METHOD FOR ISOLATING LIGNIN FROM A BIOMASS AND PRODUCTS PROVIDED THEREFROM
The process includes pretreating the biomass to provide a fluidized biomass. The fluidized biomass is then subjected to high frequency pulses and shear forces without denaturing/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 such as with hydrogen peroxide and base at a pH above 7. The second fractioned biomass is then subjected to compressive forces to provide water soluble lignin which may be precipitated by reducing the pH.
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 INVENTIONThe present invention relates to a process for isolating components of a biomass, and particularly lignin from a biomass.
BACKGROUND OF THE INVENTIONNatural 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.
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.
One component of the biomass that the isolation of which has been of interest is lignin. Lignin is a cross-linked racemic macromolecule with molecular masses in excess of 10,000 Da. It is relatively hydrophobic and aromatic in nature. The degree of polymerization in nature is difficult to measure, since it is often fragmented during typical extraction under harsh conditions and the molecule consists of various types of substructures that appear to repeat in a haphazard manner. Different types of lignin have been described depending on the means of isolation.
There are three monolignol monomers, methoxylated to various degrees: p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol. These lignols are incorporated into lignin in the form of the phenylpropanoids p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S), respectively. Gymnosperms have a lignin that consists almost entirely of G with small quantities of H. That of dicotyledonous angiosperms is more often than not a mixture of G and S (with very little H), and monocotyledonous lignin is a mixture of all three. Many grasses have mostly G, while some palms have mainly S. All lignins contain small amounts of incomplete or modified monolignols, and other monomers are prominent in non-woody plants.
There continues to be a need for improved systems and methods for isolating lignin and lignin derivatives that take into consideration factors such as environmental and energy concerns, efficiency and cost-effectiveness, while avoiding subjecting the lignin during isolation to harsh conditions, such as high temperature, high pressure, high or low pH, chemicals, etc., that denature and/or degrade the lignin.
SUMMARY OF THE INVENTIONIt 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.
The present invention provides a process for isolating lignin and lignin derivatives of biomass 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 the lignin in water soluble form while providing a biomass substantially devoid of hemicellulose, other sugars, and the water insoluble components such as lignin.
The process includes pretreating the biomass. 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 then subjected to oxidationat a pH above 7. The second fractioned biomass is then subjected to compressive forces to separate one or more water insoluble components including lignin of the biomass in water soluble and liquid form from a second fractionated biomass substantially devoid of hemicellulose, sugar and the water insoluble components (i.e., lignin) of the biomass.
The present invention also provides a lignin in water soluble form at a pH of 2 to 12 at ambient temperature. The isolated lignin, which has not been exposed to harsh reaction conditions and has not been denatured and/or degraded. The lignin has a high molecular weight mean, namely greater than 10,000 as compared to lignin isolated using conventional techniques.
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.
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.
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.
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.
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”).
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.
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 §2111.03. Thus, the term “consisting essentially of” as used herein should not be interpreted as equivalent to “comprising.”
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 measureable value may include any other range and/or individual value therein.
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).
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.
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 β-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.
Typical ranges of hemicellulose, cellulose, and lignin in, for example, a plant biomass such as corn stover are:
“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 0° C. (30 to 104° F.).
Individual components of the biomass may include, but are not limited to, lignin, cellulose, hemicellulose, other sugars, proteins, pharmaceuticals, nutraceuticals, ash, pectins, cutins, and other materials obtained from the leaves, stems, flowers, buds, roots, tubers, seeds, nuts, fruit and the like of a plant.
“Alcohol” includes, but is not limited to, methanol, ethanol, isopropanol, propanol, isobutanol, butanol, and glycol. A “short chain alcohol” generally includes C1 to C4 alcohols.
“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.
Referring now to
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. application Ser. No. 14/454,833, filed on Aug. 8, 2014 and co-pending U.S. application Ser. No. 14/454,952, filed on Aug. 8, 2014, the disclosures of which are incorporated by reference in their entireties. Such fractionation does not denature and/or degrade the components of the biomass, particularly the lignin components thereof. Thus the lignin 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. Stated otherwise, 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.
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 hemicelluloses from the biomass. The biomass may swell during this pretreatment step 90. The biomass may then 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.
In yet another embodiment, the process for extracting biomass may comprise contacting the fresh plant biomass with water via contacting with steam to provide a 20 to 50 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.
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.
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.
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 plant biomasses. 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.
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.
In another embodiment an alkaline buffer such as an alkaline metal hydroxide, carbonate, phosphate, or boron 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.
The pretreatment step 90 to hydrate or rehydrate the biomass may be conducted at ambient temperature, elevated temperature (15° C. to 90° C.) or using steam/vapor (greater than 100° C.). It is recognized that the vapor may be of the solvent. Isolation or removal of the hemicelluloses may be accomplished at this stage. Ultrafiltration or diafiltration may be utilized to provide a retentate having about 50 to about 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 molding, and then used as a raw material for ethanol production, for example.
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.
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/degraded 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.
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.
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. 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.
The fractions or extracts provided according to the present invention may be further processed as outlined in
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 above about 7 and is about 9. In one embodiment, oxidation may occur by contacting the fractionated biomass with about 0.1 to about 5 percent hydrogen peroxide. For example, with respect to lignin separation, 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 perhydroxyl anion radical. The perhydroxyl anion 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 perhydroxyl 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.
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 S2− or HS− ions) may be included as an organionic nucleophilic sulfide catalyst to facilitate separation of the lignin from the cellulose. 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 second catalyst/stabilizer 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 catalyst/stabilizer mixture may be in solid form (e.g., a powder) and is mixed with the second fractionated biomass. The oxidation mixture may then be contacted with the second fractionated biomass containing the catalyst/stabilizer mixture, preferably at room temperature to oxidize the second fractionated biomass. 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 7 to 8 percent), and a third liquid fraction high in lignin. The same catalyst/stabilizer mixture and the oxidation mixture may then be contacted with the third fractionated biomass, reacted and subjected to a compressive force with optional spinning to provide a fourth fractionated biomass substantially low in lignin (i.e., often less than 1 percent and a four liquid fraction substantially high in lignin. The isolating the biomass steps and repeated contacting with the catalyst/stabilizer mixture and the oxidation mixture followed by compression can be repeated multiple times until the fractionated biomass has less than 1 to 7 percent lignin with the last step being a conventional water rinse step.
After separation, the now water soluble lignin can be further separated, isolated and/or purified from the cellulose fractionated biomass and the cellulose further separated, isolated, purified, and used such as described in copending U.S. application Ser. No. 14/619,406, filed Feb. 11, 2015 (Attorney Docket No. 1237-4IP), 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 lignin fraction. In one embodiment, the first membrane is a 50K to 300K 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 1K to 10K dalton screen. A further 1K dalton screen can be used to further isolate the desired component.
In another embodiment, the lignin can be isolated, centrifuged and decanted wherein the decant is neutralized to a pH of 7.0 such as, for example, using dilute hydrochloric acid. The lignin can be precipitated by contacting the various liquid fractions with dilute acid such as dilute sulfuric acid and adjusting the pH to less than about 4.0. Alum or the like may be added in small amounts, about 10 to 40 ppm, to wash out the lignin above a pH of about 3. It is believed the lignin precipitates because the glucose and perhydroxyl anions which maintain the lignin solution, removed from the lignin and the lignin becomes soluble. The precipitated lignin may then be centrifuged and dried, for example, at about 30° C. to about 50° C. for one to fifteen hours.
It is believed that because the lignin has not been subjected to harsh conditions such as high temperature, high pressure, severe chemical conditions, and high or low pH, that its chemical groups have not chemically reacted and the isolated lignin may be more reactive for such processes a polymerization, carbonization, and the like. Moreover, because the lignin has not been subjected to harsh conditions, high molecular weight (i.e., greater than about 9000 and, sometimes greater than about 10,000) and purer lignin can be obtained using the present invention. The lignin isolated potentially as a broad range of molecular and has a high polydispersity and the change lengths vary over a wide range of molecular weights. By utilizing various membranes lignin having various molecular weights may be isolated and can have molecular weight mean greater than 10,000.
Specific examples of the applications and uses of lignin provided by the present invention include, but are not limited to, for example: cement and concrete; animal feed pellets; animal feed molasses additives; road binder/dust control; pesticides; oil well drilling muds; adhesives; resins and binders; wallboard; dispersants; emulsifiers and wetting agents; agglomerants; chelants; leather treatment; anti-bacterial activity; lead acid batteries; oil recovery; water treatment; industrial cleaners; emulsion stabilizers; carbon black; inks and azo pigments; dyestuffs; micronutrients; fertilizers; refractories and ceramic brick additives; ore processing; and kitty litter, but are not limited to, for example: paper and paper products; paper coatings; fibers;
In some embodiments, the lignin provided according to the present invention may comprise chemically modified lignin, derivatives of lignin or lignin derivatives, for example, lignosulfonates or lignin amine. In a further embodiment, the lignin provided by the present invention is used as a binder. Lignin or lignin derivatives can be used as an adhesive, serving as a binding agent in pellets or compressed materials. Lignin or lignin derivatives can be used in dust control, for example, on unpaved roads to reduce environmental concerns from airborne dust particles and stabilize the road surface. The ability of lignin to act as a binder makes lignin useful as a component in, for example: biodegradable plastic; coal briquettes; plywood and particle board; ceramics; animal feed pellets; carbon black; fiberglass insulation; fertilizers and herbicides; linoleum paste; dust suppressants; and soil stabilizers.
In some other embodiments, the chemically modified lignins or lignin derivatives may be chosen from, for example, hydroxylalkylated lignins, such as hydroxylpropyl lignin (HPL), acetyloxypropyl lignin (APL), acylated lignins, such as an acetate ester of lignin, or other lignin derivatives. In yet other embodiments, the chemically modified lignins or lignin derivatives provided may be acetylated, nitrated, propionated, and the like. The method by which these chemically modified lignins or lignin derivatives are prepared is not particularly limited and the chemically modified lignins or lignin derivatives may be prepared by any method that would be understood to one of skill in the art.
In still other embodiments, lignins, lignin derivatives or chemically modified lignins may be blended or copolymerized with a plastic or thermoplastic, such as for example, polybutylene succinate (PBS), polycaprolactone (PCL), poly (lactic acid) or polylactide (PLA), polyhydroxylalkanoate (PHA), aliphatic-aromatic copolymers (AAC) and the like. The method of blending or copolymerization is not particularly limited, and any process or technique that would be appreciated by one of skill in the art may be used preparing lignins, lignin derivatives or chemically modified lignins that are blended or copolymerized with a plastic or thermoplastic. In one embodiment, the lignins, chemically modified lignins or lignin derivatives are blended or copolymerized with PLA to provide, for example, a graft copolymer of PLA with lignin, such as is described in U.S. Patent Application Publication No. 2014/0080992, a chemically modified lignin, such as HPL or APL, blended and chemically modified with PLA through trans-esterification, such as is described in U.S. Pat. No. 8,865,802, or HPL or APL blended and chemically modified with high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polyethylene (PE), or polypropylene (PP), such as is described in PCT International Publication No. WO 2014/070830.
In other embodiments, the lignin provided by the present invention is used as a dispersant. Lignin or lignin derivatives can prevent the clumping and settling of undissolved particles in suspensions. Lignin or lignin derivatives can prevent particles in suspension from being attracted to other particles and can reduce the amount of water needed to use a product comprising said particles in suspension. The ability of lignin or lignin derivatives to act as a dispersant make lignin useful as a component in, for example: cement mixes; leather tanning; clay and ceramics; concrete admixtures; dyes and pigments; oil drilling muds; and pesticides and insecticides.
In still other embodiments, the lignin provided according to the present invention is used as an emulsifier. Lignin or lignin derivatives may stabilize emulsions of immiscible liquids, for example, oil and water, making them highly resistant to separating. The ability of lignin, lignosulfates and lignin amine to act as an emulsifier makes lignin or lignin derivatives a useful component in, for example: asphalt emulsions; pesticides; pigment and dyes; and wax emulsions.
In yet other embodiments, lignin provided according to the present invention is used as a sequestrant. Lignin or lignin derivatives can interact with metal ions, preventing them from reacting with other compounds and becoming insoluble. Metal ions sequestered with lignin or lignin derivatives stay dissolved in solution, rendering them available to plants and preventing scaly deposits in water systems. The ability of lignin and lignin derivatives to act as a sequestrant makes lignin a useful component in, for example: micronutrient systems; cleaning compounds; and water treatments for boilers and cooling systems.
In a particular embodiment, lignin provided by the present invention can be used in concrete. Lignin or lignin derivatives can aid in, for example: high performance concrete strength; concrete grinding; reducing damage caused by moisture and acid rain; and retarding cement composition setting. Specifically, lignosulfonates can contribute higher adsorption properties and zeta potential to cement particles and provide better dispersion characteristics to the cement matrix. Lignins can also improve the compressive strength of cement pastes.
In another embodiment, lignin provided by the present invention can be used as an antioxidant. Lignin can act as a free radical scavenger, and provide thermal protection to, for example, styrene polymers, butadiene polymers, rubber polymers, rubber, polypropylene and polycaprolactam. The natural antioxidant properties of lignin make it useful in cosmetic and topical formulations, and lignosulfonates have been used in cosmetic compositions, such as makeup for decorative use and/or correction on skin.
In yet another embodiment, lignin provided by the present invention can be used in asphalt. Examples of uses include crack filling compositions for asphalt, enhancing water stability of asphalt, emulsifying agents for asphalt and fluidity modifiers that decrease production costs of asphalts.
In another embodiment, lignin provided by the present invention may be applied to and/or used in or with carbon or graphite fibers, carbon fiber reinforced polymers and carbon nanotubes. In yet other embodiments, lignin provided by the present invention may be used to prepare carbon or graphite fibers, carbon fiber reinforced polymers and/or carbon nanotubes. For example, the lignin of the present invention, or the lignin of the present invention blended or grafted with polyethylene oxide (PEO) or polyethylene glycol (PEG), may be used to prepare lignin based carbon fibers via any process known to one of skill in the art for preparing carbon fibers, for example, melt-spinning or electrospinning processes.
In yet another embodiment, lignin provided by the present invention may be applied and used in the production of fiberboards, particleboards, wood fiber insulation boards, strawboards, oriented strand boards and the like as part of a binder composition. For example, a lignin may be added to a resin to provide a binder with reasonable wet strength. Lignin based modifiers, wherein lignin or lignosulfonate can be added to formaldehyde based binder systems, for example, phenol formaldehyde, urea formaldehyde, melamine formaldehyde, resorcinol formaldehyde and/or tannin formaldehyde resins. The resulting board binder may then be used for panel boards, for example, in plywoods, hard boards, fiberboards or particle boards.
In another embodiment, lignin provided by the present invention may be applied and used in foams, plastics and/or polymers. For example, polyurethanes comprising lignins can have improved flame resistance and/or fire retardance. Epoxy resins can comprise a curing agent that comprises a lignin and/or a lignin derivative, such as a lignin-derived acetic anhydride. Lignins, for example S-free lignin, can be used in epoxy resins for fabricating printed circuit boards, or in products, such as automotive brakes. Lignins may be added to polymers, for example, polyphenylene oxide-based polymers, to enhance modulus of elasticity, tensile strength and elongation at break values of the polymer. Lignin can also act as a water absorption inhibitor and/or as a fluidization agent to facilitate polymer, for example, polyamide, processing, such as by injection molding, blow molding, extrusion or blow extrusion, to fabricate articles when mixed in solid or melt form. Lignins, for example, alkali lignin poly(propylene carbonate), can also be used to improve the thermal stability and mechanical properties of polymers.
In yet another embodiment, lignin provided by the present invention may be applied and used in dust control. For example, lignin and glycerin in water, can be applied to areas in which dust is a problem, such as, for example, in coal mines, transportation of coal, railways, roads, stock yards and the like. Lignin, for example, particular calcium lignin sulfonate powders, have been shown to stabilize contamination following a nuclear accident. Dust movement can also be controlled on a road surface by spraying with an emulsion comprising asphalt, lignosulfonate and water.
In another particular embodiment, lignin provided by the present invention may be applied and used in papers as a sizing agent, to enhance paper tensile strength, and/or as a packaging laminate.
In yet another embodiment, lignin provided by the present invention may be applied and used to provide chemicals through depolymerization or deconstruction of lignin. Depolymeriziation of lignin can provide, for example, phenols, cresols, catechols, resorcinols, quinolines, vanillin, guaiacols, cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid, p-hydroxycinnamic acid and the like.
In yet another embodiment, the depolymerization or deconstruction products of lignin may be provided as part of a clathrate, for example, a β-cyclodextrin clathrate, and utilized in, for example, as an antibacterial or antimildew agent, or utilized in agricultural, horticultural and/or cosmetic applications. In one embodiment, the clathrate of lignin depolymerization or deconstruction products may be used as an inhibitor of ethylene production.
In yet another embodiment, lignin provided by the present invention may be acidified and washed to reduce ash content of the lignin in order to alter or improve characteristics of lignin for use in value-added products, for example, but not limited to, resins, carbon fiber and polymers/copolymers, etc. such as set forth herein and as would be appreciated by one of skill in the art. The lignin may also be esterified or transesterified.
In yet another embodiment, lignin provided by the present invention may be applied and used in batteries and to enhance the performance of energy storage devices. For example, graphite powder in batteries comprising a thin layer of lignin can be used to prevent the graphite powder from decreasing H overvoltage, while not affecting the condition of the graphite powder. Lignin can also be used to protect negative plates of batteries from the formation of a passivating lead sulfate layer thereon.
In yet another particular embodiment, lignin provided by the present invention may be applied and used as a fuel additive, or can be catalytically converted to gasoline/diesel by a combination of pyrolysis, thermal cracking, hydrocracking, catalytic cracking or hydrotreatment. Lignin may further be used in catalytic hydrothermal gasification to provide fuel gas. Lignin may also be used to wood pellets to produce better quality pellets with higher fuel value, or in artificial fire logs to provide improved flame properties.
In another embodiment, lignin provided by the present invention may be applied and used as an additive to improve the characteristics of lubricants. For example, lignosulfonates can be used as a thickening agent for lubricating greases. Greases can comprise lignin compositions to provide improved corrosion protection properties of the grease. Additionally, greases comprising lignin, for example, hydrolytic lignin, can provide greater wear resistance to devices using the same. Greases comprising lignin, such as lignosulfonate, can improve the antifriction properties of the grease, and provide longer lubrication life for the grease.
In yet another particular embodiment, lignin provided by the present invention may be applied and used in the production of latex and/or rubber. For example, lignin can be added to latex and/or rubber and function as a filler, pigment, modifier, extender or reinforcement for the same. Lignin added to latex can increase oil resistance and/or tensile strength of rubber latex films. Rubbers reinforced with lignin can exhibit improved ozone resistance compared to rubbers without lignin added. The method by which the lignin provided by the present invention is incorporated into latex and/or rubber is not particularly limited, and may be carried out by in any manner that will be appreciated by one of skill in the art.
The following example is provided to illustrate the present invention, and should not be construed as limiting thereof.
EXAMPLES Example 1 Wheat Grass10 kg of dried wheat grass (straw) is chopped to a stalk length of ¾ 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 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.
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 using the Green Extraction Technology fractionation apparatus described in U.S. application Ser. No. 14/454,833 filed on Aug. 8, 2014. 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.
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 2423 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) within 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 10 kD ultrafiltration membrane to remove the acetic acid and formic acid as a permeate for reuse in the process.
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 with pulses of 912 to 1824 times 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.
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 4% 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 3%.
The liquid fractions are then individually centrifuged and neutralized to a pH of 7 using diluted HCl. The third liquid fraction is precipitated at a pH of 3.5 with diluted sulfuric acid. The fourth and fifth liquid fractions are precipitated at a pH of 2 using diluted sulfuric acid. All are then centrifuged at 4000 rpm for 5 minutes, washed three times in water, and then dried at 40° C. for 8 hours.
The solid lignin precipitated from the fourth liquid fraction (“Lignin A”) and the solid lignin precipitated from the third liquid fraction (“Lignin B”) are then analyzed via thermal decomposition. Lignin A and Lignin B are sulfonated and then thermally decompressed. The results are in Table 1.
The content of the lignin is as follows in Table 2.
A NMR spectra of the third liquid lignin fraction is provided at
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.
Claims
1. A process for isolating lignin from a biomass in water soluble form and a biomass substantially devoid of hemicellulose, sugar and the water insoluble components, the process comprising:
- a) pretreating the biomass;
- b) subjecting the pretreated biomass to high frequency pulses and shear forces without denaturing/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 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 force to separate lignin in water soluble form from the second fractionated biomass, wherein the lignin is substantially devoid of hemicellulose, sugar and the water insoluble components of the biomass.
2. The process of claim 1, further comprising after step e) contacting the second fractionated biomass substantially devoid of hemicelluloses and sugars with a second basic solution and subjecting the second fractionated biomass to compressive force to separate at least one first water insoluble component of a biomass in water soluble form from the second fractionated biomass substantially devoid of hemicelluloses and sugars.
3. The process of claim 2, wherein the first and second basic solutions comprise sodium hydroxide.
4. The process of claim 1 wherein the steps are conducted at ambient temperature to about 60° C.
5. The process of claim 1 wherein step f) of subjecting the second fractionated biomass substantially devoid of hemicelluloses and sugars to oxidation included contacting the second fractionated biomass substantially devoid of hemicelluloses and sugars with a hydrogen peroxide solution.
6. The process of claim 1, wherein the water insoluble component of a biomass in water soluble form is purified by contacting with a membrane.
7. A water insoluble component of a biomass in water soluble form provided by the method claim 1.
8. A process for providing lignin of a biomass and a biomass substantially devoid of hemicellulose, sugar and the water insoluble components, the process comprising:
- a) pretreating the biomass;
- b) subjecting the pretreated biomass to high frequency pulses and shear forces without denaturing 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) monitoring the amount of hemicellulose in the first fractionated biomass to determine if first fractionated biomass substantially devoid of hemicellulose and sugar,
- e) subjecting the first fractionated biomass, if not devoid of hemicellulose and sugar to the same high frequency pulses and shear forces of step b);
- f) 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;
- g) subjecting the second fractionated biomass substantially devoid of hemicellulose and sugars to oxidation at a pH above 7; and
- h) subjecting the second fractionated biomass following oxidation to compressive forces to separate one or more water insoluble components of a third fractionated biomass and to provide a third liquid fraction comprising lignin in water soluble form substantially devoid of hemicellulose, sugar and the water insoluble components of the biomass.
9. The process of claim 8, further comprising after step h):
- i) subjecting the third liquid fraction comprising lignin in water soluble form to a precipitation step comprising adjusting the pH of said liquid fraction to a pH of less than about 5.0 to provide precipitated lignin.
10. The process of claim 8, further comprising after step h):
- i) subjecting the third fractionated biomass to oxidation at a pH above 7;
- j) subjecting the third fractionated biomass following oxidation to compressive forces to separate one or more water insoluble components of a fourth fractionated biomass and to provide a fourth liquid fraction comprising lignin in water soluble form; and
- k) combining the third and fourth liquid fractions to provide lignin in water soluble form substantially devoid of hemicellulose, sugar and the water insoluble components of the biomass.
11. The process of claim 10, further comprising after step k):
- l) subjecting the combined fractions comprising lignin in water soluble form to a precipitation step comprising adjusting the pH of said liquid fraction to a pH of less than 4.0 to provide precipitated lignin.
12. The process according to claim 1, wherein the organic solvent is selected from the group consisting of methanol, ethanol, propanol, butanol, and glycol.
13. The process according to claim 1, wherein the solvent is any one selected from a group consisting of a short chain alcohol, glycerin and water, or a co-solvent mixture of any combination thereof.
14. A lignin that is substantially the same as prior to isolation from a biomass wherein the lignin is high in molecular weight and has not been denatured or degraded during delignification of the biomass.
15. The lignin of claim 14 having a molecular weight mean greater than 10,000.
16. A lignin that is substantially the same as prior to isolation from a biomass wherein the lignin is high in molecular weight and has not been denatured or degraded during delignification of the biomass prepared by the process of claim 1.
17. A lignin that is substantially the same as it was prior to isolation from a biomass wherein the lignin is high in molecular weight and has not been denatured or degraded during delignification of the biomass prepared by the process of claim 8.
18. A polymer or copolymer comprising the lignin of claim 14.
19. The polymer or copolymer of claim 18, wherein polymer or copolymer comprises PLA.
20. A carbon or graphite fiber, carbon fiber reinforced polymer or a carbon nanotube comprising the lignin of claim 14.
21. A deconstruction product of the lignin of claim 14.
22. The deconstruction product of claim 21, wherein the product is selected from the group consisting of phenols, cresols, catechols, resorcinols, quinolines, vanillin, guaiacols, cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid andp-hydroxycinnamic acid.
23. A process for providing lignin isolated from a biomass comprising subjecting a biomass to conditions to separate cellulose and lignin from the biomass to provide a fraction comprising cellulose and lignin without denaturing or degrading the cellulose or lignin, oxidizing the fraction, and separating the cellulose from the lignin.
Type: Application
Filed: Feb 11, 2015
Publication Date: Sep 3, 2015
Inventor: Melvin Mitchell (Penrose, NC)
Application Number: 14/619,451
