i
EXTRACTION OF WAX FROM SORGHUM BRAN •
1
HSIEN-WEN HSU <&
. ***£/
B. S., National Taiwan University, China, 1951
A THESIS
»
submitted in partial fulfillment of the
requirements for the degree
MASTER OF SCIENCE
- Department of Chemical Engineering
KANSAS STATE COLLEGE OF AGRICULTURE AND APPLIED SCIENCE -
1955
»
k Lo
i~i ii
Q^cu^v^Js TABLE OF CONTENTS
INTRODUCTION 1
PREVIOUS WORK 3
MATERIALS 6
GLASS SOXHLET EXTRACTION AND ANALYSIS OF WAX AND OIL IN MISCELLA 7
Procedure of Using Soxhlet Extractor 7
Separation of Wax from Oil by the Acetone Method.. 8
Summary of Results 9
PILOT PLANT EXTRACTION 15
SEPARATION OF WAX AND OIL 16
Effect of Temperature in the Acetone Method 16
Urea Complex Method of Separation. 17
Theory 17
Experimental Procedure 22
Summary of Results 26
COST ESTIMATION OF A WAX RECOVERY PLANT 29
DISCUSSION 30
CONCLUSIONS 35
ACKNOWLEDGMENTS 36
BIBLIOGRAPHY 37
APPENDIX 39 INTRODUCTION
i One of the functions of the Agricultural Experiment Station is the
never ending search for means of better and fuller utilization of the agri-
cultural products that are of particular interest in the state of Kansas. In
line with this broad objective, the extraction of economically valuable lipid
materials from the sorghum bran has been studied in several theses in the
Departments of Chemical Engineering and Chemistry in recent years. Generally
the emphasis has b. en placed upon either the chemical and physical properties
of these lipides or the equipment design and performance for the solvent ex-
traction operation. A brief review of the previous work is presented in the
ensuing section.
' All the soluble material that is extracted from the bran is thence-
forth referred to as "miscella n and its weight expressed on a solvent-free
basis. The fraction of the miscella that remains in the solid state at room
temperature after the separation, is referred to as "wax"; the other frac-
tion being the "oil". The objectives of the present investigation can be
stated as follows:
1. To develop an economically feasible process for the separation of
the wax and oil fractions in the miscella. Since the sorghum wax resembles
the commercially valuable Carnauba wax (Bunger and Kummerow, 2) in many of
its physical properties, the desired process must recover the wax fraction
more completely and in purer form whereas the yield and quality of the oil
fraction is only of secondary importance.
2. Also to see whether or not some new solvent, or mixture of solvents,
> could be found that would be superior to the one used previously, namely,
Skellysolve-B, a commercial product consisting of mixed hexanes. The first criterion is its selectivity; that is, not only must it be able to extract
large amounts of miscella, but furthermore it must extract wax in preference
to oil.
The analytical procedure used previously in the laboratory to determine
the wax content of aiscella wa3 based on the precipitative crystallization
principle using acetone as the precipitative solvent. For large scale sep-
aration, this method has some serious inherent difficulties: One, the re-
frigeration cost would be considerable. Two, the filtration of fine wax
crystals would be slow. If this method could not be successfully developed
for production purposes, then other alternatives must be investigated, such
as:
Separation by differences in molecular size and shape—thermal diffusion.
Separation by differences in volatility—fractional distillation.
Se aration by differences in spatial and molecular structure—urea- complex or thio urea-complex method.
Separation by differences in solubility—solvent extraction.
Thermal diffusion is inherently a slow process which has little pos-
sibility of developing into a production process on the industrial scale.
Because of the thermal sensitivity of the materials, distillation would have
to be performed under vacuum. Through literature research and exploratory
experimentations, these two approaches were abandoned, at least tentatively.
During the course of the present investigation, the urea-complex method was
studied and a laboratory procedure evolved that appeared to be promising.
Also an equipment flow sheet of this process was prepared to serve as a basis
for the pre-construct r on cost estimation of an industrial plant. The labor- tory
' procedures, experia-ntal data and their evaluation are presented in detail in j
the latter part of the body of this report. 3
If a sufficiently selective solvent could be found, then it would be possible to recover wax from bran by a single step of solvent extraction.
The select!vety of seven single solvents and two azeotropic mixtures has been studied in a series of extraction runs with a Pyrex Soxhlet extractor.
The results are presented in the first part of the body of thi3 thesis.
PREVIOUS WORK
A brief review of several previous theses carried out in the Chemical
Engineering Department during the years from 194-7 through 1951 is as fol-
lows:
Foveaux (3) investigated the various possible solvents for wax and oil
extraction. After a comparison of properties he concluded that trichloro-
ethylene would be a suitable solvent, with the major drawback being the high
cost per gallon. He al30 built and operated a screw type conveyor for ex-
traction of the whole grain. Wax was his main product.
French (A), following the recommendation of Kummerow (7) and Foveaux (3)
that the wax extraction be carried out on the bran fraction only, obtained
data on the equilibrium values of ax and solvent. The data thus gathered
were on a batch process with extraction temperatures from 68 to 122° F. He
also presented a method for transposing these data to the design of a con-
tinuous extraction unit.
Medlin (9) built and operated a pilot plant that used a basket type of
conveyor and trichloroethylene for the extraction operation. He found,
through a short series of runs at a temperature of 160° F. over small time
intervals, that the main product was wax. The recommendation was made that
work be initiated on the possibility of obtaining a commercial wax, without further refining by the selection of optimum operating conditions.
Hub (5) carried on with Madlin's extraction unit making many minor
changes in the construction of the unit. After several futile attempts to reproduce Medlin's results, Hub came to the conclusion that the basket type of extraction unit was not the one for the particular job at hand. He pointed out that becaus. the unit was not enclosed in a vapor-tight housing, it was virtually impossible to maintain the extracting temperature high enough to do any good. With that he brought the entire project back to the small scale laboratory and conducted a series of extractions in an at-
tempt to obtain valuable data which could be used in the design of some
other more desirable type of extraction unit. Hub presented curves showing
the effect of temperature, time of contact, solvent ratio, and moisture
content of the bran on the amounts of wax and oil extracted. All of his data apply when using trichloroethylene as the solvent.
Kehm (6) carried out Hub's investigation by using Skellysolve-B as a
solvent whereas Hub's investigation was confined to using trichloroethylene
as the solvent. Kehm also presented breakdown curves of the miscella (total
extractables) curves into its component curves, that of wax and oil re-
spectively. He found that the bran previously used had not been properly
mi '.led and that the bulk of the weight could be attributed to grain fractions
other than bran. He made a more thorough separation of the bran and ran
extractions on each separated fraction. He found that when the bran is
properly milled, wax is the predominant constituent and oil is a secondary
constituent. Excellent results were obtained with the pure bran fraction.
He also made a crude economic analysis of a proposed twenty-five ton Ken-
nedy unit indie ting that the extraction process should be an economical one. .
some related work carried out pre- The following is a brief review of viously elsewhere: vax was removed from the hull Kummerow (7) reported that the sorghum Skellysolve-B and the oil removed by extracting the unround grain with the ground grain with Scelly- from the germ and endosperm by extraciing possible to extract the wax and solve-F. This sug-ests that it might be extraction, using such selec- oil from sorghum bran by fractional solvent Skellysolve-F, alternately. tive solvents as Skellysolve-B and
is composed of the following Warth (16) indicated that carnauba wax
substances:
59° C.), probably heptacosane (C H ) (1) A hydrocarbon (m.p. 27 56 and H 0H, m.p. 76° C), probably ceryl alcohol, (2) An alcohol (C26 52
not necessarily the n-alcohol, 1-hexacosanol. has been named An alcohol (C H 0H, m.p. 30-82.5° C), which (3) 2? 55 carboceryl alcohol, an isomer of 1-heptacosanol.
H 0H, m. p. 33.2° C), identified as octacosanol. U) An alcohol (C28 57 m.p. 86.4-36.8° C), which is probably (5) An alcohol (C^H^ OH,
triacontanol.
39.4° C.), in greater proportion than (6) n alcohol (C^jOH, m.p. proved alcohol, and isolated by Koonce and brown in the the C3o
state of 10056 purity, probably 1-dotriacontanol.
H (0H) m.p. 103.5-103.8° C^ convertible (7) A dihydric alcohol ZJ25 50 2 ,
to the corres onding dibasic acid (m.p. 102.5° C.).
72.5° C.), described as an isomer (8) Cernaubic acid (C^H^, m.p.
of lignoceric acid (m.p. 34.2° C). ~ m# 32,5 C# The acid UaS th&t f±C3t diS (9) An acid ^^fa* ?' ° ^ covered by Brodie in the free state, but is now conceded to be a .
mixed dimer of the and Cpg n-aliphatic acids. G2£
Cerotic acid C H m * ^° C, which is almost entirely (10) ( 26 52°2» p * ^» combined with myricyl alcohol to form the alkyl ester myricyl
cerotate
(11) An w- actone of 21-hydroxyl-l-uncosanic acid (m,p. 1C3.5 C,),
Since the elting point of sorghum wax is slightly lo . r than that of carnauba wax, the composition of sorghum wax may consist more of those lower melting substances than carnauba wax,
Schwarz (13) included an official list from the Brazilian Ministry of Agriculture which describes the specifications of various commercial types of carnauba wax* These types are designated as "flow type", "first type", "medium type", "sandy type", and "fat type". The specifications include wax, moisture and impurity percentages, Iodine index and color description.
HATEiilALS
The bran used ia the entire work was obtained from Grain Products
Company, Dodge City, Kansas, in May, 1954* /verage moisture content:
10$ by weight of bran dried under 26 inches Hg vacuum at 100° C for six hours.
Screen Analysis: (15 minutes shaking) Weight %
below 20 mesh 11.' 6 + 1.46
20 - 3C mesh 13.37 + 1.S7
30-40 mesh 25.42 2.69
40-50 mesh 29. 11 + 2.01
50-70 mesh 15.83 + 1.81
Above 70 mesh 5.21 + 1.35 100.00 The solvents used and their sources are listed below:
Boiling Source Grade roipt =>c
Sk llysolve-B Skelly Oil Company Kansas City, Missouri Technical 69
cetone Chemistry Department Technical 56
Methyl Ethyl Ketone Missouri Solvent and Chemical Co., St. Louis, Missouri Technical 30
'bsolute Alcohol Chemistry Department Technical 78
Secondary Butyl Alcohol Eastman Kodak Company Rochester, New York Reagent .5
n-Butyl Ether E stman Kodak Company Rchester, New York Reagent UZ,A
Ethylene Di chloride Chemistry Department Technical 8*
. .ethanol Chemistry Department Technical 67
Urea Merck Company Rahway, New Jersey Reagent M.P. 132 - 133°C
GLASS SOXHLET EXTRACTION AND ANALYSIS OF WAX AND OIL IN MISCELLA
Procedure of Using Soxhlet Extractor
A photograph of the Pyrex glass Soxhlet extractor is shown on Plate I.
At the start of each run, about 3C grams of bran were carefully weighed and charged into the fresh extraction thimble. The bran was extracted with 250 J. of solvent for eight hours. After removing the hot plate, the thimble was lifted above the solvent level to allow all the excess solvent to drain back into the 3f€ ml flat bottom flask. Usually two or three minutes draining time was sufficient. Then the flask containing all the collected extract 8
cone to was disconnected from the S^xhlet assembly and placed on a steam was trans- recover the bulk of the solvent by distillation. Next the flask to ferred into a vacuum oven and maintained at 9C°C for about eight minutes drive off the last traces of solvent from the miscella. 'fter cooling over
calcium chloride for 30 minute3, the fla3k and ts contents were weighed
to determine the amount of niscella obtained.
Separation of Wax from Oil by the Acetone Method
In this part of the experimental work, the term wax refers to that
portion of the miscella which remains solid in acetone at 6°C Twenty-five ml of acetone were added to the molten miscella which as obtained from each
Soxhlet extraction run. A swirling action was applied to the fla3k to in-
sure sufficient mixing. Then another 25 ml. of acetone were added to wash
down any miscella adhering to the inside surfaces of the flask. The flasks
were stoppered and placed in a refrigerator at 6°C for at least 16 hours.
Then the solvent containing the oil fraction was filtered from the wax
through an asbest03-lined Gooch crucible into an evaporating dish. Two
additional It -ml, portions of cold (6°C) acetone were used to rinse the
flask and wash the filter cake.
The above mentioned filtration was carried out by using a vacuum
desiccator with the crucible mounted in the top of the desiccator and the
evaporating dish inside the desiccator as shown in Plate 1. The crucible was filled with pure pre-cooled acetone before turning on the vacuum valve.
As the vacuum valve was opened, the acetone-mi see 11a mixture was slowly
poured into the crucible while the pure acetone receded. The filtration proceeded faster when the crucible was not allowed to be sucked empty before i
all the acetone-misoella mixture had been poured from the flask. Before waahing, the wax cake should be allowed to air-dry first, otherwise the filtration through the wet cake would be so slow as to allow the crucible and wash acetone sufficient time to warm up to a temperature high enough to dissolve some of the wax. Then the crucible was placed in a vacuum drying oven at 90°C for about five minutes or until the wax began to melt around the edge of the cake. After cooling for % minutes over calcium chloride, the crucible and wax wer- weighed.
The bulk of acetone in the evaporating dish was evaporated over a steam cone; the r sidual acetone and moisture were removed from the flasks and evaporating dishes by heating in a vacuum drying oven for five minutes at 9C°C. After cooling for 3C minutes over calcium chloride, the containers and contents we -e weighed. The wax content of a sample was determined from the combined weights of the wax in the flask and crucible, while the oil was found in the evaporating dish. The procedure of this method is summarised in the flow diagram in Fig. 1.
Summary of Results
Eight single solvents: skellysolve-B, acetone, me uhyl-ethyl ketone, absolute alcohol, secondary butyl alcohol, n-butyl ether, ethylene dichloride and methanol, have been tried for Soxhlet extraction. Acetone was used as solvent for the separation of the oil and wax fractions in the aisceila.
The following results were obtained
The largest amount of miscella was obtained by using absolute alcohol as the extracting solvent and this gave also the highest weight ratio between wax and oil. During the extractions, however, suspension of wax-like material 10
30 g. 250 ml. B r a m -I Skellysolve-B
Extraction
IIL Raffinate Miecella + Skellysolve-B
Evaporation
50 ml. H * Acetone » Miscella Skellysolve-B
Kept at 6 8 C. over night
Filtration
Wax Oil + Acetone
Evaporation
Acetone Oil
Pig. 1. Flow diagram of acetone method, bench scale. EXPLANATION OF PLATE I
Soxhlet Extractor and Crude Separation Equipment
A. V cuum desiccator
B. Asbestos-lined Gooch crucible
C. Evaporating dish
D. Two-way stopcock
E. Trap
F. Condenser
G. Soxhlet extractor and thimble
H. Hot plate 12
PLATE I 13
so came out of the solvent and obstructed the overflow tube in the Soxhlet as to prevent the recycle of solvent. Bunger and Kummerow (2) indicate that this solid is probably a polymerization product :f the wax and the alcohol.
Also two azeotropic mixtures have been used as the extracting solvent: ethylene di chloride-heptane-water (volume ration 2:2:1) and methyl-ethyl ketone-heptane-water (volume ration 2:2:1). Sixteen extracting runs were made with each mixture and no increase in the yield of miacella was defected over the single solvents. But after cooling to room temperature some wax- like solid material was seen to float at the water-organic interface of the mixed solvent. Also the bran in the extract thimble was partially disin- tegrated by the hot water. The weight ratio between the wax and oil fractions was also the same as that obtained by single solvents, but the color of both fractions was a little darker.
The experimental data seem to suggest the following correlation between the azeotrope mixture and single solvents:
+ H = NaWa + NbWb
Where W the weight of mi3cella extracted with mixed solvent.
= respectively Na»b thc mole fraction of solvent a,b,
= solvent a, b, wa»b the wei Sht of miscella extracted with pure
respectively.
The melting point of the wax fractions was determined with th Fisher-
Johns Melting Point Apparatus; the refractive index of the oil fraction was deter.rdned with the Abbe refractometer at 28° C. The readings are 3hown in
Table 1 below. The higher melting points indicate better separations of wax from oil, and a narrow melting po : nt range indicates the purity of the wax. u
fractions Table 1. Melting point of waxes and refractive index of oil
: :
: Refractive Index Solvent Used J Melting point • Ranse °C. : at 28> C.
Skellysolve-B 67 -74 1.4693
Acetone 73 - 76 1.4652
Methyl ethyl ketone 69 - 74. 1.4661
Absolute alcohol 72-74 1.4652
Secondary butyl alcohol 72-76 1.4652
n-Butyl ether SL - 65 1.4729
Ethylene di-chloride 32-34 1.4652
Methanol 71-75 1.4652
Methy ethyl ketone-heptane- water 63-69 1.4652
Ethylene dichloraride- heptane-water 64-68 1.4652
The color of the wax fraction from the Skelly3olve-B extract was grayish
green and the oil fraction was dark green. Both wax and oil from the absolute
alcohol and methanol extracts were deep tan. The products from all other
solvents were tan. It was also observed that in a few earlier extraction runs
where the temperature of the hot plate was set too high, the color of the
resulting fractions were darker.
Altogether 16 extractions w.re made with each solvent. The r. suits
are averaged and shown in Tabe 2. The complete data are included in the
Appendix, 15
Table 2. Summary of the results of Soxhlet extractions and he separation of wax by the acetone method at 6° C.
: rift, ration wax Solvent ; (wt. per wt. of dry Bran) x ICO tMlscella Wax Oil : '1
Skellysolve-B 6.35 + 0.29 2.76 + C.27 4.09 + C.32 0.719 + C236
Acetone 8.58 + C.39 3.33 ± 0.20 5.31 + 0.33 0.64C + 0.136
diethyl ethyl Ketone 8.20 + 0.23 2.33 + 0.24 5.36 + 0.21 .532 + C.198
Absolute alcohol 12.93 + 0.34 7.86 + C .35 5.01 + 0.23 1.536 + C.291
Secondary butyl alcohol 10.17 + 0.20 5.05 +0,22 5.12 + 0.19 0.993 + 0.120 n-Butyl ether 3.86 + 0.33 2.51 + 0.10 6.53 + 0.39 0.396 + C.C20
Ethylene dichloride 7.35 + C.3' 2.40 + 0.26 4.94 + C.48 0.493 + O.C64
Methanol 12.56 + 1.54 7.32 + 0.18 5.24 + O.64 1.412 + 0.276
Ethylene di chloride- heptane-water 7.03 + 0.18 2.80 + 0.43 4.23 + 0.28 C.656 + 0.C61
ifethyl ethyl ketone- heptane-water 7.00 + 0.31 2.38 + 0.32 4.13 +0,30 0.669 + 0.59
PILOT PLANT EXTRACTION
In order t: obtain a sufficient amount of raiscella for the subsequent investigation of the separation of wax from oil, a large batchwise extraction was carried out with the Pfaudler distillation unit in the pilot plant. A
hotograph of this unit is shown on Plate II, It operates on the same ; principle as the bench scale, Pyrex glass Soxhlet extractor. Skellysolve-B was used as tho extracting solvent in all the pilot plant runs. 16
In each batch, 20 pounds of bran contained in a nylon cloth bag
we e placed in the basket extraction chamber and seven gallons of Skelly-
solve-B were charged into the steam-jacketed still pot. The solvent was
first vaporized then condensed in the overhead, water-cooled condenser,
then accumulated in the b sket extraction chamber to come in contact with
the bran. When the sol -ent level reached the top of the overflow pipe,
it was automatically siphoned back into the still pot to start another
cycle. At the end of about 15 such cycles, or about eight h^urs of op-
eration, all the extract was dr ined into the still pot and the receiver was disconnected from the rest of the st : ll through proper valve arrange- ment on the by-pass line. Then the solvent was distilled off as over-head and recovered and the solvent-free miscella was withdrawn from the bottom of the still pot. The Isoella was then placed on a steam cone to drive off the residual traces of solvent.
Starting with 20 pounds of bran and seven gallons of solvent, a typical batch yielded 850 grams of 1.6 pounds of miscella. No attempt was made to recover that portion of the solvent which was retained by the bran. The avera e solvent loss was about 1 gallon per batch.
The miscella was dark green in color while in the molten state. Upon cooling to room temperature, it solidified into a light green paste. This paste was used as the starting material in the subsequent studies of various methods of wax-oil separation,
SEPARATION OF WAX AND OIL
Effect of Temperature in the Acetone Method
Previously, the precipitative crystallization of wax from oil with the 17
aid of acetone was all done at 6° C. T: 3tudy the couple tene 33 of
separation at a lower temperature, 52 separation runs were made using the
same batch of mi see11a extracted in the pilot plant as the starting material.
Twenty-six were carried out at -8° C. and another 26 runs at 6 C, other- wise following the identical procedures as described in a previous section.
The results were averaged and are shown in T ble 3. The complete data are
included in the Appendix section. Note the increase in the amount of wax
and its melting ^nt at the lower refrigeration temperature.
T- ble 5. Temperature Effect in the 'cetone J-fethod.
: : : Refractive 1
Refrigeration:..'ax, Wt. % :Oil, Wt. % :Wax to : : Index at Temperature :of aiscclla iof miscella ;Oil ratio ;M. p.. °C. ;28° C.
-8° C. 26.4 ± 2.8 73.6 + 2.0 0,359 68-78 1.4672
+6° C 16.8 + 3.7 83.2 + 3.7 0.200 67 - 74 1.4700
Urea Complex Method of Separation
Theory . Recently it has been found that urea can be made to form com- plexes with certain types of organic compounds. This new technique offers a m thod for the separation of compounds by size and shape rather than by other physical properties such as boiling point or solub'lity (Mange, 3).
X-ray analyses show the urea complexes to be a hollow tubular-like structure oomposed of urea which encloses the organic component.
The structure of a typical urea adduot is illustrated by Plate III.
The urea molecules form a triple interlocking helix arranged in the hexa- gonal system, thus forming long hollow tubes in which the molecules of the EXPLANATION OF PLATE II
Pilot Plant Extractor
1. Still
2. Basket extraction chamber
3. Condenser
U» Overflow pipe
5. By pass pipe 19 PLATE II 20
internal components can be acco^imodated. The unit cell contains six mole- o cules of urea spiralling over a length of 11.1 A, The carbon, nitrogen,
and oxygen atoms of the urea molecules are coplanar and each oxygen is
hydrogen-bonded to four nitrogens, and each nitrogen to two oxygens. There
are no bonds between the urea molecule and the component enclosed, and the
only forces holding the two components together 3eem to be Van der Waal's forces (unless there is enclosed a molecule with a very polar group in which case there may be some hydrogen bonding) . When the enclosed organio
component is removed, then the hexagonal urea lattice rearranges to its more stable tetragonal form.
The cross section of the hexagonal urea crystal is shown in Fig. 1, o Plate III. The inside diameter of the channel is approximately 5.5 A.
Based on the Van der Wa- 1 radii, the maximum diameter of an extended linear hydrocarbon is about 4.5 A so it may be easily accomodated. If the cross section of an organic compound is greater than about 5#5 a., it normally will not complex (e.g. isoctane).
In g. ncral, ease of formation and stability of ure-. complexes increase
with increasing chain length. The maximum chain length re ; orted to form a
urea complex with hydrocarbons is Cc with ester3 Cȣ . These should not necessarily be considered as upper limits, however (Swera, 14.) . Certain branched chain compounds or even those containing cyclic structures will form urea complexes provided that there is a sufficiently long straight chain in the molecule and the branch or cycle is not too large.
The use of urea to form complexes with certain types of organic com- pounds has found application in the separation of free fatty acids, which readily form urea complexes from fats, tall oil, polym&rized fatty acids, 21
and other noncomplex-form" ng substances. Also urea can be used to frac-
tionate mixtures of fatty acids, esters, alcohols, and ather derivatives.
There are three main types of separations, namely, separations based on
differences in chain length, in degree of saturation and in branching re-
spectively. In separation based on differences in chain length, advantage
is taken of the fact that the longer chain compounds form urea complexes
preferentially. That is, if insufficient urea is employed to combine with
all the components of a mrxture the longer chain components will combine with the urea and precipitate as complexes. For the best results, the
components to be separated should differ in chain length by at least four
carbon atoms and preferably by six. When the chain length difference is
six or more carbon atoms, other separation methods can be used, such as
distillation or low temperature crystallization (-9C C for example).
The principle in separations based on differences in unsaturation is
that as a long chain fatty component becomes more unsaturated it shows
greater deviation from the normal straight chain structure. Therefore, at
a given chain length, saturated components of a mixture would be expected
to form urea complexes preferentially to mono-unsatvun ted, mono-unsaturated
preferentially to di-unsaturated, etc. Taking advantage of this difference
in complex forming ability, purified saturated, oleic, linoleic, linolenic,
and more highly unsaturated fatty acids, a3 well as their methyl-esters,
have been isolated from natural sources. The method has also been applied
to alcohols and nitriles. No temperature below about 0° C. is required in
these separations, whereas the usual fatty acid or ester solvent purification
techniques may require crystallization temper tures in the range of -50° to -9C° C. 22
In studies on wool wax and other alcohols as well as other classes of
compounds, the separation of straight chain or only slightly branched cjm- pounds from the more highly branched has been accomplished b/ perferential urea complex formation (11) •
In general, waxes ore considered as mixed esters of mono- and di-hydric alcohols with fatty acids, and oils are mixtures of the glycerides of various fatty acids. In view of the above theory, it was bell: /ed that the separa- tion of the wax and oil in the miscella extracted from sorghum bran might be carried out by virtue of their difference in molecular structure. According- ly, experimental procedures were developed and tested in the laboratory.
These are discussed in the ensuing sections.
"xperlmental Procedure . Twenty-six separation runs were made with 1- gram batches of miscella. The laboratory procedure for each run is sum- marized as follows: Fifty gram3 of urea were dissolved in JOC ml, of hot
(about 50° C.) methanol to prepare a saturated urea-methanol solution.
Fifty ml. of this saturated solution were mixed with the carefully weighed sample of molten miscella. On standing th crystalline complex separated out shortly. After the mixture of miscella and urea-methanol solution reached room temperature, in order to complte the formation of the com- plex, the mixtures were kept in the refrigerator at 6° C. over night. The complex precipitated out and accumulated at the bottom of the flask. Then
250 ml. of hot water (6C° C.) were added to the cold complex mixture and stirred. As the complex formation was destroyed the wax coalesced and floated on the surface of the liquid. The wax fraction was then filtered off with an asbesto-lined Gooch crucible mounted on a vaccuam desiccator.
The filtrate was boiled to release the oil fraction from the aqueous solution EXPLANATION OF PLATE III
Fig. 1. Lattice arrangement of hexagonal aduct of urea complex
Fig. 2. Cross section of urea complex aduct
a. n-paraffin
b. Benzene
c. 3-methylheptane
d. 2,2,-4 Trimethylpentane i
2U
PLATE III
2 4- *> 9 10 A i i i i——
a
Fig. 2.
Fi«. 1. 25
the solution of urea and methanol. The oil fraction now floating on top of methanol was was recovered by means of a separator? funnel. Fifty W&+ of neces- used to wash the funnel and added to the oil fraction. It was found alcohol sary to add a small amount of either methanol, acetone, or absolute
Other- to the oil in order to drive off the last traces of entrained water.
the wise violent bumping or sputtering occurred towards the latter part of evaporation period. The aqueous solution separated from the hot filtrate was evaporated to dryness to recover urea.
To check material balances the weight of wax in the crucible was added to the weight of oil from the separatory funnel. If the combined weight did not approach the weight of the starting miscella closely, the wax was again washed with hot (60° C.) water to make certain that all urea was re- covered. The wax was allowed to air dry for at least 2U hours before weigh- ing.
The procedure is illustrated in the flow diagram of Fig. 2. Also two additional separation runs were made with approximately half-pound batch of miscella. The same procedure as indicated above was followed.
Methanol was chosen as the carrier solvent in this procedure because of the high solubility of urea in this alcohol. The solubility of urea in other solvents at 30° C. are given below for comparison:
Alcohol Grams per ICO g. Alcohol
Methanol 27.7
Ethanol 7*2
n-Propanol 3 .6
Isobutanol 2.3
Iso amyl alcohol 1.6 26
The solubility of urea in water at var' ous temperatures was reported as follows (1):
Temp °C Solubility (.a-ams r>er ICC g. water
66.7
10 85.2
20 1C8
30 135
40 167
50 213
60 251
70 310
30 400
90 525
100 733
These data sug ested the use of hot water (60°C.) in this procedure
to destroy the urea-complex after it has precipitated out.
Sury^ry of Results . There was nearly a two-fold increase in the wax
fraction yield when the urea complex method was used instead of the acetone
method at -3°C. The wax fraction obtained by the urea complex method was
light yellow in color and harder than that separated by the acetone method.
The melting point increased to 74-31°C. as compared to the melting point of
the wax obtained by the acetone method which varied between 68° and 78°C.
The detailed data of the 26 runs of 1-gram size batches are given in
the Appendix. The average values are tabulated below: —
27
~ Urea \- 1 g. 50 ml.sat'd-.- Miscella solution Methanol
Kept at 6°C. over night
Mixing H20, 60° C.
Filtratiom
Wax + Urea Oil + Urea + Me-OH + H H20, 60*C, 2
Wax Urea HoO Heating H Purification Separation by separatory funnel
Wax product
Urea + Me-OH + H Oil 2 J Purification Heating
Urea Me-OH + H 2 Oil product
'V
Fig. 2, Flew diagram of urea complex method, bench scale. 23
Wax, % of Miscella 58.36 + 1.01 Oil, % of Miscella 41.64 + 0.44 Melting point range 74-31°C Refractive Index at 28°C. 1.4661
The3e results were reproducible In larger batches wherein about one half pound of ffdacella was treated.
Wt.(aram) %{ based on total yield)
Wax fraction 150.2 53.2 Oil fraction 108.2 41.8 Total yield 258.4 M % Starting Miscella 269.9 Wt. loss 11.5, or 4.2356 of Miscella
*
The temperature of the hot water used to destroy the complex was the most sensitive factor in the separation. The upper limit is the melting point of the wax fraction. On the other hand, if the temperature is too low, the dissociation of the wax fraction from the complex would not be complete and some urea would still remain in the wax product. Thi3 can be checked br a material balance in the last step in the procedure. The optimum temperature for dissociation was found to be 60 C. In the present procedure, methanol was diluted to about 9 percent mole fraction concen- tration by 60°C. hot water.
In the other large batch run with 223.3 gm. of miscella, the step of using 6C°C. water to destroy the complex before filtration was omitted.
Instead, the urea complex along with the enclosed wax was filtered off first and then washed with 6C°C. water. The result was unsatisfactory. The filter cake turned into a viscous paste contaminated with large amounts of oil. It was concluded then that the treatment with 60°C. water before fil- tration was necessary not only for destroying the complex but also for the removal of oil contamination. 29
The crude wax product still needs to be recrystal ized either with acetone or with alcohol in order to purify it. Because of this disad- vantage, it appears that the urea method would be more applicable if the product to be recovered in the purer form were the oil fraction instead
of the wax fraction. In such case, the addition of hot water to destroy
the complex would not be necessary. The urea complex together with the
enclosed wax could be filtered off to obtain a filtrate which contains mainly
oil and methanol. Thus one would not have the large volume of dilute methanol-water solution to contend with.
During e final recovery of urea by evaporation, tr?ce3 of oil were
found floating on the surface of the methanol solution. This indicates
that the oil fraction of misoella was not completely recovered. These
small weight losses of the oil fraction also appear in the material bal-
anoe of T'ble U in the Appendix.
COST ESTIMATION OF A WAX RE C VERY PLANT
An equipment flow sheet of the urea complex process for a plant cap-
able of processing one ton of miscella per eight-hour shift has been pre-
pared as shown on Plate IV, This preliminary design was made on the basis
of the laboratory procedures and results reported in the preceding sections.
The size of the major pieces of equipment has been determined from the
approximate material balance and heat balance calculations. Prom the equip-
ment specifications the initial costs were esti:nated. Then the annual
operating cost and fixed cost were computed. Finally the percent return
on investment was computed to indicate the feasibility of this projected
plant. The results and the various assumptions are summarized as follows 30
3
and the detailed calcul tlon3 are included in the Appendix section.
The essential assumption involved in the calculations are as follows:
1. The methanol loss of the process Is 5% 2. The urea loss of the process is 1Q% 3. Two percent of Skeilysolve-B loss is assumed in the initial extraction step, and this cost is charged to the urea com- plex separation process as the cost of the starting raw material, namely miscella.
The summary of preliminary cost estimation of the wax are as follows:
1. Size of t e plant 1 ton of miscella per 8-hour shift
2. Materials required a. Methanol 13,2CC cal./day $ 9,240 b. Urea 17,000 lb./day 850 c. Water 74,000 gal./day 10
3. Heat required 76,300,000 Btu/day - By using waste steam assume the cost is negligible
A. C it .1 Cost 1 235,690
5. Ye rly manufacturing cost a. fixed cost 9,172 b. direct operat ne cost 198.200 # 207,372
6. Exoected Yenrly Sales a. Wax 360,000 lbs./yr. .0.70 $ 252,0C0 b. Oil 2^0,000 lb3./yr. 0.10 24.000 $ 276,000
7. Cost of the Wax f 0.51 / lb.
:. Annual profit before tax $ 63,623
9. Annual return on investment before tax 2956
DISCUSSION
The temperature of the Soxhlet extraction is dependent on the boiling
point of the solvent, the power input to the hot plate and the radiation from
• rHo/cn^tmvOt'-eoo HrlHrfrtrlrlHHrHNNtVN
,
33
the hot plate, the temperature and the rate of circulation of the cooling
water in the condenser, etc. In the 16C extraction runs no special attempt
was made to control the temperature other than to re^rulate the boiling and
condensation at a steady rate. Aocording to a report of the Southern
Regional Research Laboratory (11) on their experience with the extraction
of rice bran, it was possible to remove the oil first by cold hexane before
removing the wax by hot hexane. Since the solubilities of sorghum oil and
wax are not preferentially influenced by temperature (Hub, 5) , any effect
such as re orted in the rice-bran c;:3e would probably bt; due to the varia-
tion in diffusion rates with temperature. This would surest a need for
future investigation of the effect of temperature on the diffusion rates
of oil and wax, respectively.
In the urea complex method of separation, thiourea might also be
used instead of urea. Thiourea also forms complexes with many branched
chain and cyclo-aliphatic compounds but Generally not with straight chain
compounds, aromatics and terpenes. Furthermore, Swern (14) reported a number of compounds which would form complexes with thiourea exclusively and not with urea. F;r instance, if sorghum wax contains appreciable amounts of such cosanes as 3-ethyltetracosane , 2-cyclohexyleicosane and
1-cyclopentylheneicosane, then thiourea would be a more effective separ- ation agent than urea.
The equipment flowsheet and plant cost estimation were prepared for the urea complex method mainly because of its high wax yield. Further: lore there are also several operational difficulties that would render the acetone method less desirable as an industrial process. These disadvantages are:
1. In the acetone method, it is necessary to have low temperature far X
crystalliza ion. The refrigeration O03t could be considerable.
2. The filtration of fine wax crystals would be difficult. The size
of crystals foriaed depends on the cooling rate during crystallization. Thus
the requirement on temperature control would be critical.
3. It would require 16 hours or so to complete the crystallization
and settling. This would cause large material hold-up and large equipment
volume in the process.
4. Acetone is highly volatile and inflamable, he:;ce the necessity of
special provisions in handling and safety precautions.
Sakurai (12) reported that in the formation of urea complexes with
fatty acid and methyl-ester, respectively, in a methanol solution, the
effect of agitation and temperature were not appreciable. Therefore, the
refrigeration equipment and cost were not considered in the preparation of
the flow sheet and the cost estimation. The other essential assumptions
involved are:
1. The methanol loss of the process is 5%» 2. The urea loss of the process is 10$. 3. 2% Ske lysolve-B loss is assumed in the initial extraction step, and this cost is charged to the urea complex separa- tion process as the cost of the starting raw material, namely, mi see 11a.
These estimations and specifications are by no means final or complete.
A ositive recommendation as to the feasibility of this process can not be made until further pilot plant tests and detailed design calculations have
been performed. The preliminary flow sheet and specification should be helpful in the planning of such further studies in the future. 35
CONCLUSIONS
1. One hundred sixty extraction runs were made in the Pyrex Soxhlet
Extractor with 3 single solvents and 2 azeotrope mixtures. Absolute alcohol was found to extract the largest amount of mi see 11a from the bran and pro- duce the highest wax to oil ratio in the miscella,
2. Fifty-two separation runs were made by the acetone method. By lowering the crystallization temperature from 6°C. to -8°C, the amount of crude wax separated from the miscella was increased by approximately 50 per cent.
3. A laboratory procedure for the separation by the urea-complex method was developed. By this method the crude wax yield doubled that which was obtained by the acetone method at -8°C.
4* Cost-wise the major problem in the urea-complex method is the necessity to concentrate large volumes of dilute methanol and urea solutions, respectively. However, these concentration steps can be carried out in the usual distillation and evaporation equipment. Therefore, technically these should not pose any problems in ado ting the urea-complex process on an industrial scale.
5. An equipment flow sheet for the urea-complex process was prepared for a plant capable of processing one ton of miscella per 3-hour shift.
Although there are indications that thi3 process could be made feasible on an industrial 3cale, a positive recomendation can not be made until further pilot plant tests and detailed calculations have been performed. 36
ACKNOWLEDGMENTS
Col- The author wishes to express his gratitude to the Kansas State which lege Agricultural Experiment Station for the financial assistance made this research possible, and to:
Professors Henry T. Ward, S. L. Wang, William H. Honstead and Raymond
invaluable advice C. Hall of the Chemical Engineering Department for their and encouragement in carrying out this project. 37
BIBLIOGRAPHY
(1) Crystal Urea Polychemical Department, E, I. Dupont De Nemours and Company, Inc., Wilmington 93, Delaware,
(2) Bunger, W. B. and F. A. Kumiaerow A Comparison of several methods for the separation of unsaponifiable material from cornauba and sorghum grain waxes. The Journal of the American Oil Chemists' Society, March 1951, Vol. 23, No. 3. p. 121.
(3) Foveaux, M. T. Construction and operation of a pilot plant for the continuous solvent extraction of wax from sorghum grain. Unpublished Master's Thesis, Kansas State College, Manhattan, Kms^s. 50p. 1947.
(4) French, R. 0. The solvent extraction of wax from sorghum grain bran. Unpublished Master's Thesis. Kansas State College, Manhattan, Kansas. Alp. 1943.
(5) Hub, K. A. The solvent extraction of lipid material from sorghum bran. Unpub- lished Master's Thesis. Kansas State Colle ;e, Manhattan, Kansas. 32p. 195C.
(6) Kehm, R. J. The solvent extraction of wax from sorghum bran. Unpublished Master *s
Thesis. Kansas State Colleg , Manhattan, Kansas. 63p. 1951.
(7) Kummerow, F. A. The composition of the oil extracted from 14 different varieties of Andropogen Sorghum var Vulgaries. Oil and Soar> September 1946, Vol. 23, No. 9, p. 273.
(3) Mange, F. E. Tret-Olite chemical company, St. Louis, Missouri, Private communi- cation.
(9) Medlin, R. P. The design, construction and operation of pilot plant equipment for the continuous extraction of lipid materials from sorghum grain bran. Unpublished Master's Thesis. Kansas State Colle e, Manhattan, Kansas. 28 p. 1949.
(10) Oil, Paint, Drug Reporter. Vol. 164, No. 26, 1953 p. 21.
(11) Rice bran yields oil, wax. Agriculture Research. United States Department of Agriculture, Vol. 3, No. 11, April 1955 p. 13. (12) Sakurai, H # Complexes of urea fatty adds and their derivatives. Journal of the Ch#« (13) Sohwarz, L. •««««* Sanitary produotst New York .MacNair-Dorland Company, pp. 115-Ho. (14) Swern, D. _. _, Urea and thiourea eomple»a In aepareting organic compounds! Indue- trial and Engineering Chemistry. Februery 1955, Vo. 47 p. 213-219. (15) Vllbrandt, P. C. Chemioal engineering plant desigm 2nd. Edition, Hew York. MoQrav Hill Company, 1942. (16) Verth, A. H. UJ The chemistry and technology of waxes* Hew York, Roinhold Publishing Corporation, 1947. (17) Zimmerman, 0. T. and I. Lavine Chemical engineering oost3t Dover, Hew Hampshire. 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M rH rl^rt H H H H CM *1 8& 11 O ? O c- H o 55 «H o .a £- >t f^ CT» in -sf C«» Oi C> o Q WCVOQ IS o• o• o• o« o• • •« •• •• O wt3 I cj H ir\ o ir\ cv +1 » o • • • • • to to to to to vO Is >r\ m u\ m »a en 9-3 en :: I ^3 \0 vo o vO 8 o• o• o• o• o• o H tO ^OvO tv to O CM 2 © OS O H Oi C\ sfin NO S5 w cm cm cQ <\i 56 COST ESTIMATION FOR UREA COMPLEX PROCESS Approximate Material Bv lance 1. Methanol-urer. saturation tan (Equipment No. 5)* a. Ureau 2,000 lb. x (50/6) 17,000 lb. /day = 2,125 lb./hr. b. Methanol 1 m3 x (300/6) = 50 mVday = 13,200 gal./day = 1,650 gal./hr, 2. CrystrJLizer (Equipment No. 6)* a. Miscella 2,000 lb./day • = 250 lb./hr. b. Methanol If 650 gal./hr. c. Ureau * 2,125 lb./hr. 3. Crystalizer, Hot water mixing section (Equipment No. 7)* U0° F. (6C° C.) vat r 66,000 gal./day = 3,250 gal./br. 4. Rotary vacuum filter (Equipment No. 3)* To Equipment To E uipment No. 13 * No. 9 a. Hot watar 3,250 gal./hr. b. Methanol 1,650 gal./hr. c. Urea* 2,125 lb./hr. d. Oil fraction 2,000x(0.4) = 800 lb. /day = 100 lb.hr e. Wax fraotion — 150 lb./hr. 9,900 gal./hr. 150 lb./hr. 100 lb./hr. « •Refers to the equipment number on the flow sheet, p. 32. 57 5. Urea washing-off section (Equipment No. 9)* Water 8,0C0 gal. /day 1,000 gal./hr. 6. Rotary vacuum filter (Equipment No. 10)* To Equipment To Equipment No. 21 No. 11 a. Filtrate 1,C00 gal./hr. b. Wax fraction 150 lb./hr. 7. Vacuum dryer (Equipment No. 11)* jfaH 150 lb./hr. 3. Settling Tank (Equipment No. 13)* To Equipment To R-uipment No. 18 No. 15 • a. Water 3,250 gal./hr. b. Methanol 1,650 gal./hr. c. Urea 2,125 lb./hr. d. Oil fraction ICC lb./hr. 9,900 gal./hr. ICC lbs./hr. 2,125 lb./hr. 9. Evaporator (Equipment No. 15)* a. Oil fraction 100 lb./hr. b. Solvent 100 gal./hr. 10. Methanol-water-urea fractionation column (Equipment No. 19)* a. Water 8,250 gal./hr. b. Methanol 1,650 gal./hr. c. Urea 2,125 lb./hr. Mole fraction of methanol 1650 on urea free basis: 32. = 0.10 1650 + 3250 32 18 Mole fraction of water t 1 - 0.10 = .90 •Refers to the equipment number on the flow ah et, p. 32. • 58 11. Evaporation Kettle for Urea recovery (No. 21)* gal./hr. a. Water 9,250 2 1Z Ib./hr. b. Urea » ^ Approximate Heat Balance Assume that he t capacity of water and methanol ar: equal to 18 Btu. per 1 lb.-iuole per °F. and the temperature of city water is 68 F. 7)* 1. Crystalizer, Hot water mixing section (Equipment No* Heat required to raise city watd' to 140° F.: Water 3,250 gal./hr. 69.300 lb./hr. = 3,350 lb.-mole/hr. 3,350 x 13 x (140-63 = 5,539,600 Btu/hr. 2. Settling tank (Equipment No. 13)* Assume that the temperature drop of the solution during the pro- cess ia 40o F. from the 140° F. hot water: Methanol 1,650 gal./hr. = 13,360 lb./hr. = 433 Ib.-mole/hr. 433 x 18 x (212-1CC) = 872,903 Btu/hr. 3. Evaporator (Equipment No. 15)* Assume that teia erature of the oil fraction at the inlet of the unit is at 13C° F. and the boiling point of purifying solvent is 180° F, and the volume ration of oil and the solvent i3 one to four. Temper turL of the oil and solvent mixture is: 100 gal. x 180 = 18,000 +) ACC gal, x 63 = 27.200 500 gal. 45,200 Average temperature 45,200 # 500 90° F. Assume that the average molecular weight of the mixture is 50 500 x 18.1) x .18 x (180-90) = 136,080 Btu/hr. 50 4. Methanol-water-urea fractionation column (Equipment No. 19)* Water 9,250 gal./hr. = 4,356 lb.-mole/hr. Methanol 433 lb.-mole/hr. (4,856 + 433) x 18 x ) 200-130) = 190,404 Btu/hr. *Referr= to the equipment number on the flow sheet, p. 5. Ifraporatar for Urea recov. ry (Eaiipment No. 21)* Neglect the boiling point elevation of the urea-water mixture 4,356 x 13 x (212-130) = 2,797,056 Btu/hr. Total hect required: 5,539,600 + 372,908 + 136,03c + 190,404 + 2,797,056 =9,536,043 Btu/hr. =9,600,000 Btu/hr. Since 1 Boiler H.P. = 33,475 Btu/hr. Therefore 9.600.000 = 287 Boiler Horsepov .r required 33,476 +Refers to the equipment number on the flow sheet, p. 32. % 60 Table No. 5. Specifications of equipment and their costs • t :Unit * Items Quantity x Price : Amount Methanol-urea Saturation tank Baameled lined, steam jacketted with 5 H.P. agitator, = Ca acity 2,CC0 gal. 1 |2,000 $2,000 Crystalizer and washing off section G lvanized screw conveyer with tight cover 6" dia. x 20 • with \% H.P. motor Capacity = 315 cu. ft./hr. r.p.io. 160 4 2.40 960 Rotary vacuum filter 5 1/4 • dia. x 3 », 139 sq.ft., steel, 39 ton/hr., with 1 1/2 H.P. motor 1 4,500 4,500 Rotary vacuum filter 1 3* dia. x 2 , 13 sq. ft., cast-iron drum, ton/hr. with 5.4 1/2 H. P. motor 1 1,200 1,200 Evaporator -aam jacketted, capacity 725 gal, 1 1,000 1,000 with condenser and premixer >ettlin^- tank Steel, cylindrical, capacity = 30,000 gal, with 100 sq, ft. heating coil and condenser 1 3,000 3,000 Aequeous phase receiving tank Steel, cylindrical tank, Capacity 30,000 gal. 2 3,000 6,000 Methanol-urea-water fractionation column Capacity = 1,000 gal, alcohol/hr. 12 theoretical plates 1 47,000 47,000 Evaporation kettle for urea recovery Capacity = 1,000 gal. 10 1,200 12,000 Oil storage tank C-pacity = 1,000 gal. 1 1,000 1,000 Vacuum chamber dryer .Shell size 39 • x 39 • 1 1,800 1,300 Total $30,460 Tne^e are "delivered &gw«l cost", as reported by Vllhrandt (l5). - . 61 Table 6. Estimation of capital requirements. , Cost , Item ,„., _ , Machinery and Equipment $ 80,460 Installation cost (43$ of the delivered cost of equipment) (17), including the oost of « foundation, support, insulation, erection- and necessary piping 34,600 Land and Building 50,000 Seven days raw material stock (10) Methanol |0.7C / gal. 64,680 Urea #0.05 / lb. 5,950 Total $ 235,690 - Yearly manufacturing cost. • a. Machinery and equipment depreciation (17). Items A B A - A Initial Cost Average life, Ye?vr B Depreciation/yr 1. Methanol-urea saturation tank t 2,000 15 $ 124 2. Crystalizer and washing off section 960 15 59 3. Rotary vacuum filter 4., 500 15 230 4. Rotary vacuum fi It r 1,200 x5 68 5. Evaporator 1,000 20 48 6. Settling tank 3,000 20 143 7. Aequeous phase re- ceiving tank 6,000 30 193 8. Methanol-urea-water fractionation column 4-7,000 20 2,240 9. Evaporation Kettle for urea recovery 12,000 25 443 10. Oil storage tank 1,000 30 33 11. Vacuum chamber dryer 1,800 20 86 Total 1 3,722 • 62 • b. Cost of mi see11a (Assume 2% Siellysolve-B loss) * 13,200 c. Raw Mater al Loss (3C-working days base) 133,600 1. Methanol 13,200 x 0.05 = 66C gal./day 60C x 0.7 =462 dollars 'day (10) 462 x 300 =133,600 dollars/year 2. Urea I033 (Assume 10$ loc ,) 25,500 d. Insurance and tax (17) 2% of capital invested 4,700 e. Depreciation of Building and maintenance fee 1,750 (assume 556 of initial cost) f. Water and Power 4,500 Labor and Supervision 14,400 (Assume 3 workers, at $2»0C/hour 3x300x3x2 = U,4C0 h. Others 1,000 Total $207,372 Amount of yearly sale Crude Wax: 1,200 lb./day 252,000 1,200 x 0.7 = 340 dollars/day (10) 3-40 x 300 = 252,000 dollars/year 011: 800 lb ./day 300 x 0.1 = 30 dollars/day (10) 30 x 300 m 24,000 dollars/year 24,(00 Total $276,000 • 63 - Sales values of byproduct ,. Coat of the wax = Annual Manufacturing Coat o. of Pound of wax produced = 13?. 372 x 100 = 51 cents/lb. of wax 1,2(C x 300 = 276,000-207,372 = Annual Frofit before tax = Net sales-Manufacturing Cost 6S.62B dollars/ysr x 10c = 29* Annual Return oa Investment Annual Profit frftffij Capital Investment 236,690 J return on investment Note* The express ons of annual profit and annual Robert S. were obtained from Chemical Engineering Cost Estimation by Aries and Robert D. Newton. EXTRACTION OF WAX FROM SORGHUM BRAN ty HSISK-VFN HSU B. S., National Taiwan University, China, 1951 AN ABSTRACT OF A THESIS submitted in partial fulfiT1.irtp.nt of the requirements for the degree MASTER OF SCIENCE Department of Chemical Engineering KANSAS STATE COLLE OF AGRICULTURE AND APPLIED SCIENCE 1955 One of the functions of the Agricultural Experiment Station is the never ending search for means of better and fuller utilization of the agricultural products that are of special interest in the state of Kansas. In line with this broad objective, the recovery of wax from the sorghum bran has been studied in several theses in the Departments of Chemical Engineering and Chemistry in recent years. The present work has been concerned primarily with the second phase of the recovery process, that is, the separation of wax from the miscella which was extracted from sorghum bran with Skellysolve-B, The temperature effect of the precipitative crystallization method of separation using acetone as the solvent was studied. It was found that by lowering the crystallization temperature from 6°C. to -8°C, the crude wax yield could be increased by appr ximately % per cent. A laboratory procedure of separation was developed applying the urea- complex technique. It was found that this method would give a nearly two- fold increase in the crude wax yield over th^ acetone method at -8°C. The amount of the wax and oil fractions recoverable by the various methods, re- ported as weight per cent of the starting miscella, :-re summarized as follows: Method of Separation Wax Fraction Oil Fraction Acetone at 6° C. 16.8 + 3.7% 83.2 + 3.7% Acetone at -8° C. 26.4 + 2.8% 73.6 + 2.0% Urea-Complex 53.36 + 1.01% 41.64 + 0.44% Cost-wise the major problem in the urea-complex method is the necessity to concentrate large volumes of dilute solutions of methanol and urea, re- spectively. These concentration steps can be carried out with the standard technically, it should distillation and evaporation equipment, therefore, to be adopted for plant not introduce any difficulties were this method urea-complex method could be operation. An equipment flow sheet for the recommendation can not be feasible on an industrial scale, a positive calculations have until further pilot plant tests and detailed design been performed. ti on was to seek another The secondary objeotiv of this invest!,: llysolve-B in that it could solvent, or solvents, that is superior to Set bran and it could also increase extract larger amounts of adsoella from the additional solvents and two the wax to oil ratio in the aisoella. Sev n 16c extraction runs with the aseotrope mixtures were studied in altogether include the following! acetone, Pyrex Soohlet. The single solvents studied secondary butyl alcohol, n-butyl ;i»thyl ethyl ketone, absolute aloohol, The aaeotrope mixtures were ether, ethylene diohloride, and methanol. ethyl ketone-heptane-water. ethylene di ohloride-heptane^ater and oethyl for comparison. It Also a series of runs were made with Scellyaolve-B highest yield of adsoella as was found that the absolute aloohol gave the well as the highest wax-oil rctio in the .idsoelle. m >r» ff>o OCM -*WNCM in r> sO men o co cm en -4- 32£ o +1 • • • • • • • • • * • • « » •p en Cn cr\ C\ 0"\ m sfen cm en en en en en CM en en 5ill en • en