THE COOKING PROCESS IX. PULPING WOOD WITH ALCOHOLS AND OTHER ORGANIC REAGENTS S. I. ARONOVSKY AND ROSS AIKEN GORTNER Minnesota Agricultural Experiment Station, St. Paul, Minn.
@A
LIPHATIC monohydroxy and polyhyfitted with a thermometer well and a constant-pressure regudroxy alcohols have been used in recent lator, and heated with gas. years in the isolation of lignin, especially The following pulping procedure, with the noted exceptions, in those cases where i t was desired to study the composition, was used: structure, and properties of this substance. Phillips (10) One hundred grams of air-dry aspen sawdust (89.9 grams ovencites a large number of references on this subject. Hagglund dry) were placed in the autoclave, and a total volume of 1500 cc. and Urban (6) used ethyl, isobutyl, and amyl alcohols with of the reagents was added. I n the case of liquid reagents, equal hydrochloric acid; Hibbert and Rowley ( 7 ) used glycol and volumes of the reagent and distilled water were employed; the either iodine or hydrochloric acid as a catalyst; and Rassow solid cooking reagents were used with 1500 cc. distilled water. The autoclave cover was bolted on, and the heating started by and Gabriel (11) used ethylene glycol and glycerol. The means of a ring burner placed at the bottom of the autoclave solvents were used without the addition of water and the raand connected with the pressure regulator. The digesting prestios of solvent t o wood were generally about 20 to 1. Analysure was about 10 atmospheres, or 10 kg. per sq. cm. (150 pounds sis of t h e isolated lignins indicated that some of the solvents per square inch). The time necessary to reach this cooking pressure was about 1 to 1.5 hours. The digestion was held at this had combined with the lignin in the form of alkoxy1 groups. pressure for 4 hours (except in cook 112), after which the presKleinert and Tayenthal (8) cooked wood above E O o C. sure was slowly reduced to atmospheric by releasing the vapors, with aqueous ethyl alcohol solutions and obtained good yields through a valve, into the air (20 to 30 minutes). The cover of of cellulose of low lignin content. They used hydrochloric the autoclave was then removed, and the contents were poured into a canvas bag, using distilled water to remove any of the acid as a catalyst. Engel and Wedekind (5) treated wood fibers adhering to the autoclave walls. The bag was then pressed with dioxane and hydrochloric acid at temperatures near the with the hands to remove as much of the liquor as possible. The boiling point of nTater and obtained a pulped residue. liquor was poured into a bottle. The residual wood was washed The experiments described in this paper were undertaken with water until the washings were colorless, pressing the bag contents between each addition of water. The washed residues t o compare the effects of these various reagents and to deterwere dried, weighed, and prepared for analysis by grinding in a mine whether, by these procedures, it would be possible t o Wiley mill to pass through a 40-mesh sieve. produce pulp which could compete with the present comThe aspen chips were cooked in the steel, steam-heated rotating mercial chemical wood pulps. digester previously described (2). This cook was made a t 186"C . A series of cooks was run on aspen sawdust with water, aqueous solutions or mixtures of alcohols, and other organic reagents in order t o TABLEI. YIELDSOF RESIDUALWOODSBEFORE AND AFTER EXTRACTION WITH BENZENE-ALCOHOL determine the pulping effects of the individual Residual Wood reagents in regard to the yields and qualities of Yields the pulp and by-products obtained. The followCooking Cook Unex- ExColor and Pliability of ing reagents were used as the cooking agents: XO. Cooking Agent Temp. Time tracted tracted Residual Wood water, methyl alcohol, ethyl alcohol, n- and C. Hr. % % 99 w a t e r 186 isopropyl alcohols , n-, iso-, and tert-butyl alco106 Water-methyl alcohol 158 hols, n-, iso-, and tert-amyl alcohols, dioxane, 112 Water-ethyl alcohol 165 172 117 Water-n-propyl alcohol ethylene glycol, glycerol, d-glucose, d-mannitol, 115 Water-isopropyl alcohol 162 Light brown, semi-pulped 109 Water-n-butyl alcohol 174 and urea. &Glucose was included in this group Light brown, soft 174 110 Water-isobutyl alcohol to determine whether i t would act as a polyhyReddish brown, soft 157 118 Water-terl-butyl alcohol Brown, semi-pulped Water-n-amyl alcohol 113 177 droxy alcohol. Some of the n-butyl alcohol pulp Light brown soft 114 Water-isoamyl alcohol 177 Reddish bro4.n. soft 159 119 Water-tert-amyl alcohol was recooked with this reagent to determine Brown, pliant 116 Water-dioxane 176 whether the first cooking had removed all of 122 Water-n-butyl alcohol (recook of n-butyl alcothe extractive substances from the wood. One Light gray, pulped hol pul ) 176 4-4 5 0 . 4 5 0 . 4 123 Water-n-gutyl alcohol cook in this series was also made on aspen chips Light gray, pulped (aspen chips) 186 4 5 0 . 1 50.1 using n-butyl alcohol as the pulping agent. Sot 103 Water-ethylene glycol
--
--O
Experimental Procedure The sawdust used was from the batch described previously (2), which had been placed in large tins sealed with paraffin. The reagents used were all c. P. or U. S. P. grade. The digester was a small bronze autoclave, about 2 liters in capacity, Previous papers in this series appeared in INDUSTRIAL AND ENGINEERING CHEMISTRY in 1930. 1933, 1934, and 1935. 1
102
recorded sot
Water-glycerol
rPPndLcI
108 Water-400/, d-glucose 107 Water-40 d-mannitol urea 104 Water-& Water-n-butyl alcohol ZOyo urea 128 Water-n-butyl alcohol 10% urea 130 Water-n-butyl alcohol 5 % urea 127
1270
+ +
+
182 182 sot recorded
53.2
Brown, semi-pulped
4
62.2
4 4 4
64.3 54.9 77.6 67.9 69.6 58.1
Light brown, semi-pulped Brown, Dark brown, s o f t pliant
4
82.1 78.6
Dark brown, pliant
175
4
74.4 74.3
Brown, pliant
175
4
68.5 68.1
Light brown, soft
176
4
67.2
Light brown, soft
66.2
NOVEMBER, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
(final pressure about 13 kg. per sq. cm.) and cooked at that temperature for 4 hours, using 200 grams of air-dry aspen chips and 3 liters of cooking liquor, composed of 1.5 liters of n-butyl alcohol and 1.5 liters of water. The digester contents were then poured into a canvas bag, pressed, washed n-ith a small volume of butyl alcohol and then with water. On screening this pulp, no screenings were found. The cooking and analytical data are given in Tables I t o I11 and sh0N-n graphically in Figures 1 and 2. T h e analytical results are t'he mean of two or inore determinations.
Residual Liquors
1271
ing liquors having little or no hydrolytic effects on the wood constituents. Ethylene glycol was the best pulping agent of all the polyhydroxy alcohols used in these experiments, giving the lowest yield of residual wood. The poorest polyhydroxy cooking agent in this series was d-glucose. Dioxane was similar to water in respect to the yield of residual wood obtained.
Benzene-Alcohol Extractives of Residual Woods T h e data in Table I1 show t h a t t h e quantities of benzene-
alcohol (2-1) extractives decreased with the increased degree of pulping, when the pulping agents consisted of only alcoholwater mixtures. T h e residual woods with the lowest benzenealcohol extractives TTere those obtained with n-butyl alcohol (cooks 109, 122, and 123). The values obtained for the residual woods of the ethyl, isopropyl, tert-butyl, and tert-amyl alcohols were similar. The use of urea resulted in residual woods n i t h relatively small amounts of benzene-alcohol extractives. The ammonia formed by the hydrolysis of the urea, or perhaps the urea itself, may have combined with the lignin depolymerization products (soluble in benzene-alcohol) to form products insoluble in this solvent. Previous reports (3) showed that, when alkaline pulping agents such as the carbonate, sulfite, sulfide. or hydroxide of sodium were used, the quantities of benzene-alcohol extractives obtained were small Aspen sawdust was cooked with aqueas compared with those obous solutions of aliphatic monohydroxy tained from essentially acid and polyhydroxy alcohols and of glucose, pulping agents. It is theremannitol, dioxane, and urea. The norfore apparent that the addimal primary alcohols were better pulping tion of small amounts of urea to the alcohol-water mixtures agents than the secondary or tertiary will reduce t h e b e n z e n e alcohols. Normal butyl and amyl alcoa l c o h o l extractives of the hols yielded better pulped residues than residual woods. were obtained with the other alcohols. The benzene-alcohol exThere appeared to be a definite relation t r a c t i v e s of the residual woods obtained by cooking between the aqueous solubilities of the aspen sawdust with the polymonohydroxy alcohols and their pulping hydroxy alcohols were fairly properties. The pulping efficiencies of large in amount. Since diluthe alcohols also seemed to be related tion of the residual liquors to the zeta potentials at the cellulosewith water caused a flocculent precipitate to be formed, alcohol interfaces. Aspen chips cooked i t is probable t h a t a portion with normal butyl alcohol yielded a pulp of these extractives remained which was comparable to the usual comin the residual woods in the mercial aspen soda pulp in strength form of residual liquors at t h e characteristics. Coniferous woods were time of emptying the autoclave and were precipitated not pulped by butyl alcohol as readily as on the pulp when water was the aspen. The residual liquors of the a d d e d t o the latter. Less cooks made with normal butyl and amyl benzene-alcohol e x t r a c t i v e alcohols consisted of two layers; the top material was found in the alcoholic layer contained the organic dioxane residual wood than in t h a t obtained by cooking substances extracted from the wood, with water only. and the lower aqueous layer contained
T h e residual liquors from till of these cooks, except those in which urea was used (cooks 104, 127, 128, and 130), were acid t o litmus. T h e water-soluble alcohols and other reagents gave light tan t o very dark, reddish brown, turbid residual liquors. The water-insoluble alcohols-namely, nand isobutyl, and n-, iso-, and tert-amyl-resulted in residual liquors which separated upon cooling into two layers; the top black alcoholic layer contained most of the material extracted from the wood, and the slightly colored lower aqueous layer contained only small quantities of water-soluble substances, acids, sugars, etc. This property of butyl and amyl alcohols formed the basis of a patent (1) granted on the use of these alcohols in digesting ligneous cellulosic materials.
Residual Woods T h e mixtures of n-butyl, n-amyl, and isoamyl alcohol with water gave semi-pulped residues and the lowest yields. '4myl alcohol yielded a lower quantity of residual wood than the corresponding butyl alcohol. T h e residual wood yields decreased with increasing molecular weights of the normal alcohols used. For alcohols of the same molecular weights, the residual wood y i e l d s increased with decreasing length of straight hydrocarbon chain. Cooking aspen s a TI d u s t with a n aqueous solution of urea gave a high yield of residual wood, probably because of the alkalinity of the digestion liquor. The addition of urea t o t h e b u t y l alcohol-water mixtures also caused increased yields of residual woods, the increases being greater with the larger quantities of urea used. It was noticed, during the reduction of pressure in t h e autoclave, that ammonia was given off from cooks 104,127, and 128 (no ammonia was d e t e c t e d i n t h e ' c a s e of cook 130). Cnder the conditions obtaining in these cooks, the urea was probably hydrolyzed to ammonia, thus neutralizing the formic and acetic acids normally formed in the cooking process (4). A slight excess of ammonia resulted in a l k a l i n e cook-
only small quantities of water-soluble substances. This pulping procedure provides a means of obtaining the ligneous material of the wood uncontaminated by inorganic compounds not present in the original wood. Some of the properties of the extracted ligneous material are given.
Lignin in Residual Woods The n-butyl alcohol-water mixtures were the most efficient of the organic reagents in removing lignin from wood by cooking. The pulps from cooks 122 and 123 contained 3.1 and 2.7 per cent lignin,
TABLE11. YIELDSOF RESIDUALWOODAND ITSMAIN COMPONENTS"
Cook No.
VOL.28,NO. 11
INDUSTRIAL AND ENGINEERING CHEMISTRY
1272
Cooking Bgent
Clz ConI n Benzene-Alcohol-Extracted sumption Residual Woods Benzene- in C . & C - -h Residual Alcohol B.b CelluC. & B.b Wood Exlose L/gcellu- a-Cellu- PentoYields tractives Detn. nin lose lose sans
%
%
%
%
63.4 9.5 13.5 Water 22.3 70.2 5.2 14.7 Methyl alcohol 9.8 62.5 8.9 E t h y l alcohol 13.8 7.7 4.8 n-Propyl alcohol 12.3 5.5 60.0 7.8 Isopropyl alcohol 16.3 8.9 66.1 0.8 n-Butyl alcohol 3.0 54.1 7.6 1.9 Isobutyl alcohol 57.1 9.7 4.6 7.0 tert-Butyl alcohol 19.4 68.1 10.3 1.4 n-Amyl alcohol 51.5 4.2 9.6 1.4 Isoamyl alcohol 8.9 52.6 3.7 7.2 tert-Amyl alcohol 18.6 60.2 9.2 4.2 Dioxane 16.1 63.4 8.2 n-Butyl alcohol (double cook) 50.4 0.0 4.4 1.6 123 n-Butyl alcohol (as50.1 0.0 5.3 1.4 pen-chips) 53.2 6.7 2.9 9.0 103 Ethylene glycol 54.9 13.8 9.3 102 GI cerol 6.6 67.9 32.2 9.8 22.9 108 d-dlucose 58.1 22.7 11.9 11.6 107 &Mannitol 3.4 78.6 25.9 104 Urea 17.5 127 n-Butyl alcohol 0.1 20% urea 74.3 17.4 11.3 128 n-Butyl alcohol 0.4 68.1 15.5 10% urea 8.8 130 n-Butvl alcohol -I1.0 8.3 66.2 16.6 6%'urea Original aspen sawdust be2.6 23.5 97.4 28.4 fore cooking a All figures are on the basis of original wood unextracted with b Cross and Bevctn.
99 106 112 117 115 109 110 118 113 114 119 116 122
+ +
%
%
%
48.1 57.7 53.1 52.6 53.9 50.1 51.4 53.7 46.6 47.8 49.3 53.3
35.0 47.2 44.3 44.3 45.3 42.7 43.2 44.6 39.2 39.9 38.0 44.6
2.6 8.5 5.9 4.8 6.6 3.9 3.8 7.1 1.8 1.9 3.0 5.7
47.9
36.7
2.8
48.1 49.4 47.5 43.6 44.8 57.5
42.9 39.8 37.6 33.3 31.6 45.7
2.6 1.9 1.7 1.0 1.2 10.6
61.1
46.9
13.0
57.8
45.9
10.7
56.4
46.2
8.8
62.7 46.8 benzene-alcohol.
respectively. Amyl, isoamyl, and isobutyl alcohols were similar in their activity in removing lignin from the wood, extracting somewhat smaller quantities than did n-butyl alcohol. The lignin contents decreased generally with decreased yields of residual woods. The lignin determinations, as well as those of Cross and Bevan cellulose, alpha-cellulose, and pentosans, in this series of cooks were run on the residual woods which had been previously extracted with benzene-alcohol. The unextracted woods would no doubt have shown higher lignin contents since, as indicated in earlier work on pulping with water only (Z),the benzene-alcohol extractives of the residual woods were insoluble in the 72 per cent sulfuric acid used in the lignin determination. The residual wood of the cook made with an aqueous solution of urea retained about 75 per cent of the lignin present in the untreated wood. On substitution of n-butyl alcohol for 50 per cent of the water used in cooking, a greater removal of lignin was effected; decreasing the quantities of urea resulted in still better lignin extraction. It appears from these data that urea exerts a definite protective action against the effects of water on the lignin. Of the polyhydroxy alcohols, ethylene glycol effected the greatest lignin removal. d-Glucose apparently had the greatest inhibiting effect on the extraction of lignin from the wood, about 97 per cent of the original lignin remaining in the residual wood. Aqueous dioxane removed more lignin from the wood than did water alone.
Cross and Bevan Cellulose in Residual Woods The Cross and Bevan cellulose contents of the residual woods obtained b y cooking with alcohol-water mixtures followed the yields of residual woods fairly closely (Tables I1 and 111, Figure 1). Generally an increased yield of residual wood indicated that a larger quantity of total cellulose remained unattacked in the cooking prooess. The lowest Cross and Bevan cellulose yield in the alcohol-water cooks was obtained with n-amyl alcohol. Isoamyl, tert-amyl, n-butyl, and isobutyl alcohols followed n-amyl alcohol in the order of increasing cellulose yields. All of the other alcohols yielded still larger quantities of Cross and Bevan cellulose, but the
17.2
residues were not pulped although they were softened The highest yields of Cross and Bevan cellulose were obtained with urea and with methyl alcohol, but these two reagents had but little pulping action on the wood. The addition of urea to the butyl alcohol-water mixtures resulted in increased cellulose contents of the residual woods, these increases being greater for the higher urea concentrations. However, the residual woods with the higher Cross and Bevan cellulose contents were not as well pulped as those which showed lower residual yields and less cellulose. It is apparent from these data that the butyl alcohol-water mixture works best in a slightly acid medium. It should be possible, however, to obtain good yields of pulp with high cellulose contents by adding small enough amounts of urea to the cooking liquor to keep the latter just slightly acid during the digestion. Of the polyhydroxy alcohols, ethylene glycol showed the highest yield of Cross and Bevan cellulose. Although d-glucose gave the highest yield of residual wood, the greatest amount of Cross and Bevan cellulose destruction occurred when d-glucose was used. I n its action on Cross and Bevan cellulose, dioxane was similar t o ethyl alcohol.
.
Alpha-Cellulose in Residual Woods The effects of the various reagents on the alpha-cellulose contents of the residual woods followed, in general, the effects of these reagents on the Cross and Bevan cellulose contents. I n the cooks run with mixtures of alcohol and water, the semi-pulped or pulped residues contained less alpha-cellulose than did those which were not pulped. I n respect t o retention of alpha-cellulose, the butyl alcohols were better pulping agents than the amyl alcohols. The high yield of alpha-cellulose in the cook with methyl alcohol indicates that the latter had an inhibiting effect on the hydrolytic action of the water. The addition of urea to Rater alone and to water-alcohol mixtures resulted in practically no losses of alpha-cellulose, probably because of a mild alkalinity of the digesting liquors. It appears from these data that very small amounts of urea TABLE 111. PERCENTAGES OF ORIGINAL MATERIALS REMOVED FROM WOOD IN COOKING PROCESS Cook No. 99 106 112 117 115 109 110 118 113 114 119 116 122 123 103 102 108 107 104 127 128 130
Cooking Agent Water Methyl alcohol E t h y l alcohol n-Propyl alcohol Isopropyl alcohol n-Butyl alcohol Isobutyl alcohol tert-Butyl alcohol n-Amyl alcohol Isoamyl alcohol tert-Amyl alcohol Dioxane n-Butyl alcohol (double cook) n-Butyl alcohol (aspen chips) Ethylene glycol G1 cerol d-8lucose &Mannitol Urea n-Butyl alcohol 20% urea n-Butyl alcohol -4- 10% urea 5% n-Butyl alcohol urea
+
+
Wood Lignin
C. & B. Cellu- a-Cellu- Pentolose lose sans
%
%
%
36.6 29.8 37.5 40.0 33.9 45.9 42.9 31.9 48.5 47.4 39.8 36.6
42.8 58.4 67.4 76.7 62.0 87.2 80.5 56.0 82.0 84.1 60.7 65.1
23.4 8.0 15.4 16.1 14.0 20.2 18.1 14.4 25.7 23.8 21.5 15.1
25.2 -0.7 5.5 5.5 3.3 8.8 7.8 4.8 16.4 14.7 18.8 4.8
%
%
49.6
93.4
23.6
21.6
83.9
49.9 46.8 45.1 32.1 41.9 21.4
94.2 87.9 72.0 2.6 49.1 25.5
23.4 21.3 24.3 30.5 28.5 8.3
8.5 15.0 19.7 29.0 32.5 2.4
85.2 89.0 90.3 94.2 92.9 38.7
25.7
51.7
2.7
-0.2
24.5
31.9
62.6
7.8
1.9
38.1
33.8
64.5
10.1
1.4
49.0
85.2 51.0 65.8 72.3 61.9 77.4 78.1 58.7 89.7 89.0 82.6 67.1
NOVEMBER, 1936
INDUSTRIAL AND ENGINEERING CHEMISTRY
Cookinq Aqents
FIGURE1. EFFECT OF INCREASING CARBOS WEIGHT) OF CHAINLENGTH(OR MOLECULAR NORMAL ALIPHATIC ALCOHOLSON ASPEN WOOD AND ITSMAIN COKSTITUEKTS
would decrease the conversion of the alpha-cellulose into the alkali-soluble celluloses. T h e use of polyhydroxy alcohols and water as pulping agents resulted in greater destruction or conversion of the alpha-cellulose than was the case with the monohydroxy alcohols. Aqueous d-mannitol and d-glucose solutions were more destructive toward alpha-cellulose than was water itself. Dioxane was similar to ethyl alcohol in its effect on the alpha-cellulose content of the residual wood.
Pentosans in Residual Woods The mixtures of monohydroxy alcohols and water mere generally less destructive toward the pentosans of the wood than was water alone. The effects of these mixtures on the pentosans increased generally with the increasing molecular weights of the alcohols. The data are given in Tables I1 and 111 and shown graphically in Figure 1. Amyl alcohol-mater mixtures caused a greater destruction of pentosans than was found by cooking with water alone. Urea exerted a protective izction on the pentosans, this action decreasing with decreasing concentration of the urea. This was probably due to the fact that the alkalinity of the cooking liquors containing urea prevented the hydrolysis of the pentosans. The polyhydroxy alcohols were more destructive toward pentosans than was water alone. Dioxane behaved like ethyl alcohol in its effect on the pentosans of the wood. The data in Tables I to I11 and in Figure 1 show interesting results. The alcohols reduced the destructive effects of water upon all the constituents of wood except lignin. While the pulping effects of the normal alcohols increased with increasing molecular weights of these alcohols, the isomeric or branched-chain alcohols gave different results. The isopropyl, tert-butyl, and tert-amyl alcohols resulted in yields
1273
similar to those obtained with methyl alcohol. These four alcohols behaved essentially alike in removing lignin from the wood. Their action upon the other wood constituents also showed some similarity. It follows, therefore, that the molecular structure of the alcohol has a profound effect on its ability to pulp wood. An apparent relation also exists between the straight-chain length of carbon atoms of the alcohol, its water solubility, and its pulping characteristics. The data show that the increase in the straight-chain length of carbon atoms resulted in decreasing yields of residual woods and increasing pulping properties. Apparently a n alcohol must have a t least four carbon atoms, three of which are in a straight chain, in order to produce a well-pulped residue from wood under the conditions used in these experiments. Since the aqueous solubility of the alcohol decreases with increasing length of the straight chain of carbon atoms, it follon-s that the more insoluble alcohols mill be the better pulping agents. This was found to be true d h i n the range of alcohols used in these experiments. The orientation of molecules at the interface between two surfaces probably plays an important role in pulping wood with alcohols. Martin and Gortner (9) stated that the “zeta potential a t a cellulose-organic liquid interface is a function of the structure of the molecules oriented a t the interface, and the relative symmetry of the molecules with respect to polar groups or double bonds determines the sign and magnitude of the potential.” Although a methylene group in the straight chain of the homologous series of normal aliphatic alcohols alters the zeta potential by about 1 3 6 millivolts, the substitution of a methyl group for a hydrogen atom to form a branched chain alters the zeta potential by only *4 millivolts, The zeta potentials of the following alcohols, a t cellulosealcohol interfaces, are (9) : Alcohol Methyl Ethyl n-Propyl
Zeta Potential iMzilzoozls -55.3 -19.9 +17.1
Alcohol Isopropyl n-Butyl Isobutyl
Zeta Potential ’Mzllzvolts -16.2
+51.7 +l2.4
These figures show that ethyl and isopropyl alcohols, in one case, and n-propyl and isobutyl alcohols, in the other, are nearly alike in their electrical properties a t cellulose interfaces. The cooking data on these alcohols show that ethyl and iso-propyl alcohols or n-propyl and isobutyl alcohols show similar pulping effects. This relation is shown graphically in Figure 2 .
Pulping Aspen Chips with n-Butyl AlcoholWater Mixtures A series of cooks or extractions with mixtures of equal volumes of n-butyl alcohol and water was made on aspen chips containing 21 t’o 33 per cent moisture. h stainless steel, steam-jacketed, 5-gallon (19-liter) rotating autoclave was used in these experiments. The autoclave vas connected wit’h two steam-jacketed tanks so that fresh cooking liquor, water, or any other desired solution could be streamed through the autoclave, displacing the liquid already there. The general procedure used was as follows: The chips (2.0 t,o 2.5 kg. oven-dry basis) and liquor were charged into the autoclave, and the latter was heated by passing steam into the jacket and rotating at frequent intervals. Steam was then passed into the jackets of the two auxiliary tanks containing the water and the fresh butyl alcohol-water mixture, in order to bring these liquors to the desired pressures. At the end of the first cooking or extraction period the pressures in the autoclave and the tank containing the fresh cooking liquor were equalized by means of suitable pipe connections. The spent liquor from the digester was forced into a container fitted with a condenser, being displaced by the fresh liquor from the tanks. The cooking was continued in the autoclave for the desired period. Then the liquor in the autoclave was displaced by water from the
INDUSTRIAL AND ENGIKEERING CHE3CIISTRY
1274
VOL. 28, NO. 11
results similar to those obtained at 185" C., but longer cooking periods were required. $ Double extraction resulted in 3 70 4 % pulps of lower lignin content than a : when only a single cooking period was used. The pentosan con" 2 F\ 60 tents of the pulps decreased in general, with increasing time of $ 2 cooking. The Cross and Bevan c e l l u l o s e s increased, of course, 5 \ 50 z g with decreasing pulp yields. The alpha-cellulose c o n t e n t s of the L iynin r q Residual Wood pulps g e n e r a l l y followed the >$IO\ Cross and B e v a n c e l l u l o s e s . These data are given in Table V. u The best pulp obtained in this s o series on aspen chips was that flathyl €f&l n-Propy/ ho-Propyl n-Bufqrl ho-butyf ?Zec-Butyl n-Amyl b o from cook 206. The pulp yield was Alcohol Cooking Agents lower than the general average, FIGURE 2. EFFECT OF MOLECULAR STRUCTURE O F ALIPHATIC ALCOHOLS ON PULPING OR b u t i t was high in Cross and Bevan DELIGXIFICATION OF ASPEN WOOD c e l l u l os e , valpha-cellulose, and pentosans, and low in lignin. It other auxiliary tank. This was again displaced by fresh water was grayish in color and bleached fairly easily to a high white. and the charge was blown into a cyclone separator. In the case of cook 207 the pulp was grayish and apparently The stock blown from the autoclave was washed with water overcooked, although a fairly good yield was obtained.. and screened in the laboratory screens. When the blow was inThe data in Table V I were calculated from the yields of complete, the chips remaining in the autoclave were mixed with the blown portion, and the whole Fas broken up in the laboratory screened pulp and the Cross and Bevan cellulose, alpha-cellubeater, care being taken not to beat the stock. This mushed lose, pentosan, and lignin contents of these pulps. These stock was then screened. Bleachability, strength tests, and results show that the variations in cooking time or procedure chemical analyses were run on the screened pulps. had remarkably little effect on the carbohydrate constituents The alcoholic layer of the spent liquor was distilled, and the distillate was neutralized with calcium carbonate and re-used for of the wood. A pine kraft pulp treated with a butyl alcohollater cookings. The ligneous residue was removed from the still water mixture for 1.5 hours (45 minutes a t 186" C.) showed a and put away for further experimentation. total loss of only 4 per cent. The strength characteristics of these pulps (bursting The cooking and analytical data are given in Tables I V to strength and tear resistance) were similar to those obtained VI. The analytical results are t h e mean of two or more with the usual commercial alkaline aspen pulps. The alcohol determinations. pulps were more absorbent and softer, and they appeared to ASPEXPULPS.Table I V shows t h a t about 1.5 t o 2.0 hours "hydrate" faster during beating. a t t h e cooking temperature were sufficient to produce pulps JACK PIKEPULP. Cooks made n-ith a butyl alcohol-water of fairly high yields n-ith low screenings. Multiple cooking or mixture on jack pine chips indicated that different conditions extraction gave lower yields of lighter colored pulps even of digestion are necessary for coniferous and deciduous woods. though the total cooking period of the two extractions was This is probably due to the fact that the lignins in these two less than t h a t of the single extraction. The completeness or species are different. The jack pine also contains resinous incompleteness of the blow made little or no difference in the substances which are absent from aspen. screened pulp yields, since the chips remaining in the autoALCOHOL RECOVERY. The recovery of the butyl alcohol clave were not allowed to dry out or bake thoroughly, and from the spent liquor and washings should not be very difficult. they could therefore be easily mushed. The colors of the The spent liquor could be distilled directly, leaving a residue pulps varied from light brown to gray. of ligneous material in the still. The distilled liquo; could then be neutralized with an alkaline material such as lime or calcium carbonate, and TABLE IV. COOKIXG DATAAND PULP YIELDSOF BCTYLALCOHOL-ASPEN re-used, or it could be redistilled to recover some Ratio, Total Total Time of the volatile organic acids, essential oils, etc. Liquor Cooking KO. Steam: Yields-? Cook t o -CookingPeriods Water ine t o ScreenThe liquor used for mashing could probably be No. Wood Temp. Time 1st 2nd Washes Blow Pulp ings Total Remarks re-used for this purpose several times, in order to Vol.:wt. " C . Hr. Hr. H r . Hr. % % % increase its solids concentration, and then added 195 6 . 9 : 1 188 2 . 2 5 2 . 2 5 . . . 2 3 . 2 5 5 4 . 1 0 . 5 5 4 . 6 Clean blow 1.5 196 6 . 9 : l 188 2 . 5 1.0 2 3 . 2 5 4 9 . 8 1 . 3 5 1 . 1 Incomplete blow t o the spent liquor. Since 100 parts of water 1.5 ... 2 2.5 197 6 . 4 : l 188 1 . 5 5 0 . 6 3 . 0 53.6 Incomplete blow 198 6 . 4 : l 188 1 . 5 1.5 ,.. 2 2 . 7 5 5 3 . 4 0 . 7 5 4 . 1 Incomplete blow d i s s o l v e 8 to 9 parts of n-butyl alcohol, the 199 6 . 4 : l 188 2 . 0 2.0 2.5 4 8 . 4 0 . 7 4 9 . 1 Incomplete blow ... 2 aqueous portion of the spent liquor mould have to 2 200 7 . 1 : l 188 1 . 7 5 1 . 7 5 . . . 2 . 5 5 0 . 6 0 . 9 5 1 . 5 Clean blow 201 7 . 1 : l 190 3 . 2 5 3 . 2 5 . . . 2 3 . 7 5 5 2 . 8 0 . 1 5 2 . 9 Clean blow be used conservatively. Further experimenta203 6 . 5 : l 188 3 . 2 5 3 . 2 5 2 3 . 7 5 4 9 . 0 3 . 6 5 2 . 6 Clean blow 206 7 . 3 : l 186 2 . 7 5 1 . 2 5 1:5 2 3 . 7 5 4 7 . 0 4 . 1 5 1 . 1 Incomplete blow tion will be necessary t o work out the economics 5 207 8 . 6 : l 188 5 6 . 2 5 4 9 . 5 0 . 1 49.6 Clean blow 2 of the alcohol recovery. 208 8 . 6 : 1 188 1 . 7 5 1 . 7 5 2 5 5 , o 0 . 2 55.2 Incomplete blow 2.5 210 6 . 5 : l 188 1 . 2 5 1 . 2 5 2 2 0 5 3 . 2 1 . 8 5 5 . 0 Incomplete blow LIGSEOUSEXTRACTIVES. The ligneous mate211 6 . 5 : l 187 1 . 5 1 . 5 2 2 . 7 5 5 6 . 5 1 . 3 5 7 . 8 Clean blow 2 212 6 . 5 : 1 . , . 1 . 7 5 1 . 7 5 rial obtained from wood cooked with n-butvl 2.5 5 2 . 3 2 . 9 55.2 Incomulete blow alcohol is probably more nearly like the or;& nal lignin in wood than are the lignins obChanging the ratio of n-butyl alcohol to water from 1: 1 to tained by the usual commercial inorganic chemical processes. 6 : 4 had but little effect on the yields or quality of pulp obIt has not been subjected to drastic chemical treatment with tained. Cooking a t lower temperatures (176" C.) gave caustic soda, calcium bisulfite, or similar pulping agents, 80
.
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3s
7-
KOVEMBER, 1936
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1275
lignins containing no other alkoxyl groups than those present in the original untreated lignin. PULPsa =Ilthough butyl alcohol-water ratios of I to 1 and 6 to 4 were C1, Used found suitable for pulping wood, greater increase in the alcohol Yield in C. & B. Cook Screened Cellulose C. & B. concentration decreased the pulping effects of the butyl alNo. Pulp Detn. Cellulose a-Cellulose Pentosan8 Lignin cohol-water mixtures. This behavior apparently indicates % % % % % % that one function of the alcohol is to act as a solvent for the 86.8 74.2 3.3 9.5 13.0 195 54.1 49.8 8.5 92.0 79.3 i:; depolymerized lignin. 88.2 79.5 50.6 13.1 197 lg6 198 53.4 15.1 85.1 73.6 4.7 10.7 Although little experimental work has been carried out on 90.2 79.9 48.4 13.5 199 the ligneous material removed from the wood by cooking with i:: 200 50.6 14.3 87.5 78.1 201 52.8 11.1 90.8 26.1 ::$ a butyl alcohol-water mixture, there are theoretically many 203 49.0 15.0 86.2 r4.s 206 47.0 6.4 95.0 85.4 5.0 3.7 uses to which this material may be put. Some of these are 207 49.5 13.5 87.8 73.0 1.4 9.2 given in the simplified flow sheet of the alcohol pulping proc208 55.0 14.4 88.2 18.0 5.1 9.6 210 53.2 18.3 84.5 (6.4 i:; 19":; ess (Figure 3). 211 56.5 17.6 83.6 z2.0 10.3 The butyl alcohol extractives of jack pine were washed 15.0 86.7 (5.5 4.5 212 52.3 a All figures are giyen on a pulp basis. with ether, dried, and ground, yielding a fine chocolate-brown powder. This powder was found to be more or less soluble, qualitatively, in the TABLE VI. ORIGIXALCOMPOSENTS OF Woo0 REMAIKINQ IN PULP following reagents : sodium hydroxide, methyl, C. & B. Cellulose ---a-Cellulose---Pentosans----Lignin----. ethyl, propyl, and butyl alcohols, dioxane, glacial Basis Basis Basis Basis Basis Basis Basis Basia original original original original original original original original Cook acetic acid, ethylene glycol, acetone, and chlorolignin wood a-cellulose wood pent,osans tiood wood cellulose No. form; slightly soluble in the amyl alcohols and in % % % % % % % % Original ethyl, butyl, and amyl acetates; and insoluble in 100.0 23.5 17.2 100.0 46.8 100.0 wood 62.7 100,o water, glycerol, ether, carbon tetrachloride, ben5.1 21.7 10.5 75.0 40.1 85.7 1.8 195 47.0 3.2 13.8 84.4 2.2 12.8 73.1 39.5 196 45.8 zene, xylene, and nitrobenzene. 20.0 85.9 2.9 16.9 44.6 71.1 40.2 197 24.2 2.5 14.5 72.4 84 0 39.3 45.4 198 The dried powder was dissolved in acetone 14.5 3.4 82.7 9.9 1.7 38 7 69.7 43.7 199 and coupled with diazotized sulfanilic and an20.0 4.7 84.4 14.0 2.4 39.5 70.7 200 44.3 14.0 10.5 3.3 1.8 40.2 85.9 76.4 201 47.9 thranilic acids,, yielding dyestuffs with indicator 4.8 20.4 1.8 10.5 36.7 78.4 67.3 42.2 203 7.2 1.7 2.4 40.1 14.0 85.7 71.3 44.7 properties similar to those of methyl orange. 206 19.6 4.6 4.1 0.7 36.1 77.1 69.4 43.5 207 This ligneous material was also coupled with 22.6 5.3 16.3 2.8 91.7 42.9 77.4 48.5 208 6.4 27.2 14.0 2.4 86 8 71.8 40.6 210 45.0 diazotized benzidine yielding a copious quantity 22.1 5.2 2.1 12.2 40.7 87.0 75.3 47.2 211 23.0 5.4 2.4 14.0 84.4 39.5 72.3 212 45.3 of a purplish red product, soluble in aniline but only slightly soluble in t h e usual organic solvents and insoluble in water. Crude attempts to combine the jack pine ligneous material and it is uncontaminated by inorganic materials other than with pulp a t raised temperatures and pressures indicated those present in the original wood or lignin. The organic that by this means it may be possible to produce dense, hard acids (formed during this alcohol pulping process) and the boards more or less impervious to moisture. water probably cause some changes in the degree of polymerization of the lignin molecules, rendering the latter soluble Acknowledgment in the butyl alcohol. Although the use of alcohols without The experiments on the cooking of chips reported in the additional water resulted in the presence of added alkoxyl section on pulping aspen chips were conducted in the mill groups in the isolated lignins (6), the presence of water during laboratories of the Northwest Paper Company, Cloquet, the cooking, as pointed out by Kleinert and Tayenthal (8) in Minn. The writers desire to express their sincere thanks for their experiments with ethyl alcohol, probably resulted in TABLE V-. ANALYTICALD . 4 ~ aON BUTYLALCOHOL-ASPEN
9":; i::
t:;
;:+
FIGURE 3. SIMPLIFIED FLOWSHEET OF
ALCOHOL
PULPING PROCESS
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the permission granted by the officials of the Northwest Paper Company to include these data in the present paper. Without their wholehearted coiiperation this study could not have been completed for publication.
Literature Cited Aronovsky, S. I., U. S. Patent 2,037,001 (April 14, 1936). Aronovsky, S. I., and Gortner, R. A., IND. E s G . CHEM.,22, 264 (1930).
Ibid., 22, 941 (1930); 25, 1349 (1933); 26, 61, 220 (1934). Ibid., 27, 451 (1935). Engel, O., and U'edekind, E., German Patent 581,806 (-4ug. 3, 1933). Higglund, E., and Urban, Helmut, Cellulosechem., 8, 69 (1927); 9, 49 (1928).
VOL. 28, NO. 11
(7) Hibbert, H., and Rowley, H. J., Can. J. Research, 2, 357 (1930). ( 8 ) Kleinert, T., and Tayenthal, K., Z . angew. Chem., 44, 788 (1931); U. S. Patent 1,856,567 (May 3, 1932). (9) M ~ McK., ~ and ~ Gortner, ~ ~R, A , , J ,Phys. Chem., 34, 1509 (1929). (10) Phillips, Max, Chem. Rea., 14, 103 (1934). (11) Rassow, B., and Gabriel, H., Cellulosechem., 12, 227, 248, 290, 318 (1931).
w.
RECEIVEDAugust 28, 1936. Presented before the Division of Cellulose Chemistry a t the 92nd Meeting of the American Chemical Society, Pittaburgh, Pa., September 7 t o 11, 1936. Published with permission of the director as Paper KO.1443, Journal Series, Minnesota Agricultural Experiment Station. 5. I. Aronorsky was Cloquet Wood Products Fellow, University of Minnesota; the fellowship wae established by the Northwest Paper Company of Cloquet, Minn. At present he is Resident Fellow of the Sorthwest Paper Company a t the Institute of Paper Chemistry, Appleton, Wis.
Germicidal Action of Benzylphenols
I
r\' THE past few years considerable information has appeared in the literature concerning high-coefficient germicides, which show phenol coefficients ranging from 10 or 20 u p to values as high as 2000. The investigation of germicides of such high potency has proved attractive. By their use it is possible to conceive of new types of antiseptic solutions which possess a high killing power against disease organisms and a t the same time are free from the faults of the older phenolic diainfectants, such as odor and causticity. In many of the studies reported on these high-coefficient germicides, an attempt has been made to correlate killing power with chemical structure. The reasons for such an attempt can readily be understood, since organic research workers have for years been correlating chemical structure with purely phyqical properties such as viscosity, index of refraction, etc. However, in dealing with killing power upon microorganisms, we are dealing with a biological phenomenon which can be measured only by selecting certain standard conditions for the measurements. The need for suck standardization in determining the phenol coefficient was early recognized by bacteriologists and has resulted in the adoption of three technics: the Rideal Walker (R. W.) method; the standard used in England, the Hygienic Laboratory method (H. L.) ; and the Food and Drug Administration (F. D. A.) method, ahich is standard in the United States. Since American conditions are dealt with here, the F. D. A. method is considered in connection with the phenol coefficient. Reddish ( 7 ) recently pointed out that the phenol coefficient is readily reproducible when the standard conditions of 'the technic are rigidly observed. The more important conditions are : 1. Use of Bacillus lyphosus as the test organism. The strain selected is killed by phenol in a concentration of 1:90 in 10 minutes but not in 5 minutes under the standard conditions. 2. A test temperature of 20" C. 3. Dilution with water of the germicide to be tested.
The phenol coefficient technic was originally developed for testing phenolic or cresylic germicides prepared for use by the ultimate consumer. That is, the germicides for which the test was intended were either water-soluble or were emulsified in such a way that they could readily be diluted in water and thus observe the standard conditions of the test.
Effect of Formulation with Sulfonated Oil T. S.CARSWELL AND J. A. DOUBLY Monsanto Chemical Company, St. Louis, Mo.
A serious departure from the standard test occurred when recent investigators tried to measure the phenol coefficient of high-potency germicides. These germicides differ radically in chemical composition and physical nature from the phenols and cresols for which the test was originally proposed. The most important deviation lies in their low water solubility. I n many cases the water solubility is so low that it is impossible to obtain an aqueous solution which can be diluted in the phenol coefficient test and still retain killing power. As a result, some investigators resorted to the use of alcohol or sodium hydroxide to retain the high-molecular-weight phenols in solution. The result was that figures were obtained which may not accurately represent the phenol coefficients of the materials in question, depending upon the quantity of solubilizing agent added and its effect either upon the microorganisms or upon the germicidal properties of the phenol itself.
Recent publications indicate the germicidal and fungicidal value of benzylphenols and their substitution products. I n this paper the effect of formulating benzylphenols with sulfonated oil is described. The facts presented are of theoretical interest since previous investigators in the field of high-potency germicides frequently have considered only the germicidal power as determined in dilute aqueous or aqueous-alcoholic solution. Such solutions have little practical sig-
