Note: Descriptions are shown in the official language in which they were submitted.
1 316'379~
PROCESS FOR TREATING CELLULOSIC MATERIAL
AND PRODUCTS PRODUCED ~HEREFROM
This invention relates to a process of producing
cellulose which has been rendered susceptible to microbial
attack. By microbial a-ttack is also included enzymatic
hydrolysis wherein the microbes producing the enzymes
are not in contact with the cellulose, but wherein only
the enzymes are brought in contact with the cellulose.
More speci~ically, this invention teaches a process for
treating lignocellulose with ozone to break the lignin
bonds with the cellulose and thus convert the lignocellu-
lose into usable cellulose.
It has been found that a larye proportion
of waste material is of the lignocellulose type. This
waste material is a by~product of agricultural products,
the lumber industry, the paper industry, etc., in the
form of waste pulp, sawdust or waste reduced to this
form~
The disposal of this material has become a
problem, both financially and ecologically. Industry,
therefore, is attempting to derive a use for this product
whereby the disposal problem is solved and usable products
produced.
~5 ' ~,3
~IB979~
One such product has been the conversion of ligno-
cellulose into animal feed. The feeding of livestock has
been of some concern because of the direc~ competition between
feed for livestock and food for man, in view of the large
amounts of grain usually incorporated in livestock feed.
Although this competition is evident in many instances, in
some areas it does not exist.
This latter situation is exemplified by herbivorous
animals, particularly, ruminants, such as cattle, which
possess digestive abilities that man does not.
Cellulose, although undigestible by humans, can be
digestible by ruminants because of the action of bacteria
in their digestive system on the cellulose molecule.
Critical to this ability is the presence of a multi-component
complex stomach which, through the presence of various micro-
organisms, hydrolizes the chemical linkages of cellulose,
eventually producing energy and releasing plant cellular
components, which are also utilized by the animal. Only
herbivorous animals can utiliz~ cellulose as a source of
energy since other species do not possess digestive facilities
for the degradation of cellulose. The major problem in
cellulose waste is their high content of lignin, a natural
wood polymer that is extremely resistant to biodegradation.
Lignin is the major non-carbohydrate constituent of wood and
woody plants and it comprises between 18~ and 38~ of the mass
of such vegetation. Lignin functions as a natural plastic
binder for the cellulose
~'
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~ 1~9794
fibers and is stated to be, composition-wise, a polymeric
substance of subs-tituted aromatics, largely of the phenolic
type. The molecular weight of lignin and its derivatives,
since they are polymeric in nature, vary somewhat depending
upon the method employed for their determination. If the
cellulose is bound up with the lignin, it may be impossib~e
~or bacterial action in the ruminant to occur and the celIu-
lose is thus unavailable to the animal ~or d}gestion. In
some plants, almost all o~ the cellulose may be in the
~orm of lignocellulose and thus of no feed value.
It has been ~ound that it is possible to che~ically
attack the lignin without destroying the cellulose and
thus convert the lignocellulose into usable cellul~se. A
number of methods have been proposed for doing this and
these provide a satisfactory level of conversion, but
they are expensive and,in other aspects, undesirable!
One method for producing animal feed from bagasse is
disclosed in Patent No. 3,903,307, issued to Y. Kimuar,
which combines the bagasse with yeast in a fermentation
process.
Another paten~ disclosing the conversion of waste
cellulosic mat~rial to protein is Patent No. 3,627,095,
issued to V. R. Srinivasan et al. Mineral acids have been
used for converting cellulosic material as, for instance,
Patent No. 4;006,253 to K. L. Ber(Jer et al. ~long this
line, Patent No. ~,053,6~5, lssued to J. W. Jelks, discloses
the use of nitric acid. Alkalis have also been used, as
9 4
. .
~aught in Patent No. 4,048,341 to G. B. Lagerstrom et al~
Glycols have been used to treat wood and wood wastes for
the production of animal feeds as set forth in Patent No.
~,017,642 to G.O. Orth, Jr. et al.
One of the recent developments, which is set forth
in Patent No. 3,939,286 to ~.W. Jelks, discloses the
treatment of cellulosic material by oxidizing and hydrolizing
the same to produce animal food. This process uses oxygen
in the form of air and a!catalyst of metal or acid or both to
break the beta linkage and the glucose rings in the cellulose
chain.
A11 of the above processes produce a cellulose product
of some caliber which is capable of being further treated to
produce various products. It can be treated by the bacteria in
the stomach of the ruminant to produce nutritive value to
cattle or it can be fermented with other microorganisms to
produce various products, such as alcohols or organic chemicals
which are equivalent or can be substituted for compounds currently
obtained from petroleum. ~hen microorganisms are used, they
20 function as enzyme producers which, in turn, hydrolizes the
cellulose. It is also possible to produce these products by
treating the cellulose product directly w;th en~ymes which are
produced elsewhere.
All of the above methods have various drawbacks or
necessitate further steps before products can be produced.
Those methods using acid or alkali treatment will have to be
.
7 9 ~
neutralized prior to being used as a feed or before fermen-
ting to other products. Many of these processes require
that the treated material must be sterilized prior to
fermentation so as not to contaminate the finaL product
with unwanted microbial growths.
Further, many of them require excessive heat
or pressure which will destroy some of the organic products,
i.e.~ glucose, which are necessary for fermentation to
produce other products such as alcohols, acetone, etc.
Many of the above processes produce cellulose material
suspended in a slurry which is difficult to handle and
requires further process steps.
In view of the above, it is seen that there
is a need for a process of treating cellulosic material,
particularly lignocellulose, which is simple and effic-
ient for producing a cellulose product which is suscep-
tible to microbial or enzyme attack and which does not
require treatments and various process steps and additives
and which is capable of being performed in small or large
batches or even in a continuous manner.
It has been found that cellulosic material
containing lignin can be made susceptible to microbial
or enzyme attack and, therefore, capable of being used
as a feed for ruminants, being fermented by other micro-
organisms or being hydrolyzed by enzymes to produce various
products, by removing the lignin from the cellulosic
material.
It has further been found that the lignin bonds to
~ the cellulosic material can be broken by attacking it
- 30 with oxygen in the form of ozone. Although ozone will
attack cellulose, it attacks aromatic systems, such as
- ~ ~6~7~
., . , . ~.
phenols, much more readily.
Further, this reaction can be more efficiently
carried out if the cellulosic material is ground to fine
particle sizes and mixed with water under ambient
conditions. Stirring, pH and certain catalysts can also
aid somewhat to produce a better product. Subsequently,
the product produced therefrom can be used as a feed
for ruminants susceptible to the attack of the bacteria
in the stomach of the ruminant or it can be fermented
by microorganisms or treated with enzymes to produce
various products, such as ethanol, acetone, butanol,
and a number of other organic chemicals which are equivalent
to or can be substituted for compounds currently obtained
from petroleum.
In accordance with the present invention, there-
fore, there has been found a new process for treating
cellulosic materiai, which process will break the bonds
between the lignin and the cellulose and thus produce
cellulose which is susceptible to microbial or enzymatic
attack.
In accordance with the present invention, there
is provided a process for treating cellulosic material
to produce lignin-free cellulose which is susceptible
to microbial attack comprising treating said cellulosic
material with ozone. Usually, the process consists of
chopping up or grinding the cellulose, mixing it with
water, and treating it with ozone under ambient conditions.
Preferably, the lignocellulose is ground to a size of
from dust to about 4 mm, mixed with water in a ratio ~~
of from 1 to 10 to 10 to 1, and exposed to ozone in
an amount of from 0.75 to 6.8% to produce a cellulose
-- 6
~ ~697~ll
.: .. . . . . .. . . .
which is capable of being hydrolyzed.
The present invention produces cellulose which
is susceptible to microbial or enzyme attack from ligno-
cellulose by treating the lignocellulose with ozone.
Ambient temperatures and pressures of from
atmospheric to 10 psi (gauge) with ozone may be used.
The cellulose is usable as a feed for ruminants, or may
be fermented to produce alcohol, acetone, or other products.
The process that is non-polluting, using only
ozone produced electrically from air forms a sterile
product.
In the past, cellulosic material has been treated
with acid, alkalis, and even oxygen with acid and metal
catalysts to produce similar products. The previous
processes, however, had the disadvantages of the necessity
of neutralizing the acid or alkali before use, causing
further waste material which must be disposed of, or
the use of high pressures and temperatures. High pressures
and temperatures often destroy some of the products produced,
which made the final product less susceptible to fermen-
tation to certain alcohols or other products. Further,
the processes of the prior art do not lend themselves
to on-site production
- 7/8 -
9 ~
or using simple apparatus. In ot~er instances where particular
products are desired by the use of Permentation, it was
necessary to sterilize the lignin-ree cellulose prior to
fermentation so as to prevent the formation of unwanted
microbial growth.
The above difficulties have ~een obviated by the
present invention in that the ozone is produced electrically
and thus can be made on-sit~ in small or large quantities
as preferred using very simple apparatus.
Further, the present invention can be performed
under ambient conditions so as not to destroy certain of
the products sugars as would ordinarily be produced. The
present process, because of the use of ozone which is a
sterilizing gas, also sterilizes the cellulose while breaking
the lignin bonds. The present invention is simple, requires
- little material, and is faster and more complete than prior
art processes.
The following tests were made to determine the
parameters of sol`ds to water ratio. The effect of the
amount of water used in the lignocellulose-water mixture
being ozonized has been studied using solids/water ratios
from over dry lignocellulose to a very large excess of water
(ca 1/10 solids/water ratio). The first tests made are shown
in the following Table I.
~r~
/.'~?.
g 4
The follo~ing apparatus and method was used for
performing the tests et forth in Table I.
All of the work was done using a simple tube reactor
25 mm in diameter and 250 mm lenyth, fitted with a gas entry
tube and a gas disperslng frit on the bottom. A twenty
gram sample of lignocellulose (hardwood sawdust except when
otherwise noted) was mixed with the indicated amount of water
and any other materials mentioned and charged into the tube.
Ozone gas produced from cylinder oxygen by a small Welsbach
ozone generator was passed through a water trap and into the
bottom of the reactor at the rate of 0.5 liters/min. The
oxygen/ozone mixture contained about 2% ozone. Digestibility
was subsequently determined by the Tilley-~rry In Vitro
Method (J. Brit. Grasslands Soc., 18 1963~ Modif. by NC-69).
This bioassy method is widely accepted as a standard technique
for determination of digesti~ility (for ruminant animals) of
cellulose containing feeds. Initial studies indicate an ozone
consumption of about 9~ of the weight of the lignocellulose
sample. The approximations in the digestibility figures arise
from the iact that the samples were not homogenous after
o~onelysis.
--10--
979~
.
TABLE I
Effect of ~a'.er Content and Effec* o'f E'xposure Time
. _ , . . _ _
Water Content Time'of Exposure % Digestible
large excess 12 hours O
same 12 hours 10.7
1/1 wood/water 15 minutes 20 (avg)
same 35 minutes 42 (avg)
same 1 hour about 50
same 2.5 hours about 60
,10 same 6.75 hours about 58
same 9 hours about 68
same 16 hours about 71.1
-lOa
~1
7 9 ~
In enzymatic hydrolysis testing, there was used
a commercially available preparation of cellulase enzyme
produced from Tricoderma Virdi. The quantity of enzyme used
i~ su~icient to hydrolyze approximately 5~% of a sample of
pure microcrystalline cellulose. This is a convenient
standard and has been used as a measure of enz~ne actiYity
by others. By increasin~l the enæyme concentration, one s
could, of cour~e, increase the extent of cellulose hydrolysis.
Howe~er, excessive concentrations of enzyme would possibly
mask the effects produced by the ~arious changes in the
pre-treatment conditions being tested. The conversion of 50
of the cellulose in~o reducing sugars-is thus an arbi~rary
level. The conversions of pre-treated lignocellulose into
reducing sugars were measured relative to this conversion
of pure cellulose. The amount of reducing sugars pxoduced
... . . .
was determined by the well-establishe~ colorimetric method
using dinitrosalcyclic acid (Saeman, J.F., Moore, W.E., and
Millett, M.A., "Methods in Carbohydrate Chemistry", Vol. III-
Cellulose, pp 54-59 (1963), Academic Press~. This enzymatic
assay procedure was similar to that used by others in evaluating
other pre-treatments (Mandels, M., Hontz, L., and ~ystrom, J.,
"En~ymatic Hydrolysis of Waste Cellulose", Biotechnology and
Bioengineering XVI, 1471-1493 (1974)). Prior to enzyme testing,
.
the ozonized material was divided into two portions. One
portion was washed with three portions of boiling water (100 ml
H20 per 5 g sample) and the other portion was used without
washing, These are designated "washed" (W) and "unwashed" (U) t
respectively. The wasll liquid contained a colored material
which was probably partly ozonized lignin. The wash also
.
r~
. .
7 9 4
appeared to contain some celli~.iosc, ~u~ appar~ntly no glucose.
Under some ozonization c~n~itiorls, ~r.illlarily lon~ ozonization
times, the material beinq washed out appeared to be somewhat
inhi~i~ing or toxic to the enzyme and to ~icrooryani~5. In
other cases, such d~ short ozonization p~riods, this was
not noted. In all cases, the enzyme as~ay was cond~cted
separately for each and both results are show~ in the following
tables.
Some further tests relative to the solids/water
ratio and other ~arameters were performed as shown in ~he
following tables using stirred reactors and enzymatic hydrolysis
t.esting.
TABLE II
DESCRIPTION ENZYME HYDROLYSIS SUSCEP~
BILITY (W.R.T. CELLULOSE)
(1 hr. tLme, [03] ~ 6%
SOLIDS/WATER RATIO = 9/1 U ~ 28.. 1
W = 22'.7
5/1 U = 51.4
W - 43.7
4/1 U - 59.1
W = 54.4
: 3/1 U = 91.0
W = 91.0 .
2/1 U = 100.5
W = 97.5
1/1 .U - 7908
W - 76~9
excess ~2 U~W - 1.6
. .
~ .
-12-
~ ~ ~ .
697g4
:
TABLE I I I
One hour run in stirred reactor with çold ~ir
feed (ca 3% ozone)
DESCRIPTION OF SAMPLE ~ SUSCEP,~IBILITY ~W.. ~.T.
PURE CELLULOSE)
Oven dried, ca 05 water . U ~. 2.. 5%
, W ~ 15.8
Air dried (ca 10% water)U = 36.3
W = 31.7
Solids/Water = 3/1u.= 95.O
W = ~8.3
Solids/Water - 10/1. U = 20.0
W = 12.2
Control sample of completely
untreated oak ~awdust, no
ozonization or water added
or washing 12.8%
:. - .
Using an uns~irred reactor indicated an optimum
solids/water ratio of 1/1 based only on Tilley-Terry analy5is
as seen in Table I. In Tables II and III, the conversion at
S/W = 2/1 is seen to be slîghtly better, because.the
:. consistency of that mixture is some~hat ~etter for a stirri~g
.. action. It was concluded that for this set of reactions the
. optimum S/W ratio was 2/1.
.
The following tests were macle to determin.e the
,
effect of particle size on speed of reaction and ultimate
conversion. The rapid~y with which ozone reacts with ligno-
cellulose to provide an effective pre~treatment is dependent
on particle size. For example, 106 micron size is sufficiently
- \ reacted after 1 to 2 hours to give an eventual sugar con-
.
.. . . .
.
--13--
l ~ B~7g4
version which i5 80% of that of pure cellulose. For 250
micron size~ 2-3 hours of ozone treatment were required,
while 500 micron size re~uired 3-4 hours. Sizes of 1 mm and
larger did not reach this level of convertability even with
very long ozonization times with the simple,unstirred colurnn
type reactor used here and in prior work. However, using a
stirred blade reactor, there was accomplished the conversion
of very coarse material (greater than 4mm) solid/water
ratio = 2/1 using 3% ozone and one hour treatment time. The
observed susceptibility of enzymatic hyclrolysis was:
Unwashed = 68.3% of that of pure cellulase
Washed - 58.6% of that of pure cellulase
From this, it was concluded that even very larse
particle sizes ~ 4 mm) can be treated to yield moderately
susceptible material if proper conditions are chosen. On
further testing of larger pieces of wood, it has been found
that substantial reaction takes place in a reasonable amount
of time on pieces of cellulose that have a dimension of at
least 5 mm, or less, in at least one dimension. It could,
~0 therefore, work on a large piece of wood, provided it is at
least as thin as 5 mm in one dimension.
The effectiveness of the ozonization treatment is not
necessarily increased by long ozone reaction times. In
almost all cases, an initial rapid increase in enzyme
-13a~
, ~
~"~
1 31~9~9~
digestibility is noted, but the rate of increase falls off
quite rapidly after a certain point and a plateau or even
a decrease is observed. This data were ~btained using a
.
simple unstirred reactor (as previously described) and an
ozone concentration near 2%.
When using a stirrer, ~ simple blade stixred
reactor wa~ used to improve sample homogeniety during
ozone treatment. Stirrin~ was slow, ~ 30 rpm. Using
sti~red reactor to evaluate various ozonization conditions
it was found:
~ The amount of digestibility il~crease in a fixed
-time (1 hour) was greatly increased for every particle
size tested using the stirred reactor compared with an
unstirred reactor. ~'or example, the conversion reached
by 500 micron material in an unstirre~ reactor in one
hour was approximately 55% with 6~ ozone. In ~he stirred
reactor, the conversion was approximately 80%. In both
cases, the percentage is relative to purecellulose~
The particle size of the cellulosic material,
therefore, is inversely proportional to the rate of re-
actlon. If the particle size decreascs, the rate of react.ion
increa~e-R. A range ~f from dust to greater than 4 mm can be
used. This can be seen in the data of Table IV. ~rhe preferred
slze is below 500 microns. It has been found that particles
below 500 microns react almost as swiftly as particles
below 250 microns.
The reaction time will vary anywhere from 15 minutes
to 16 hours, depending on the other variables of particle size,
water content, temperature, pressure, and the amount of ozone usedO
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--15--
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.
Table IV shows the result of vaxying the partic~e
siæe and the ratio of water to celluloslc material along
with varying the time. In the Table, ~he results are
represented in terms of digestibility of the cellulosic
mater~alO
In this Table, lignocellulose of known water conten~
wa8 mixed with varying amounts of added water. There was
a small increase of digestibility when oven (110C for
24 hours) dry material was ozonized and also when ligno-
cellulose suspended in a large excess of water was treated.
'~he maximum amount of conversion in any given time period
was obtained when the ratio, by weight, of lignocellulose
to water-was 1 1.
The ultimate amount of lignocellulose conversio~
which can be effected by ozone is no,t very depended upon
particle size of the lignocellulose. After a very long treat-
ment time, the coarser particles reach the same degree of
conv~rsion as the finer ones. Ho~ever, the rate at which~the conver-
sion occurs is much faster in the case of the finer particies.
While this kinetic efect probably holds true down to the
very finest ~article size available, in a practical w~y a
partic~e size of under 500 microns reacts with the ozone
practically as fast as one of less than 250 microns~ These
sizes are attainable with commercial grinding equipment.
rrhe ef~ect of ozone concentration was determined
by te~ting various concentrations between about 6~% by
weight and about 0O75~. It was found that 0.75'~ gave no
appreciable pre-treatment effect. At about 1.6%, some effect
-16-
~ ~ ~ 979 4
on enzyme digestibility was noted which increases with in-
creasing levels of ozone used in the pre~treatment until
about 3.0 to 3.5%, which gave a maximum effect. Higher
concentrations gave lower pre-treatment effects. The
' following tables indicate the results of these tests.
TABLE V
;~ The results for 500 micron material with 3:1
solids water ratio, stirred for l hour treat-
ment time are:
10OZONE CONCENTRATION ENZYMATIC HYDROLYSIS
SUSCEPTIBILITY ~W.R.T.
CELLULOSE)
6.8% U = 59.8%
W = 51.7%
6.08% U = 91.4%
W = 77.1%
3.36~ U = 100.3%
W = 93.6%
3.37% U = 88.5%
~1 = 89.8%
TABLE VI
The results using 2:1 solids/water ratio with
500 micron material for one hour treatment time
are:
OZONE CONCENTRATION (avq) HYDROLYSIS SUSCEPTIBILITY
(W.R.T. CELLULOSE)
0.75~ U = 6.8%
W = 6.2%
1.6% U = 34.4%
W = 26.4%
3.0% U = 64%
W = 58%
It was concluded that using a stirred reactor and
3/1 and 2/1 S/W ratios, the optimum ozone concentration seems
-17-
. ~
1 ~B~7~
to be about 3%. The higher ozone concentrations actually
give less effective resu~ts, probably because of excessive
oxidation.
The effect of pH was also studied and it was found
that a small increase in pH caused by the addition of sodium
hydroxide to the water mixture of lignocellulose produced the
following results:
TABLE VII
Molarity of NaOH Initial Final Digestibility
Solution Used pH pH
1.0 2.30 2.22U = 71%
W = 76%
2.0 9.45 3.16U =-84%
W = 7s%
5.0M 10.29 4.12U = 91%
W = 68%
10.0~ 11.41 5.05U = 60%
W = 70%
From this, it is seen that the somewhat acidic
sawdust~water mixture, even when neutralized, does become
acidic again upon ozonization, probably because of the
formation of various organic acids. It was concluded that
some benefit is afforded by initializing pH at about 10 pH
units.
The effect of catalysts were also studied and it
was found that soluble iron salts, such as ferric chloride
or ferric citrate, increased the effectiveness of the treat-
ment when added to the water-lignocellulose mixture in small
amounts. For example, 500 micron lignocellulose, 3.5% ozone,
1 hour, solids/water = 2/1. Iron salt used was FeC13.6 H2O.
-18-
~.
697~
The iron chloride Was dissolved in the water added to the
lignocellulose to bring its water corltent up to the desired
2/1 ratio. The iron concentration is expressed as a percent
of the dry solid present:
T~B~E VIII
PERCENT IRON SUSCEPTIBILITY TO
HY~ROLYSIS
(W.R.T. CELLULOSE)
- 0 (control) U = 70.3
W = 66.8
.02% U = 73.7
W = 60.8
.04% U = 81.1
W = 75.9
.08% U = 74.6
W = 66.3
.16% U = 76.0
W = 65.6
.20% U = 68.g
W = 55.3
Use of other soluble iron salts give similar results,
but iron chloride is prob~bly the least expensive and works
as well as any other iron salt tested.
From the above, it was concluded that the use of
iron salts in the amount of about .04% of the oven dry weight
of the solid present provides some increase in the effectiveness
of the treatment. Lesser amounts are not as effective and
greater amounts are increasingly less effective, becoming
actually harmful at concentrationsof about .2%.
Increased temperature and pressure will speed up
the reaction, however, this is unnecessary for the reaction
to be completed in a relatively short period of time. It has
been found that increased pressure up to 10psi ~gauge) will
increase reaction time. This may cause some decrease in efficiency.
--19--
'~.,i
~ . , .
9 ~
~ however Above lOpsi (~uge), it ~as found that the ozone
may break down and, therefore, a yreater amount of ozone
- would be necessary.
As indicated above, treatment time required is a
function of the particlé siæe for a given amount of conversion.
For practicality, a conversion yielding a product which is
at least 50~ digestible is desired for animal feed.
For fermentation processes to yield alcohol or other chemicals,
a greater or lesser amount may be required depending on the
process. In the case of fermentation to alcohol by conventional
yeasts, it is accepted that the material being fermented should
be at least 20% fermentable material, in this particular
instance sugars. It has been found that, using particle sizes
less than 500 microns and with a lignocellulose ratio of 1:1,
conversion of up to about 60% can be attained after exposure to
2% ozone for one hour. For times less than one hour~ the
amount of conversion was roughly linear with treatment ~ime.
Times greater than one hour did not yield proportionately more
conversion. Sixty percent is about the maximum attainable
from this particular material, the remainder being ash and other
substances, including the non-digestible lignin itself.
The optimum treatment conditions for ground peanut
shells, a typical lignocellulose material, are: grinding to
a particle size of less than S00 microns, mixture with
sufficient water to give a lignocellulose/H20 ratio of 1 1
by weight, and exposure to 2% ozone in oxygen (without
stirring) for one hour.
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The percent of digestible material in the treated sample is
about 60% by weight. The treatment is conducted at room
temperature (about 25C). The gas pressure in the reaction
is about one atm.
As can be seen by the above test data, various
parameters effect the rate of reaction and extent of reaction.
The major requirements, however, are that the cellulosic
material be of a size of from dust to about 5 m~ ln at least
one dimension, that it must be mixed with water in a ratio of
solid/water of 1 to 10 to 10 to 1, and that it be treated with
o~one in a concentration of between 0.75% to 6.8%. The
above parameters will give a completion of reaction to at
least 50~ within a reasonable amount of time, the preferred
ranges of a particle size are from 250 to 500 microns, and
a solids/water ratio of 2:1, if the reaction medium is stirred.
The ratio is 1:1 if there is no stirring. The ozone concen-
tration is most efficient when the concentration is from 3 to
3.5%.
Further as can be seen from the above tests, increases
in time and results are achieved using stirring of the reaction
medium during ozonization and slight increases are achieved by
the addition of catalysts and slight increases in pH.
With regard to the ~ermentation products capable of
being produced from the lignin-free cellulose produced by the
above process, there are various processes involved. It is
possible, however, for one to use various well-known processes,
depending upon the product desired. As, for instance, if one
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desires acetic acid, they could use the process set forth
in Langwell Patent No. 1,443,881. If one desires alcohols,
such as ethyl alcohol, one may use any of the processes of
the following: 1,639,571, 2,023,087, 3,990,944, and
4,009,075. Other processes capable of being used with the
present invention are noted in U.S. Pa-tent Nos. 3,764~47'
and 3,627,096.
Having thus described the process of the invention
in terms of the preferred embodiments, as set forth in the
description and examples of the before said specification,
it is apparent to those skilled in the art that various
changes and modifications could be made in the process
without departing from the scope of the invention. Thus,
for example, it is possible for the various parameters to
be changed in relation to one another to accommodate the
system under which it is performed. Further, depending upon
the product desired, various treatments can be performed on
the cellulosic mater al.
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