Amil. 1922
T H E JOURA'AL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
307
New Solvents for Rosin Extraction' By H.I(. Bensonz and A. L. Bennett LABORATORY OF I N D U S T R I A L CHEMISTRY, UNIVERSITY O F WASHINGTON, SEATTLE, WASHINGTON
TARLE 11-EFFECT OF TIME AND SIZE OF W O O D O N EXTRACTION When resinous wood of pulp size is treated at 70" C. with eight Concentimes its weight of 5 per cent ammonium hydroxide for 10 hrs., tration Extraction (Per cent Size of Wood Time of Rosin Soxhlet EEciency 94.5 per cent of the rosin is extracted. The ammonia extract deHrs. Per cent Per cent Per cent SOLVENT Volume) Inches composes slowly in the air at ordinary temperatures; at 90° to 100" Alcohol 88 1 X 1/8 X 1/8 5 26.40 13.8 65.7 70 1 X 1 / 8 X 1/8 5 31.96 12.8 71.7 C. it is rapidly and completely decomposed, yielding ammonia 44.5 5 17.41 21.8 50 1 X 1/8 X1/8 vapor and finely dioided rosin and humus in suspension. Rosin Ammonium and humus may be separated by gasoline. None of the solvent hydroxide 8 1 X 1/8 X 1/8 5 32.2 6.1 83.9 5 1-1/8X3/4X3/32 5 30.1 8.2 78.6 is retained in the humus after heating. 5 1 X 1/8X1/8 10 2.5.65 1.6 94.5 Wood chips saturated with ammonia solution give 03the ammonia 1-1/8 X 3/4 X 3/32 10 28.89 5.8 83.3 completely when steam-distilled. Denatured ethyl alcohol at a dilution of 70 per cent is as eficient The results are plotted against the temperature in Fig. 1. a solvent for rosin as ammonia, benzene, turpentine or petroleum Rapid decomposition took place a t 93" to 100' C. When ether. 'slowly heated, ammonia was not given off below 80" C.
HE use of ammonia as a solvent for rosin has been described in a previous article,3 the resinous wood having been reduced to sawdust, shavings, and small chips previous to its extraction. In view of the rapidly increasing proportion of coniferous woods in pulp manufacture it seemed advisable to determine the efficiency of ammonia as an extraction agent in the case of pulp chips and to compare it with other solvents which might be used. EXPERIMENTAL
T
The resinous wood was hogged to pulp size (1-1/8 in. x 3/4 in. x 3/32 in.), placed in pressure bottles, covered with the solvents, and placed in a thermostat at 70" C. for 5 hrs. The extraction liquor was next drained off, the chips washed, and the combined liquors evaporated until all solvent was removed, leaving "humus" and rosin in the case of ammoniacal extraction and rosin alone in the other samples. The humus and rosin were separated by dissolving the rosin in petroleum ether, filtering off the humus, and evaporating to dryness to recover the rosin. The efficiency of extraction was determined by drying the extracted wood at 100" C., grinding it to fineness in a Grumbaugh mill, and extracting in a Soxhlet apparatus. The results obtained are given in Table I. A 50-g. sample was used in each case. TABLE I-cOMPAR4TIVE ExPT Volume No SOLVENT Cc 1 Turpentine 200 2 Benzene 200 3 Petroleum ether 200 4 Ammonium hydroxide 400 6 Ammonium hydroxide 400 6 88% alcohol 200 7 70% alcohol 200 8 50% alcohol 2110
EFFICIENCY O F ROSINSOLVENTS Extraction Eiii,---Washing-of Rosin Soxhlet ciency Cc Per cent Per cent Per cent Per cent 60 , 20 10 24 35 46 2 50 17 86 26 85 40 0
...
17 01
21 25
44 4
200
1
16 51
20 13
45 0
200 50 50 50
1 85
17 00 15 46 16 52 14 71
25 05
40 40 42 34
50
70 50
22 60 22 05 27 60
5 3 8 7
The effect of length of time and size of wood on extraction of rosin is given in Table 11. The volume of alcohol used was 200 cc. and of ammonium hydroxide 400 cc. in each case, the chips being washed as before. DECOMPOSITION OF AMMONIA EXTRACTS-when the SOlUtions obtained from the ammonia extraction were left standing in the air, the color changed from a light cream to dark brown. By raising the temperature evenly a t the rate of 5" C. every half hour and absorbing the ammonia in wash bottles, the quantity of ammonia given off was estimated. 1 2
3
Received August 4, 1921. Professor of Chemical Engineering, THISJOURNAL, 7 (1915), 918.
and a t 100" C. none remained.
FIG.2 LOSS OF SOLVEKTS IN Hums-The extraction residue after the ammonia had been driven off consisted of rosin and humus of tar-like consistency. When treated with gasoline, benzene, or some similar solvent the rosin dissolved, leaving the humus as a residue. This was removed by filtration and dried to a fine powder. Humus in the dry state was saturated with solvent; after draining off the latter, the bottle containing the humus with adhering solvent was weighed to determine the weight of solvent absorbed. It was next heated in an oven at 100" C. for 10 min.; then allowed to cool in a desiccator containing an atmosphere of vapor of the solvent used, and weighed. From a succession of such weighings, the rate and extent of removal of solvent from the humus were determined. The results in the case of gasoline are shown in Fig. 2. The gasoline used for this purpose showed by the Bureau of Standards method of analysis that 44 per cent was volatile a t 100" C. or below. Inasmuch as the curve shows likewise that 44 per cent of the gasoline is volatilized by heating the humus for 50 min. a t 100" C. none of the solvent was retained by the humus. AMMONIA RECOVERY-The liquor from an ammonia extraction was distilled slowly and the vapors absorbed in 1: 3 sulfuric acid. The waste liquor was treated in the same manner. The extracted wood chips were steam-distilled and the condensate redistilled and absorbed in acid. The results, .given in Table 111, show that although 3.12 per cent ammoniaremains in the wood, it can be completely recovered.
