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I X D USTRIAL A N D E X G I X E E R I S G CHl3JllSTRY
lower tensile strength, they would hardly be expected to compete with hemp, ramie, or jute as a source of cordage material. Their comniercial adaptation is more logically to be found, like that of flax, in the textile industry. Stem Tissue
Analyses of the stern tissue (Table IV) indicate that this material offers a good source of alpha-cellulose. Its lignin content is lower than that of the seed fibers, Pulping experiments both upon laboratory and semi-plant scales have clearly demonstrated that these stems possess many desirable properties which heretofore have been associated largely with softwood pulps. For instance, the fibers possess a splendid hydration capacity, length, tensile strengt#h,freedom from discolor, and finally a generous amount of alpha-cellulose almost equal to that of spruce (10). The pulp produces a fine board material and also a newsprint of note. A high pulp yield of 86 per cent of the dry weight of the tissue was obtained from the stems when no preliminary cook was applied. I n this mechanical treatment hydration of the fibers occurred during the beating process. A 10 per cent caustic soda cook for 8 hours a t 20 pounds’ pressure resulted in too drastic a treatment. The resultant board was dark, exceedingly hard, and warped badly. A pulp yield of only 65 per cent was obtained. A 10 per cent lime cook for the
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same period and pressure produced a much superior board and netted a yield of 82.5 per cent. The latter procedure approximated that for mechanical pulp from the standpoint of both yield and quality. While it is recognized that there are many sources for pulp material in the cellulose wastes of today, nevertheless the amount and quality found in milkweed stems compares favorably with that present in many woods ( I O ) . The seed fibers together with those of the stem offer an inviting annual source of cellulose material which cannot escape increasing attention in the future. Literature Cited Anon., J. SOC.Chem. Ind., 34, 524 (1915). Assocn. Official Agr. Chem., Methods, 1925, p. 120. Bishop and Teik, .Malayan Agr. J., 16, 97 (1927). Britton and Brown, ”Illustrated Flora,” Vol. III,p. 4. Scribner, 1898. Dischendofer, Angew. Bot., 8, 281 (1926). Fox, Indie Rubber Wwld, 60, 645 (1914). Gerhardt, J. Agr. Reseavch, 39, 837 (1929). Henry and Morrison, “Feeds and Feeding,” p. 709, Henry Morrison, 1923. Mathews, “Textile Fibers,” p. 666,Wiley, 1924. Mehta, Biochem. J . , 19, 958 (1925). Meitzen, Dissertation University Gottingen, 1862. Neish. J . SOC.Chem. I n d . , 32,l (1913). Saleeby, Philippine Is. Bur. Agr., Bull. 26, 7 (1922). Saunders, Proc. Am. Pharm. Assocn., 23,655 (1875). Schorger, IND.Exo. CHEX.,17, 642 (1925). Shoemaker, U.S. Dept. Agr., Tech. B1111.33 (1927).
Ferric Alumina’ A Modern Development in the Field of Coagulation A. R. Moberg and E. M . Partridge PAIGE& JOYES CHEMICAL COXPAXY, HAMMOND. IXD.
Development of New Coagulant LMOST coincident with the dawn of water purification and softening was the use of coagulants. The most It is evident that the first essential toward floc formation readily available and best known was aluminum from any coagulant shall be the reaction of that coagulant sulfate, more commonly known as filter alum or alum. A1- with some salt present in or added to the water. This reacthough development has followed development in 1he gradual tion produces solid phase of such degree of subdivision and perfection of mechanical means, and although many improve- dispersion as to verge on the colloidal, if it is not actually ments have been made in the type and quality of reagents colloidal. The second essential is that this colloidal solid used, filter alum has remained more or less the standard co- phase shall agglomerate or coagulate, a t the same time enagulant. This in spite of the many difficulties attendant training the solids to be removed. upon its use. Endeavoring to circumvent the inhibiting effects of ionized In 1924 Hatfield (2) presented a series of tests and curves buffering salts, pre-precipitated hydrous alumina was conshowing the solubility of aluminum a t various pH values. sidered, since this would immediately eliminate the first This followed shortly after the work of Theriault and Clark (5) essential of floc formation. The vital objection to a pure and slightly preceded the work of Miller (3) on the same hydrous alumina was twofold: (1) the hydrous alumina must subject. The question of paramount importance IT as whether be freshly prepared as the aged gel fails to coagulate; and (2) these tests indicated the solubility of aluminum or its degree it in no way counteracts the peptizing action of oppositely of reactivity. I n 1926 Moberg (4) and in 1927 Christman (1) charged organic colloids that may be present in the water. brought evidence tending to prove that the latter was true. It was decided that if a protected cplloid could be formed by The mass of ei-idence taken as a xvhole formed the basis for peptizing the freshly prepared hydrous alumina some of these the assumption that “the degree of reactivity of any common difficulties could be overcome. If a t the same time the coagulant is dependent upon the amount and type of other protector could itself be a colloid, or a t least could be so unsalts or colloids present in the water.” Briefly, then, a com- stable that it would readily react to form a colloidal solid mon coagulant reaches its ultimate efficiency only a t a definite phase having an electric charge opposite to that carried by the isoelectric point, which is variable and dependent, upon the hydrous alumina, then might be found the solution to the amount and type of buffering salts and colloids prment. problem. The research on and subsequent production of Ferric I n the production of hydrous alumina it was found that a n Alumina have been clone with the thought that a given acid aluminum salt must be used whose anion had little or no amount of effort would be more wisely spent on the produc- coagulating power. A salt such as aluminum sulfate could tion 3f a new coagulant than on means of circumi-enting the not be used, since the coagulating powers of its anion preeccentricities of the old. vented sufficient dispersion to permit peptization. 1 Received October 4 , 1929. Either aluminum chloride or aluminum nitrate could be
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used, although the chloride suggested itself from the standpoint of economy. The acid aluminum salt could be precipitated by almost any number of alkalies, although again economy suggested the use of an aluminate since the amount of hydrous alumina produced per unit of alkali would thus be increased. Another point for consideration was that aIuminum-containing by-products or trade wastes could be used provided that the contaminating elements would not precipitate conflicting salts at a neutral pH. It was understood that the hydrous alumina must be carefully washed to remove electrolytes released by the reactions. After washing, the excess moisture could be removed by filtration, filter-pressing, or centrifuging. The method used would be determined by local conditions and by the amount of material to be produced. Another phase that should not be overlooked was that as the gel ages it becomes more difficult to peptize, and so all processesmust be controlled within the minimum of time. An iron salt seemed to be a desirable peptizing agent both from the standpoint of economy and because of the heavier precipitate formed by its reaction. The same considerations would apply to the use of the peptizing agent as applied in the formation of the hydrous alumina-namely, that the anion of the salt must have as little coagulating power as possible. This essentially limited the peptizing agent to either ferric chloride or the ferric nitrate, and economy considerations still further limited the choice to ferric chloride. It may be argued that the use of chloride anions in place of sulfate anions weakens the coagulating power of the finished material. The coagulating power of the anions, however, is of secondary importance compared to that of the trivalent metallic ions, and the complexities of reaction of the sulfate coagulants overshadow any advantages possessed by the sulfate anions. N a t u r e and Properties of Ferric A l u m i n a
The material which has been named “Ferric Alumina” is essentially a colloidal sol of hydrous alumina peptized by the addition of ferric chloride. The hydrous alumina is formed by exactly neutralizing an acid and an alkali aluminum salt as mentioned in the foregoing paragraphs. After washing, the precipitate is mixed with ferric chloride to give a ratio of 1 part of aluminum to 3 parts of iron, or it can be made in various proportions. It can be made in various proportions of aluminum to iron, depending upon whether it is to be used as a coagulant in water softening or filtration and as to whether it is desirable to increase or decrease the pH of the residual water. The aluminum, being pre-precipitated, is not subject to the vagaries of reaction common to aluminum salts. The ferric chloride acting as a protector exists in a very unstable form and reaction is thus obtained with unusual ease. Inasmuch as only part of the positive ions are coupled with negative radicals, the alkalinity requirements for reaction are exceptionally low. If the mol equivalents of aluminum to iron are balanced, the material wilI allow precipitation at virtually any pH common to water treatment and in spite of any inhibitive colloids present. This is readily explainable since reaction of the ferric chloride releases the aluminum colloid, which being amphoteric takes an electric charge o p posed to that of the iron colloid; and if the two are balanced the charges are neutralized and the isoelectric point of coagulation is obtained between the two coagulating colloids, allowing agglomeration to take place independent of inhibitive factors. Results Accomplished w i t h Ferric A l u m i n a
As a concrete example of the results obtained with this material, we might consider the case of a large corn-products
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plant in the Middle West, where a river water is used that has appreciable colored colloidal contamination, and where this same water is used to cool the product before it is clarified. At certain periods leaks have developed which have allowed dextrins and sugars to enter the river water prior to clarification. When the water is free from contamination other than that present in the river, it is found that 2.5 to 3.5 grains of alum are required for coagulation, and the isoelectric point is normally at approximately pH 6.4. Any contamination from the process is immediately noted, since the isoelectric point of coagulation swerves sharply to the acid side and the required alum dosage is greatly increased. Virtually no coagulum formation is obtained if the alum dosage is insufficient to bring the water to the isoelectric point. When the Ferric Alumina is used as a coagulant, it is found that from 1 to 1.5 grains of the material are sufficient to effect satisfactory coagulation and that process contamination does not materially increase the amount of material required. It has further been observed that coagulation is obtained a t virtually the pH at which the water is found in the river, which varies from 6.8 to 7.4, and the optimum zone of coagulation is not altered by the presence of process contamination. Another illustration is the water at the city filtration plant at East Chicago, Ind., where the water is drawn from Lake Michigan. This water is contaminated by various trade wastes from surrounding industries, and the amount and type of contamination is extremely varied. When alum is used as a coagulant, the fluctuations of the isoelectric point are so violent and rapid that it is extremely difficult to adjust the dosage to obtain adequate coagulation at all times. The use of sodium aluminate in conjunction with the alum has increased materially the efficiency of operation in this plant, but it is still found that the dosage must be varied from day to day to meet the fluctuations in the quality of the water. The dosage of alum has varied from 1.5 to as high as 4.5 grains, and the dosage of sodium aluminate from a minimum of 0.3 to a maximum of 1 grain per gallon. Tests with Ferric Alumina have demonstrated that this material will adequately coagulate the water with a fluctuation varying between l and 1.5 grains per gallon. L i t e r a t u r e Cited Chtistman, Am. Water Works Assocn., 1917 Convention. Hatfield, J. Am. Water Works Assocn., 11, 554 (1924). Miller, Pub. Health Regts., 40, 351 (1926). Moberg, U. S. Patent 1,679,777. Theriault and Clark, Pub. Health Repts., 38, 181 (1923). ~~
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How to Flame-Proof Fabric A report published in the British Fire Prevention Committee Red Books, Nos. 128, 148, 159, 162, 167, and 245, outlines the method generally known as non-flame process which gives good fire-retardant effect and has the further merit that this effect remains after the material has been subjected to washing or the weather. In tests made by the British Fire Prevention Committee, flannelettes were found t o have been little changed after twenty washings. The process consists in steeping the cloth in a solution of 3 pounds of sodium stannate per gallon of water (sp. gr. 1.21). After wringirfg and drying it is passed through a solution of l l / p pounds of ammonium sulfate per gallon of water used (sp. gr. 1.07). After wringing and drying it is rinsed several times in running water and finally dried. A less permanent treatment can be made by subjecting the cloth to a solution consisting of 2 pounds of ammonium sulfate and 4 pounds of ammonium chloride (sal ammoniac) in 3 gallons of water. Sodium silicate is fairly effective for interior decorations where change of color or luster is not important. For this purpose 1 volume of commercial water glass (1.39 sp. gr.) is diluted with 1 to 5 volumes of water, depending upon the kind of fabric and the degree of fire-retardant effect desired.
