INDUSTRIAL AND ENGINEERING C H E i I S T R Y
952
Vol. 22, s o . 9
Effect of Fine Division on the Solubility of Cellulose'" D. F. J. Lynch COLORAKD FARMWASTE DIVISIOX,BUREAUOF CHEMISTRY
I
r\' THE extraction of cellulose from farm wastes and in
the subsequent purification of this raw cellulose for the production of high alpha-cellulose, considerable variance was observed in the quantity of the sample found to be soluble in the hot dilute alkali-soluble test used by nitrators of cellulose and in the cold concentrated alkali test used in the alpha determination. Some variance in the solubility of most commercial celluloses in hot dilute and in cold concentrated alkali has been found by analysts. Raimondo (d), in his investigation on the solubility of different celluloses in hot dilute and in cold concentrated alkali, used unbleached and bleached wood pulp as well as esparto, straw, and hemp stalk pulp. Raimondo found that, with the exception of poplar wood pulp, more of the commercial wood-pulp samples were soluble in hot dilute sodium hydroxide than in the cold concentrated alkaline solution. The reported difference averaged from 1.7 to 3.8 per cent. Poplar wood showed nearly the same solubility in both solutions. With esparto, straw, and hemp stalk pulps the solubilities were reversed, and from 2.8 to 4.3 per cent more of these samples were dissolved in the cold solution than in the hot dilute hydroxide. Since the results obtained in this division by the general commercial hot-alkali-soluble test and the cold alpha-cellulose determination showed even greater variance with other celluloses, and since there seemed to have been no comparison on the solubility of high alphacelluloses, the following comparative investigation was undertaken.
A S D SOILS,
cent) sodium hydroxide solution were poured into the flask; the flask was provided with a reflux condenser and heated for 3 hours a t 100" C. This sodium hydroxide solution was made up from the same source and the strength determined in the same manner as were the alkali solutions used in the alpha determinations. At the end of 3 hours' heating the solution and fiber were poured into a liter of distilled water. Sufficient acetic acid was added to the solution to give a decided acid reaction with litmus paper. The undissolved cellulose was collected in a weighed Jena glass crucible. The pulp was washed thoroughly with cold water, hot water, alcohol, and ether. The pulp residue was dried to a constant weight at 102-105O C. I n both determinations each tared crucible containing the cellulose residue, upon removal from the drying oven, was placed in a weighing bottle and the weighing bottle closed before being placed in the desiccator, because otherwise oven-dried cellulose absorbs moisture from the atmosphere so rapidly that it makes exact weighing impossible. I n Table I are shown the great variances in the solubility of peanut-hull cellulose in hot dilute alkali and in cold concentrated alkali. The determinations on wood pulp were included to emphasize by comparison these great variances, and those run on cottonseed hull pulp show that such large variances are not peculiar to peanut-hull pulp. Table I-Differences in Solubility of Peanut-Hull and Other Pulps in Cold 17.5 Per Cent a n d in H o t 7.14 Per Cent Sodium Hydroxide - -..- ._ .. .
1 Received April 23, 1930. Presented before the Division of Cellulose Chemistry at the 77th Meeting of the American Chemical Society. Columbus, Ohio, April 29 to M a y 3, 1929. 2 179th Contribuaon from the Color and Farm Waste Division, Bureau of Chemistry and Soils.
SOLUSOLU17.5% BILITY IN BILITY IN NaOH COLD HOT J~-CELLU- 1 7 . 5 % 7 . 1 4 % LOSS) NaOH NaOH Per cenl Per cent Per cent INCOLD
Tests
Of the various reported procedures for the alpha-cellulose determination, it was decided, after trial, to use the one followed by Schorger (3). Samples of pulps for the alphacellulose determinations were air-dried to a 4.5 to 6 per cent moisture content. Both the 17.5 and the 8 per cent alkaline solutions, mentioned in the procedure, were made from the clear supernatant liquid, after allowing the 50 per cent sodium hydroxide to stand for at least one week to permit the settling out of sodium carbonate and other impurities. The strength of these solutions was determined by titrating weighed samples of each, and all the solutions selected for use agreed with the specifications within *0.1 per cent. It was found more convenient to substitute a tared Jena glass crucible for the tared alundum crucible recommended by Schorger. I n all other details his procedure was followed. The procedure for the alkali-soluble determination, the determination generally used by cellulose nitrators, was as follows: The sample was dried in an oven a t 100-103° C. Approximately 2 grams of the dried cellulose were transferred into a 250-cc. Erlenmeyer flask. A sample of about the desired amount was removed from a tared weighing bottle containing a known amount of dry cellulose, and the exact weight of the sample determined by loss in weight. One hundred cubic centimeters of 7.14 per cent (b0.1 per
WASHINGTON, D C .
PULP
Peanut-hull pulp (F-6) 93.5 93.1 Peanut-hull pulp (F-7)a 96.7 Peanut-hull pulp No. 14 95.7 Peanut-hull pulp (J-4)a 97.2 Peanut-hull pulp (5-3)" 90.8 Peanut-hull pulp No. 1 5 O 95.5 Peanut-hull pulp No. 20" 96.2 Cottonseed-hull pulp 92.8 Cottonseed-bran pulp 84.7 Filter paper 92.7 Pine pulp No. 6 b 89.7 Poplar pulp No. 5 b a These samples were composed of very fine b High alpha.
6.5 6.9 3.3 4.3 2.8 9.2 4.5 3.8 7.2 15.3 7.3 10.3 fibers.
12.8 17.5 8.4 12.1 10.0 18.1 16.5 7.3 12.5 13.7 9.6 11.5
DIPPERENCE I N
SOLUBILITY
Per cenl 6.3 10.6 5.1 7.8 7.2 8.9 12.0 3.5 5.3 -1.6 2.3 1.2
The samples of peanut-hull pulp described as very fine pulp were prepared from ground peanut hulls. The fact that these samples showed a greater solubility in hot dilute alkali and the fact that Jonas (1) found that the copper number of a sample of cellulose was affected by the very fine division of the sample tested led to the following determinations to ascertain whether or not the state of division of the cellulose sample affected the results obtained in the alkali-soluble tests. Some samples of long fiber cotton and cotton linters were cut up with shears before testing. Other samples, designated in Table I1 as ground, were run through a Wiley laboratory mill (4) and passed through a 50-mesh sieve. This grinding operation was carried out with air-dry cellulose and attended with no observable rise in temperature. From the results obtained in the determinations listed
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
September, 1930
953
of Fine Division on Solubility of Cellulose i n Cold 17.5 Per Cent a n d in Hot 7.14 Per Cent Sodium Hydroxide INSOLUBILITY I N COLD SOLUBILITY SOLUBILITY 17.5% NaOH I N HOT DIFFERENCE IN COLD PULP No. ~ ~ E L L U L O S E ) 17.5% NaOH 7.14% NaOH IN SOLUBILITY REMARKS Per cer't Per cent Per cent Per cent Bleached poplar pulp No. 5 I 78.2 21.8 21.7 0.1 Table 11-Effect
High alpha poplar pulp No. 5 High alpha poplar pulp No. 5, ground Bleached pine pulp No. 6 High alpha pine pulp No. 6 High alpha pine pulp No. 6, ground Cotton Cotton, cut with shears Cotton, ground in mill
Linters Linters, cut with shears Linters, ground in mill Viscose commercial wood pulp Viscose wood pulp, ground in mill Peanut-hull pulp (J-2) Peanut pulp (J-2), ground
I1 I11 IV V
VI VI1 VI11 IX X XI XI1
89.7 89.0 83.5
92.7
XI11 XIV
92.2 98.5 98.4 97.9 99.4 99.3 99.1 86.3 86.2
XVI
98.3
xv
98.3
10.3
11.5
13.3 17.3
11.0 16.5 7.3 7.8 1.5
9.6 11.6 1.8 2.1 4.7 2.3 2.4 3.5 20.3
1.6 2.1 0.6
0.7 0.9
13.7
in Table 11, the state of division of the cellulose sample affects the solubility of cellulose in hot dilute F,odium hydroxide, if the state of subdivision is very fine. The cutting of long fiber cellulose into short lengths with ordinary shears seems to have little effect on the solubility of the cellulose sample in hot dilute alkali. Even the very fine cutting of the fibers in a grinding mill seems to have little, if any, effect on the solubility of the sample in cold concentrated alkali (alpha test). 'The solubility of the cellulose sample,
From same source as I I1 ground in mill
2.3 3.8 0.3 0.5 2.6
From same source as I V V ground in mill
1.7 1.7 2.6 *
6.6 13.0 5.4 6.4
26.8 7.1 8.1
13.8 1.7 1.7
1.2
2.3 0.8
VI1 cut with shears VI1 ground in mill Commercial linters for nitration X cut up with shears X ground in mill
XI11 ground in mill X V ground in mill
however, in hot dilute alkali (nitrator's alkali-soluble d e termination) is materially increased by a very fine state of division of the cellulose. Literature Cited (1) jonas, Z . angew. Chem., 41, 960 (1928). (2) Raimondo, N o f i s . chim. i n d . , 2 , 247 (1927). (3) Schorger, "Chemistry of Cellulose and Wood," p . 539 (1926). (4) Wiley, IND.END.CHEM.,17, 304 (1925).
Cracking of Hydrocarbons at Temperatures Higher than Critical Temperatures' Ralph H. McKee and Antoni Szayna DEPARTMENT OF CHEXICAL ENGINEERING, COLUMBIA
YORK,N. Y
A new method of studying the cracking of hydroHIS paper is B report Under these conditions carbons by following the changes in critical temperaof an investigation of cuts of different gasolines tures is described. The amounts of materials used boiling within the range of the changes in critical are of the order of 0.05 cc. per run. temperature which low-boil120"to 126' C. (248" to 259' Ordinary gasolines crack at one rate, saturated ing hydrocarbons undergo F.), together with a number hydrocarbons somewhat more rapidly, and unsatuwhen subject to cracking at of pure hydrocarbons, esperated hydrocarbons still more rapidly. temperatures higher than the cially isomeric hydrocarbons, The results obtained are in disagreement with a critical temperature. Crackh a v e been s t u d i e d . F o r common theory of knocking and with some common ing lowers t h e average comparison t o l u e n e has beliefs of the mechanism of cracking. b o i l i n g Doint. and hence been used as representing a proportToia1ly t h e c r i t i c a1 t y p i c a l aromatic hydrocartemperature (6). For example, in a Cross process run the bon. The materials used were: charging stock showed a critical temperature of 435" C. MATERIAL BOIGIND Poxm (815" F.), whereas the crude product therefrom showed a SAMPLE c. F. critical temperature, even after allowing the gases produced 1 %Octane. CRHIS 125 257 2 Octylene,' c~H;; 1 2 2 . 5 252.5 by cracking to escape, of 395" C. (743" F.) (5). 3 2,2,4-Trimethylenepentane,CsHls 99.3 211 The conditions used by the writers are rrtther closely 4 2,2,3-Trimethylbutane, C I H I ~ 80 9 177.6 5 3-Methylhexane, C7Hla 91.8 197.2 parallel to those present when modern cracking methods6 n-Heotane, C7Hm 98.4 209 7 Commercial toluene containing some benzene for example, Cross, Holmes-Manley, tube and tank, and 8 Midcontinent straight-run gasoline 120-126 248-259 Bergius-are applied commercially. The results obtained 9 Shale-oil gasoline 120-126 248-259 10 Gyro vapor-phase cracked gasoline 120-126 248-259 also have interest in that they apply directly to certain 11 High-sulfur straight-run gasoline from Warm Springs field, Wyo. 120-126 248-259 theories of the cause of knocking when gasoline is used in 12 High-sulfur straight-run gasoline from the automobile motor. For example, it has been stated (9) Poison Spider field, Wyo. 120-126 248-259 that the knocking characteristic of different hydrocarbons "diminishes with the thermal stability" and that "knocking For samples 1, 3, 4, 5, 8, and 10 we wish to thank the Ethyl is due to the thermal decomposition of the large fuel mole- Gasoline Corporation (John C. Pope). For samples 11 and cules into a number of smaller molecules with corresponding 12 we are indebted to the White Eagle Oil and Refining increase of local pressure." The results obtained by the Company (R. C. French). Kormal octylene was made present writers are not in harmony with such a theory of the from castor oil by the method previously worked out by one cause of knocking. of the writers ( 3 ) . The shale gasoline was one made in 1925 in this laboratory, and had stood on the laboratory Experimental shelves exposed to light in a half-filled bottle but was still This investigation is primarily concerned with cracking at (1930) free from color or gum separation. The toluene temperatures in the range of 405" to 420" C. (761 to 788" F.). sample was from the laboratory supply. The cracking and determination of critical pressures were Received May 5, 1930.
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