INDUSTRIAL A N D ENGINEERING CHEMISTRY
September, 1923
TABLEV--BLEACHINGPOWDER REQUIREDFOR SULFITEAND SODAPULPS BY MODIFIEDHYPOBROMITE METHOD (0.6-gram sample, 10 cc. 0.1 N hypobromite solution, acting 20 minutes at 23" C.) BLEACHING POWDERREQUIRED Forest Products 0.1 N LaboHypobroHyporatory bromite Moismite Method Method ture Consumed WOODSPECIES % cc. No. % % Mitscheulich Sulfite Pulps 20.4 24 Spruce 4.4 3.85 31 20.8 3.95 Av. 2 0 . 6 17.7 18 Spruce 5.4 3.30 120 18.0 3.35 Av. 17.9 13.8 12 Spruce 7.9 2.50 96 13.7 2.48 Av. 13.8 15.5 1.5 101 15.0 15.0 Av. 15.1 Spruce 6.6 2.12 11.6 12 103 11.7 2.15 2.15 11.7 Av. 11.7 12 12.8 Spruce 3.9 2.47 149 13.2 2.52 Av. 1 3 . 0 Spruce 4.3 2.67 15 14.2 154 14.2 2.67 Av. 14.2 Quick Cook SulJle Pulps Spruce 4.3 2.98 15.8 15 22 15.8 3.00 Av. 1 5 . 8 Jack pine 4.0 2.85 15.0 14 142 2.92 15.3 Av. 15.2 16.4 Jack pine 4.0 3.10 18 145 16.4 3.10 Av. 16.4 Soda Pulps
116
Aspen
6.2 6.2
2.01 2.05
94
Aspen
5.6 5.6
3.03 3.19
42
Aspen
3.9 3.9
1.63 1.66
17
Aspen
5.2 5.2
2.32 2.38
80
Jack pine
5.6 5.6
3.42 3.37
MODIFIED ANALYTICAL
10.9 11.1 Av. 11.0 16.3 17.1 A v . 16.7 8.6 8.7 Av. 8 . 7 12.4 12.7 Av. 12.6 18.4 18.1 Av. 1 8 . 2
18 20
.. 17 30
937
a variation of 3.5 per cent from the results of the Forest Products Laboratory method, due possibly to the high amount of bleach required. Possibly, for pulps having a bleach consumption greater than 20 per cent either a larger amount of hypobromite or a larger factor will be necessary. With Nos. 96 and 120 there is a maximum variation from the results of the Forest Products Laboratory method of 1.8 per cent and 0.3 per cent, respectively. No. 22,;a quick cook, shows a bleach value only 0.2 per cent less than the Forest Products Laboratory result. The bleach requirements of the soda pulps, Nos. 116, 94, 17, and 80, were difficult to determine accurately by the Forest Products Laboratory method. The relation between these results and those in mill practice has not been as thoroughly established as for the sulfite pulps, so that variation between the two methods cannot be used as evidence against the values obtained by the hypobromite method. This is especially true in view of the splendid agreement (Table VI) of the results of duplicate tests by the latter method on the same pulp. The bleach requirement is relatively high for all the soda pulps tested, and it is possible that more hypobromite or different conditions of time and temperature will be necessary to give optimum results. These have not been further investigated. TABLEVI-RATIO OR BLEACHING POWDER REQUIRED FOR SODA PULPS B Y FORESTPRODUCTS LABORATORY METHODTO BLEACHING POWDER EQUIVALENT OF HYPOBROMITE CONSUMED Bleaching Bleaching Powder Powder Required Equivalent by Forest t o HypoProducts bromite Laboratory Consumed Method A B Factor SAMPLE WOODSPECIES % % B/A Aspen 3.7 18 4.9 116 94 Aspen 5 6 20 3.6 Aspen 4.2 17 4.0 17 80 Jack pine 6.1 30 4.9
The use of the factor 3 for soda pulps indicates a bleach requirement too low in every case. Recalculation of the actual ratio between the bleach requirement as measured by the two methods gives values ranging from 3.6 to 4.9, which are far from constant.
CONCLUSIONS PROCEDURE
Place 0.6 to 0.75 gram of the pulp in a dry, 500-cc. bottle having a well-ground glass stopper. Add 30 cc. of the acid solvent consisting of nine parts by volume of hydrochloric acid (sp. gr. 1.19) and one part of sulfuric acid (sp. gr. 1.84), and shake from time to time for about an hour until the pulp is in solution. There is a certain amount of dark material that does not entirely dissolve. All hard pieces can be disintegrated with a glass rod. When solution is complete, bring to 23" C. and add 300 cc. water (23" C.), and shake thoroughly. Then add 10 cc. of alkaline, 0.1 N bromine solution (8 grams of bromine to 1000 cc. 0.1 N sodium hydroxide solution) down the side of the bottle, stopper, shake well, and allow to stand 20 minutes with occasional gentle agitation in a room at 23" C. or in a water bath a t the same temperature. Stop the reaction by adding 2 grams of potassium iodine dissolved in 25 cc. water and titrate immediately with 0.1 N thiosulfate, adding starch indicator toward the end. Since iodine is adsorbed by the pulp, the thiosulfate should be added slowly just before the end of the reaction. The final end point is reached when only a cream-colored or white suspension remains. Results should check within a range of 0.1 to 0.5 per cent bleach. Analyses of additional pulps were made to check this method, and the results are given in Table V. Duplicate tests show satisfactory agreement. In No. 31 there is
Without further investigation the hypobromite method cannot be recommended for soda pulps. For sulfite pulps, however, the method can be expected to have definite value provided the various precautions suggested in the modified method are properly observed. Advisory Board for Carnegie I n s t i t u t e of Technology One of the most important recent developments a t Carnegie Institute of Technology has been the organization of an advisory board of Pittsburgh business and scientific men to cooperate with the work of the Department of Mining and Metallurgy. C. W. Heppenstall, president of the Heppenstall Forge & Knife Company, has been elected chairman of this board. The immediate function of the advisory board will be to coijperate with the institute in the solution of current problems affecting the work of the Mining and Metallurgy Department. Beginning with the next college year, the Institute of Technology announces that special courses for graduates of liberal arts and technical colleges will be given by the Department of Mining and Metallurgy. The purpose of these courses will be to train young men for jobs in the metallurgical and allied industries leading to positions of managerial, sales, and executive capacities. A consistent demand is being made in this and other iron and steel producing districts, for college men, particularly in the nontechnical capacities, from the lack of whom this industry has long suffered. The cooperation of the newly organized advisory board has already been provided in preparing the curricula for these courses.
