLE 11. SOLUBILITY DATA (t
Weight
%
24.4OC.) Weight
%
Diethylamine 15.8 21.5 28.0 33.9 38.0 29.3 38.9 37.3 33.8 27.4 19.1 9.7
Water 1.0 2.5 5.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0
TABT,E 111.
Weight
%
Toluene 83.2 76.0 67.0 56.1 42.0 30.7 21.1 12.7 6.2
2.6 0.9 0.3
Typical data are given in Table IV. Calculation of the efficiency of this column by numerical methods (2, 9) shows H p = 5.0 feet or ( H T ) =~ 7.2 ~ feet. The calculation,of H p involves a division of the column length by the number of theoretical stages. This number is implicitly given by Equation 12 of Hunter and Nash (9), which contains an error of algebraic sign. The denominator should be a sum rather than tl difference. The column efficiencies are in the range usually encountered in pilot plant work. Even so, the differences in diethylamine concentration, as listed in Table IV for both phases, are large enough t o measure accurately. NOMENCLATURE
CW CT
K
LW LT
of diethylamine in water, -gram moles per liter = eauilibrium concentration of diethylamine in t,alume. -gram moles per liter = equilibrium concentration
=
CW/CT
= flow rate of water, liters per hour
= flow rate of toluene, liters per hour = concentration of diethylamine in inlet
wawr phase to column, gram moles per liter mi* = concentration of diethylamine in water phase whicb would be in equilibrium with outlet toluene phase, gram moles per liter cwa = concentration of diethylamine in outlet water phase from column, gram moles per liter two* = concentration of diethylamine in water phase whicb would be in equilibrium with inlet toluene phase, gram moles per liter = height equivalent t o a theoretical stage, feet HP ( H T )= ~ ~height of an over-all transfer unit based on the water phase, feet Kwa = over-all mass transfer coefficient on water film basis, (hours) -1 = number of ram moles transferred per hour $/e = effective voyume of column, liters VLW = linear velocity of water phase based on empty tube, feet per hou: I = temperature, C
C W ~
CONJUGATE LINEDATA LITERATURE CITED
(1 = 24.4'C.I
w%ht
Water
W%ht
Diethylamine
Weight
(1) Colburn, A. P.,Trana. Am. Inst. Chem. Engrs., 35, 211-36 (1939)
Toluene
(2) Elgin, J. C., and Browning, F. M., Ibid., 31, 639-70 (1935); 32, 105-9 (1936). (3) Hunter, T. G.,and Nash, J. W., J. SOC.Chena. Ind., 51, 285-97T (1932). (4) International Critical Tables, Vol. 111, p. 399, New York, McGraw-Hill Book Go., 1928. (5) Moore, T. S., and Winmill, T. F., J. Chem. SOC.,101, 1836-76 (1912). (6) Smith, J. C., IND. ENG.CHEM.,34. 234-7 (1942).
%
RECEIVED July 27, 1948
