CA1169794A - Process for treating cellulosic material and products produced therefrom - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A process for treating cellulosic material With ozone to produce cellulose which has been rendered susceptible to microbial attack wherein the cellulosic material is ground to a fine particle size, mixed with water, and subsequently treated with ozone. The temperature is ambient, and pressure can vary from atmospheric to 10psi (gauge).

Description

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.

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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 ~' -~ 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 . .
~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 .

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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 ~ ~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 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.

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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.

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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 .

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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 . .
~ .

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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-.
.. . . .
.

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~

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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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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 ~ ~ ~ 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:

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 . ~

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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.

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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.

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~ 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.

I

~ ~9~4 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 ~ 1697~

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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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for treating cellulosic material to produce lignin-free cellulose which is susceptible to microbial attack comprising treating said cellulosic material with ozone.

2. The process of Claim l wherein the cellulosic material is of a particle size of between dust and about 5 mm in at least one dimension.

3. The process of claim 2 wherein the particle size is from 250 to 500 microns.

4. The process of claim l wherein the cellulosic material is mixed with water in a ratio of 10:1 to 1:10 parts cellulosic material to parts water by weight.

5. The process of claim 4 wherein the ratio of the water to ground cellulosic material is 1:1 by weight.

6. The process of claim 4 wherein the ratio of the water to ground cellulosic material is 2:1 by weight and the cellulosic material and water mixture formed is stirred during ozonization.

7. The process of claim 1 wherein cellulosic material is treated with ozone in an amount of 0.75 to 6.8 by weight.

8. The process of claim 1 wherein the cellulosic material is treated with ozone in an amount of 3 to 3.5% by weight.

9. The process of claim l wherein the cellulosic material are treated for a time of from 15 minutes to 16 hours.

10. The process of claim 1 wherein the cellulosic material is treated with ozone under ambient conditions for a period of 1 hour.

11. A process of treating cellulosic material com-prising reducing said material to a size of from dust to about 5 mm in one dimension, mixing the cellulosic material with water in a ratio of from 10 parts cellulosic material to 1 part water to 1 part cellulosic material to 10 parts water and exposing the same to ozone for a period of time of from 15 minutes to 16 hours under ambient temperatures and pressures of from about atmospheric to 10psi gauge.

12. The process of claim 11 wherein the cellulosic.
material and water are stirred during the exposure to ozone.

13. A process of treating cellulosic material comprising grinding said material to a particle size of from 250 microns to 500 microns, mixing the cellulosic material with water in a ratio of from 2 parts cellulosic material to 1 part water and exposing the same to 3 to 3.5 ozone in air while stirring the cellulosic material under ambient conditions from about 1 hour to 4 hours.

14. The process of claims 1, 11, and 13 wherein the pH of the cellulosic material and water before ozonization is 10.3.

15. The process of claims 1, 11, and 13 wherein there is added to the cellulosic material water mixture during ozonization an iron salt to provide an amount of iron equal to 0.2% iron by dry weight of the lignocellulose present.

16. A process in accordance with claims 1, 11, and 13 including fermenting the product produced thereby to produce other products.

17. A process in accordance with claims 1, 11 and 13, including fermenting the product produced thereby to form ethyl alcohol.

18. A process in accordance with claims 1, 11 and 13 including enzymatically treating the product produced thereby to produce other products.

19. The process of claims 1, 11 and 13, including enzymatically treating the product produced thereby with cellulase.