These data were obtained with a view to ascertaining the possibility of separating acetic acid and water under conditions of reversed relative vola- tility by extractive distillation wi
Trang 1April 1950 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 727
LITERATURE CITED (1) Guertler, W., and Liepus, T., 2 Metallkunde, 17, 310-5 (1925)
(2) Harned, H S., and Davis, R., Jr., J Am Chem SOC., 65, 2030-7
(1943)
(3) Hothersall, A W., and Gardam, G E , J Electrodepositow’
Tech SOC., 15, 127-40 (1939)
(4) McKay, R J., IND ENG CHEM., 21, 1283-7 (1929)
(5) McKay, R J., and Worthington, R., “Corrosion Resistance of
Metals and Alloys,” p 369, New York, Reinhold Publishing
Corp., 1936
(6) Mellor, J W., “A Comprehensive Treatise on Inorganic and
Theoretical Chemistry,” Vol XV, p 156, London, Longmans,
Green & Co., 1936
(7) Mitchell, A M., with Mellon, M G., IND ENG CHEEK., ANAL
E D , 17, 380-2 (1945)
(8) Miiller, E., and Luber, A., 2 anorg allgem Chem., 187, 209-30 (1930)
(9) Pinner, W L., Soderberg, G., and Baker, E M., “Modern Elec- troplating,” p 242, New York, Electrochemical Society, Inc.,
1942
(10) Robl, R., 2 angew C h a , 37, 938-9 (1924)
(11) Sohlatter, Max, U 5 Patent 1,972,693 (Sept 4, 1934)
(12) Uhlig, H H., ed., “Corrosion Handbook,” p 254, New York,
(13) Wesley, W A., and Copson, H R., J Electrochem Sac., 95, 226- (14) Young, C B F., Proc Am Electroplaters’ Soc., 28, 124-35
John Wiley & Sons, Inc., 1948
41 (1949)
(1940)
R E C E I V E D August 22, 1949
EFFECT OF CALCIUM CHLORIDE ADDITION
LEO GARWIN AND KENTON E HUTCHISONl
Oklahoma Agricultural and Mechanical College, Stillwater, Okla
ECAUSE acetic acid
B and water are not too
readily separated by ordi-
nary distillation, methods
i n v o l v i n g auxiliary tech-
niques have been used for
some time These methods
include (10) a z e o t r o p i c
distillation with a water-
Experimental data are presented on the vapor-liquid equilibrium of the system acetic acid-watercalcium chloride at 1 atmosphere These data were obtained with
a view to ascertaining the possibility of separating acetic acid and water under conditions of reversed relative vola- tility by extractive distillation with calcium chloride
The results show a considerable effect of calcium chloride addition, with a reversal taking place at approximately 8 weight calcium chloride in the liquid phase
i m m i s c i b l e organic com-
pound such as butyl acetate
(Othmer process),liquid-liquid extraction with ethyl ether or ethyl
acetate, followed by the removal of the solvent from the extract by
fractional distillation, and simple extractive distillation (without
reflux) using a wood oil (Suida process) In the last-named
method, the water is removed overhead and the acetic acid-wood
oil bottoms mixture is separated by a second distillation under
vacuum
The aqueous acetic acid solution t o be separated is very fre-
quently a dilute one, and it was thought worth while t o investigate
further the separation of the components of such a mixture by an
extractive distillation process in which the acetic acid would be
taken overhead and the bulk of the mixture (water) would be re-
moved as bottoms I n order t o do this-i.e., reverse the normal
relative volatility of acetic acid and water-it would be necessary
to use, as the extractive distillation agent, a substance which
would tend to form a loose combination with the water Inor-
ganic salts seemed t o offer good prospects for this purpose
McBain and Kam (6) reported some work on the distillation of
dilute solutions of acetic acid in water in the presence of lithium
chloride, sodium chloride, potassium chloride, potassium thiocya-
nate: sodium sulfate, potassium nitrate, and sodium acetate
Quartaroli (9) did a somewhat similar study with sodium chlo-
ride, lithium chloride, calcium chloride, and sodium bromide
Calculations based on the data of these investigators showed that,
of the salts posseseing commercial possibilities, lithium chloride,
calcium chloride, and sodium chloride were the most effective,
with expected relative volatility reversals taking place in dilute
Present address, Kerr-McGee Oil Industries, Ino., Oklahoma
a c e t i c a c i d s o l u t i o n a t about 6 5 weight % lithium chloride, 10 weight % cal- cium chloride, and 12 weight
% sodium chloride
In order for this relative volatility reversal t o take place throughout the distil- lation column, it is neces- sary that the extractive dis- tillation agent be present
in the liquid in the proper concentration on all of the trays of the column That is to say, i t must be soluble in glacial acetic acid as well as in water Semiquantitative solubility studies by Davidson (1) show sodium chloride and potassium chloride t o
be rather insoluble in glacial acetic acid On this basis, it might
be expected that lithium chloride, an alkali chloride, would also be insoluble Calcium chloride, however, is quite soluble in acetic acid and data for its solubility as a function of temperature (6) are given in Figure 1 It was selected, therefore, as the salt for
further investigation
EXPERIMENTAL
A11 chemicals used in this work were analytical reagent grade The glass, electrically-heated equilibrium still employed was es- sentially the one described by Jones, Schoenborn, and Colburn
(C), but modified in the following respects:
The condensate chamber was filled with glass beads to reduce its volume relative to t h a t of the residue chamber to the greatest possible extent During operation the condensate-residue volume ratio was about 1 to 4
A wick of glass wool was substituted for the wire helix in the flash boiler This permitted better distribution of the distillate over the boiler heating surface, avoiding local overheating, and minimizing the danger of the glass cracking
The pressure on the still was maintained a t 760 * 0 5 mm by means of a Model No 5 industrial Cartesian manostat (The Emil
Greiner Company), actuated by compressed nitrogen gas from a
cylinder
Trang 2128 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol 42, No 4
T E M P E R A T U R E , O C
Solubility of Calcium Chloride Figure 1
in Glacial Acetic Acid Menschutkin (6)
was measured t o 0.1" C with a mercury thermometer inserted in
The thermometer was checked and found t o be accurate at the
range of water-acetic acid ratios with calcium chloride concentra-
being determined by the solubility of the salt in the liquid Be-
DAT-4 FOR ACETIC ACID-WATER-CALCIUM C H L O R I D E SYSTEM
(Pressure, 760 mm €Ig)
m't %
1 A 2A 3E 4A 6A
7
8
9
10
12
1 4
15
16
17 18A
19
20
21
22 25A
26
28 29A
30
31
33
34
37
38
40
0.0
0 0
0 0
0 0
0 0 10.1
9 7
9 6
9 5
19.7 19.3 20.0 19.8 19.0 29.8
2 9 2 31.0 31.6 40.1
35 6
39.1
3 6 8 36.2
4 4 7
45.1
4 9 5 53.4
5 3 2
6 0 5
61.0
91.9 61.9
4 4 2
2 3 6
1 0 6
85.3
7 6 5 41.3
2 6 5
11.8
7 9 2 66.8
4 5 1
15.3
9 3 5
83.6
7 9 8
32.1
9 1 0 86.0 71.7 55.1 18.4 84.8
7 3 4
57.1
90.4
88.6
9 7 0
98.5
91.2 85.5
93.9
81.5 71.9
5 6 5
17.4 83.7
7 3 5
3 9 6
2 5 4
11.5
7 9 9
4 9 4
30 2
18.8 81.5 51.3 16.0 67.8 50.8
3 9 2 25.4
1 6 4
7 2 47.8 48.6 33.0
20.0
51.8 65.0 50.8
100.2 101.3
1 0 1 9
104, -1
108.0 102.4 105.0 107.6 111.6 104.8 109.0 112.0
115.0
1 1 0 0
110.2 115.0 113.3 114.0
121.6
1 2 7 2
120.9
1 2 1 9
128.0
127 I)
127.5 132.3 136.0
it was possible to go to as high as 60 weight % salt in the water-
_ _ O T H M E R a G I L M O N T ( 7 )
- _ P E R R Y ( 8 )
T H I S I N V E S T I G A T I O N
-
0
0
4
f
K
w
l-
;
I
t- 4 0 -
i
-
w
e
0
WEIGHT % WATER I N L I Q U I D
Figure 2 Vapor-Liquid Equilibrium Behavior of Acetic Acid-Water
System
iich region but only t o about 30 weight % in the acid-rich range
tion was introduced into the condensate
chamber Another portion, t o which t h e neces- sary amount of anhydrous calcium chloride
ples Preliminary tests showed t hat 3 hours
the condensate chamber
and Jvater, was analyzed for the acid by titra- tion v,ith standard sodium hydroxide, using phenolphthalein as the indicator
The residue, when it contained calcium
chloride, was first titrated for acetic acid con- tent as described above It was found that
the presence of calcium chloride had no effect
on this titration The sample thus titrated
silver nitrate, using sodium chromate as the
indicator (Mohr's method) (6) It was only necessary, prior t o this second titration, t: dis- charge the caustic-phenolphthalein end point color with a fraction of a drop of acetic acid
presence of sodium acetate and phenolphtha-
lein indicator was found quite satisfactory by a
Trang 3good 150 - 8 I
Complete smoothed vapor-liquid equilib-
rium data are given in Table I11 and are
plotted in Figure 3 The number adjacent 140 -
L I N E S O F CONSTANT WT % CoClp
to each experimental point in the figure rep-
resents the calcium chloride content of the
liquid to the nearest weight per cent The
/i
60
XI0
+
the experimental points for approximately -
Trang 4730 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol 42, No 4
TABLE 111 SMOOTHED VAPOR-LIQUID EQUILIBRIUM ARD BOIL-
SYSTEM
(Pressure, 760 mm Hg)
S
0 0
0 0
0 0
0 0
0 0
0 0
0 0
1 0 0
1 0 0
1 0 0
1 0 0
1 0 0
1 0 0
1 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 0 0
2 0 0
5 0
10.0
2 0 0
4 0 0
6 0 0
8 0 0
9 0 0
9 5 0
5 0
1 0 0
2 0 0
3 0 0
5 0 0
6 0 0
70.0
8 0 0
9 0 0
9 5 0
5 0
1 0 0
2 0 0
3 0 0
5 0 0
60.0
7 0 0
9 0 0
8 5
1 6 5
4 1 8
5 2 5
6 2 2
7 8 2
9 2 8
4 5
9 0
1 8 2
2 7 6
4 6 8
6 7 0 77.5
8 8 2
3 3
6 5
1 3 0
1 9 6 33.7
4 2 3
6 7 0
8 1 6
9 0 0
T , C
111 0
1 0 8 , 2
1 0 5 1
1 0 3 4
1 0 2 3 101.7 101.2
1 0 0 8
1 0 0 , 5
1 0 0 2
1 0 0 0
1 0 9 3
1 0 5 4
1 0 4 2
1 0 2 , 8
1 0 2 3
1 0 2 0
i i i : ~
,
i i 4 : 6
1 1 2 1
1 0 8 4
1 0 7 0
1 0 5 9
1 0 4 , 4
1 0 4 5
S
3 0 0
3 0 0
3 0 0
3 0 0
3 0 0
3 0 0
4 0 0
4 0 0
4 0 0
4 0 0
4 0 0
4 0 0
5 0 0
5 0 0
6 0 0
6 0 0
6 0 0
ii
5 , 0
1 0 0
3 0 0
5 0 0
6 0 0
7 0 0
9 0 0
3 0 0
5 0 0
6 0 0 70.0
8 0 0
9 5 0 70.0
8 0 0
9 0 0
9 5 0
92 5
9 5 0
9 7 0
9 9 0
,
“t %
Y
r _
2 4
10.0
1 5 1
2 6 5
4 2 6
5 3 6
8 4 5
1 2 0
2 1 7
3 5 0
4 4 6
6 1 , 5
7 6 5
2 6 9
3 6 5
6 9 0
4 6 5
5 2 0
59 2
6 7 0
T , C
i i 9 : 0
1 1 6 8
1 1 4 5
1 1 2 8
1 1 1 5
1 1 0 6
1 1 0 3
1 2 5 0
1 2 2 1
1 2 0 0 116.9
1 1 6 3
1 1 7 8
1 2 7 , 5
1 2 4 8 126.2
1 3 5 0
1 3 6 5
1 4 0 0
because of the lack of available data on the boiling points of solu-
tions of calcium chloride in glacial acetic acid
CONCLUSIONS
The results confirm the observation of Quartaroli ( 9 ) that the
addition of calcium chloride tends t o reverse the relative volatility
of acetic acid and water The reversal takes place a t about 8 weight % calcium chloride in the liquid phase and it is possible,
by the addition of moderate quantities of calcium chloride, to obtain a reversed relative volatility which is greater in magnitude than that for the ordinary distillation
In order to explore fully the potentialities of such a separation process, further work on the continuous extractive distillation a>- pect will be required
NOMENCLATURE
S = weight per cent calcium chloride in liquid
T = temperature, C
X = weight per cent water in liquid (salt-free basis)
Y = weight per cent water in vapor
LITERATURE CITED
(1) Davidson, A W., J Am Chem Soc., 50, 1890 (19238)
( 2 ) Hall, 11‘ T., “Textbook of Quantitative Analysis,” pp 150-1,
(3) “International Critical Tables,” Vol 111, p 325, New York,
(4) Jones, C il., Schoenborn, E M., and Colburn, A P., IND Ex
(5) McBain, J W., and Kam, J., J Chem Soc., 115, 1332 (1919)
(6) Menschutkin, B N., 2 anorg Chem., 54, 89 (1907)
(7) Othmer, D F., and Gilmont, R., IND EXG CHEY., 36, 1061 (8) Perry, J H., ed., “Chemical Engineers’ Handbook,” p 1360,
(9) Quartaroli, A., Ann chim applicata, 33, 141 (1943)
New York, John Wiley & Sons, Inc., 1941
McGraw-Hill Book Co., 1928
CHEX, 35, 666 (1943)
(1944)
New York, McGraw-Hill Book Co., 1941
(10) Shrew, R N., “Chemical Process Industries,” pp 682-8, New
York, McGraw-Hill Book Co., 1945
RECEIVED J u l y 27, 1949 Presented before the Oklahoma State Meeting of the American Institute of Chemical Engineers, Stillwater, Okla., November
12, 1949
CARL J MALM, LEO J TANGHE, AND GLENN D SMITH
Eastman Kodak Company, Rochester, !V Y
S a l t effect is a measure of the increase in viscosity of
cellulose acetate caused by the presence of certain salts
A procedure for the measurement of the salt effect has
been developed The influence of salts on viscosity de-
pends on: the nature of the salt; amount of salt; pH of
the solution from which the salt is applied; solvent for the
cellulose acetate in solution; degree of hydrolysis of cellu-
lose acetate; and the amounts of carboxyl and combined
sulfate in the cellulose acetate
HE term “salt effect” is used in this paper to designate the
T ratio of the viscosity of one portion of a cellulose acetate
washed with water containing a certain salt to the viscosity of a
second portion of the same acetate washed with salt-free water
or with water containing a salt known to have no effect on the
viscosity I n general, salts of monovalent cations-e.g., sodium
chloride-are without effect on the viscosity, whereas salts of
polyvalent cations-e.g., calcium chloride-increase the vis-
cosity
This behavior was observed in cellulose acetate by Rogovin
(8) who found a salt effect in acetone but not in formic acid
Lohmann ( 6 ) has studied the salt effect in a variety of solvents
and found that i t was manifested especially in concentrated
solutions in solvents such as ketones and esters which do not
contain hydroxjl groups The salt effect in acetone was reduced
by the addition of water or methanol High viscosity, due either to high solids content or to high molecular weight of the cellulose acetate, increased the effect He observed the salt effect mainly Kith calcium chloride and found that it increased with the amount of salt added An especially significant observa- tion was that the increased viscosity of cellulose acetate due to certain salts did not add to the tensile strength of fibers spun from these solutions
Other findings in this field have been that the salt effect was more pronounced with products made from wood pulp than from cotton linters (4) Also, it increased with the degree of hydrolysis
of the cellulose ester (3) and with the p H of the wash solution
from which the salts are applied ( 7 )
Lohmann’s finding that the increased viscosity due to salts
failed to give a corresponding increase in the yarn strength makes this increase in viscosity undesirable With this background an investigation was undertaken to develop a procedure for measur- ing salt effect and t o establish factors responsible for the effect First, several of the above observations were verified using production batches of yarn-type cellulose acetate containing approximately 39% acetyl Table I gives the effect of various
salts on the viscosity of this type of cellulose acetates The acetates of the alkaline earth elements all gave about the same