INDUSTRIAL AiYD ENGINEERING CHEMISTRY
November, 192i
The materials giving values above 60 are given in the following paragraphs: Between 60 a n d 75: Pseudo-cumol, menthol, furfural, hexalin, borneol, dekalin, iodobenzene, carbazole, pyromucic acid, diphenylhydrazine (0.75 per cent), trioxymethylene, dimethylaniline. Between 75 and 100: 9-dibromobenzene, diethylnitrosoamine, pine oil, camphor, hexamethylenetetramine, anethole, pyrogallol, oleic acid, fluorobenzene, dimethylglyoxime, tetralin, benzene azo-8-naphthol, oil blue, eucalyptol, acetone extract of crude rubber, glycocoll, phenetole, diphenyl, P-iodophenol, a-picoline, furoin, benzaldehyde, amyl fluoride, piperidine, hydrazine sulfate, oenanthol. Between 100 and 150: Erythrosin, geraniol, iodol, triaminophenol hydrochloride, safrol, nicotine, vanillin, triphenylmethane, aceto-toluide. citronella, P-dichlorobenzene, oil orange, succinimide, eugenol, p-iodoaniline, isoquinoline, sudan 111, diphenylamine, guaiacol, mesitylene, piperonal, diphenylhydrazine hydrochloride, 9-aminomethyl-m-cresol hydrochloride, pyridine, carvacrol, anthraquinone, p-anisidine, acetanilide, naphthalene, methyl-o-aminophenol 4- hydroquinone, methylphenylhydrazine, furfuramide, tin salt of m-aminodimethylaniline, spirit scarlet, anisole, lemon oil, p-aminoanthraquinone, ethyl hippurate, acetamide, dicyanodiamine, methyl a-naphthylamine, antipyrine, quinoline, oil yellow, trichloroquinone. Between 150 and 200: Oil savin, aminoisoquinoline, ethyl a-naphthylamine, cyclo hexane, asparagine, galactose, oil red, aniline, diethylamine, thiosemicarbazide, oxyquinoline, dibenzalhydrazine, eugenol methyl ether, oxamide, phenyl acetanilide, m-aminophenol, cresol methyl ether, lead oleate, rhodamine B, p-nitrophenol, urea, hydrazobenzene, p-toluidine, 8naphthol, phenylpyrazolone. Between 200 and 300: Cottonseed oil, 9-chlorotoluene, 0- and p-chlorotoluenes, casein, phenanthrene, acid fuchsin, diethyl selenide, allylphenyl thiocarbamide, aceto-p-phenylene diamine, m-diamidoazobenzene, dichloroquinone, eosin, a-naphthoquinone, aluminum hydroxide, tribenzylamine, n-butyramide, p-nitrotoluene, benzoquinone, benzeneazophenol, xylidine, a-naphthol, a-naphthylamine, brucine, oxanilide, benzothiazole disulfide, carhanilide, o-ditolyl thiourea, m-cresol, lead tetraphenyl. Between 300 and 400: Cyanine, benzaldoxime, hydrobenzamide, phenyl a-naphthylamine, 0-naphthylamine, phenols from crude anthracene, methylene iodide, diphenyl thiourea, indigo, hydroquinone, anthranilic acid, bromophthalimide, dioxy-p-methyl coumarin, dimethylaminoazobenzene.
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Between 400 a n d 500: Dimethyl ammonium dimethyl dithiocarbamate, 9-methyl aminophenol ‘sulfate, P-phenylene diamine, glucose, benzidine, phenanthraquinone, Bismark brown, dinitrophenol, p-aminophenol, pyrocatechol. 9-ditolyl thiourea, safranine, diamylamine hydrobromide.
Summary and Conclusion
Of the total number of substances used in these two tests, 177 in all, 48 have shown themselres capable of having an inhibitory action on sludge formation. The remainder have either comparatively little effect, or else accelerate the reaction, the majority being in the second category. Of those having the greatest inhibitory effect, there are three which stand alone: sulfur, nitrocresol, and nitrobenzene. It seems to be quite impossible to draw any generalized conclusions from the results, as to the types of compounds which act as antioxidants, since for every compound which acts as a negative catalyst one of the same type can readily be discovered which acts as a positive catalyst. The action seems to be specific, and not to follow any general rules by means of which the effect of any particular substance might be predicted. These results refer only to the definite stated conditions of experimentation, and their extension to other conditions is liable to lead to erroneous conclusions. Acknowledgment
Thanks are due the Tide Water Oil Company for samples used in Part A and for permission to publish some of the results, the Edison Illuminating Company of Boston for the samples used in Part B, and the Standard Oil Company of New Jersey for permission t o publish the results of Part C.
Clarification of Starch Conversion Liquors in Manufacture of Corn Sugar and Corn Sirup’ Improved Method By M. S. Badollet and H. S. Paine CARBOHYDRATE D I V I S I O N , BLlRfAU OF CHEMISTRY AND
I
N THE usus1 process for the manufacture of corn sirup
and corn sugar sodium carbonate is added to the acid starch conversion liquor to reduce the acidity and cause flocculation of some of the colloidal material. In a previous investigation2 the maximum flocculation of colloids in the acid “converter liquor” was obtained by regulating the addition of sodium carbonate until the isoelectric point was reached as determined by ultra-microscopic cataphoresis measurements. It was noticed that even a t the isoelectric point addition of sodium carbonate did not remove all the colloidal material and that after filtration the filtrate became turbid after standing for some time. Further observations showed that this turbidity occurred frequently, suggesting that clarification by the use of sodium carbonate done is relatively inefficient. An attempt was made, therefore, to devise a method whereby a greater proportion of the colloidal material in acid starch conversion liquors could be flocculated and eliminated. Theory
A systematic study of a number of samples of starch conyersion liquors obtained from several manufacturers of corn 1 Presented before t h e joint session of the Divisions of Sugar Chemistry a n d Industrial a n d Engineering Chemistry a t the 73d Meeting of t h e .4merican Chemical Society, Richmond, Va., April 11 t o 16, 1927. * Paine and Badollet Facts Aboul S u g a r , 21, 1212 (19261
SOILS,
~ ~ A S H I N G T D. O Nc. ,
sugar and corn sirup revealed the fact that the colloid particles present in acid conversion liquors invariably carry a positive electric charge, whereas the colloids present in most sugar liquors, as well as in most aqueous suspensions, bear a negative charge. The positive charge is probably due to the unusually high hydrogen-ion concentration of the conversion liquor. When this acidity is reduced by addition of sodium carbonate this positive electric charge is reduced until the isoelectric point is reached, where the electric charge on the colloid particles is completely neutralized. This results in flocculation of a large part of the colloidal material but not necessarily all of it as shown by ultra-filtration tests. Since the colloid particles of the acid conversion liquor carry a positive electric charge, it was assumed that certain colloidal clays and earths, as well as other types of colloids which bear a negative charge a t the hydrogen-ion concentration of acid starch conversion liquors, would produce mutual colloid flocculation with the colloids of the conversion liquor and might thus cause greater colloid flocculation and elimination than sodium carbonate alone. Sodium carbonate would, of course, also be necessary, as a t present, in order to reduce the acidity of the starch conversion liquor. Such materials as bentonite, colloidal aluminates (sodium aluminate and calcium aluminate produced by fusion of sodium carbonate or lime with aluminum oxide were studied
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INDUSTRIAL AND ENGINEERING CHEMISTRY
especially), colloidal alkaline compounds of iron, silicates of aluminum, etc., in aqueous dispersion were found to give a n excellent flocculation and elimination of the colloidal material present in “converter liquor.” Also, such substances as bauxite or pure aluminum oxide, when dispersed in an alkaline medium, caused a more voluminous flocculation of colloids than sodium carbonate alone. This scheme of treatment was given a thorough test and was found to give satisfactory results.
may influence the character, and consequently the behavior of the colloidal material. Table I-Clarification of Starch Conversion Liquors (Data based on 100-cc. sample of each converter liquor) BENTONITE AND NazCOs INCREASE IN NazC03 ALONE Bentonite re- COLLOID ELIMpH at quired to reach INATION BY CONVERTERWeight isoelectric Weight isoelectric BENTONITE LIQUOR^ dry ppt.b pointc dry ppt.d point OVER NaiCOl Gram Gram Gram Per cent
Experimental
The colloidal clay bentonite, when dispersed in an aqueous medium, is negatively charged even a t high hydrogen-ion concentrations. An aqueous suspension of this clay was added to a portion of “converter liquor” and tested ultramicroscopically in a cataphoresis cell. Bentonite suspension Note-The apparatus required can be assembled readily and is described clsewhere.8 Because of the electroosmotic movement of an aqueous solution i n a capillary tube, in order to measure the true speed of the colloid particles i t is desirable to focus the microscope at a point in the capillary at which the electroosmotic movement of the liquid is nil. This point, as found by Mattson, is obtained by focusing at a distance of 0.293 X r (Y = radius of capillary) bslow the upper wall of the capillary.
was added until the isoelectric point was reached, as noted by the colloid particles failing to move progressively toward either electrode when under a given potential gradient. The copious flocs could be removed readily by centrifuging, sedimenting, or filtering. The resulting liquor was clear and sparkling. The acidity of the liquor clarified with bentonite may be subsequently reduced by the addition of sodium carbonate to adjust it to the p H value most suitable for the bone char filtration. When bentonite was used as a preliminary clarifying agent and was then followed (after filtration) by sodium carbonate there was a tendency for a milky turbidity to be produced a t a pH of 5.0 or higher. At p H values lower than this no turbidity resulted from subsequent use of sodium carbonate and no additional filtration was necessary. Sodium Carbonate us. Bentonite as Clarifying Agents
Table I gives a comparison of results obtained in “converter liquor” clarifications by the two methods-sodium carbonate alone as now customarily used and a new method using bentonite and sodium carbonate as suggested by the authors. When bentonite or similar material is used in addition to sodium carbonate the function of the latter is solely to reduce the acidity. When sodium carbonate is used alone it not only reduces acidity but also causes some colloid flocculation. The samples represent liquors obtained from different factories under actual manufacturing conditions. In every case the bentonite clarification gave a greater flocculation after correcting for the weight of bentonite present in the precipitate than did the customary sodium carbonate procedure, even when the sodium carbonate neutralization was adjusted to the isoelectric point. The difference in weight of the dried flocculated precipitates obtained by the two procedures is expressed as per cent increase over the weight obtained by sodium carbonate clarification. The increase in weight of flocculated precipitate for bentonite clarification over that obtained by sodium carbonate clarification varied from 3 to 258 per cent. This increase was greater for converter liquors in the corn sugar process than for those intended for production of corn sirup. I n fact with the corn sirup the advantage in favor of bentonite was small. Further data are required to determine the extent and cause of this difference in behavior. Possibly the longer conversion period used in the production of corn sugar 8
Badollet and Paine, Intern. Sugar J . . PS, 23,97, 137 (1926).
Vol. 19, No. 11
CORN SIRUP MANUFACTURE
1 2 3
0.396 0.162 0.464
4.96 5.29 4.08
0,430 0.182 0.476
0.28 0.01 0.22
9 12
3
CORN SUQAR MANUSACTURB
0.016 3.44 0.028 0.05 75 0.152 4.40 0.175 0.15 15 0.272 4.31 0,975 0.21 258 0.083 4.21 0.226 0.03 172 0.415 4.47 0.521 0.26 26 0.177 4.23 0,222 0.18 25 a The density of the converter liquors corresponded to 18’ Be., those of somewhat higher density having been diluted to this point. b Converter liquor adjusted to isoelectric point by the addition of NazCOa alone. c pH measurements were made electrometrically by use of the quinhydrone electrode. d Converter liquor adjusted to isoelectric point by addition of bentonite alone. The values given in this column are corrected for the weights of bentonite in the precipitate and therefore represent the actual dry weight of precipitate produced. 4 5 6 7 8 9
By calculating the proportion of bentonite on the basis of pounds of dry substance per thousand gallons of converter liquor, it is found that 0.8 pound of bentonite is required for clarification of sample 2 and 23.3 pounds for sample 1. These examples show the two extreme proportions of bentonite required for clarification of the liquors so far investigated. Although sample 1 required the largest proportion of bentonite, it did not show the greatest percentage of colloid elimination, because the samples of converter liquor examined were produced in different factories and under different conditions as to colloid contamination of the starch used, hydrogen-ion concentration of the converter liquors, etc. The comparison between the weights of dried precipitate produced by sodium carbonate and by bentonite show conclusively that bentonite is the better clarifying agent. When bentonite is added to converter liquor in the correct proportion the colloidal material also flocculates and settles more rapidly than when the converter liquor is adjusted to the isoelectric point with sodium carbonate. This is an advantage in that, even with ordinary methods of control and without using an ultra-microscopic cataphoresis apparatus, the liquor can be adjusted more closely to the isoelectric point by using bentonite than by using sodium carbonate. This has a distinct value in operating practice, since “overneutralization,” which would tend to redisperse the colloidal material, is more likely to take place when sodium carbonate alone is used. The method of clarifying acid starch conversion liquor suggested in this paper prepares the liquor better for treatment with bone char or other activated carbon than is accomplished by the customary treatment with sodium carbonate alone, thus tending t o reduce the rate of exhaustion of the carbon. If it be assumed that the colloidal material eliminated by bentonite and not by sodium carbonate would in any event be removed by the subsequent carbon treatment, then the possible commercial advantage in using bentonite clarification could be determined by comparing its cost with the saving effected by the increase in the period of use of the carbon before revivification is required. Sodium aluminate, which produces an effect similar to that of bentonite, is already in use with satisfactory results in the manufacture of corn sugar and corn sirup.‘ 4
Verbal communication to the authors.
