570
INDUSTRIAL A N D ENGINEERING CHEMISTRY
The compact cake formed as the result of using a duwasing aid
h more rugged and more easily washed with propane than the wax cake obtained without an aid. The filtering characteristics described above can be explained on the basis of the characteristics of the wax crystals present which, in turn, are determined by the amount of dewaxing aid present. The decrease in size and increase in density of the wax crystal clusters account for the changes in filter rate and character of the cake. It is well known that filter rate is dependent on uniformity of particle size as well tts on the actual average size. Maximum rates are obtained when the wax crystallizes into particles of maximum size mith a minimum of size variation. WITH OTHER DEWAXIXG AIDS. Several different maaterials were tried as dewaxing aids in the paraffin distillates. Those which posseszed any wax-modifying power produced the same general changes in %-axstructure as did the asphalt, so t>hatthe photomicrographs shonTn illustrate the structures obtained n-ith all the active wax modifiers invest,igated. However, the concentration of dewaxing aid required to produce a given degree of modification varied widely among the different materials. In an attempt to isolate an oil-free wax modifier, a sample of asphalt was separated into a butane-solublc and a butanc-insoluble portion (at 30" C., 86" F . ) j and the two portions were tested as dewaxing aids. Both were effective dewaxing aids, but the insoluble portion appeared to be the more effective. The butane-insoluble portion was sufficiently soluble in the propaneoil solution, ho-ivever, t o affect adversely the color of the demaxed oil: hence it had no material advantage over the original sample. h sample of cracking-coil tar (obt,aincd from a coil and tank unit) was also examined as a dewaxing aid. I t possessed crystalmodifying properties, but was inferior to asphalt because of excessive quantities (above 4.0T0) required to produce a marked degree of m-ax modification. A sample of asphalt that had been b l o m with air a t an elevated temperature was found to have little or no wax-modifying properties. Paraflow (a high-molecular-Feighb polymer used commercially as a pour depressant for lubricating oils) was also examined as a crystal modifier and it was found t o produce results similar to those produced by asphalt. Ilowever, only about one fifth as much Paraflow as asphalt was required for a given amount of crystal modification. Paraflow has two distinct advantages over asphalt: (I) It affords a higher filter rate for a given amount of crystal modification. This may result, a t least partially, from thc fact that no resinous particles, similar to those always present in asphalt-aided batches, are
VOL
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formed at any stage of thi. chiliirig perivd. ',2) It has a relatively light color and therefore does not adversely affect the color of the deffaxed oil. It has the disadvantage, however, of being relatively expensive. It was thought that small solid particles might serve as nuclei (similar to the wax nuclei previously described) about which wax would precipitate. h fincly divided solid substance, insoluble in propane and possessing niodifying properties, would be desirable as a dexwxing aid in that it would be filtered with the petrolatum arid hence would h a w no adverse effect on the color of the dewxed oil. Crushed cracking-coil coke and commercial lampblack were investigated for this purpose. but were found to possess no crystal-modifying properties. The cracking-coil coke particle size varied approximately from 3 to 30 microns, the average being about 10 microns. The lanipblack particle size was somewhat, smaller. W A X FROM A MEDIUM MOTOR OIL DISTILLATE
A study similar to that just described was also carried out on L rnid-cont,inent medium motor oil distillate. T e s t data on this stock are shown in Table I. The general effect of dem-axing aids on motor oil was observed to be the 8ame as t,hut on paraffin distillate, but, presumably because of the presence of entrained residuum, smaller additional quantities of aid were required t o obtain the same degree of wax modification. The wax precipitated from medium motor oil was very sticky (as indicated by its tendency to stick to the observation window in the cold stage), especially during the early part of the chilling period, whereas the wax from paraffin distillate did not pass through a sticky stage. The crystals precipitated from motor oil iwre about, one third to one half the size of those precipitated under similar conditions from paraffin distillate. ACKNOWLEDGMENT
The authors wish to acknowledge the assistance and cooperation of J. B. Beaugh during the course of this investigation. Appreciation is also expressed to the Humble Oil & Refining Company for permission to publish this x-ork. LITERATIIRE CITED
(I) Anderson, A. I?., and Talley, S. K., IND.E N GGEEX., ~ 29, 484 (1937). RECEIVEDDecember 6 , lY-47. Presented hefore t h e Third Southwest Regional l l c c t i n p of the Avertrcnh' (:NERIICAL SOCIGTP,Houston, Tex., Decem. her 12 and 18, 1947.
H. L. JIITCHELL, R., G. SCNREXIQ, AND H. H. KIN(; Kansas Agricultural Experiment Station, Manhattan, Kan. Experiments were performed on several finely ground solids to determine their effectiveness as carriers for preparation of solid carotene concentrates. Results of experiments show that use of less highly refined carriers resulted in a more stable concentrate. Of the carriers tested, cottonseed meal had the greatest stabilizing effect.
D
URING World War I1 much consideration was given to the preparation of carotene concentrates from plant materials a means of augmenting the short supply of vitamin A obtained
from fish oils. In general, the concentrates were prepared by dissolving the extracted plant lipides in edible oils such as soybean and cottonseed oils. However, the carotene of such concentrates was destroyed during storage. By storing a t lorn ternperatures (IO)or by adding certain antioxidants ( d ) the stability of the carotene in such concentrates was increased. Carotene concentrates are still of much interest because of the continued shortage and increased cost of fish oils. To facilitate the incorporation of such concentrates into the rations of farm animals, it perhaps would be more desirable to prepare solid,
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
March 1949
I
( I
'
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0
1
,
2
I
3
STORAX
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4 T I M E IN
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5
8
MONTHS.
7 25%.
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antioxidants in the carriers which supplemented those already present in the alfalfa extract. The stability imparted by the soybean meal used in this study appeared to be considerably less than that reported by Morgal et al. ( 7 ) , who found only 4 to 19% destruction in 169 days a t room temperature. However, their concentrates contained much less carotene, 60,000 International Units per pound as compared with about 700,000 I.U. in the concentrates used in these experiments. Hence, a strict comparison should not be made, for Bickoff and Williams ( 1 ) have reported that increasing the concentration of carotene in their solid concentrates resulted in decreased stability of the carotene. Of the carriers tested, cottonseed meal had the greatest stabilizing effect. This may be due partially to the presence of a small amount of gossypol, which functions' as an antioxidant when added t o oils (3,4, 9). A study now in progress indicates that different lots of cottonseed meal may vary considerably in their stabilizing action. Such variations in stability also may be due partially to the use of different carotene extracts.
Figure 1. Effect of Carrier on Stability of Solid, FreeFlowing Carotene Concentrates, Stored a t 25" C. I,
glucose; 2, etarch; 3, sorghum bran; 4, casein; 5, BOYbean meal; 6, ground sorghum grain; 7, cottonseed meal
freeflowing concentrates than those of semiliquid character. Invesligations on the use of finely ground solids as carriers for carotene extracts have not been extensive. Morgal, Byers, and Miller (7) studied the stability of carotene extracts on soybean Bour. Mitchell and Lease (6) investigated the use of sweet potato flour as a carrier. Bickoff and Williams ( 1 ) used rice bran, oat flour, whole wheat flour, and powdered potato as carriers. The experiments herein recorded were performed to determine the behavior of several such materials when used as carriers for the preparation of solid carotene concentrates. STABILITY OF SOLID CONCENTRATES
Three kilograms of dehydrated alfalfa meal were stirred for 1 or 2 hours with 10 liters of Skellysolve B. The solvent was filtered off and the residue was washed twice on a Ruchner funnel with fresh Skellysolve B. This procedure removed about 85% of the carotene of the meal. The chloro hylls and xanthophylls were removed by a procedure to be pubfshed later, and the resulting carotene solution was concentrated on a steam plate to a volume of 1 liter. The carotene concentration of the solution was determined spectrophotometrically according to the procedure of Silker, Schrenk, and King (8). The following carriers were used in preparing the solid concentrates: sorghum starch (Blackhull variety), glucose (Cerelose), crude casein, cottonseed meal (feed-grade containing 41 % protein), soybean meal (44% rotein), ground sorghum grain (Blackhull), and sorghum bran (€?lackhull). The desired amounts of the carotene solution were placed in a series of 600-ml. beakers and most of the Skellysolve B was driven off on the steam plate. Seventy grams of the carrier were added to one of the beakers and the contents were stirred thoroughly to djstribute the carotene and fatty materials uniformly on the carrier. Each concentrate thus prepared was transferred to a sheet of paper, thoroughly blended with a spatula, and placed in a dark cabinet for a few hours to permit evaporation of any Skellysolve B that still remained. The concentrates were then laced in 2ounce screw-ca bottles and were stored a t 25 O C. &e carotene content of eacE concentrate was determined b the method of Silker, Schrenk, and King (8) at the time o?storage and a t , monthly intervals thereafter, the readings being made at 4360 A. with a Beckman spectrophotometer. Each concentrate contained approximately 950 micrograms of carotene per gram a t the beginning of storage. The results of the experiment are presented in Figure 1. The type of carrier had a considerable influence on the stability of the carotene of the concentrate. Glucose and sorghum starch permitted most rapid destruction of carotene, owing probably to the lack of antioxidants which were removed during preparation or purification. The use of less highly refined carriers resulted In a more stable concentrate. This suggests the presence of
571
ADDITION OF ANTIOXIDANTS AND SYNERGISTS
Since cottonseed meal exerted an appreciable stabilizing effect, it was thought that this might be enhanced profitably by the addition of antioxidants or synergists. Concentrates were prepared which contained the following materials in addition t o the cottonseed meal and alfalfa extract: Sample 1. Nothing added Sample 2 . 0.1 % natural mised tocopherols Sample 3. 2% soybean lecithin Sample 4. 2% lactic acid Sample 5. 2% lecithin and 2% lactic acid Sample 6. 0.1% tocopherols, 2% lecithin, and 2% lactic acid Lactic acid was included in part of these concentrates because Mitchell, Schrenk, and King (6) found that this acid, when sprayed on alfalfa meal, had an appreciable stabilizing effect OD the carotene during subsequent storage. The tocopherols and the lecithin were dissolved in Skelly. solve B and were added to the carotene solution. This was concentrated and mixed on the meal as previously described. The lactic acid was added by diluting 2 ml. of 85% acid with 18 ml. of water and mixing thoroughly with 100 grams of meal. The desired carotene solution was then added. The samples were stored in 4-ounce bottles a t 28" C. and were analyzed a t monthly intervals. The results are shown in Table I. The addition of tocopherols did not increase the stability of the concentrate. The same result has been reported for tocopherols added to carotene in vegetable oils ( 2 , 7 ) , and is apparently a result of the fact that vegetable oils already contain sufficient tocopherols to exert their maximum influence. The addition of lecithin reduced carotene destruction to 62% in 6 months, while lactic acid reduced destruction to 54%. These values are to be compared with 70% destruction in the control sample. Lactic acid thus had a greater synergistic effect with the antioxidants in the cottonseed meal than did lecithin. The addition of lecithin with the lactic acid did not improve the effect of lactic acid (Sample 5 ) . Likewise, the addition of tocopherols to those synergists did not improve their effectiveness (Sample 6).
TABLE I. EFFECT OF VARIOUS MATERIALS ON THE STABILITY OR CAROTENE CONCENTRATES EMPLOYING COTTONSEED MEALAS A CARRIER
Sample NO. 1 2 3 4 5 0
(Storage temperature, 25' C.) Material Added Carotene Destruction, % t o Meal 1 mo. 2 mo. 3 mo. 4 mo. 6 mo. None 12.6 27.6 38.7 53.9 69.7 Tocopherol 17.5 26.3 37.6 59.4 77.0 Lecithin 9.0 24.7 33.1 46.2 62.0 Lactic acid 14.3 28.9 30.0 44.8 53.7 Lecithinandlacticacid 12.1 27.1 30.0 44.6 53.5 Lecithin, tooopherol, a n d lactic acid 7.7 20.4 29.0 42.2 52.2
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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 41, No. 3
LITERATURE ClTEli
SUAW\\IARY
Several materials were investigated to determine their effect on carotene stability when used as carriers for the preparation of solid, free-flowing carotene concentrates. Glucose and sorghum starch had the least stabilizing effect, the carotene being destroyed completely in 5 months a t 25 ' C. The use of soybean and cottonseed meals resulted in much more stable concentrates, carotene losses being 68 and 6OyG,, respectively, in 5 months. Casrin, ground sorghum grain, and sorghum bran had an intermediate effect, the carotene losses ranging from 72 to 81% in 5 months. The antioxidant action of cottonseed meal was appreciably increased by the addition of 2y0 of lactic acid. Lecithin had only a slight effect. A combination of lactic acid and lecithin was no better than lactic acid alone. Tocopherols, added alone or with lecithin and lactic arid, had no beneficial effect on thr stability of csrotenr in the concentrate. ACKNOV, LEDGMEhT
The authors are indebted to the W. J. Small Company, Inc., Kansas City, &Io., for the alfalfa meal used in preparing tht, carotene extract for these experiments.
(1)
Bickoff, E., and Willianis, K . T . , IND.EN(;,CIHFM., 36, 320
(2)
Bickoff, E., Williams, K. T . , and Sparks, M., Oil R. S o a p , 22,
(8)
Hove, E. L., J . Bid. Chem., 156, 633 (1944).
(1944).
128 (1945). (4) Mattill. H. A., Ibid.; 90, 141 (1931). ( 5 ) Mitchell, H. L., Schrenk. W.G., arid Kiiig, W . W..A?,ch.Riodiem., 16, 343 (1948). (6) Mitohell, J. H., and Lease, E . J., 9. ('arolina -407.E'zpl. Sto. Bull. 333, 3-8 (1941). (7) Morgal, P. W., Byers, 1,. W., and Miller, E. J., IND. ESQ. CHEM., 35, 794 (1943). (8) Silker, IC. E., Schrenk, IT. G., and King, H. H., 1x1). ENU. CHEW.,ANAL.ED.,1 6 , 5 1 3 (1944). (9) Smith, F. H., Brady, D. E..and Camstock, R.. E., IND.NNO. &EM., 37, 1206 (194.5). (:lo) Wall, M. E., and Kelley, E. G., Ibid., 38, 215 (1946). R B C R I V E D February o, 1948. Contribution S o . 380, Department of Cheniistry, Kansas State College. This ~ r o r l i w a p s i i i ~ i i u r t e dh y t h e KanHas Indiistrial Deat.lopmcnt Commi-sion.
SYSTEMS WITH rn- OR p-C ESOL AS ONE CORIPONENT DONALD F. ((BTH3IER, SIDNEY A. SAVITT, ALFRED ICKASNER. ALAS 11. GOLDBERG, AND DAVID 3IARKOWITZ Polytechnic Znstitute of Brooklyn, Brooklyn, iV. Y .
second conlponerits were kindly supplied by the Carbide and Carbon Chemicals Corporation and the last five by the Hoppers Company These companies also supplied data on vapor pressures of their respective materials; these data were used for the subsequent calculation of activity c o e f f i c i e n t s . The liquids were then fractionated to recover substantially ronstant boiling fractions. Analyses were in every case made by measurement of refractive indexes at 30" C. (except for @-methylnaphthalene which was a t 40' C.). As the melting point of p-cresol is 34.7 O C., most of the composition ranges were liquid a t 30' C. Graphs vere previously prepared from measurements of the refractive indexes of ten or more synthetic mixtures of each binary of known composition.
Vapor-liquid equilibrium data w-ere determined using methods previously described for systems having either n-or p-cresol as one of the components. The second components were a-ethylnaphthalene, @-methylnaphthalene,@-isopropylnaphthalene, diisopropylnaphthalene, am>lnaphthalene, ethylene glycol, diethylene glycol, acetonyl acetone, glycol diacetate, ethylhexoic acid, Carbitol, methyl Carbitol, diethyl Carbitol, and tetradecanol. From a study of activity coefficient plots made from the experiniental data for these 28 binary systems, it was shown that the second component could not be used as a separating agent for m- and p-cresols from their mixtures by either azeotropic or extractive distillation.
a
HE boiling point, o i rri-cresol \vas determined t,o lie 202.4" C. and of p-cresol to be 202.0' C., while the respective boiling points have been accepted ( 4 ) as 202.2' and 202.1" C. Because of the closeness of these boiling points and the similarity
of other physical and chemical properties of these isomers, the eeparation of t,heir commercially occurring mixture is very difficult. Twenty-eight binary systems containing either nt- or p-cresol were studied a t atmospheric pressure by methods previously described @), although data for some of the systems were obtained in a more recently developed still (3). The other liquids (second component,s of the binary solutions) and their boiling points as determined and as report,ed in the literature are given in Table I. All of these materials were tho purest commercially available. The m- and p-cresol were supplied by the Barrett Division of Allied Chemical and Dye Corporation. These were distilled, fractionated, and dried over calcium chloride. The boiling points give indication of freedom from other impurities; and the specifications indicated a purity of 98 to 100%. The first, nine of the
T-LBLE I Literature Carbitola 195.0 Methyl Carbitol" 194.2 Diethyl Carbitoiu 187.9 Ethylene glyco! 197.2 Diethylene glycol 245.0 Glycol diaoetate 190.5 .4oetonyl acetone 192.2 a
Determined 195.0 194.2 188.9 197.2 244.1 180.5 192.2
2-Ethylhexoio aoid (octoio aoid) Tetradecanal a-Ethylnaphthalene ,9-i\lothy!naphthalenc 8-Isopropylnaphthalene biisouronylnaphthalene 8-Amylnaphthalane (penbalene 103) Carbitol = 2-(2-etboxyethoxy) ethanol. *
Literatura Uetermined 226.0 264.1 258
227.0 260.0 254.2 241,Z 2 4 1 . 1 266 266.5 302 306.0 288292.3 292 ,,,
