DUPLICATING INDUSTRIAL PROCESSES IN THE SCHOOL LABORATORY DONALD D. DORRE McCook Junior College, McCook, Nebraska WILLIAM L. DUNN Colorado State College of Education, Greeley, Colorado
1. Sugar from Sugar Beets
or divided watch glass, wash a beet in cold water, using a brush if necessary to remove dirt that will discolor the final product. Quarter the beet and prepare about INTEREST in the general chemistry laboratory work 500 g. of cossettes using a vegetable grater with can be stimulated to a marked degree by using industrial inch openings,t ~~~y~~~ or bruising the beets processes, adapted to a laboratory scale, to illustrate increase the impurities obtained in the diffusion juice. the principles and reactions which are being studied. place half of the cossettes in the beaker of distilled Several such experiments have been published (1, 3,8, water a t 80°C. (Hang a thermometer through the hole 4, 6). Three more manufacturing procedures have in the cover.) Heat the suspension of cossettes to now been worked out, using readily available materials $ 0 0 ~ .and maintain this temperature,&ring fiefound in most general chemistry laboratories. One of quently with a heavy stirring rod. ~ i tempera~ h these is presented here. The other two will be pub- tures will result in greater cell decomposition, giving a lished separately. diffusion juice of lower purity. After thirty minutes In a beet sugar factory, the beets are first washed and of heating, decant the juice through a small sackx then cut intolong, narrow s h e s (cassettes) which are supported by a ring on a ring stand. Finally, transfer approximately trough-shaped. The sugar is then the cossettes to the sack and squeeze or twist slightly removed from the beets by diffusion: Impurities in the to remove more juice. Discard the used cassettes diiusion juice are removed by a series of steps including and add the remainder of thecassettes to the the addition of a calcium hydroxide suspension, which diffusion juia. Repeat tiie process with these new precipitates certain impurities, precipitation of the cosset~es, calcium ion with carbon dioxide, and filtration to ~~k~ a slurry of 13 g. of calcium hydroxide in 45 remove the precipitated calcium carbonate and inof distilled waterand add to the diffusion juice soluble impurities. Sulfur dioxide is then added to the with stirring, keeping the juice at about 800 c.4 juice to bleach i t and to lower the pH of the solution. carbon dioxide from a cylind&or laboratory generaEvaporation to a thick juice is acc mplished by the tor is bubbled through the juice and slurry at 8 0 0 ~ . use of multiple effect evaporators, an the find -poi-aA, even flow of gas is desirable, and the glass delivery tion step and crystallization of the sugar takes place in tube, attached to the source of supply by means of a large pans maintained under reduced pressure. rubber hose, should reach almost to the bottom of the Duplication of this process on a Small scale has been beaker. It may also be used as a stirrer. Remove the described in the literature (6), but the directions, delivery tube occasionally and note the tendency of the ~ublishedin Geman, are not readily available and are ~recipitateto settle to the bottom of the beaker. The inadequate in their detail. The Process here de- cirbonation should be stopped as soon as the precipitate scribed is based upon the results of numerous trials ~ 1 settle 1 quick]y. After allowing the precipitate to before using i t in the general chemistry laboratory settle, filters through a rapid filter paper in a large work. Several classes a t Colorado State College of ribbed funnel. ~ ~ the filtered h ~juice to ~ 80°C. t and Education have performed the experiment as a part carbonate again until the pH of the juice is about 9. of their regular laboratory work.
B
LABOMTORY DIRECTIONS W e 600 ml. of distilled water is being heated to 800C. in a 1000-ml. beaker covered with a metal lid' I A satisfactory lid can be made from a tin can by taking out the top and bottom and cutting it open lengthwise. A hole is punched in the cover to admit a thermometer.
An alternative method i$ to prepare the beet a3 one would prepare lattice potatoes for frying, then cut the slices along the grooves with a sharp knife, giving a crude V-shaped cossette. A 5- Or 10-lb. Sugar sack is s~tisfactW'. ' The experiment may be interrupted s t this stage if desired, since the juice is too alkaline for bacterial action. 6 Reeve Angel No. 202 (creped) filter paper is excellent for this operation.
672
~
DECEMBER, 1948
673
Tests of pH can be made with phenolphthalein on a steady drip of water into the trap from the condensed spot plate. It will be definitely pink a t this pH. vapor when the evaporation is taking place properly. Evaporate until a thick, stringy sirup is obtained. Filter the juice again. Pour the sirup on a watch glass and seed it by blowing Heat the juice to 80°C. and introduce sulfur %oxide by the method used in the carbonation,=until phenol- a little ~owderedsuear over the surface. The oeriod nhthalein on a soot late iust becomes colorless. The of time required for formation of the crystals will ;H will be about'8. '1f the juice is cloudy filter again.7 vary with the degree of supersaturation of the sirup. Using a .red marking pencil or a label pasted on the PRINCIPLES AND TECHNIQUES ILLUSTRATED beaker, indicate the level of 100 ml. in a 1000-ml. A number of principles and techniques are illustrated beaker. Pour the juice into the beaker and evaporate it to a 100-ml. volume, using heavy asbestos-centered by this experiment. Among the principles are: gauzes to prevent charring. The apparatus for boiling (1) The diffusion through a cell wall from one under a vacuum is then assembled as follows. The flask solution into a less concentrated one. is a heavy, ringed, short-neck, round-bottom flask. The coagulation of a colloidal suspension. (2) It is placed on a water bath. A thermometer is placed (3) The effect of pH on the color of indicators. in one hole of the two-hole stopper a t a depth that allows (4) The effect of external pressure and of concenthe bulb to be covered, but it should not touch the bottration of solute on the boiling point of a tom of the flask. A glass tube, wrapped with asbestos,s solution. is inserted in the other hole. Vacuum rubber tubing (5) The crystallization of a solute from a superconnects this tube to the trap, which should be of saturated solution. heavy glass for safety. Bring the water in the water Among the techniques illustrated are: bath to 80°C., and heat the flask gently with the steam. Adjust the aspirator or other vacuum source until the (1) Decanting a solution from a precipitate. (2) Saturating solutions with gases. juice boils a t about 75'C. Do not let the boiling tem(3) The use of a spot plate and indicator to deterperature drop below 70°C. There will be a slow but mine approximate pH of a solution. ' One sulfur dioxide generator will probably be sufficientfor (4) Evaporation under reduced pressure, in the a class of 15 students. laboratory. ' Bacterial action may start if the process is interrupted here, but it can be inhibited by boiling the juice in a large boiling . The authors wish to thank M;. Paul M. Smith, flask and plugging with sterile cotton. chief chemist of the Eaton, Colorado factory of the Wet asbestos paper may be placed around the glass tube Great Western Sugar Company, for information conand around the neck of the flask. It may be fastened with h e laire. This insulation keeps condensate from returning to the cerning the industrial process for o b t a e n g sugar from .. sugar beets. flask.
-
11. Ethanol from Molasses IN THE USUAL laboratory experiment in which ethanol is produced by fermentation, the starting material is sucrose or glucose. A closer parallel to the industrial process would begin with a molasses. The commercial process is outlined in several literature references (7-9) and production on a laboratory scale is described in a Cuban journal (10). The mash for the industrial process is made by diluting blackstrap molasses with water until the concentration of dry solids is about 16" B r i ~ . A ~ typical analysis of blackstrap molasses, which is the residual solution left after marketable cane sugar has been crystallized, shows about 58.54 per cent total invert sugar and sucrose.10 Nutrient materials consisting of ammonium sulfate and diammonium hydrogen phosphate are added if necessary, in order to promote yeast
, '
1
The percentage of dry substances by weight in a solution is known as degrees Brix. 'O Personal correspondence from Sidney H. Ross, Publicker Industries, Inc., Philadelphia, Pennsylvsnia.
growth. A pH of 5 is obtained by addition of sulfuric acid. An inoculum of the yeast strain, S.accharomyces cerevisiae, is added to the mash and fermentation is allowed to proceed for about 50 hours a t a temperature of 28°C. Fractional distillation of the "beer" which contains about 9 per cent ethanol by volume follows, and yields of about 90 per cent of the theoretical quantity are obtained. One gallon of 95-per cent ethanol can be manufactured from about 2'/% gallons of blackstrap molasses. LABORATORY DIRECTIONS
Inoculum sufficient for the class must be prepared the day before the experiment is to be started. In a 1000ml. Florence flask, place 64 g. of molasses," 256 g. of hot distilled water, and 0.3 a. each of ammonium sulfate
" Blackstrap molasses may be used if obtainable, but yields sre lower than those obtained with a cooking molasses (high-test molasses) which contains s. higher percentage of sugars. "Grmdma's Old-Fashioned Cwking Molasses," a sulfur dioxide free molasses containing about 30 per cent sucrose and 42 per cent invert sugsr, and manufactured by the American Molasses Company, 120 Wall Street, New York, was found to be very satisfactor".
674
JOURNAL OF CHEMICAL EDUCATION
and diammonium hydrogen phosphate. This will furnish enough inoculum for 4 or 5 people. Prepare as many flasks as will be required for the class, placing no more than the quantity mentioned in each flask. This will prevent frequent opening and consequent contamination of the inoculum when it is removed to be added to the mash. Boil the diluted molasses gently for three or four minutes, and plug tightly with cotton sterilized by heating or autoclaviug. Allow the flask to cool to room temperature. Crnmble compressed yeast on a sterilized watch glass, using a sterilized spatula. Add abont half a cake of yeast to each flask, and place in a warm dark place for 24 hours. Swirl the flasks several times during the fermentation period. To prepare the mash for the main fermentation, weigh 128 g. of molasses, of the same kind as that used in preparing the inoculum, into an 800-ml. beaker. To this add 512 g. of hot distilled water. Stir the solution and allow it to cool to room temperature. The specific gravity should be about 1.06. It may be determined by means of a hydrometer. Add 0.3 g. each of ammonium sulfate and diammonium hydrogen ~ h o s ~ h a t eThe . DH of the solution should be about 4.7 to 5.0. A pH me& is convenient for testing the solution. The dark color of the solution makes use of indicators difficult. Six normal sulfuric acid or calcium hvdroxide solution an be used to adiust the DH if necessary. (The cookmg molasses mentioned above usually requires no adjustment.) Pour the mash into a 1000-ml. short. neck, round bottom, Pyrex flask. Fasten to a ringstand above a wire gauze and heat to b o i k . Boil gently for three or four minutes and plug with sterilized cotton. Allow the flask to cool to room temperature. Prepare a delivery tube by bending a 16-in. piece of glass tubing into a U-shape with a short arm of about 4 in. and a lone arm of about 8 in. Bore a rolled cork to fit the glasskbing snugly. Insert the short arm of the bent tube into the cork and pour melted p a r a 5 over the whole cork several times in ~ r d e rto give a tight seal when it is placed in the flask. The protrnding end of the tube may be protected during tiiis operation by covering it with the rubber bulb of a medicine dropper. Remove the cotton plug from the flask and add from a sterile graduate a quantity of inocnlum equal to 10 per cent of the volume of the molasses solution. Place the cork containing the delivery tube tightly in the flask, being careful not to loosen the delivery tube which has been sealed into the cork with para&. Mount a test tube coutainmg water so that the long arm of the delivery tube is under the water and swirl the assembly gently in order to mix the inoculum and molasses.
Set the flasks in a warm place. Placing them on a window sill where the sun strikes them through the glass is satisfactory. After a few hours, air from within the flask and carbon dioxide from the fermentation will bubble through the water in the test tube. Swirl the flask several times during the first two days of the fermentation. Allow the flasks to remain until fermentation is complete (at least two days). After sufficient fermentation time has elapsed, decant the solution from the precipitate in the bottom of the flask into a large beaker. The pH should be adjusted to about 4.3 with sulfuric acid and the "beer" fractionally distilled using any convenient fractionating column or, if this is not available, a couple of fractions may be obtained by simple distillation in a distilling flask. Record the volume of each fraction and the temperature range over which it was collected. Reduce foaming by slow heating a t first. Measure the specific gravity of each fraction with a Westphal balance or pycnometer. If the percentage composition of the molasses is available, the theoretical yield can be calculated and compared with the actual vield. AND ILLUSTRATED Among the principles illustrated in this experiment are: (1) The effect of the composition of a solution on its specific gravity. (2) The variation in the potential of a glass electrode with hydrogen-ion concentration. (3) The effect of the composition of a solution on the boiling voint of the mixture. (4) The beh&ior of azeotropic mixtures.
III.
soap) detergents are manufactured. Production methods are discussed in several references (11-13) and a series of patents have been issued covering the commercial production of various k i d s of new detergents. No description of a laboratory process is available.
A New Type Detergent
VERY ~ S ~ T Lappears E in the literature concerning the details of the process by which the new type (non-
.
PRINCIPLES
Techniques illustrated include: (1) Measurine the soecificeravitv of solutions. (2) ~ d j u s t i n g t h epk of a s o l u t i k after measuring it with a pH meter. '. Inoculating a mash using sterile technique. (3) (4) Fractional distillation. . ACKNOWLEDGMENT
The authors wish to thank Mr. E. W. Haywood, Operating Superintendent, and Mr. C. J. Odom, Plant Superintendent, New England Alcohol Company, Everett, Massachusetts, and Mr. Sidney H. Ross, Publicker Industires, Inc., Philadelphia, Pennsylvania, for information concerning the process for manufacturing industrial alcohol. They also wish to thank Mr. H. A. Kauffman, American Molasses Company, New York, New York, for information concerning the composition of "Grandma's Molasses."
DECEMBER, 1948
The essential steps in the production of "Dreft" will be described.12 Coconut oil is catalytically hydrogenated to the alcohols corresponding to the fatty acids whose glyceryl ester? make up the oil. The alcoh?ls are fractionally dlstllled to give dodecanol (lauryl alcohol). The alcohol is treated with a sulfating agent such as fuming sulfuric acid, chlorosulfuric acid, or simply concentrated sulfuric. acid. The product, dodecylsulfuric acid, is neutralized by pouring it into a concentrated sodium hydroxide solution. The resulting white paste is dried. Laboratory Directions. Since it is not feasible to attempt the catalytic hydrogenation of the coconut oil, the laboratory preparation of "Dreft" starts with technical grade dodecanol. Weigh out in a small beaker 15 g. of the alcohol and add a 10 per cent excess of concentrated sulfuric acid slowly, assuming that the reaction proceeds according to the equation: CHa(CHn)uOH
+ H O S O I O H - C H ~ ( C H ~ ) ~ O S+~ ~H1O ~H
Into another small beaker (150 ml.) pour 30 ml. of 2 molar sodium hydroxide solution and add three drops of phenolphthalein indicator s~lution.'~Place the l2 Manufactured hv the Procter & Gamble Companv. . .. Ivorvdale, Ohio. Although the phenolphthalein will appear colorless in this ooneentrated solution, its characteristic pink color will reappear as tho alkali is neutralized.
675
beaker in a pan of cold water and add the dodecylsulfuric acid slowly with stirring until the pink color of the phenolphthalein appears. Then add the acid dropwise until the solution is again decolorized. If the mixture becomes too thick to stir easily, it can be liquefied by heating on a water bath for a few minutes. Spread the white sodium dodecylsulfate on a clay plate or absorbent paper and allow to dry. LITERATURE CITED (1) PRESTON; W. C., J. CHEM.EDUC.,17,476-8 (1940). (2) HOLLER,A. C., ibid., 21, 588 (1944). "A Laboratory (3) BRISCOE,H., H. HUNT,AND F. WHITACRE, Manual of General Chemistry," 1st ed., Houghton Mifflin Company, New York, 1936, pp. 5 3 4 . (4) F u s o ~ R., , R. CONNOR, C. PRICE, AND H. SNYDER, "Brief Course in Organic Chemistry," revised, John Wiley and Sons, New York, 1947, pp. 243, 254. J., T. ABBOTT, AND K. VANLENTE,"Experimental (5) NECKERS, General Chemistry," 1st ed., Thomas Y. Crowell Company, New York, 1940, pp. 237-9. M., "Praktikum der Gewerblichen Chemie," (6) HESEENLAND, J. F. Lehmann's Verlag, Munich, 1938. (7) LABAYEN, S., Sugar News, 12, 6 3 s (1931). (8) OWEN,W. L., FactS About Sugar, 31, 175-8 (1936). (9) Ibzd., 33, 5 0 4 (1938). (10) RIVERA,G. V., Memoria de la Conferencia Annual Assmiation de Teenieos Aeucareros, 18, 25542 (1944). (11) BRISCOD,M., Chemical Trade Journal, 90, 76-8 (1932). E., Soap, 13, 27-30,734 (1937). (12) MULLIN,CHARLES J., Manufacturing Perfumer, 3, 346-7 (1938). (13) WAKELIN,
