I N D U S T R I A L A N D ENGINEERING CHEMISTRY
714
Vol. 15, ?\To.7
Distribution of Methoxyl in the Products of Cooking Jack Pine by the Soda Process‘ By S. S. Aiyar2 FOREST PRODUCTS LABORATORY, MADISON, WIS.
This is a continuation of the work on “Distribution of Mefhoxyl HE wood, chipped in Total methoxyl was dein the Products of Wood Distillation,”s and the same general methods the usual way, was termined in one part of the were used. Soda COO,^^ on j a c t pine (Pinus dioaricata)‘ were in cooked in a rotary samples of the black liquor progress at the Forest Products Laboratory under the direction of S. and another part was disvertical digester with direct D . Wells to study the eflect of modifications of the process, and it was tilled to a thick sirupy resiand indirect steam heating arranged to procure the necessary samples from each cook to deterB ef or e due. The methoxyl was arrangements. determined in this residue mine the methoxyl distribution. starting the cook the chips It was planned to determine methoxyl in the original wood and i n were impregnated with the as fixed methoxyl, and the the pulp and black liquor as produced under different cooking concaustic lye in the cold a t a volatile methoxyl of the ditions; the methoxyl in the black Iiquor was also dioided into oolatile black liquor was computed pressure of 110 lbs. per sq. by difference. in., and the liquor was and nonuolatile. Duplicates of all deterpartly withdrawn, leaving minations were made and behind enough to complete the cook. The lye in the digester was in every case made the averages of the two, usually varying not more than up to the same strength before turning on steam. As far as 0.1 or a t most 0.2 per cent, are shown in the tables. possible, all the other factors-viz., concentration of the lye RESULTS AND DISCUSSION before the cook, amount of caustic on the basis of the Table I gives the results of the methoxyl determinations on wood, time to reach maximum temperature and pressure, the products of soda cooks of jack pine. It will be seen from weight of wood, etc.-were kept constant. I n every cook the table that not only the methoxy content of the pulp falls enough wood to yield 100 lbs. bone-dry wood was used. as the duration of cook is lengthened, but also the total The only variable was time. The concentration of the lye methoxyl in the pulp based on a constant weight of wood. at the start and of the cooking liquor was kept a t about 96 After 2 hrs. the progressive reduction in both the figures is not g. per liter in every case. so marked as before. I n fact, there seems to be no advantage Samples of white liquor, or caustic lye, were taken before in cooking for longer periods than 2 hrs. from the standpoint and after impregnation. Steam was then turned on and the of the removal of noncellulose material. Though this is cooks started according to fixed schedule. After the pre- no new fact to the industry, yet it is of interest that it has scribed time a sample of black liquor was drawn off through been brought out by a different procedure. a condenser from each cook and the cook discharged as usual. While the pulp loses methoxyl, the liquor gains it, as would Samples of pulp were taken after the cooked stocks were naturally be expected (Table I, Columns 7 and 8). The washed and pressed. figures for 4 and 6-hr. cooks need some explanation. The EXPERIMENTAL methoxyl content of black liquor of these two cooks seems to Zeisel’s method4 with the modified apparatus described in be lower than the one above (Column 7 ) , and hence the the previous paper was used for the determination of the column, instead of showing an ascending series of figures, methoxyl in the products. Since the white liquor was re- shows a fall in the last two figures. This is due t o the conpeatedly used to impregnate the wood before cooking, the densation of a larger amount of water from steam as compared liquor naturally contained a small amount of methoxyl. This with the 2 and 3-hr. cooks and consequent dilution. There is was a t no time high, as fresh liquor was added with the con- another discrepancy in both these cooks in that the total sumption of old stock. Yet, an appreciable amount of methoxyl content of black liquor is above that of wood, which methoxyl was found to be present in the white liquor both be- is impossible. There must have been some error in the weight fore and after impregnation, and this had to be taken into of the black liquor, thus showing a high total methoxyl conaccount in the computations. Knowing the weight of the tent. The figures for the 4-hr. cook are especially questionwhite liquors introduced and withdrawn, and their methoxyl able through all the tables. Even leaving that out of consideration, the conclusions are in no way affected. contents, the required coErection could be calculated. It will be seen in Table I1 that the maximum of the volatile 1 Received December 12, 1922. methoxyl compounds is reached in half to one hour after the 2 Mysore Government Foreign Scholar. maximum pressure is attained, and then falls gradually. One * Hawley and Aiyar, THISJOURNAL, 14 (1922),1055. 4 Zeisel, Monatsh., 6, 089,and 7,406. would expect that the longer the cook the greater would be the
T
TABLE I-METHOXYLIN 1 Duration of Cook from Maximum Pressure Hrs.
2
Dry Pulp from 100 Lbs. Drv W o o d Lbs.
3
4
THE PRODUCTS O F SODA COOK O F JACK PINEa
5
6
7
8
Total Weight of Total Weight OCHs in OCHJ in Black Liquor OCHs in OCHa in the of Pulp Pulp the Pulp after Cook Black Liquor Black Liquor Kg. % Kg. Kg. % KZ. -0.5 80.7 36.7 4.67 1.714 130.8 0-.430 0.69 0 66.5 30.2 3.96 1.196 244.8 0.460 1.127 58.4 +0.5 26.5 3.45 0.914 247.7 1.40 0.567 1 51.6 23.4 2.74 0.64 186.3 1.83 0.985 2 44.6 20.3 1.60 0.33 194.2 0.975 1.89 46.0 3 21.0 I.515 0.32 161.9 I. 180 1.92 4 37.1 16.8 1.95 0.33 279.0 2.70 0.980 6 45.7 20.8 1.19 0.24 252.5 0.927 2.34 a The wood used contained 4.84 per cent methoxyl giving 2.2 kg. methoxyl in each charge: b White liquor samples were n o t available for the last cook, and hence the correction factor IS not known.
9 Corrections to be Applied for. OCHs in White Liquor
-0.08 -0.14
-0.024
-0.20 -0.14 -0.19 +o. 12 (b)
10 Total OCHs in Products Kg. 2.22
2.18 2.3 2.3 2.10 2.10 2.90 2.58
July, 1923
I N D U S T R I A L A N D ENGINEERING CHEiVISTRY
TABLE 11-FIXED
amount of methanol formed, owing to the hydrolysis of lignin in the wood. But, curiously enough, it seems as though the volatile methoxyl compounds recombine to form stable nonvolatile compounds. The equilibrium seems t o be shifted backwards as the concentration of the alkali falls and more woody material is dissolved in the liquor. This reduction cannot be explained by loss of the volatile products, since almost all the methoxyl of the wood is apparently recovered in the products. Although the figures for the last two cooks are questionable, for reasons already mentioned, these conclusions are strongly indicated. Fig. 1 shows this more definitely. According to Bergstrom5 pine and spruce yield the same amount of methanol in the sulfate process, 15 kg. for 1000 kg. of cellulose manufactured. Five kilograms of this are obtained from the vapors and the rest while concentrating the black liquor. This works out to 1.5 per cent of the cellulose, which is only about 40 per cent of the wood. So, on the basis of wood, the yield of methanol in the sulfate process is not over 0.6 per cent. From small-scale cooks with soda, Bergstrom obtained the following yields of methanol :
Duration of Cook from Maximum Pressure Hrs.
-0.5 0
4-0.5 1 2 3 4 6
Fichte ( P i c e a e x c e l s a ) . . . . . . . . . . . . . . Kiefer (Pinus sil . . . . . . . . . . . . . . . . . . 0.67 Pi?ZUS fialustris.. Pinus ebhi?aata., Aspen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Birch .................................... Gum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0.67 0.81
0.83
The yield is much less in the case of the sulfite process. The pines, according to the table, yield methanol on an average of 0.67 per cent of the wood. I n the work of the authors as much a.s 1.56 per cent of methoxyl volatile products have been obtained. Of course, this may include not only methanol, but also other volatile methoxyl derivatives. Furthermore, their method of estimation was more quantitative than obtains in the commercial recovery of methanol. The main reason for Bergstrom’s low yield is probably that he recovered the methanol after periods of cook longer than one hour, while the author’s results show that the volatile products of methoxyl diminish after that period. I n Column 7 of Table I1is given a set of figures which represent those in Column 6, corrected for the methoxyl in the liquor introduced for the cook, on the assumption that this methoxyl is fixed. Since this methoxyl is brought into the liquor by its repeated use for impregnation, it may not be far wrong to assume it to be fixed. The fact that the figures in Column 7 show greater regularity than those in Column 6 8
Paprev-Fabr., 10 (1912),677, 359.
VOLATILE METHOXYL IN
THE BLACKLIQUOR Total Volatile OCH, Compounds(Diff. OCHs Total in of Columns 2 and 5) OCHs Residue Residue Corrected as in Black on Black OCHs yo (Fixed- Uncor- per Table I, Liquor Liquor of the Methoxy) rected Column 9 Residue Kg. Kg. % ICg. Kg. AND
0.59 1.13 1.40 1.83 1.89 1.92 2.70 (?) 2.34
19.0 23.9 22.9 32.5 29.2 34.7 26.7 30.87
0.86 1.44 1.13 2.10 2.65 2.93 2.44 2.90
. 0.22 0.84 0.64 1.27 1.50 1.64 1.64 2.26
seem? to bear out the assumption. The curves for both corrected and uncorrected figures are given in Fig. 1 , A yery interesting relation exists between the lignin and the methoxyl contents of the pulps. Representing these in terms of the percentages based on the lignin and methoxyl in the wood, the figures show a close parallel.
I
Per cent
715
TABLE 111-RELATIONBSTWEEN LIGNINAND METHOXYL I N T H I S PIJLPQ Duration Actual OCH? in of Cook Pulp Weight Lignin in Pulp-on OCHj from Obtained of Lignin Pulp on Maximum in Each Lignin in Pulp so Lignin of Content Pressure Cook Pulp Obtained Wood of Wood Hrs. % % Lbs. 7” 9% .. -0.5 0 +0.5 1 2 3 4
80.7 31;7 66.5 25.1 58.4 23.7 51.6 17.4 44.6 10.45 46.0 . 10.05 37.1 11.9 6 45.7 7.0 a I n each cook 100 Ibs. dry weight
were used.
25.5 80.4 77:9 16.7 51.4 54.0 13.9 43.8 41.5 9.0 28.4 29.1 4.7 14.8 15.0 14.5 14.5 4.6 4.4 13.9 15.0 4.4 13.9 10.91 ( ? ) of wood containing 32.8 Ibs. of ligniii
The last two columns of Table 111 show this in a striking manner. Allowing for the experimental errors, and more especially for the difficulty in attaining scientific accuracy in the semicommercial cooks on which this study is based, the figures are practically identical. This is in spite of the fact that the methoxyl determinations were conducted by the author and the lignin determination by the Ost and Wilkenung6 method by Mr. Bray.’ Hence, there seems to be no doubt that all methoxyl is associated with lignin and that the methoxyl is combined with the lignin in only one .way.
CONCLUSIONS As the duration of cook is Iengthened the methoxyl in the pulp falls rapidly for the first 2 hrs., and thereafter the methoxy removal is very slow. The liquor contains volatile and nonvolatile methoxyl
* Chem. Zlg., 34 (1910),461. 7 Chemist in Forest Products, Pulp and Paper Section of the Forest Products Laboratory.
I N D U X T R I A L A N D ENGINEERING C H E M I S T R Y
71 6
compounds, the former attaining a maximum in half to one hour from the time of maximum pressure in the digester. Thereafter, their quantity seems to diminish. The lignin and methoxyl contents of pulps from cooks of different duration, expressed in percentages of those of wood are almost identical, thus showing that all the methoxyl is associated with lignin.
Vol. 15, No. 7
This study also shows that there is no advantage in cooking for longer than 2 hrs. a t 100 to 110lbs. per sq. in.
ACKNOWLEDGMENT The author is indebted to J. A. Staid1 and R. H. Grabow for supplying the samples and for all the data on the cooks other than the methoxyl determinations.
Consistency Determination of Greases' By Charles B. Karns and Oscar L, Maag RESEARCH LABORATORIFS OR
vv
THE
GALENA-SIGNAL OIL CO., F R A N K L I N ,
HILE it has been the practice for many years in classifying liquid lubricants to give consideration to their body in determining their value as a specified lubricant in connection with the service requirement, which body or viscosity is determined by instruments available for this purpose, the same cannot be said of solid lubricants such as greases. For many years greases have been used as lubricants, yet no instrument has been available to determine satisfactorily their consistency or body and thus furnish reliable data as to the general classification of greases for their many different requirements. The writers with this in mind have spent considerable time in developing a suitable apparatus which d l determine accurately the consistency or solidity of not only the soft greases, but the harder solid greases as well. This machine was developed principally for plant control in the manufacture of many kinds of greases, and has been successfully used in this respect for over a year, proving an important factor in the control of grease manufacture, as well as in designating the various grades of greases for general and special lubrication. By means of this apparatus it is possible t o classify greases similar to the way that viscosity classifies liquid lubricants such as oils. The apparatus is so constructed that by pressing a trigger a set of jaws opens and allows a ball of definite weight and diameter to fall a specified distance into the center of a standard cylinder containing the grease to be tested. The depth that the ball penetrates into the grease is measured in millimeters by a depth gage and recorded as the consistency or degree of solidity of the grease. For lubricants which are too hard to be determined in this manner, such as hard greases for railroad lubrication, the ball falls upon-a pin which is held by a disk in the standard cylinder centrally above the sample of hard grease contained in a small cylindrical cup. The depth in millimeters that this pin penetrates into the hard grease is recorded as its consistency. Consistencies determined by the ball falling directly into the grease are denoted by scale S, while readings procured by using the pin are designated by scale H, in order to distinguish results obtained by the two methods. The tabulated results of consistency determinations of typical greases that cover the hardness ordinarily encountered in these lubricants give an idea of the results obtained with this apparatus. The effect of temperature is quite noticeable on some greases-for example, a soft grease which had a consistency of 35.0, scale S, a t 75" F., gave a result of 22.5, scale S, a t 35" F. Also, a hard grease, such as used for railroad lubrication, which had a consistency of 7.5, scale H, a t 75" F., gave aresult of 3.0, scale H, a t 35" F. 1
Received December 25, 1922.
PA.
Consistency Taken MOTOR-CUP GREASES at 75' F. Heavy grade.. . . . . . . . . . . . . . . . . . . . . Medium grade... . . . . . . . . . . . . . . . . . Soft grade.. ...................... Especially soft lubricating grease.. . . 35.5 HARDGREASES FOR RAILROAD LUBRICATION No. 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . N o . 2 ............................ 9 . 0 Scale H No. 3 ............................ 11.5 7.5
i
The writers have found the temperature of 75" F. to be very convenient for determining the consistency of most greases; however, for unusually soft greases a temperature of 35" F. is sometimes more satisfactory. I n order that different consistometers may give concordant results it is essential that the parts be thoroughly standardized in their manufacture. The writers are collecting data with this consistometer relative to the properties of various greases, which they will publish as soon as the work under progress is completed.
