Comparison of Charcoal
The following table shows a comparison of charcoals from different sources. The method of activation was identical and the times of treatment were those approximately giving the highest service time. The results against chloropicrin, therefore, represent roughly the relative excellence of the charcoal obtainable from various raw materials, using this method of activation:
Comparison of Various Active Charcoals Activated in Laboratory
| Base Material | Apparent Density | Steam Treatment at 900° | Accelerated Chloropicrin Test Results | |||
|---|---|---|---|---|---|---|
| Primary Carbon | Activated Carbon | Time Min. | Weight Loss Per Cent | Weight Absorbed Per Cent | Service Time Min. | |
| Sycamore | 0.158 | 0.080 | 18 | 53 | 41 | 7.3 |
| Cedar | 0.223 | 0.097 | 60 | 88 | 78 | 16.0 |
| Mountain mahogany | 0.420 | 0.236 | 60 | 44 | 32 | 16.3 |
| Ironwood | 0.465 | 0.331 | 60 | 44 | 31 | 20.8 |
| Brazil nut | 0.520 | 0.316 | 120 | 71 | 46 | 32.2 |
| Ivory nut | 0.700 | 0.460 | 120 | 70 | 48 | 47.0 |
| Cohune nut | 0.659 | 0.502 | 120 | 48 | 51 | 53.4 |
| Babassu nut | 0.540 | 0.322 | 210 | 68 | 85 | 58.7 |
| Cocoanut | 0.710 | 0.445 | 120 | 60 | 61 | 58.4 |
| Cocoanut | 0.710 | 0.417 | 180 | 75 | 72 | 64.4 |
| Briquetted Materials | ||||||
| Sawdust | 0.542 | 0.365 | 120 | 66 | 53 | 40.0 |
| Carbon black | 0.769 | 0.444 | 240 | 64.3 | 53 | 50.5 |
| Bituminous coal | 0.789 | 0.430 | 165 | 61 | 58.3 | 46.8 |
| Anthracite coal | 0.830 | 0.371 | 480 | 81 | 53 | 40.7 |
“In conclusion, it will be of interest to compare the charcoals manufactured and used by the principal belligerent nations, both with one another and with the above mentioned laboratory preparations. Data on these charcoals are given in the following table:
Comparison of Typical Production Charcoals
of the Principal Belligerent Nations
| Country | Date | Raw Material | Apparent Density | Service Time Corr. to 8-14 Mesh | Remarks |
|---|---|---|---|---|---|
| U. S. A. | Nov. 1917 | Cocoanut | 0.60 | 10 | Air activated |
| U. S. A. | June, 1918 | Mixed nuts, etc. | 0.58 | 18 | Steam activated |
| U. S. A. | Nov. 1918 | Cocoanut | 0.51 | 34 | Steam activated |
| England | 1917 | Wood | 0.27 | 6 | Long distillation |
| England | Aug. 1918 | Peach stones, etc. | 0.54 | 16 | |
| France | 1917-18 | Wood | 0.23 | 2 | |
| Germany | Early | Wood | ? | 3 | Chemical and steam treatment |
| Germany | June, 1917 | Wood | 0.25 | 33 | Chemical and steam treatment |
| Germany | June, 1918 | Wood | 0.24 | 42 | Chemical and steam treatment |
“It is at once evident that the service time of most of these charcoals is very much less than was obtained with the laboratory samples. However, in the emergency production of this material on a large scale, quantity and speed were far more important than the absolute excellence of the product. It will be noted, for instance, that the cocoanut charcoal manufactured by the United States, even in November, 1918, was still very much inferior to the laboratory samples made from the same raw material. This was not because a very active charcoal could not be produced on a large scale, for even in May, 1918, the possibility of manufacturing a 50-min. charcoal on a large scale had been conclusively demonstrated, but this activation would have required two or three times as much raw material and five times as much apparatus as was then available, due to the much longer time of heating, and the greater losses of carbon occasioned thereby.
“It should furthermore be pointed out that the increase in the chloropicrin service time of charcoal from 18 to 50 min. does not represent anything like a proportionate increase in its value under field service conditions. This is partly due to the fact that the increased absorption on the high concentration tests is in reality due to condensation in the capillaries, which, as has been pointed out, is not of much real value. More important than this, however, is the fact that most of the important gases used in warfare are not held by adsorption only, but by combined adsorption and chemical reaction, for which purpose an 18-min. charcoal is, in general, almost as good as a 50-min. charcoal.”
Typical Absorptive Values of Different Charcoals
Against Various Gases
- LEGEND:
- (A) = H₂O Content, (%)
- (B) = Accel. Chloropicrin Service Time, (Min.)
- (C) = Chloropicrin
- (D) = Phosgene
- (E) = Hydrocyanic Acid
- (F) = Arsine
- (G) = Cyanogen Chloride
- (H) = Trichloromethylchloroformate
- (I) = Chlorine
| No. | Charcoal | Nation | (A) | (B) | Service Time, Minutes Standard Conditions | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| (C) | (D) | (E) | (F) | (G) | (H) | (I) | |||||
| 1 | Poor cocoanut | U. S. A. | 0 | 10 | 120 | 175 | 20 | 18 | 55 | 50 | 270 |
| 2 | Medium cocoanut | U. S. A. | 0 | 30 | 350 | 260 | 25 | 25 | 65 | 65 | 370 |
| 3 | Good cocoanut | U. S. A. | 0 | 60 | 620 | 310 | 27 | 30 | 75 | 70 | 420 |
| 4 | Same as No. 2 but wet | U. S. A. | 12 | 18 | 320 | 330 | 35 | 16 | 35 | 95 | |
| 5 | No. 2 impregnated | U. S. A. | 0 | 35 | 400 | 700 | 70 | 400 | 70 | 190 | 510 |
| 6 | Wood | French | 0 | 2.5 | 25 | 75 | 9 | 0 | 1 | 20 | |
| 7 | Wood | British | 0 | 6 | 70 | 90 | 18 | 4 | 5 | 30 | |
| 8 | Peach stone | British | 0 | 16 | 190 | 135 | 30 | 25 | 65 | 60 | |
| 9 | Treated wood | German | 0 | 42 | 230 | 105 | 20 | 20 | 22 | 25 | |
| 10 | No. 9 impregnated | German | 30 | 9 | 90 | 320 | 16 | 1 | 110 | 120 | |
Standard Conditions of Tests
| Mesh of absorbent | 8-14 |
| Depth of absorbent layer | 10 cm. |
| Rate of flow per sq. cm. per min. | 500 cc. |
| Concentration of toxic gas | 0.1 per cent |
| Relative humidity | 50 per cent |
| Temperature | 20° |
| Results expressed in minutes to the 99 per cent efficiency points. | |
| Results corrected to uniform concentrations and size of particles. | |