INDUSTRIAL AND ENGINEERING CHEMISTRY
1018
VOl. 22, No. 9
Relationship between Alpha-Cellulose Content and Potassium Hydroxide Solubility of Certain Degraded Cellu1osesya H. LeB. Gray, C. J. Staud, and J. T. Fuess EASTMAN KODAKCOMPANY, ROCHESTER, N. Y.
Series of oxidized celluloses and of hydrocelluloses SEARCH of cellulose hydrochloric acid were added have been prepared using acidic potassium permangaliterature, as well as 34.30 grams of cellulose, both nate and hydrochloric acid solutions, respectively. inquiry among the inthe cellulose and the acid beThe alpha-cellulose content and solubility in hot dustrialists, has failed to give ing at 54' * 0.5" C. before 10 per cent potassium hydroxide solutions have been information regarding the rethe addition. The materials determined. lationship between alpha-celwere held a t 54' * 0.5" C. The relationship y2 = 697.2 45x - 0 . 5 2 6 ~has ~ been lulose content and potassium They were then filtered, the found t o hold satisfactorily in both series down to 75 hydroxide solubility of decellulose being allowed to form per cent alpha-cellulose, and the curve expressing this graded celluloses except in its own mat, washed until the very general terms. Because relationship is given. wash waterafter standing in of the increased use of the contact with the hydrocellupotassium hydroxide solubility and alpha-cellulosedetermina- lose for 24 hours at 23-25' C. was neutral to bromothymol tions, it appeared of interest to make a preliminary study. blue, and dried at 50" C. Samples were acid-treated for It is hoped that eventually a conversion of one to the other 1, 2, 4, 6, and 8 hours. may be possible, and the data given below seem to offer Alpha-Cellulose Determinations promise in this direction. Two series of degraded celluloses, which appear representaThe method used for the determination of the alphative of the types of degradation usually encountered, have cellulose content was Tentative Method IV given in a report been prepared. One series was of oxidized cellulose, pro- by Sub-Committee 2 of the Division of Cellulose Chemistry, duced by the action of acidic potassium permanganate; American Chemical Society. The average values from triplicate analyses are given in the other, of hydrocellulose resulting from the action of warm hydrochloric acid solutions. An extension of this Table I and graphically in Figure 1. work will be necessary before the quantitative relationship Table I-Alpha Cellulose between the alpha-cellulose content and potassium hydroxide solubility is established. TIMEOF OXIDIZED CELLULOSE ,HYDROCELLULOSE
A
+
Oxidized Cellulose Experiments
The raw material employed was Eastman filtration cotton, a long fiber cotton, purified by mild treatment. I t has the following analytical constants: DETERMINATION Alpha-cellulose KOH solubility Copper number Cuprammonium viscosity Moisture Ash
CONSTANT
98.7% 3.81% 0.064% 5522 c 4.05% 0.072%
METHOD A. C. S. Tentative Modification of Griffin (8) Staud and Gray (4! A. C. S. Proposed (1) Drying 16 hours at 105' C. Direct ignition
The concentration of the oxidant was so chosen that there unit of would be 0.5 mol of available oxygen per C~HIOOS cellulose. I n each case 6.4 grams of potassium permanganate (c. P.) were added to 1200 cc. of 1 N (grams per liter) phosphoric acid solution. This was allowed to stand overnight in 9 stoppered flask and filtered through asbestos. There were then added 34.30 grams (32.40 grams or 0.2 mol of oven-dry material as C6HloOs)of cellulose. The materials were held at 23' * 0.5' C. for varying periods of time, filtered, the cellulose being allowed to form its own mat, and washed with water. The manganese dioxide formed was removed with dilute sodium bisulfite solution acidified with hydrochloric acid. The product was then washed with water until neutral to bromo-thymol blue, and dried at 50' C. Samples were oxidized for l/2, 1, 2, 4, 6, and 8 hours. Hydrocellulose Experiments
The same type of cellulose was used as in the oxidized cellulose experiments. To 1200 cc. of 3 N (grams per liter) 1 Received June 21, 1930. Presented before the Division of Cellulose Chemistry at the 79th Meeting of the American Chemical Society, Atlanta, Ga., April 7 to 11, 1930. 1 Communication N o 429 from the Kodak Research Laboratory.
TREAT-
1
I
I Hours 0 1/2
1 2 4 6 8
I
%
98.70 96.40 94.20 87.80 74.00 52.05 55.20
I1
I11
%
%
98.70 96 50 94:30 87.40 74.90 52.10 54.70
Av. %
I %
98.70 98.70 96.45 94:40 94.30 87.60 74:30 74.40 52.10 52.10 54.90 55.00
%
98.70 93.60 92.60 92.00 72.70 60.70
...
I11
Av.
98.70 93.40 93.40 91.65 73.55
98.70 93 50 93:lO 91.70 73.07 61.00
I1 %
98.70 93.50 93.40 91.35 72.95 61.30
...
%
... ...
...
Potassium Hydroxide Solubility Determinations
Since there appears to be no generally accepted method for the determination of the solubility of cellulose in hot caustic solutions, it was decided to use Griffin's method for the determination of oxycellulose (2) with modifications, which led to greater ease of manipulation without loss of accuracy. The method is as follows: A sample of approximately 2 grams is placed in a tared weighing bottle, accurately weighed, dried a t 102-105" C. for 15 hours, and again accurately weighed. The moisture content is calculated. The sample is transferred to a test tube (21.6 by 3.8 cm.), the weighing bottle again weighed, and the sample weight obtained by difference. To the sample are added 100 cc. of caustic solution containing 10 * 0.1 per cent by weight of potassium hydroxide. This should contain less than 0.5 p'er cent potassium carbonate. The tube is closed with a rubber stopper which has been boiled in 10 per cent potassium hydroxide and which carries a glass air condenser (50 cm. by 7 mm. tubing). The tube is then placed in a bath of boiling water in such a manner that it is immersed to a t least 1 inch (2.5 cm.) above the level of the sample. Digestion is carried on for 3 hours a t 99-100" C. At the end of this time the tube is removed and the contents poured into 1 liter of distilled water contained in a 2-liter beaker. The fibrous material is completely removed from the tube by first rinsing with the clear supernatant liquid after dilution and finally
INDUSTRIAL AND ENGINEERING CHEMISTRY
September, 1930
1019
Calculations 1
-50 h,
3
-402
L-,
-30:
6
The curve representing the correlation given above was found to follow closely from 100 to 75 per cent alpha-cellulose content the curvature of an ellipse as shown in Figure 3. I n this figure are plotted the average values for the two abscissas corresponding to each alpha-cellulose value, as given in Figure 2. Other curves were tried, but they did not agree so well in the lower values as the one given.
3
-
--I
20; 50
4
k
I
1
'O
Q
-
h
d
Q
I
I
b
T I M E (IN HOURS)
Figure 1-Effect
of T i m e of Treatment o n Alpha-Cellulose and KOH Solubility Content
with 25 cc. of distilled water. The alkaline solution is neutralized with glacial acetic acid, using alcoholic phenolphthalein as indicator, and a 5-cc. excess of glacial acetic acid (98 per cent or higher) added. The contents of the beaker are filtered with suction through a tared Jena glass filter crucible with a sintered glass bottom of medium porosity. The sample is thoroughly washed with a t least 750 cc. of hot distilled water, using moderate suction, and finally sucked as dry as possible. It is placed in its weighing bottle and dried a t 102-105" C. to constant weight. The difference in weight between the dry original sample and the dry digested sample is taken as the caustic-soluble content. Since determinations are made on dry samples, the moisture content is not taken into account.
The average results of duplicate analyses are given in Table I1 and graphically in Figure 1. Table 11-KOH
SAubility
OXIDIZEDCELLULOSE T I M E O F TRE.4TMEXT
I
I1
%>
%
3.786 11.41 15.66 23 66 33.13 44.34 42.41
3.845 11.54 15.62 23.52 32.33 43.83 41.65
Hours
Av.
% I %
3.81 11.48 15.64 23.54 32.73 44.09 41.98
I1
Av.
'A
%
3.786 3 845 3.81 1 7 . 1 5 17 65 17.40 1 7 . 9 0 18 15 18.03 2 0 . 1 3 19 89 20.01 36.10 37 65 36.90 44.75 45.95 45.35 45 125 45 05 45.09
I
40
50
I
7Q
60
60
$0
IO0
PER CENT ACPHA CELLULOSE Figure 3-Comparison of Calculated Curve with Average Observed Values
The equation representing the ellipse as shown in Figure
3 is y2
=
697.2
+ 4 5 -~ 0 . 5 2 6 ~ ~
where y is equal to the potassium hydroxide solubility and x represents the alpha-cellulose content. This equation is valid only when the alpha-cellulose content is 75 per cent or greater, as can be seen in the figure. The close agreement between the values calculated from the equation and the observed values is indicated in Table 111. Table 111-Relation
between Calculated and Observed Values K O H SOLUBILITY
a-CELLULOSE
CONTENT( x ) %
1
Calculated ( v )
Observed
Difference
%
%
%
OXIDIZED CELLULOSE
Correlation of Alpha-Cellulose w i t h P o t a s s i u m Hydroxide Solubility
The relationship between the alpha-cellulose content and the solubility in hot 10 per cent potassium hydroxide solution is given for the oxidized cellulose and for the hydrocellulose in Figure 2. It will be observed that when the --I
I
98.70 96.45 94.30 87.60 74.40
3.81 12.05 16,22 24.54 33.68
3.81 11.48 15.64 23.54 32.73 Average difference
3.81 17.50 17.90 20.02 34.30
3.81 0.0 17.40 0.1 18.03 0.13 20.01 0.01 36.90 -2.6 Average difference 0 , 5 7
0.0
0.47 0.5s 1.00
0.95 0.60
HYDROCELLULOSE
98.70 93.50 93.10 91.70 73.07
Discussion
I 40
SO
60
70
80
so
I
IW
PER CENT ALPHA CELLULOSE Figure 2-Relation between Alpha-Cellulose Content and KOH Solubility
alpha-cellulose is 7 5 per cent or greater the curve for the hydrocellulose superimposes upon the curve for oxidized cellulose, while below 75 per cent alpha-cellulose the curves diverge rapidly.
It will be observed from Figure 1 that in all cases where values could be obtained, the alpha-cellulose and KOH solubility us. time curves show a tendency to reversion between the 6- and %hour values. This inflection may be ascribed to the effect of continued action of acid or oxidizing agent on the cellulose, resulting in the solution of a part of the material which in previous samples had not dissolved but had appeared in the alkali-soluble portion. This hypothesis gains credence from data given by Murray, Staud, and Gray ( 3 ) , which show that during similar treatment cellulose dissolves in the solutions of acid and of potassium permanganate to a rapidly increasing amount with increased severity of treatment. Since the object of this investigation was to study the
INDUSTRIAL AhTD ENGINEERING CHEMISTRY
1020
relationship between alpha-cellulose content and solubility in hot 10 per cent potassium hydroxide, no attempt was made to duplicate the time curves for the oxidized cellulose and hydrocellulose series. From the final results as given in Figures 2 and 3 the irregularities in the time curves do not appear to affect the relationship under investigation. The samples were evidently uniform throughout, as indicated by the agreement in analysis and also by the fact that the irregularities of the alphacellulose and potassium hydroxide solubility curves are such that these curves approximate mirror images. I n Table I alpha-cellulose content for the sample which had been acid-treated for 8 hours was omitted because such treatment resulted in a product of such short fiber length that filtration was precluded. The coincidence of the relationship between alpha-cellulose content and solubility in hot 10 per cent potassium hydroxide solution to a point where the alpha-cellulose content was but 75 per cent in materials degraded by such widely different methods was an unexpected result. Since the preponderance of cellulose materials for technical use contain in excess of 75 per cent alpha-cellulose, the results give
Vol. 22, KO.9
promise of wide application if combinations of oxidation and hydrocellulose formation are found to give concordant results. The divergence of these curves for more degraded materials may be due in part to the increasing difficulty in manipulation. This is especially true for alpha-cellulose determinations. Although the alpha-cellulose content when the potassium hydroxide solubility is known may be calculated from the equation, in practice, it is probably preferable to read the values directly from the curve. Acknowledgment
The authors wish to express their gratitude to R. E. Burroughs, of the Physics Department, Research Laboratory, Eastman Kodak Company, for the derivation of the equation represented by the curve shown in Figure 3. Literature Cited (1) American Chemical Society, Cellulose Division, Standard Method, IND.ENG.CHEM., Anal. Ed., 1, 49 (1929). (2) Griffin, “Technical Methods of Analysis,” 2nd ed., p. 492. (3) Murray, Staud, and Gray, J. Am. Chern. SOC.,82, 1508 (1930). (4) Staud and Gray, IND.END.CHEM.,17, 741 (1925).
Purification of Water b y Electroosmosis’ Edward Bartow and R. H. Jebens STATEUNIVERSITY OF IOWA, IOWA CITY,IOWA
HE purification of water by the removal of salts from a central section of a cell through diaphragms t o cells containing anode and cathode poles has been developed in Germany. By passing the water from the central compartment of a series of cells, the water in this compartment becomes gradually purer until the anions and cations are practically all removed. The water so purified, it is claimed (2, S), is equivalent to distilled water and can be obtained at a much lower cost.
T
Apparatus
I n order to check these claims and to test the applicability of the apparatus to local water, an apparatus was obtained from Germany.2 This apparatus (1) consists of ten cells placed side by side. The purified water passes by siphons through the central compartment of each cell. The anode and cathode water are removed by wash water, which is fed from dripping nozzles and escapes from overflow pipes in the anode and cathode cells, respectively. Cells 9 and 10 are washed with purified water. The efficiency of the apparatus depends on the amount of current used, the amount and quality of purified water, and the amount of flow of the wash water. The quality of the water was judged by determining the electrical resistance, alkalinity, chloride, residue, and ash. The resistance was determined by usual methods. The apparatus used gave a value of 176,000 ohms for the distilled water used in the laboratory. The temperature of the water tested was within 0.5 degree of 25” C. for all readings obtained. Other tests were made in accordance with methods given in standard methods of water analysis. The apparatus is supplied with 110-volt generator current with a maximum capacity of 30 amperes. The current is passed through the cells with connections so arranged that the 1 2
Received May 19, 1930. Manufactured by the Electro-Osmose, -4. G.
potential increases as the water becomes purer. When cells 1,2,3,4 are in series, 5,6,7 in series, 8,9 in series, and the last cell is across the bus bar, we have what is called the 4,3,2,1 system of connection. The average voltage across the first four cells is 27.5; across the next three, 37; the next two, 55; and across the last cell, 110 volts. As the resistance of each cell increases from cell to cell, the voltage across the first cell is considerably lower than that of the fourth cell. Standard Conditions
The process was started by filling the cells in each chamber uniformly with water. Wash water was regulated to run a t 24 liters per hour; that is, 12 liters were used to wash the anodes and 12 to wash the cathodes. The current was turned on and when it began to drop, feed water was added a t 24 liters per hour. The above rates of make-up water and wash water were called standard conditions and variations in flow were compared with this standard. Tests
Test I-Variation of Wash Water. The wash water was varied from 12 liters to 200 liters per hour. From 12 to 49 liters per hour no difference was noted; with 200 liters the resistance was lowered. Test 2-The Effect of Changing Rates of Feed Water. Zeolitesoftened water was used and the rates were 15, 20, and 50 liters per hour. With 50 liters per hour there was an increase in amperage required, an increase in the alkalinity and residue, and a decrease in resistance. This shows the necessity for limiting the rate of flow of feed water. Test 3-Varying Method of Connecting Cells to Bus Bars. The best water was given by system 3,2,2,1,1,1, but it required more current. The poorest was system 5,3,2. This required fewer amperes but the water contained chloride, was alkaline, had low resistance, and high residue and ash. We would conclude that the fewer number of cells connected
