U.S. patent application number 14/619406 was filed with the patent office on 2015-06-04 for method for isolating cellulose from a biomass and products provided therefrom.
The applicant listed for this patent is Melvin Mitchell. Invention is credited to Melvin Mitchell.
Application Number | 20150152598 14/619406 |
Document ID | / |
Family ID | 52449176 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150152598 |
Kind Code |
A1 |
Mitchell; Melvin |
June 4, 2015 |
METHOD FOR ISOLATING CELLULOSE FROM A BIOMASS AND PRODUCTS PROVIDED
THEREFROM
Abstract
A pretreated biomass is subjected to high frequency pulses and
shear forces without denaturing and/or degrading the individual
components of the biomass. The biomass is then subjected to
compressive force to separate a first liquid fraction from a first
fractionated biomass. The first fractionated biomass may again then
be subjected to the same high frequency pulses and shear forces as
previously, particularly if there are hemicellulose and/or sugars
still present in the first fractionated biomass. Compressive forces
are used to separate a second liquid fraction from a second
fractionated biomass. The second fractionated biomass is subjected
to oxidation. The second fractioned biomass is then subjected to
compressive forces to separate out one or more water insoluble
components of the biomass in water soluble form and to provide
cellulose that has not been denatured and/or degraded and has a
lignin contact of less than 7 percent.
Inventors: |
Mitchell; Melvin; (Penrose,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitchell; Melvin |
Penrose |
NC |
US |
|
|
Family ID: |
52449176 |
Appl. No.: |
14/619406 |
Filed: |
February 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14454972 |
Aug 8, 2014 |
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14619406 |
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61864853 |
Aug 12, 2013 |
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61909418 |
Nov 27, 2013 |
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61919194 |
Dec 20, 2013 |
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Current U.S.
Class: |
162/56 ;
162/100 |
Current CPC
Class: |
C08B 15/08 20130101;
D21C 1/02 20130101; C08G 63/06 20130101; D21C 3/02 20130101; C08B
37/0057 20130101; C08H 6/00 20130101; C08H 8/00 20130101; C08G
63/912 20130101; D21C 3/224 20130101; D21H 11/00 20130101 |
International
Class: |
D21C 1/02 20060101
D21C001/02; D21C 1/08 20060101 D21C001/08; D21H 11/00 20060101
D21H011/00 |
Claims
1. A process for providing cellulose isolated from a biomass, the
process comprising: a) pretreating the biomass; b) subjecting the
pretreated biomass to high frequency pulses and shear forces
without denaturing and/or degrading the individual components of
the biomass; c) subjecting the biomass to compressive force to
separate a first liquid fraction from a first fractionated biomass;
d) subjecting the first fractionated biomass to conditions to raise
the pH above 9 and then subjecting the biomass to the same high
frequency pulses and shear forces of step b); e) subjecting the
first fractionated biomass to compressive forces to separate a
second liquid fraction from a second fractionated biomass wherein
the second fractionated biomass is substantially devoid of
hemicelluloses and sugars; f) subjecting the second fractionated
biomass substantially devoid of hemicelluloses and sugars to
oxidation at a pH above 7; and g) subjecting the second
fractionated biomass to compressive forces to separate one or more
water soluble components from the second fractionated biomass to
provide a third fractionated biomass comprising cellulose that is
substantially devoid of hemicellulose, sugar, and lignin.
2. The process of claim 1, further comprising after step e):
subjecting the second fractionated biomass again to conditions to
raise the pH above 9 and subjecting the second fractionated biomass
to compressive force to separate one or more water soluble
components from the second biomass biomass.
3. The process of claim 1, wherein the steps are conducted at
ambient temperature to about 60.degree. C.
4. The process of claim 1, further comprising after g): h)
subjecting the third fractionated biomass to oxidation at a pH
above 7; and i) subjecting the third fractionated biomass to
compressive forces to separate one or more water soluble components
from the biomass to provide a fourth fractionated biomass
comprising cellulose that is substantially devoid of hemicellulose,
sugar, and lignin.
5. A cellulose having less than 7 percent lignin that has not been
denatured and/or degraded by extreme temperature, pressure or
chemical conditions.
6. A cellulose having less than 7 percent lignin that has not been
denatured and/or degraded by extreme temperature, pressure or
chemical conditions prepared by the process of claim 1.
7. A paper or paper product prepared from the cellulose of claim
5.
8. A process for providing cellulose isolated from a biomass
comprising subjecting a biomass to conditions to separate cellulose
from the biomass to provide a fraction comprising cellulose and
lignin without denaturing or degrading the cellulose and then
oxidizing the fraction to provide cellulose having less than 7
percent lignin.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 14/454,972, filed Aug. 8, 2014, which claims
priority to U.S. Provisional Patent Application Ser. No.
61/864,853, filed Aug. 12, 2013, U.S. Provisional Patent
Application Ser. No. 61/909,418, filed Nov. 27, 2013, and U.S.
Provisional Patent Application Ser. No. 61/919,194, filed Dec. 20,
2013, the disclosures of which are incorporated herein by reference
in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for isolating
components of a biomass. Examples of fractions and extractives
provided in the process include the extraction, isolation, and
purification of lignin, cellulose, sugars, hemicellulose, fibers
and/or extractives.
BACKGROUND OF THE INVENTION
[0003] Natural cellulosic feedstocks are typically referred to as
"biomass." Many types of biomass, including wood, paper,
agricultural residues, herbaceous crops, and lignocellulosic
municipal and industrial solid wastes have been considered as
feedstocks for the production and preparation of a wide range of
goods. Plant biomass materials are comprised primarily of
cellulose, hemicellulose and lignin, bound together in a complex
and entangled gel-like structure along with amounts of
extractables, pectins, proteins and/or ash. Thus, successful
commercial use of biomass as a chemical feedstock depends on the
efficient and/or economical separation and isolation of these
various constituents.
[0004] Many steps are often required in production, harvesting,
storage, transporting, and processing of biomass to yield useful
products. One step in the processing is the separation, or
fractionation, of the biomass into its major components:
extractives, hemicellulose, lignin, and cellulose with smaller
amounts of pectins, ash, protein, and cutin. Many approaches have
been investigated for disentangling the complex structure of the
biomass. Once this separation has been achieved, a variety of paths
are opened for further processing of each component into marketable
products. For example, the possibility of producing products such
as biofuels, polymers and latex replacements from biomass has
recently received much attention. This attention is due to the
availability of large amounts of cellulosic feedstock, the need to
minimize burning or landfilling of waste cellulosic materials, and
the usefulness of sugar and cellulose as raw materials substituting
for oil-based products.
[0005] One component of the biomass that the isolation of which has
been of interest is cellulose. Cellulose, particularly delignified
cellulose is of particular interest to the paper industry and in
the production of biofuels. Cellulose is an organic compound with
the formula (C.sub.6H.sub.10O.sub.5).sub.n, a polysaccharide
consisting of a linear chain of several hundred to over ten
thousand .beta.(1.fwdarw.4) linked D-glucose units. Cellulose is an
important structural component of the primary cell wall of green
plants, many forms of algae and the oomycetes. Cellulose is an
extremely abundant organic polymer on Earth. The cellulose content
of cotton fiber is 90%, that of wood is 40-50% and that of dried
hemp is approximately 45%. Cellulose is mainly used to produce
paperboard and paper. Smaller quantities are converted into a wide
variety of derivative products such as cellophane and rayon. Using
cellulose as a feedstock can be problematic if the cellulose has
been denaturated and/or degraded due to harsh conditions such as
high temperature, high pressure chemical exposure, high acidic
conditions and/or high basic conditions.
[0006] Thus, there continues to be a need for improved systems and
methods for providing cellulose and cellulose substantially devoid
of lignin, hemicellulose, other sugars and ash that take into
consideration factors such as environmental and energy concerns,
efficiency and cost-effectiveness, while limiting the denaturating
and/or degrading of the cellulose composition.
SUMMARY OF THE INVENTION
[0007] It should be appreciated that this Summary is provided to
introduce a selection of concepts in a simplified form, the
concepts being further described below in the Detailed Description.
This Summary is not intended to identify key features or essential
features of this disclosure, nor is it intended to limit the scope
of the invention.
[0008] The present invention provides a process for isolating
cellulose that may be adapted to large-scale production, uses
environmentally friendly solvents and/or is energy efficient.
Moreover, the present invention provides a process for isolating
and delignifying cellulose wherein the cellulose is substantially
devoid of lignin, hemicellulose, other sugars, and various other
water insoluble components, while maintaining its structure
substantially similar to that of it in the biomass.
[0009] The process includes subjecting the biomass to conditions to
isolate the cellulose from the biomass in a non-denaturated or
non-degraded form and then subjecting the cellulose to oxidation to
remove any remaining hemicelluloses, lignin, and the like to purify
the cellulose fraction. The process includes pretreating the
biomass to, for example, remove a substantial portion of the
hemicellulose component. Pretreatment may include mechanically
altering the fibers to, for example, open up the fibers and to form
a fluidized biomass. The biomass with opened up fibers is then
subjected to high frequency pulses and shear forces without
denaturing the individual components of the biomass. The biomass is
then subjected to compressive force to separate a first liquid
fraction from a first fractionated biomass. The first fractionated
biomass may again then be subjected to the same high frequency
pulses and shear forces as previously, particularly if there are
hemicellulose and/or sugars still present in the first fractionated
biomass. Compressive forces are used to separate a second liquid
fraction from a second fractionated biomass. The second
fractionated biomass is high in cellulose and water insoluble
components including lignins and proteins, and is substantially
devoid of hemicelluloses and sugars. The second fractionated
biomass is subjected to oxidation. The second fractioned biomass is
then subjected to compressive forces to separate one or more water
insoluble components of the biomass in water soluble and liquid
form from a second fractionated biomass high in cellulose and
substantially devoid of hemicellulose, sugar and the water
insoluble components of the biomass, particularly lignin.
[0010] The cellulose of the second fractionated biomass is not
denatured or degraded, i.e., it is substantially similar to the
cellulose in the biomass prior to isolation. It is believed that
because the process of the present invention avoids high
temperature, high pressure, extreme chemical conditions, high
acidic or basic conditions, and the like, denaturing and/or
degrading the cellulose is avoided and provides the delignified
cellulose in a form particularly suitable as a feedstock.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 depicts a flow chart that outlines an embodiment of
the process of the invention.
[0012] FIG. 2 depicts a flow chart that outlines another embodiment
of the process of the invention.
[0013] FIGS. 3A and 3B depict various DSCs taken on the third
fractionated biomass of Example 2.
DETAILED DESCRIPTION OF EMBODIMENTS
[0014] In the following detailed description, embodiments of the
present invention are described in detail to enable practice of the
invention. Although the invention is described with reference to
these specific embodiments, it should be appreciated that the
invention can be embodied in different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art.
[0015] The terminology used in the description of the invention
herein is for the purpose of describing particular embodiments only
and is not intended to be limiting of the invention. As used in the
description of the invention and the appended claims, the singular
forms "a," "an" and "the" are intended to include the plural forms
as well, unless the context clearly indicates otherwise. The
invention includes numerous alternatives, modifications, and
equivalents as will become apparent from consideration of the
following detailed description.
[0016] It will be understood that although the terms "first,"
"second," "third," "a)," "b)," and "c)," etc. may be used herein to
describe various elements of the invention should not be limited by
these terms. These terms are only used to distinguish one element
of the invention from another. Thus, a first element discussed
below could be termed a element aspect, and similarly, a third
without departing from the teachings of the present invention.
Thus, the terms "first," "second," "third," "a)," "b)," and "c),"
etc. are not intended to necessarily convey a sequence or other
hierarchy to the associated elements but are used for
identification purposes only. The sequence of operations (or steps)
is not limited to the order presented in the claims or figures
unless specifically indicated otherwise. Steps may be conducted
simultaneously.
[0017] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the present application and relevant art
and should not be interpreted in an idealized or overly formal
sense unless expressly so defined herein. The terminology used in
the description of the invention herein is for the purpose of
describing particular embodiments only and is not intended to be
limiting of the invention. All publications, patent applications,
patents and other references mentioned herein are incorporated by
reference in their entirety. In case of a conflict in terminology,
the present specification is controlling.
[0018] Also as used herein, "and/or" refers to and encompasses any
and all possible combinations of one or more of the associated
listed items, as well as the lack of combinations when interpreted
in the alternative ("or").
[0019] Unless the context indicates otherwise, it is specifically
intended that the various features of the invention described
herein can be used in any combination. Moreover, the present
invention also contemplates that in some embodiments of the
invention, any feature or combination of features set forth herein
can be excluded or omitted. To illustrate, if the specification
states that a complex comprises components A, B and C, it is
specifically intended that any of A, B or C, or a combination
thereof, can be omitted and disclaimed.
[0020] As used herein, the transitional phrase "consisting
essentially of" (and grammatical variants) is to be interpreted as
encompassing the recited materials or steps "and those that do not
materially affect the basic and novel characteristic(s)" of the
claimed invention. See, In re Herz, 537 F.2d 549, 551-52, 190
U.S.P.Q. 461, 463 (CCPA 1976) (emphasis in the original); see also
MPEP .sctn.2111.03. Thus, the term "consisting essentially of" as
used herein should not be interpreted as equivalent to
"comprising."
[0021] The term "about," as used herein when referring to a
measurable value, such as, for example, an amount or concentration
and the like, is meant to encompass variations of .+-.20%, .+-.10%,
.+-.5%, .+-.1%, +0.5%, or even .+-.0.1% of the specified amount. A
range provided herein for a measurable value may include any other
range and/or individual value therein.
[0022] The term "biomass" includes any non-fossilized, i.e.,
renewable, organic matter. The various types of biomass may include
plant biomass, animal biomass (any animal by-product, animal waste,
etc.) and municipal waste biomass (residential and light commercial
refuse with recyclables such as metal and glass removed).
[0023] The term "plant biomass" or "ligno-cellulosic biomass"
includes virtually any plant-derived organic matter (woody or
non-woody) available for energy on a sustainable basis.
"Plant-derived" necessarily includes both sexually reproductive
plant parts involved in the production of seed (e.g., flower buds,
flowers, fruit, nuts, and seeds) and vegetative parts (e.g.,
leaves, roots, leaf buds and stems). Plant biomass can include, but
is not limited to, agricultural crop wastes and residues such as
corn stover, wheat straw, rice straw, sugar cane bagasse and the
like. Plant biomass further includes, but is not limited to, woody
energy crops, wood wastes and residues such as trees, softwood
forest thinnings, barky wastes, sawdust, paper and pulp industry
waste streams, wood fiber, herbal plant material brewing wastes,
and the like. Additionally grass crops, such as switchgrass and the
like have the potential to be produced in large-scale amounts and
to provide a significant source of another plant biomass. For urban
areas, potential plant biomass feedstock comprises yard waste
(e.g., grass clippings, leaves, tree clippings, brush, etc.) and
vegetable processing waste.
[0024] The biomass comprises three basic chemical
components/fractions, namely hemicellulose, cellulose, and lignins.
The biomass may also include lesser amounts of proteins,
extractives, pectins, cutin, and ash depending on the biomass.
Specifically, hemicellulose is a polymer (matrix polysaccharide)
comprising the pentose and hexose sugars xylon, glucuronoxylon,
arabinoxylon, glucomannon, and xyloglucan. The sugars are highly
substituted with acetic acid, and because of its branched
structure, hemicellulose is amorphous. Hemicellulose is also easy
to cleave via hydrolysis. In contract, cellulose is a linear
polymer (polysaccharide) of glucose sugars bonded together by
.beta.-glycosidic linkages to form lengthy linear chains. Hydrogen
bonding can occur between cellulose chains results in a rigid
crystalline structure which is resistant to cleavage. Lignin is a
polymer of phenolic molecules and is hydrophobic. It provides
structural integrity to plants, i.e., it is the glue that maintains
the plant intact.
[0025] Typical ranges of hemicellulose, cellulose, and lignin in,
for example, a plant biomass such as corn stover are:
TABLE-US-00001 Component Biomass Dry Weight Cellulose 30-50%
Hemicellulose 20-40% Lignin 10-25%
[0026] "Ambient temperature" includes the temperature of the
surroundings in which the process of the invention takes place.
Ambient temperature may include, but is not limited to, "room
temperature," and any temperature within the range of about 0 to
about 40.degree. C. (30 to 104.degree. F.).
[0027] Individual components of the biomass may include, but are
not limited to, lignin, cellulose, hemicellulose, others sugars,
proteins, pharmaceuticals, nutraceuticals, ash, pectins and cutin,
and other materials obtained from the leaves, stems, flowers, buds,
roots, tubers, seeds, nuts, fruit and the like of a plant.
[0028] "Alcohol" includes, but is not limited to, methanol,
ethanol, isopropanol, propanol, isobutanol, butanol, and glycol. A
"short chain alcohol" generally includes C.sub.1 to C.sub.4
alcohols.
[0029] "Water" includes, but is not limited to, deionized water,
spring water, distilled water, mineral water, tap water and well
water, and mixtures thereof. "Water soluble" includes a component
that can be dissolved in water or other solvent at ambient
temperature. "Water insoluble" includes a component that cannot be
dissolved in water or other solvent at ambient temperature.
[0030] Referring now to FIG. 1, operations for the fractionation
and extraction of various biomasses, according to some embodiments
of the present invention, will be described. A pretreatment step 90
may be conducted optionally at ambient temperature. The biomass may
be subjected to a pre-soak step 100 and/or disassembly step 110.
The disassembly step 110 may include mechanical disassembling of
the biomass to provide the biomass in a fluidized or flowable state
or condition. The pre-soak step 100 may include contacting with a
solvent with or without additives to facilitate the separation of
the individual components. In another embodiment, the pretreatment
step may include hydrolysis (or rehydrolysis of biomass in dried
condition) to about 20 to 50 percent moisture gain. The hydrolysis
may be accomplished by treating the biomass with steam. The
pretreated biomass may then be subjected to a separation step 105
using conventional separation techniques such as using
ultrafiltration or diafiltration membranes. After the pretreatment
step 90, the biomass may be subjected to high frequency pulses and
high shear forces to fractionate 120 or extract via, for example,
the biomass fractionation apparatus and methods described in
co-pending U.S. patent application Ser. No. 14/454,833, filed on
Aug. 8, 2014 (Attorney Docket No. 1237-3) and co-pending U.S.
patent application Ser. No. 14/454,952, filed on Aug. 8, 2014
(Attorney Docket No. 1237-2), the disclosures of which are
incorporated by reference in their entireties. Such fractionation
does not denature and/or degrade the one or more individual
components of the biomass the components of the biomass,
particularly the cellulose. The cellulose is in a form
substantially the same as it was naturally as a component of the
biomass. Such fractionation provides a fraction or extracted
product that may be separated from the fractionated or extracted
biomass. The pulsation and shear forces avoid altering the chemical
characteristics of the individual components and does not
substantially result in the fragmentation of such components. The
fractionated or extracted biomass may be subjected to separation,
namely filtration or screening 125 with or without agitation,
followed by a compression force 130, and then followed by
additional filtration and/or separation with or without agitation
140. The fractions may be used to provide a desired product stream
150. In one embodiment, the amount of hemicellulose and sugars in
the fractionated biomass are monitored such as using a brix meter.
If significant hemicellulose or sugars still are present the steps
of subjecting to high frequency pulses and shear forces and
subjecting to compressive forces may be repeated.
[0031] As briefly discussed above, in an initial pretreatment step
90 the biomass may be pre-soaked and contacted with a solvent such
as with an alcohol, an aqueous alcohol, water or glycerin or
co-solvent or mixture thereof in order to begin the fractionation
or extraction of the biomass, particularly to begin isolating the
hemicelloses from the biomass. The biomass may swell during this
pretreatment step 90. The biomass may be disassembled 110 such as
by chopping, cutting, fraying, attrition or crushing prior to
contact with the solvent 100. In a particular embodiment, if the
biomass is, for example, fresh plant biomass or herbal plant
material, the material may be contacted with alcohol. If the
biomass is dried plant biomass or herbal plan material, it may be
contacted with an aqueous alcoholic solution. This aqueous
alcoholic extraction may be performed in aqueous alcohol at
different concentrations. Suitable alcohols may be short chain
alcohol, such as, but not limited to, methanol, ethanol, propanol,
isopropanol, butanol and isobutanol. In a particular embodiment,
the alcohol is ethanol. The alcohol may be a co-solvent mixture
such as a mixture of an alcohol and water. The aqueous alcoholic
solution may comprise from 0-100% (v/v) alcohol. More particularly,
the aqueous alcoholic solution may comprise from 25-95% (v/v)
alcohol. In a particular embodiment, the aqueous alcoholic solution
is 25% (v/v) or more alcohol. In another particular embodiment, the
aqueous alcohol may be 60% (v/v) alcohol. In another embodiment,
the aqueous alcoholic solution may be 70% (v/v) alcohol. In yet
another embodiment, the aqueous alcoholic solution may be 86% or
more (v/v) alcohol. In yet other embodiments, the process for
fractionating or extracting biomass may comprise contacting the
biomass with glycerin or an aqueous glycerin solution.
[0032] In yet another embodiment, the process for extracting
biomass may comprise contacting the biomass with water via
contacting with steam to provide a 20 to 40 percent moisture gain.
Typically, in other embodiments of the invention, the ratio of
biomass/solids contacted with a solvent/liquids used may be 1:1 to
1:10 of solids to liquid. During contact with the solvent (alcohol
or water) the fibers of the biomass may swell.
[0033] With respect to disassembling the fibers, the fibers are
initially opened up by chopping, cutting, fraying, attrition or
crushing the biomass and are thereby provided in a fluidized or
flowable form. For example, the biomass fibers may be processed in
a mechanical high consistency fluidization machine such as a
refiner or disk mill. An exemplary disk mill is available from
Sprout Waldron, Beloit or Andritz. By utilizing a refiner or disk
mill, the biomass and particularly the fibrous material thereof may
be altered without destroying the fibrous nature of the fibrous
material so that the high frequency pulses and shear forces of the
fractionation apparatus are accessible to the fibrous material. The
processing may take place for any amount of time necessary as would
be understood by one of skill in the art as necessary to affect
this step. In a particular embodiment, the disassembly process is
performed for one minute or less.
[0034] The overall pretreatment step 90 may take place for any
period of time that is sufficient for the fractionation or
extraction process and may take place in any vessel, container or
mixer suitable for contacting the biomass with a solvent and/or
disassembling the fibers. In some embodiments, the pretreatment
step may be any length of time between, for example, 15 minutes, 30
minutes or one hour, and 72 hours. In another embodiment, the
pretreatment step may be 15 minutes or less. The pretreatment step
may be one minute or less. In the pretreatment step, the biomass in
contact with the solvent may optionally be subjected to a
compressive force, which can facilitate absorption of the solvent
into the biomass. The compression in the pretreatment step 90 may
take place according to any technique that will be appreciated by
one of skill in the art. In an embodiment of the invention,
compression during the pretreatment step may be affected by a screw
press.
[0035] In another embodiment, the pretreatment may include the
addition of a mild acid to prehydrolyze the biomass to facilitate
removal of the hemicellulose. Suitable acids for acidifying the
pretreatment solution (solvent) include inorganic acids such as
nitric acid, hydrochloric acid and phosphoric acids, and organic
acids, such as acetic acid or formic acid. It is recognized that
the addition of mild acids like acetic acid or formic acid may not
be necessary because of natural amounts of the same being present
in the biomass. If acidification/hydrolysis is desired, the pH of
the solution will be about 0.5 to 7.0 and often may be between
about 1.0 to 5.0. A sequestering agent or chelating agent such as
an aminocarboxylic acid or aminopolyphosphoric acid may also be
used.
[0036] Additionally a compound to help catalyze delignification may
be included. In one embodiment, an anthraquinone (AQ) may be
utilized. Exemplary anthraquinones and derivatives thereof
including 1-methylanthrazuinone, 2-methylanthraquinone,
2-ethylanthraquinone, 2-methoxyanthraquinone,
2,3-dimethylantraquinone, and 2,7-dimethylantraquinone.
[0037] In another embodiment an alkaline buffer such as an alkaline
metal hydroxide, carbonate, phosphate, or borate may be included to
facilitate separation of the hemicellulose and lignin individual
components. Suitable buffers may include sodium hydroxide, sodium
carbonate, and sodium borate. Mixtures or blends of the hydroxides,
carbonates, and borates may be used. If an alkaline metal hydroxide
is added, the pH may be between about 7.0 to about 13.0 and often
may be between about 8.0 to about 11.0.
[0038] The pretreatment step 90 to hydrate or rehydrate the biomass
may be conducted at ambient temperature, elevated temperature
(20.degree. C. to 90.degree. C.) or using steam/vapor (greater than
100.degree. C.). It is recognized that the vapor may be of the
solvent.
[0039] Isolation or removal of the hemicelluloses may be
accomplished at this stage. Ultrafiltration or diafiltration may be
utilized to provide a retentate having 80 to 95 percent of the
hemicelluloses of the biomass and a permeate comprising the biomass
with a substantial portion of the hemicelluloses removed. It is
noted that the retentate may include isolated organic acids such as
acetic acid or formic acid which may be removed from the retentate
and used to pretreat the biomass as described above. The
hemicelluloses may be dried to avoid fermentation or mold
production and then used as a raw material for ethanol production,
for example.
[0040] Overall the desire is to provide the fibers in a form
wherein the components of the fibers can be readily fractionated
using the high shear forces and pulses of the fractionation
apparatus with a substantial portion of the hemicelluloses having
been removed. The selection of the conditions of the pretreatment
step 90 such as solvent choice, temperature, pressure, time,
additives, and the like will be dependent on the biomass and the
components of that biomass to be fractionated and isolated, and
will be within the skill of one in the art without undue
experimentation. Extreme and harsh conditions may be avoided so as
to not denature and/or degrade the cellulose component.
[0041] Following removal of the hemicelluloses 105, the biomass is
in fluid or flowable form may be subjected to fractionation 120 to
fractionate or extract the biomass using shear forces and
pulsation. It will be appreciated that in a particular embodiment,
shear forces and pulsation are used in which the components of the
biomass are not denatured or altered, and the chemical properties
of the individual components are maintained wherein a portion of
the fractions or extracts may be separated from the biomass. The
subjecting of the biomass to shear forces and high frequency pulses
may take place for any amount of time necessary as would be
appreciated by one of skill in the art as necessary to affect this
step. In a particular embodiment, this step may takes place for one
minute or less. In operation the fluidized biomass is rapidly
accelerated from about 4 mph to about 120 mph under greater than
1000 pulses per second of energy while avoiding attrition of the
biomass particles. This facilitates the ability of the cellular
structure of the biomass to release its various fractions or
constituents from the complex and entangled structure of the
biomass without having the chemical properties and characteristics
of the components being denatured or degraded.
[0042] The fractionated biomass material may then be subjected to a
compression force 130 e.g., a crushing or macerating force
optionally in the presence of additional solvent, wherein the
compression force removes liquid fraction for collection while
discharging a low liquid solids cake primarily being cellulose. The
compression force may be applied according to any technique that is
appreciated by one of skill in the art. In a particular embodiment,
the compression force is affected by screws of a screw press that
macerate the fractionated biomass and may include optional
stirring.
[0043] The steps of subjecting to fractionation 120 and subjecting
to fractionation can continue until the biomass fraction is
substantially free of hemicellulose and sugars. This can be
monitored or measured in a wide variety of matters including using
a brix meter to measure sugar content, differential scanning
calorimeter (DSC) to measure melt temperatures and differential
thermal analysis (DTA) to measure area under melt curves.
[0044] In one embodiment, the first fractionated biomass may be
subjected to conditions to raise the pH of the first fractionated
biomass to above about 9. For example, the biomass may be contacted
with mild caustic, e.g. 0.1 to 0.5% w/w based upon water, sodium
hydroxide.
[0045] The fractions or extracts provided according to the present
invention may be further processed as outlined in FIG. 2. The
screened liquids (e.g., liquid fractions) can be contacted with
additional biomass, the biomass disassembled 210, fractionated 220,
screened 240, subjected to a compressive force 230, and the solid
fractionated biomass primarily being cellulosic and the liquid
fractionated product stream separated 250. It is recognized that
although the solid fractionated solid is substantially cellulose,
it still has lignin and some hemicelluloses bound to the cellulose
molecules. Not wishing to be bound to a single theory, Applicant
believes that small amounts of hemicellulose allow the lignin to be
water soluble and are removed during precipitation.
[0046] Once the fractionated biomass is substantially free of
hemicellulose and sugars, the biomass is subjected to oxidation at
a pH above 7 noting that the fractionated biomass typically has a
pH of about 7 and is about 9. In one embodiment, oxidation occurs
by contacting the fractionated biomass with about 0.1 to about 5
percent hydrogen peroxide. For example, with respect to lignin
removal, isolation, and purification, the hydrogen peroxide allows
the lignin ether bond to cleave. Specifically, the phenolic groups
in the lignin are ionized and the resulting radical is mainly of
the phenoxyl radical type. Then hydrogen peroxide is formed through
dismutation of the superoxide anion. The superoxide anion itself is
not very reactive but the decomposition products of hydrogen
peroxide include the very reactive hydroxyl radical. The hydroxyl
radical not only reacts with the lignin structures but also readily
attacks the polysaccharides with subsequent glycosidic bond
cleavage and the creation of new sites for peeling reactions. Once
the perhydoxyl radical attaches to the lignin (or protein or water
insoluble extractive) these individual components of the biomass
become more polar and water soluble. Other oxidation agents include
alkali metal peroxides such as organic and inorganic peroxides
including sodium peroxide, calcium peroxide, magnesium peroxide,
and sodium percarbonate. Moreover this reaction can be facilitated
by inclusion of anthraquinone or its derivatives or other catalysts
in the pretreatment step.
[0047] In another embodiment, an oxidation mixture is formulated.
The oxidation mixture is provided by mixing together an alkaline
buffer such as alkaline metal hydroxide, carbonate, phosphate, or
borate, a source of oxyanions and a short chain organic acid to
provide an oxidation mixture. Suitable alkaline buffers include
sodium hydroxide, sodium carbonate and sodium borate. Suitable
sources of oxyanions include hydrogen peroxide and organic and
inorganic peroxides such as sodium peroxide, calcium peroxide,
magnesium peroxide, and sodium percarbonate. Optionally, sulfuric
acid or sodium sulfate (i.e., a source of S.sub.2.sup.- or HS.sup.-
ions) may be included as an oxyanionic nucleophilic sulfide
catalyst to facilitate delignification. Such will also facilitate
base catalyzed esterification and transesterification of the
cellulose when used as a feedstock. In one embodiment, the
oxyanions may be generated electrically by ozonation. Suitable
short chain organic acids may include acetic acid (vinegar) and
formic acid. A stabilized catalyst mixture is provided by mixing
together an alkali metal carbonate stabilizer such as sodium
carbonate or sodium bicarbonate and a manganese catalyst. An
exemplary manganese catalyst is a chelated manganese acid such as a
manganese amino acid chelate. The stabilized catalyst mixture in
one embodiment may be in powder solid form.
[0048] The stabilized catalyst mixture is then applied to the
second fractionated biomass, for example, by mixing the catalyst in
powder form with the second fractionated biomass. The liquid
oxidation mixture is then added to the second fractionated biomass
and mixed, and oxidation is allowed to occur for about one minute
to about 48 hours. The oxidized second fractionated biomass is then
subjected to compressive force with optional spinning to provide a
third fractionated biomass low in lignin (i.e., often less than
about 4 to about 8 percent), and a third liquid fraction high in
lignin. The third fractionated biomass may again be oxidized as
above and subjected to a compressive force with optional spinning
to provide a fourth fractionated biomass substantially lower in
lignin (i.e., often less than about 2 to about 4 percent and a four
liquid fraction substantially high in lignin. The isolating of the
biomass steps and repeated contacting with the oxidation mixture
followed by compression can be repeated multiple times until the
fractionated biomass has less than about 0 to about 2 percent
lignin with the last step(s) being a conventional water rinse
step.
[0049] After separation, the now water soluble individual
components, e.g., the lignin, can be further separated, isolated
and/or purified, such as described in copending U.S. application
Ser. No. ______, filed Feb. 11, 2015 (Attorney Docket No.
1237-4IP2), the disclosure of which is incorporated herein by
reference in its entirety. In one embodiment, the centrifugation is
used to provide a decant. Then, for example, ultrafiltration or
diafiltration membranes, available from Millipore, Billerica,
Mass., may be used. A first membrane can be used to remove any
remaining hemicellulose from the liquid fraction. In one
embodiment, the first membrane is a 10K dalton screen. The
retentate will comprise the hemicellulose and the permeate will
primarily comprise lignins, proteins, and extractives with a small
amount of hemicellulose, sugars, and fiber fragments. The second
membrane will isolate the lignin, protein or extractive depending
on the membrane as a retentate and any remaining hemicellulose,
sugars, fragments, contaminants (e.g., heavy metals) as the
permeate. In one embodiment, the second membrane is an 8K dalton
screen. A further 3K dalton screen can be used to further isolate
the desired component. The cellulose may be subjected to based
catalyzed esterification or transesterification.
[0050] In a particular embodiment, the cellulose and/or cellulose
pulp provided by the fractionation and/or extraction process of the
present invention can be used or applied in the preparation of
paper and paper products. Examples of paper products include, but
are not limited to: paper; paperboard; and card stock. Use of the
paper products prepared from the cellulose and/or cellulose pulp
provided by the present invention is not particularly limited. The
paper products can be produced with a wide variety of properties,
depending on its intended use, which range from, for example:
representing value, such as in paper money, bank notes, checks,
security, vouchers and tickets; for storing information, such as in
books and notebooks, scrapbooks, magazines, newspapers, art,
letters; for personal use, such as in diaries, notes to oneself,
etc. and scratch paper; for communication, such as in communication
between individuals and/or groups of people; for packaging and
containers, such as in paperboard, kraft board, containerboard,
linerboard, beverage and/or food containers, liquid containers,
corrugated boxes, paper bags, envelopes, wrapping tissue, Charta
emporetica and wallpaper; for cleaning, such as in toilet paper,
handkerchiefs, paper towels, facial tissue and cat litter; for
construction, such as in papier-mache, origami, paper planes,
quilling, paper honeycomb, used as a core material in composite
materials, paper engineering, construction paper and paper
clothing; and other uses, such as in emery paper, sandpaper,
blotting paper, litmus paper, universal indicator paper, paper
chromatography, electrical insulation paper (see also dielectric
and permittivity) and filter paper.
[0051] The method by which the cellulose and/or cellulose pulp
provided by the present invention is used in the production of
paper and paper products is not particularly limited, and any
method that would be appreciated by one of skill in the art may be
used in the production of paper and paper products using the
cellulose and/or cellulose pulp provided by the present invention.
For example, the cellulose pulp provided according to the present
invention can be fed to a paper machine where it is formed as a
paper web and the water is removed from it by pressing and drying.
The cellulose pulp provided by the present invention may also be
bleached to make the pulp whiter. Typical chemicals and processes
used in the bleaching of pulp include: chlorine; sodium
hypochlorite; extraction with sodium hydroxide; oxygen; alkaline
hydrogen peroxide; ozones; chelation to remove metals; enzyme
treatment; peroxy acids; and sodium dithionite. Typical chelation
agents include, but are not limited to, EDTA and DTPA. Although not
particularly limited by the method of bleaching of the cellulose
and/or cellulose pulp provided by the present invention, elemental
chlorine free (ECF) and/or total chlorine free (TCF) methods of
bleaching provide more environmentally friendly methods of
bleaching. TCF bleaching, for example, prevents the formation of
toxic chemicals such as dioxins. An example of a TCF sequence for
the bleaching of pulp is wherein the pulp would be treated with
oxygen, then ozone, washed with sodium hydroxide then treated in
sequence with alkaline peroxide and sodium dithionite.
[0052] In other embodiments, the cellulose and/or cellulose pulp
provided according to the present invention can be used or applied
in the preparation and/or manufacture of paper coatings. Cellulose
and cellulose derivatives have been used to coat papers to enhance
physical characteristics, for example, but not limited to,
appearance, e.g., glossiness and finish, strength, rigidity and
water resistance. The manner in which the paper coatings prepared
from the cellulose and/or cellulose pulp provided according to the
present invention is not limited and the method used may be any
that would be appreciated by one of skill in the art.
[0053] In yet other embodiments, the cellulose and/or cellulose
pulp provided according to the present invention can be used in the
preparation of fibers. Examples of fibers include, but are not
limited to, regenerated cellulose fibers, for example, cellophane
and rayon.
[0054] In yet other embodiments, the cellulose and/or cellulose
pulp provided according to the present invention can be used in
consumables. The type of consumable is not particularly limited,
and applications can include, but are not limited to:
microcrystalline cellulose or powdered cellulose used as inactive
fillers in drug tablets; thickeners and/or stabilizers Powdered
cellulose may also be used to improve characteristics of processed
foods or foodstuffs, for example, to prevent caking and/or clumping
of the processed food or foodstuffs within a container.
[0055] In yet other embodiments, the cellulose and/or cellulose
pulp provided according to the present invention can be used in
scientific applications. Cellulose is commonly used in the
laboratory as the stationary phase for chromatography, in
particular, thin layer chromatography. Liquid and gel filtration
typically use products prepared from cellulose, either alone or in
combination with other filtration media, for example, diatomaceous
earth. Various filtration made may comprise the cellulose of the
invention.
[0056] In yet other embodiments, the cellulose and/or cellulose
pulp provided according to the present invention can be used in
construction and building materials. Cellulose insulation made from
recycled paper is becoming popular as an environmentally preferable
material for building insulation. It can be treated with boric acid
as a fire retardant. Moreover, hydrogen bonding of cellulose in
water can produce a sprayable, moldable material as an alternative
to the use of plastics and resins. The recyclable material can be
made water and/or flame-resistant or fire retardant, and can
provide sufficient strength for use as a building material.
[0057] In another embodiment, the cellulose can be treated with
cellulose enzymes to hydrolyze the crystalline cellulose to glucose
followed by fermentation of the glucose with yeast or suitable
microorganism to provide biofuel and/or bio feedstock. It is
recognized that the hemicellulose and/or sugars previously
separated from the fractionated biomass may be added back to be
co-fermented with the cellulose.
[0058] In another particular embodiment, fractionation or
extraction according to the invention provides hemicelluloses and
sugars. Sugars and/or hemicelluloses provided by the process
according to the invention may further be used in the preparation
of biofuels such as, but not limited to, ethanol or the preparation
of polymers/plastics. One such embodiment is the fermentation of
the provided fractions to produce the ethanol. In another
embodiment, the polymer is polylactic acid (PLA). In another
embodiment the lignin may be further separated and emulsified for
further processing. Because the lignin has not been subjected to
high temperatures, its functional groups have not chemically
reacted and the isolated lignin may be more reactive.
[0059] The following example is provided to illustrate the present
invention, and should not be construed as limiting thereof.
EXAMPLES
Example 1
Wheat Grass
[0060] 10 Kg of dried wheat grass (straw) is chopped to a stalk
length of 3/4 to 2 inches. The straw was briefly rinsed with cold
clean water to remove sand and dirt. The wheat straw is then
subjected to water or steam injection into a disk mill for a few
seconds to mechanically disassemble the cellulosic structure. The
fluidized wheat grass is then subjected to high shear forces for
1.5 to 3 seconds with pulses of 1824 to 912 times without
denaturing and/or degrading the components of the wheat straw. The
combined mixture is subjected to compressive forces to separate the
stream into liquid and a 20-60% cellulosic solids fractions. The
liquid fraction containing hemicellulose is retained.
[0061] The solid fraction is pretreated with NaOH sufficient to
raise the pH of the cellulosic water slurry from about 4-7 to
10-12. This basic mixture is allowed to age from a few seconds to 1
hour and again processed through the system starting at the disk
mill which is subjected to water or steam injection in the mill for
a few seconds to mechanically disassemble the cellulosic structure.
The fluidized wheat grass is then subjected to high shear forces
for 1.5 to 3 seconds with pulses of 1824 to 912 times without
denaturing the components of the wheat straw. The combined mixture
is subjected to compressive forces to separate the stream into
liquid and a 20-60% cellulosic solids fractions. The liquid
fraction containing hemicellulose is added to the first and second
fraction and undergoes further processing.
[0062] The solid fraction is treated with an oxidation agent
hydrogen peroxide, sufficient to raise the pH of the cellulosic
water slurry from about 10-12 to 8-10. This basic mixture is
allowed to age from a few seconds to 1 hour and again processed
through the system starting at the disk mill which is subjected to
water or steam injection in the mill for a few seconds to
mechanically disassemble the cellulosic structure. The fluidized
wheat grass is then again subjected to high shear forces for 1.5 to
3 seconds with pulses of 1824 to 912 times without denaturing the
components of the wheat straw. The combined mixture is screened and
subjected to compressive forces to separate the stream into liquid
and a 20-60% cellulosic solids fractions. The liquid fraction
containing lignin is retained. The solid fraction is then treated
again to raise the pH and the liquid fraction containing
hemicellulose is added to the first and second fraction and
undergoes further processing. The solid fraction is then treated
with an oxidation agent and rerun through the fractionation unit.
The liquid fraction containing lignin is added to the first liquid
lignin fraction and further separated using a membrane.
Example 2
[0063] 423 grams of dry switch grass is steam activated to
rehydrate at about 25 to 50 percent water in a single disk refiner
to provide the switch grass in a fluidized or flowable condition.
Naturally occurring carboxylic acids (acetic acid and formic acid)
with the switch grass lower the pH to below 3. The
hydrated/activated switch grass is subjected to compressive force
to separate a liquid high in hemicelluloses and a biomass high in
cellulose and lignin. The hemicellulose/liquid is then subjected to
a 1 to 5 kD ultrafiltration membrane to remove the acetic acid and
formic acid as a permeate for reuse in the process.
[0064] The biomass is then subjected to high frequency pulses and
shear forces without denaturing and/or degrading the lignin using
the Green Extraction Technology fractionation apparatus described
in U.S. application Ser. No. 14/454,833 filed on Aug. 8, 2014. The
biomass is fractionated for about 15 to about 30 seconds at pulses
of 912 to 1824 to provide a first fractionated biomass and a first
liquid fraction. The first fractionated biomass is contacted with
0.3% w:w based upon water sodium hydroxide to raise the pH above
about 9. The first fractionated biomass is then subjected to
compressive force to separate a second liquid fraction with most of
the remaining hemicellulose from a second fractionated biomass high
in cellulose and lignins.
[0065] The second fractioned biomass is then subjected to oxidation
to separate the lignin from the cellulose. An oxidation mixture is
formed and comprises 2000 ml of hydrogen peroxide at 3% buffered
with 60 g of sodium hydroxide and 300 ml of acetic acid. A
catalyst/stabilizer mixture is formed by mixing 2 g of sodium
carbonate stabilizer and 15 mg of manganese amino acid chelate
catalyst in powder form. The powdered catalyst/stabilizer mixture
is applied to the second fractionated biomass and then it is
contacted with the liquid oxidation mixture and oxidized for 60
minutes. The oxidized second fractionated biomass is subjected to
compressive forces using a two screw press with stirring to provide
a third fractionated biomass high in cellulose with a lignin
content of less than 7% and a third liquid fraction high in water
soluble lignin. The third fractionated biomass is then oxidized
again for 60 minutes using 1500 ml hydrogen peroxide and the same
amounts of the other components of the oxidation mixture and the
catalyst/stabilizer mixture. The oxidized third fractionated
biomass is then subjected to compressive forces to provide a fourth
fractionated biomass high in cellulose with a lignin content of
less than 7% and a fourth liquid fraction high in lignin. The
entire oxidation process is then repeated using 1000 ml hydrogen
peroxide oxidized for 120 minutes and then subjected to compressive
force to provide a fifth fractionated biomass high in cellulose
having a lignin content of less than 5%.
[0066] DSCs of a third fractionated biomass are provided in FIGS.
3A and 3B, noting that FIG. 3B illustrates that the cellulose has
been acetylated due to the presence of acetic acid.
Example 3
[0067] 423 grams of dry wheat straw is steam activated to rehydrate
at about 25 to 50 percent water in a single disk refiner to provide
the switch grass in a fluidized or flowable condition. Naturally
occurring carboxylic acids (acetic acid and formic acid) within the
wheat straw lower the pH to below 3. The hydrated/activated wheat
straw is subjected to compressive force to separate a liquid high
in hemicelluloses and a biomass high in cellulose and lignin. The
hemicellulose/liquid is then subjected to a 1 to 5 kD
ultrafiltration membrane to remove the acetic acid and formic acid
as a permeate for reuse in the process.
[0068] The biomass is then subjected to high frequency pulses and
shear forces without denaturing and/or degrading the lignin using
the Green Extraction Technology fractionation apparatus described
in U.S. application Ser. No. 14/454,833 filed on Aug. 8, 2014. The
biomass is fractionated for about 15 to about 30 seconds at pulses
of 912 to 1824 to provide a first fractionated biomass and a first
liquid fraction. The first fractionated biomass is contacted with
0.3% w:w based upon water sodium hydroxide to raise the pH above
about 9. The first fractionated biomass is then subjected to
compressive force to separate a second liquid fraction with most of
the remaining hemicellulose from a second fractionated biomass high
in cellulose and lignins.
[0069] The second fractioned biomass is then subjected to oxidation
to separate the lignin from the cellulose. An oxidation mixture is
formed and comprises 2000 ml of hydrogen peroxide at 3% buffered
with 60 g of sodium hydroxide and 300 ml of acetic acid. A
catalyst/stabilizer mixture is formed by mixing 2 g of sodium
carbonate stabilizer and 15 mg of manganese amino acid chelate
catalyst in powder form. The powdered catalyst/stabilizer mixture
is applied to the second fractionated biomass and then it is
contacted with the liquid oxidation mixture and oxidized for 60
minutes. The oxidized second fractionated biomass is subjected to
compressive forces using a two screw press with stirring to provide
a third fractionated biomass high in cellulose with a lignin
content of less than 7% and a third liquid fraction high in water
soluble lignin. The third fractionated biomass is then oxidized
again for 60 minutes using 1500 ml hydrogen peroxide and the same
amounts of the other components of the oxidation mixture and the
catalyst/stabilizer mixture. The oxidized third fractionated
biomass is then subjected to compressive forces to provide a fourth
fractionated biomass high in cellulose with a lignin content of
less than 7% and a fourth liquid fraction high in lignin. The
entire oxidation process is then repeated using 1000 ml hydrogen
peroxide oxidized for 120 minutes and then subjected to compressive
force to provide a fifth fractionated biomass high in cellulose
having a lignin content of less than 5%.
[0070] The wheat straw fractionated biomass was analyzed for
percent lignin contact, Kappa number, and fiber quality. The
results are provided in Table 1.
TABLE-US-00002 TABLE 1 Fiber Quality Analyzer (FQA) - Acid
Insoluble Lignin, % Fiber Analysis Pulp Sample Test 1 Test 2 Avg.
Kappa # Length Fines Kink Curl Coarseness Wheat 5.19 5.15 5.17
33.52 0.667 19.93 2.25 0.128 0.097 Straw
Example 4
[0071] Example 3 was repeated with wild oats. The wild oats
fractionated biomass was analyzed for lignin contact and Kappa
number. The results are provided in Table 2.
TABLE-US-00003 Acid Insoluble Lignin, % Pulp Sample Test 1 Test 2
Avg. Kappa # Wild Oats 3.12 3.37 3.25 22.11
Example 5
[0072] Example 2 is repeated except the oxidized fifth fractionated
biomass is subjected to oxidation using 1000 ml hydrogen peroxide
again. This pulp is then combined with Northern bleached softwood
kraft ("NBSK") at a 80 percent pulp of the invention/20 percent
NBSK blend to which is added 8 percent calcium carbonate. This is
made into paper to mimic ink jet type papers.
Example 6
[0073] Example 3 is repeated except the oxidized fifth fractionated
biomass is subjected to oxidation using 1000 ml hydrogen peroxide
again. This pulp is then combined with Northern bleached softwood
kraft ("NBSK") at an 80 percent pulp of the invention/20 percent
NBSK blend to which is added 8 percent calcium carbonate. This is
made into paper to mimic ink jet type papers.
[0074] Table 3 provides testing against commercially available ink
jet paper for paper made according to Examples 5 and 6.
TABLE-US-00004 TABLE 3 Stiffness Tensile Tensile Gloss Porosity
Thickness (gram- Tear Burst (DRY) (WET) Abrasion Fold @60 (coresta
Opacity Brightness (microns) force) (gram-force) (psig) (kg/15 mm)
(g/15 mm) (strokes) (cycles) (%) units) (%) (%) Control 237 870 64
5 2.0 160 1 2 4.6 3461 93 86 (repulped commercial ink jet paper) A
80% 189 1039 78 30 6.0 300 8 46 4.6 451 93 80 Switchgrass/ 20% NBSK
(+8% CaCO3) B 80% Wheat 184 968 76 27 4.7 250 8 29 4.6 534 93 78
Straw/20% NBSK (+8% CaCO3) C
[0075] This shows that the papers of the invention have
significantly higher strength and toughness as compared to the
control paper due to the avoidance of denaturing and/or degrading
the cellulose using the process of the invention.
[0076] Although selected embodiments of the present invention have
been disclosed for illustrative purposes, those skilled in the art
will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying
claims.
* * * * *