WO2025035142A1 - Lignin compositions for improved bioprocess utilization - Google Patents

Abstract

A method of producing a lignin composition comprising contacting a lignin obtained from a renewable resource with an aqueous fluid a plurality of times to produce a washed lignin; contacting the washed lignin with an acid under conditions suitable for formation of an acid washed lignin; contacting the acid washed lignin with one or more cellulases to form a pretreated lignin; and fermenting the pretreated lignin to form a crosslinked high molecular weight lignin. A composite material comprising a high molecular weight crosslinked lignin and at least one material selected from the group consisting of carbon fiber, polymers, a precursor for carbon-based materials, nanomaterials, cement, concrete and combinations thereof.

Description

LIGNIN COMPOSITIONS FOR IMPROVED BIOPROCESS UTILIZATION

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63/518,493 filed August 9, 2023 entitled “MULTI-STREAM INTEGRATED BIOREFINERY FOR SUSTAINABILITY AND ECONOMICS,” which is hereby incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

[0002] This present disclosure relates to biosourced platform chemicals, more particularly the present disclosure relates to novel lignin-based materials and methods of making and using same.

BACKGROUND

[0003] Lignin is the second most abundant biopolymer on earth but there are significant challenges to broader utilization of this material in chemical manufacturing. The lignocellulose matrix comprises three primary types of bonds among its significant components: ether bonds, ester bonds, and carbon-to-carbon (C-C) bonds. The positioning and bonding of these linkages can vary, creating connections within the individual constituents of lignocellulose and interconnecting the different elements to form a complex structure . Lignin, which encompasses various linkages with cellulose and carbohydrates, forms associations primarily with hemicellulose and disperses within the interstitial spaces of the matrix, creating a three-dimensional structure that enhances structural integrity. In contrast, lignin and hemicellulose are cross-linked through hydrogen and covalent bonds. These intermolecular lignin-carbohydrate (LC) chemical bonds between lignin and hemicellulose biopolymers are believed to occur naturally. As a result, cellulose, hemicellulose, and lignin intertwine to create a complex cell wall structure that resists biodegradation. Furthermore, the lignin- carbohydrate complex (LCC) poses challenges to the isolation of individual components, complicating the recovery process. The key to sustainable biomass utilization lies in the more complete utilization of all components to achieve higher carbon efficiency. The current bioconversion process results in a large amount of unexploited lignin residue that devalues the lignin valorization for biorefineries. An ongoing need exists to utilize the remaining lignin from fermentation to achieve a more complete utilization of biomass. SUMMARY

[0004] Disclosed herein is a method of producing a lignin composition comprising contacting a lignin obtained from a renewable resource with an aqueous fluid a plurality of times to produce a washed lignin; contacting the washed lignin with an acid under conditions suitable for formation of an acid washed lignin; contacting the acid washed lignin with one or more cellulases to form a pretreated lignin; and fermenting the pretreated lignin to form a crosslinked high molecular weight lignin.

[0005] Also disclosed herein is a composite material comprising a high molecular weight crosslinked lignin and at least one material selected from the group consisting of carbon fiber, polymers, a precursor for carbon-based materials, nanomaterials, cement, concrete and combinations thereof.

[0006] Also disclosed herein is a method of producing a lignin composition comprising contacting a lignin obtained from a renewable resource with an aqueous fluid a plurality of times to produce a washed lignin; contacting the washed lignin with an acid under conditions suitable for formation of an acid washed lignin; esterifying the acid washed lignin to form an esterified lignin; contacting the esterified lignin with one or more cellulases to form a pretreated lignin; and fermenting the pretreated lignin to form a crosslinked high molecular weight lignin.

[0007] Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those skilled in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] For a detailed description of various exemplary embodiments, reference will now be made to the accompanying drawings in which:

[0009] Figure 1 is a schematic of a method for production of a high molecular weight crosslinked lignin and composite materials. DETAILED DESCRIPTION

[0010] The following discussion is directed to various exemplary embodiments. However, one skilled in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

[0011] Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

[0012] Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11 , 0.12, 0.13, etc.).

[0013] To define more clearly the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions are applicable to this disclosure. If a term is used in this disclosure but is not specifically defined herein, the definition from the IUPAC Compendium of Chemical Terminology, 2^nd Ed (1997) can be applied, as long as that definition does not conflict with any other disclosure or definition applied herein, or render indefinite or non-enabled any claim to which that definition is applied. To the extent that any definition or usage provided by any document incorporated herein by reference conflicts with the definition or usage provided herein, the definition or usage provided herein controls.

[0014] Groups of elements of the periodic table are indicated using the numbering scheme indicated in the version of the periodic table of elements published in Chemical and Engineering News, 63(5), 27, 1985. In some instances, a group of elements can be indicated using a common name assigned to the group; for example alkali earth metals (or alkali metals) for Group 1 elements, alkaline earth metals (or alkaline metals) for Group 2 elements, transition metals for Group 3-12 elements, and halogens for Group 17 elements.

[0015] Regarding claim transitional terms or phrases, the transitional term “comprising,” which is synonymous with “including,” “containing,” “having,” or “characterized by,” is inclusive or open-ended and does not exclude additional, unrecited elements or method steps. The transitional phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. The transitional phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the subject matter described herein. A “consisting essentially of” claim occupies a middle ground between closed claims that are written in a “consisting of” format and fully open claims that are drafted in a “comprising” format. Absent an indication to the contrary, when describing a compound or composition “consisting essentially of” is not to be construed as “comprising,” but is intended to describe the recited component that includes materials which do not significantly alter the composition or method to which the term is applied. For example, a feedstock consisting essentially of a material A can include impurities typically present in a commercially produced or commercially available sample of the recited compound or composition. When a claim includes different features and/or feature classes (for example, a method step, feedstock features, and/or product features, among other possibilities), the transitional terms “comprising,” “consisting essentially of,” and “consisting of” apply only to the feature class which is utilized and it is possible to have different transitional terms or phrases utilized with different features within a claim.

[0016] Within this specification, use of “comprising” or an equivalent expression contemplates the use of the phrase “consisting essentially of,” “consists essentially of,” or equivalent expressions as alternative aspects to the open-ended expression. Additionally, use of “comprising” or an equivalent expression or use of “consisting essentially of” in the specification contemplates the use of the phrase “consisting of,” “consists of,” or equivalent expressions as an alternative to the open-ended expression or middle ground expression, respectively. For example, “comprising” should be understood to include “consisting essentially of,” and “consisting of” as alternative aspects for the aspect, features, and/or elements presented in the specification unless specifically indicated otherwise. [0017] While compositions and methods are described in terms of “comprising” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components or steps.

[0018] The terms “a,” “an,” and “the” are intended, unless specifically indicated otherwise, to include plural alternatives, e.g., at least one.

[0019] For any compound disclosed herein, the general structure or name presented is also intended to encompass all structural isomers, conformational isomers, and stereoisomers that can arise from a set of substituents, unless indicated otherwise. Thus, a general reference to a compound includes all structural isomers unless explicitly indicated otherwise; e.g., a general reference to pentane includes n-pentane, 2-methyl-butane, and 2,2-dimethylpropane while a general reference to a butyl group includes an n-butyl group, a sec-butyl group, an iso-butyl group, and a tert-butyl group. Additionally, the reference to a general structure or name encompasses all enantiomers, diastereomers, and other optical isomers whether in enantiomeric or racemic forms, as well as mixtures of stereoisomers, as the context permits or requires. For any particular formula or name that is presented, any general formula or name presented also encompasses all conformational isomers, regioisomers, and stereoisomers that can arise from a particular set of substituents.

[0020] Features within this disclosure that are provided as minimum values can be alternatively stated as “at least” or “greater than orequal to” any recited minimum value for the feature disclosed herein. Features within this disclosure that are provided as maximum values can be alternatively stated as “less than or equal to” for the feature disclosed herein.

[0021] Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim.

[0022] Processes described herein can utilize steps, features, compounds and/or equipment which are independently described herein. The processes described herein may or may not utilize step identifiers (e.g., 1 ), 2), etc., a), b), etc., i), ii), etc., or first, second, etc., among others), feature identifiers (e.g., 1 ), 2), etc., a), b), etc., i), ii), etc., or first, second, etc., among others), and/or compound and/or composition identifiers (e.g., 1), 2), etc., a), b), etc., i), ii), etc., or first, second, etc., among others). However, it should be noted that processes described herein can have multiple steps, features (e.g., reagent ratios, formation conditions, among other considerations), and/or multiple compounds and/or compositions using no descriptor or sometimes having the same general identifier. Consequently, it should be noted that the processes described herein can be modified to use an appropriate step orfeature identifier (e.g., 1 ), 2), etc., a), b), etc., i), ii), etc., or first, second, etc., among others), feature identifier (e.g., 1 ), 2), etc., a), b), etc., i), ii), etc., or first, second, etc., among others), and/or compound identifier (e.g., first, second, etc.) regardless of step, feature, and/or compound identifier utilized in a particular aspect described herein and that step or feature identifiers can be added and/or modified to indicate individual different steps/features/compounds utilized within the processes without detracting from the general disclosure.

[0023] Disclosed herein are methods for the production of a lignin composition comprising conversion of lignin from biomass by fermentation to form a cross-linked lignin composition characterized by a high molecular weight. In one or more aspects, the cross-linked lignin composition characterized by a high molecular weight is chemically distinct based on differences in one or of more of the following parameters: hydroxyl content, solubility, molecular weight, functional group content, and subunit type. A method of the present disclosure comprises production of one or more crosslinked lignin compositions characterized by a high molecular weight that can be utilized in the production of materials with improved properties. Herein a cross-linked lignin composition characterized by a high molecular weight for use in the improvement of material properties is termed product improving lignin (PIL).

[0024] In an aspect, a lignin feedstock for formation of the PIL may be obtained from any suitable biomass and may comprise any lignocellulosic material. Nonlimiting examples of lignocellulosic material suitable for use in the present disclosure include hard or soft wood, grasses, agricultural waste, agricultural material, municipal waste, or a combination of one or more biomasses. In one or more aspects, the agricultural material or waste which may be used as the lignin feedstock comprises corn stover, corn cobs, corn kernels, corn fibers, straw, banana plantation waste, rice straw, rice hull, oat straw, oat hull, corn fiber, cotton stalk, cotton gin, wheat straw, sugar cane bagasse, sugar cane trash, sorghum residues, sugar processing residues, barley straw, cereal straw, wheat straw, canola straw, soybean stover and combinations thereof.

[0025] The processes and systems of the present disclosure for production of a PIL can accommodate a wide range of feedstocks of various types, sizes, and moisture contents. For example, biomass such as forest products, grasses, and other cellulosic material may be used. In an aspect, the lignin feedstock comprises agricultural waste, alternatively the lignin feedstock comprises lignin obtained from a pulping process such as Kraft lignin. In one or more aspects, the lignin feedstock is pretreated before fermentation.

[0026] In one or more aspects, a method of the present disclosure comprises reducing the impurities of the lignin feedstock. Without wishing to be limited by theory, impurities that may be found in a lignin feedstock derived from sources such as a pulping process or biorefinery fermentation typically include water soluble chemicals such as alkalis, acids, enzymes, or salts which were used to react or facilitate lignocellulosic processes. These chemicals remain as extra residual impurities in the lignin precipitate [0027] Any suitable methodology may be utilized to reduce the level of impurities in a lignin feedstock. In one or more aspects, a method of the present disclosure comprises a solvent purification step. Specifically, the level of impurities in the lignin feedstock may be reduced by contacting the lignin feedstock with an aqueous fluid, alternatively with water, or alternatively with deionized (DI) water. For example, the lignin feedstock may be contacted with excess DI water a plurality of times, designated y, where y may range from about 1 to about 5 times, additionally or alternatively, from about 1 to about 4, additionally or alternatively, from about 2 to about 4 or, additionally or alternatively, from about 3 to about 5. The resultant materials is a washed lignin feedstock.

[0028] Additionally or alternatively, the lignin feedstock may be acid-treated to facilitate the separation of cellulose from the lignin. In one or more aspects, pretreatment comprises immersing the lignin feedstock in an acid present in an amount ranging from about 1 weight percent (wt.%) to about 10 wt.% or, additionally or alternatively, from about 1 wt.% to about 5 wt.% or, additionally or alternatively, from about 1 wt.% to about 3 wt.% based on the total weight of the solution. Any suitable acid may be used such as sulfuric acid, phosphoric acid, nitric acid, combinations thereof and the like. In one or more aspects, the lignin feedstock is contacted with the acid at temperatures ranging from about 60 °C to about 150 °C, additionally or alternatively, form about 80 °C to about 150 °C or, additionally or alternatively, from about 100 °C to about 120 °C. [0029] Additionally or alternatively, the lignin feedstock may be subjected to mechanical or physical pre-treatment to allow for size reduction. Size reduction of the feedstock may alter the physical structure, increase porosity, decrease the degree of polymerization, and increase the specific surface area of biomass. [0030] Additionally or alternatively, the lignin feedstock may be contacted with one or more cellulases under conditions suitable for reduction of the cellulose content of the feedstock. Cellulases are a class of hydrolytic enzymes that catalyze cellulolysis or hydrolysis of the polysaccharide, cellulose, into monosaccharides such as p-glucose, or shorter polysaccharides and oligosaccharides.

[0031] In one or more aspects, lignin feedstock subjected to one or more of the aforementioned processes (washing, acid treatment, cellulase treatment) may be solubilized. Solubilization of the lignin feedstock may be carried out using any suitable methodology. For example, solid residue from the reaction of the lignin feedstock may be contacted with water and caustic (e.g., metal hydroxide at temperatures ranging from about 60 °C to about 150 °C, or alternatively form about 80 °C to about 150 °C or, additionally or alternatively, from about 100 °C to about 120 °C. The caustic may be present in an amount ranging from about 1 weight percent (wt.%) to about 10 wt.% or, additionally or alternatively, from about 1 wt.% to about 5 wt.% or, additionally or alternativley, from about 1 wt.% to about 3 wt.% based on the total weight of the solution. The resulting material is termed a treated lignin feedstock and may be subjected to fermentation.

[0032] In one or more aspects, the treated lignin feedstock is fermented. Fermentation of the treated lignin feedstock may be carried out under conditions suitable for the formation of polyhydroxyalkanoates (PHA) using any suitable microorganism. In an aspect, the microorganism is by Pseudomonas putida (P. putida) or an engineered microorganism such as P. putida KT2440. Fermentation may be carried out using any suitable methodology for the microorganism. The resulting material is termed the fermented lignin feedstock.

[0033] In one or more aspects, lignin is recovered from the fermented lignin feedstock. Recovery of lignin may be carried out using any suitable methodology. For example, the lignin may be recovered by precipitation or solvent evaporation. In one or more aspects, the recovered lignin is used without further processing. In other aspects, the recovered lignin is further processed to remove impurities. For example, the recovered lignin may be washed with dilute acid and dried. The recovered material is a PIL. An overview of the process for production of a PIL is present in Figure 1 .

[0034] In one or more aspects, a PIL of the present disclosure is used without further processing. In some aspects, the PIL is subjected to esterification. In one or more aspects, a method of the present disclosure comprises esterification of the PIL. In one or more aspects, the PIL is esterified by reaction with an anhydride, additionally or alternatively, an organic anhydride.

[0035] Nonlimiting examples of organic anhydrides suitable for use in the esterification of the PIL include acetic anhydride, octanoic acid anhydride, n-octanoic anhydride, caprylic anhydride, n-caprylic anhydride, propionic anhydride, cratonic anhydride and a combination thereof. In an aspect, the organic anhydride comprises cratonic anhydride.

[0036] In one or more aspects of the methods disclosed herein, the PIL is reacted with an organic anhydride (e.g., cratonic anhydride) in the presence of a suitable catalyst and solvent (e.g., DMF, 1 ,4 dioxane) at a temperature of from about 120°C to about 180°C, additionally or alternatively, from about 120°C to about 140°C, additionally or alternatively, from about 140°C to about 160°C or, additionally or alternatively, from about 160°C to about 180°C for a time period of from about 0.5 hours to about 8 hours, additionally or alternatively, 0.5 hours to about 1 hour, additionally or alternatively, from about 1 hour to about 4 or additionally or alternatively, from about 4 hours to about 8 hours, A catalyst suitable for use in the present disclosure may be a hypernucleophilic acylation catalyst such as chiral bicyclic amidines and isothioureas (e.g., 4- dimethylaminopyridine). The organic anhydride may be present in the hypernucleophilic acylation reaction mixture in an amount of from about 10 weight percent (wt.%) to about 60 wt.%, additionally or alternatively, from about 10 wt.% to about 20 wt.%, additionally or alternatively, from about 20 wt.% to about 40 wt.% or, additionally or alternatively, from about 40 wt.% to about 60 wt.%. The resultant product is termed an esterified PIL.

[0037] In one or more aspects, a method of the present disclosure further comprises reacting the esterified PIL with a crosslinking agent. Prior to crosslinking of the esterified purified lignin, the product of the reaction with an organic anhydride may be processed to meet one or more user and/or process goals. For example, prior to crosslinking of the esterified purified lignin, the product of the organic anhydride reaction may be subjected to one or more processes for purification such as filtration. [0038] Nonlimiting examples of crosslinking agents suitable for use in the present disclosure include 1 -ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC), dicyclohexyl carbodiimide (DDC), N-hydroxysuccinimide esters (NHS), maleimides, or a combination thereof. The crosslinking agent may be present in an amount of from about 1 wt.% to about 10 wt.%, additionally or alternatively, from about 1 wt.% to about 3 wt.%, additionally or alternatively, from about 3 wt.% to about 6 wt.% or additionally or alternatively, from about 6 wt.% to about 10 wt.% based on the total amount of esterified PIL.

[0039] The esterified PIL may be contacted with the crosslinking agent at a temperature of from about 120°C to about 180°C, additionally or alternatively, from about 120°C to about 140°C, additionally or alternatively, from about 140°C to about 160°C or, additionally or alternatively, from about 160°C to about 180°C for a time period of from about 0.5 hours to about8 hours, additionally or alternatively, from about 0.5 hours to about 1 hour, additionally or alternatively, from about 1 to about 4 hours or, additionally or alternatively, from about 4 hours to about 8 hours in a solvent of DMF or 1 ,4 dioxane. The resulting material is a high molecular weight esterified lignin or HIMWELL-PIL.

[0040] A PIL of the present disclosure may be characterized by an increased degree of crosslinking among the lignin molecules. The result of the increased crosslinking is an increased weight average molecular weight. A PIL of the present disclosure may be characterized by a weight average molecular weight (M_w ) of from about 5000 grams/mole (g/mol) to about 50000 g/mol, additionally or alternatively, from about 10000 g/mol to about 40000 g/mol, additionally or alternatively, or from about 15000 g/mol to about 30000 or, additionally or alternatively, from about 15000 g/mol to about 25000 g/mol. The M_w describes the weight-average molecular weight of a polymer and can be calculated according to Equation 1 :

wherein N, is the number of molecules of molecular weight M,. All molecular weight averages are expressed in gram per mole (kg/mol).

[0041] A PIL may be characterized by increased homogeneity such that the number of chemically distinct lignin molecules within the composition are reduced when compared to the number of chemically distinct lignin sets obtained from a natural source. For example, the lignin obtained from a natural source may have N chemically distinct sets of lignin molecules while PIL may have X sets of lignin molecules wherein X is from about 5% to about 50% less than N, additionally or alternatively, from about 10% to about 50% less than N or, additionally or alternatively, from about 25% to about 50% less than N. Thus, the lignin compositions disclosed herein display an increased homogeneity when compared to the lignin compositions obtained from a natural source.

[0042] In one or more aspects, a PIL of the present disclosure is utilized in the preparation of a one or more composite materials. In one or more aspects, a PIL is included in the preparation of materials such as carbon fiber, polymers such as recyclable plastics and virgin polymer materials, a precursor for carbon-based materials, bioplastics, nanomaterials, cement, concrete and combinations thereof. Nonlimiting examples of polymers suitable for use in the present disclosure include wherein the polymeric material comprises low-density polyethylene (LDPE), high- density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polytetrafluoroethylene, thermoplastic polyurethanes (TPU), polyacrylonitrile or combinations thereof.

[0043] In such aspects, the PIL may be present in a mixture suitable for preparation of a material in amounts ranging of from about 1 wt.% to about 50 wt.% based on the total weight of the mixture, additionally or alternatively, from about 1 wt.% to about 40 wt.%, additionally or alternatively, from about 1 wt.% to about 25 wt.%, additionally or alternatively, from about 1 wt.% to about 10 wt.% or, additionally or alternatively, from about 1 wt.% to about 5 wt.%.

[0044] In one or more other aspects, the PIL is present in one or more materials (e.g., plastic) in order to form a composite material. The material in which a PIL is included may display an increase in one or mechanical properties. Hereinafter for simplicity, reference is made to a material comprising a PIL, designated MCP.

[0045] In one or more aspects, a MCP (e.g., plastic, carbon fiber) is characterized by a modulus of elasticity that is increased by from equal to or greater than about 10% to about 100%, additionally or alternatively, from equal to or greater than about 40% to about 100% or, additionally or alternatively, from equal to or greater about 50% when compared to the material without a PIL. The modulus of elasticity refers to the ratio of stress to elastic strain in tension and may be determined in accordance with ASTM D3039.

[0046] In one or more aspects, an MCP (e.g., plastic, carbon fiber) is characterized by a tensile strength that is increased by from equal to or greater than about 10% to about 100%, additionally or alternatively, from equal to or greater than about 40% to about 100%, additionally or alternatively, from equal to or greater about 50% to about 100% when compared to the material without a PIL. The tensile strength indicates a material’s ability to withstand loads and forces during its lifetime and may be determined in accordance with ASTM D638.

EXAMPLES

[0047] The presently disclosed subject matter having been generally described, the following examples are given as particular aspects of the subject matter and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification or the claims in any manner. In the following examples, percentages refer to weight percent based on the total weight of the sample being described unless indicated otherwise. METHODS

Materials

[0048] Crotonic anhydrate, sulfuric acid, sodium chloride, sodium hydroxide, 4- Dimethylaminopyrdine (4DMAP), 1 ,4 Dioxane, 2,2-Azobis(2-methylpropionamidine) dihydrochloride, and N, N-dimethylformamide (DMF, 99.8%) were purchased from Sigma-Aldrich, USA. Polyacrylonitrile (PAN, MW150,000 g/mol) was purchased from Pfaltz&Bauer, USA.

Corn stover biomass pretreatment

[0049] The corn stover pretreatments were employed to deconstruct the components of corn stover and facilitate the separation of cellulose and lignin for bioconversion. Dilute sulfuric acid pretreatment was conducted with an autoclave at 121 °C and a residence time of 60 min at 10% (w/w) solid loading and 1 % H2SO4 (w/w) in 2.0-L glass flask. After pretreatment, the slurry was washed by water to recycle the acid and then filtered by vacuum filtration to separate solid from the liquid stream for the enzymatic hydrolysis.

Enzymatic hydrolysis

[0050] The enzymatic hydrolysis assays were applied using the enzymatic preparations CELLIC CTEC2 and HTEC2. Filter paper activity (FPU) of CELLIC CTEC2 was 96 FPU ml"¹, and the cellulase activity of p-glucosidase was 1270 CBU ml^-1. To evaluate the performance of performed at 10% (w/w) solid loading in a 0.05 M citrate buffer solution (pH 4.8) with a CELLIC CTEC2 loading of 5 FPU/g glucan and a volumetric ratio 9: 1 of CTEC2 and HTEC2 in a 250-ml Erlenmeyer flask at 50 °C and 200 rpm for 7 days. A 1.0 ml sampling of supernatant was collected the end of enzymatic hydrolysis for sugar analysis. Sugar conversion was calculated based on the solid used in the hydrolysis.

Lignin solubilization of the enzymatic hydrolysis residues.

[0051] For lignin PHA bioconversion, the solid residue from enzymatic hydrolysis was used to produce soluble lignin and to improve lignin reactivity for microbial conversion. In detail, 100 g of oven dried pretreated solid residue was loaded into a 2.0-L glass flask at 10% (w/w) solid/DI water loading and 1 % NaOH (w/w). Then the solubilization was conducted with mild conditions at 121 °C for 60 min using Amsco LG 250 Laboratory Steam Sterilizer.

[0052] The solid residue with high crystalline cellulose was vacuum filtrated through a Brinell funnel with No.1 waterman filter paper to separate the soluble lignin stream. After conditioning, the liquid stream containing soluble lignin was used as carbon source in PHA fermentation.

Polyhydroxyalkanoate (PHA) fermentation

[0053] The soluble lignin stream from the solubilization was used as carbon source to produce PHAs by engineered P. putida KT2440. The seed culture followed the procedure shown in Supplementary Information. P. putida KT2440 cell pellets for inoculation were collected by centrifuging the seed culture at 2,200 xg for 10 min (Avanti JXN-30, Beckman Coulter, USA). To prepare the medium, the soluble lignin was adjusted carefully to pH 7.0 by 1.0 M sulfuric acid and mixed well with 10 mL 10X Basal salts and 1 mL 100X Mg/Ca/B1 /Goodies mixture to make 100 mL medium. Fermentation was conducted using fed-batch mode in a 250-mL Erlenmeyer flask with a working volume of 100 mL at pH 7.0, 28 °C, and 200 rpm for 24 h.

[0054] For the analysis of cell dry weight and PHA content, the cell biomass was harvested by centrifugation at 13,800 xg for 10 min (Avanti JXN-30, Beckman Coulter, USA) and washed two times using 0.9% NaCI solution. The cell biomass was freeze- dried by a lyophilizer at -50 °C for 24 h (Labconco Corporation, USA). Cell dry weight was determined by a gravimetric method. PHA content in dried cell was analyzed using the GC-MS method. In detail, 5~10 mg of freeze-dried cells was subjected to methanolysis with a solution containing 2 mL of 15% (v/v) sulfuric acid in methanol and 2 mL chloroform at 100 °C for 140 min. After cooling, 1 mL of ddH2O was added and the lower chloroform organic phase containing the resulting methyl esters was separated at 1 ,200 xg for 10 min (Avanti JXN-30, Beckman Coulter, USA). A total of 0.5 mL chloroform mixture and 0.5 ml_ 0.1 % caprylic acid in chloroform were mixed well and filtered with 0.22-pm polytetrafluorethylene (PTFE) membrane. Gas chromatography-mass spectrometry (GC-MS) analysis was performed on a GC-MS- QP2010SE (Shimadzu Scientific Instruments, Inc.) with a Shimadzu SH-Rxi-5Sil column (30 m x 250 pm x 0.25 pm). The eluted sample was analyzed using helium as a carrier gas at a flow rate of 1.0 mL/min, while the temperature maintained at 50°C for 3 min and then increased to 300 °C at 10 °C/min. The injector and transfer line temperature was maintained at 250 °C. Mass spectral peak area was performed using GCMS solution software Ver. 2.6. All experiments were performed in triplicate.

EXAMPLE 1

Lignin recovery from residual lignin solution for carbon fiber.

[0055] The 200 mL soluble lignin stream before the PHA fermentation and after the PHA fermentation were used to precipitate lignin for carbon fiber, respectively. Briefly, a HCI solution (0.5 mol/L) was added into the residual lignin solution to precipitate lignin until pH 2. Then the liquor was centrifuged at 6000 rpm for 5 min and filtered. In order to remove extra impurities, acidified water at pH 2 was employed to wash the lignin two more times before using DI water to remove the acid. After that, the purified lignin samples were freeze vacuum dried for 1 day. The final com stover lignin samples were stored in a desiccator for further characterization and usage for lignin-based carbon fiber.

EXAMPLE 2

[0056] A 2g recovered lignin samples after PHA fermentation was dissolved in 2mL of 1 ,4 dioxane in 25mL round-bottom flask, and then 2mL crotonic anhydrate as a reactant and 0.02g 4DMAP as a catalyst were added. The reaction was conducted at 105°C for 6 hours with a magnetic stirrer and glass condensing. After the reaction, the modified lignin was collected by adding boiling water while stirring to separate the excess catalyst, acid, and modified lignin precipitate. The resulting modified lignin was collected through a filtration system with 10pm nylon filter membrane. After that, the treated lignin was redissolved in 1 ,4 dioxane with a ratio of 1 :2 (w/v) in the 25mL beaker, and 1 % 2,2-azobis(2-methylpropionamidine) dihydrochloride was added as a radical initiator for a heat cross-linking reaction. The temperature was increased from room temperature at 1 °C/min to 130°C and held 2 hours before naturally cooling down under a nitrogen atmosphere. Then the treated lignin sample was stored in the desiccator for future use to produce carbon fiber.

EXAMPLE 3

Carbon fiber manufacturing process

[0057] Precursor Fiber Spinning:. Briefly, the Lignin sample was spun into fibers by a customized wet spinning system. Lignin powders were first mixed with PAN at a weight ratio of 1 :1 , then the mixture was dissolved in dimethylformamide (DMF) with the concentration of 10 %. Lignin/PAN precursor was sonicated using a Branson 1510 sonicatorfor 60min before spinning to remove existing air bubbles. The precursor was then injected into a methanol coagulation bath (below 0 °C) at a rate of 0.03 mL/min to form fibers. As-spun fibers were wound onto a rolling drum. After washing with methanol, the fibers were cut and hung under a 10 g load for drying.

EXAMPLE 4

Thermostabilization and Carbonization:

[0058] As-spun lignin precursor fibers were thermostabilized and then carbonized into carbon fibers. The thermostabilization was carried out using a muffle furnace (GSL 1200X, MTI Corporation, Richmond, CA) under air. The heating was from room temperature to 250 °C at a heating rate of 1 °C/min. The holding time at 250 °C was 1 h. The thermostabilized fibers then underwent carbonization in a split tube furnace with a vacuum system under a nitrogen atmosphere (60 mL/min) (GSL 1600X, MTI Corporation, Richmond, CA). The temperature for carbonization was increased with a heating rate of 5 °C/min from room temperature to 1500 °C and held for 1 h before naturally cooling down.

EXAMPLE 5

CMF/PHA/carbon fiber composite manufacturing process

[0059] Cellulose microfibrils (CMF) preparation: The cellulose was collected from the solid residues after enzyme hydrolysis and lignin separation. The crystalline cellulose was obtained after converting the low molecular and amorphous cellulose to carbon source through acid pretreatment and enzyme digestion for biofuels. After obtaining the crystalline cellulose, the residual cellulose was further treated by 4% NaCIO solution to bleach cellulose, then the CMF was collected and dried for further composite manufacturing. [0060] PHA preparation: The PHA oligomers were obtained from lignin waste fermentation from multi-stream integrated biorefineries process as above.

[0061] Carbon fiber preparation: The carbon fibers (CF) were prepared from lignin waste after PHA fermentation as above.

[0062] Composite preparation: To prepare the CMP solution, the 3 WT.% CMP was dispersed in DI water using a shear mixer for 10 mins, and the resulting solution was transfer to the aluminum dish for natural drying. For the CMF/PHA composite, the 20%wt (relative to cellulose) of PHA powders were mixed in the 3% cellulose solution using a shear mixer for 10 mins and then dried in aluminum dish. For the CMF/PHA/carbon fiber composite, 5%wt PHA was dissolved in chloroform mixed with 5%wt (relative to PHA) of short length carbon fibers using a magnetic stirrer. After natural drying the chloroform solution, the PHA-encapsuled carbon fibers (with a PHA:CF ratio of 20:1 ) were ground and dispersed in the 3%wt CMF solution (at a 20%wt concentration relation to cellulose) to prepare CMF/PHA/CF composites. The composite film precursors were then dried and pressed at 140°C for 5 minutes to enhance the performance of the final products.

Materials characterization

EXAMPLE 6

[0063] Composition analysis method: Composition analysis including carbohydrates and lignin was conducted according to the Laboratory Analysis Procedures (LAP) of the NREL. Briefly, 300 ± 10 mg biomass was treated with 3 mL of 72 % sulfuric acid at room temperature first. The sulfuric acid was then diluted to 4% followed by autoclaving the samples at 121 °C for 1 h. The acid insoluble part as lignin was weighted after filtration and drying. The acid soluble part was measured using a UV- visible spectroscopy at 280 nm and calculated with the absorptivity of E 280nm^{1 %} = 19.9 L/g cm. Lignin content was reported as the total content of insoluble lignin and the acid-soluble lignin. On the other hand, sugars in the solid and liquid fraction were analyzed by an Ultimate 3000 HPLC System (Thermo Scientific, USA) equipped with an Aminex HPX-87P carbohydrate analysis column (Bio-Rad Laboratories, CA) and a refractive index detector using HPLC grade water as the mobile phase at a flow rate of 0.6 mL/min. PHA yield in fermentation was calculated based on the consumption of substrate in medium including both lignin and residual glucose by P. putida KT2440. Mass balance was carried out in the whole fractionation process. Sugar yield in the whole process was calculated based on the corn stover feedstock used for each pretreatment.

[0064] Lignin characterization: The lignin obtained before and after PHA fermentation and treated lignin were used for further analysis. 2D ¹H-¹³C HSQC nuclear magnetic resonance (NMR), 31 P NMR spectra, 1 H NMR spectra and Fourier-transform infrared spectroscopy (FTIR) spectra of the lignin samples was obtained to analyze the structure and modification of the lignin and evaluate its processibility for bioconversion. Gel-permeation chromatography (GPC) was employed to determine the molecular weight of the lignin samples. Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) were employed to determine the thermal properties of lignin samples.

[0065] Carbon fiber characterization: The mechanical performance of the renewable carbon fibers produced from lignin precursors were measured by the tensile test. The crystalline structure of renewable carbon fibers was characterized by the XRD and Raman test. The morphologies of renewable carbon fiber were measured by SEM. RESULTS

[0066] Chemical Structure Analysis of Lignin Residue After Fermentation Reveals Higher Molecular Weight, More Uniform and More Linear Lignin

[0067] Mass balance data of the PHAs bioconversion rate derived from lignin demonstrated that only 33.2% of the lignin can be served as substrates for microbes to synthesize the PHAs, the utilization for the rest of large molecular lignin residue with amounts of linkages after PHAs microbe fermentation is still problematic. PILs of this disclosure are characterized by a higher molecular weight, more p-O-4 linkages and better uniformity. Therefore, the lignin residue obtained after PHAs bioconversion could be a promising precursor to synthesize lignin-based carbon fiber.

[0068] Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR) analyses were used to understand the structural transformation of lignin after PHA fermentation. It was observed that lignin after fermentation (AFL) increases 79.9% in molecular weight compared to lignin before fermentation (BFL), 6517 g/mol vs. 3623 g/mol. This result suggests that low molecular weight lignin is consumed by P. putida during PHA fermentation while the high molecular structure remains available for further processing. [0069] The contents of various hydroxyl groups were analyzed by by a quantitative ³¹ P NMR analysis in samples of lignin before and after fermentation. The results showed a slight increase in the content of phenolic, aliphatic and carboxylic OH groups on the lignin structure after fermentation. This increase in OH group after fermentation could be due to the cleavage of aryl-ether linkage and further depolymerization of lignin, which agrees with the slight increase in polydispersity index (PDI). The HSQC NMR spectra also revealed differences in the lignin chemical structures and linkages BFL and AFL Table 1.

Table 1

[0070] The results showed that H-lignin decreased after fermentation from 21.3% to 15.2% while S-lignin and G-lignin subunits slightly increased. Table 1 also shows that p-coumarates were consumed during the fermentation with P. putida for mcl-PHA production. In addition, the ratio of lignin linkage profiles also changed having a higher content of the p-O-4 linkage in AFL as compared to BFL. This more uniform structure and higher molecular weight is expected to enhance the properties of lignin-based carbon fiber.

Post-Bioconversion Lignin Serves as Superior Substrate for Chemical Processing to Achieve High-Molecular Weight Esterified Linkage Lignin

[0071] Mechanistic Study Revealed that Post-Bioconversion Lignin Enhances Crystalline Micro-structure of Carbon Fiber with Better Performance

[0072] Lignin after PHA fermentation produce lignin-based carbon fiber (AFLCF) was evaluated and compared the performance with lignin-based carbon fiber produced from biorefinery without PHA fermentation (BFLCF). The hypothesis was that fermentation can consume the small lignin molecules while leaving the large lignin molecules as an optimal precursor for high performance carbon fiber production.

[0073] Consistent with the aforementioned hypothesis, the mechanical properties of AFLCF exhibited improved mechanical properties as compared to BFLCF. For example, the tensile strength of AFLCF reached 826.6 MPa, which represents a 63.9% increase compared to BFLCF. Similarly, the modulus of elastic (MOE) of AFLCF achieved 46.2GPa, representing a 10.3% increase compared to BFLCF at 41 .9 GPa. Carbon fibers were prepared using the PILS of the present disclosure. The carbon fibers before fermentation, designated OBFLCF, and after fermentation, designated OAFLCF, were analyzed. The tensile strength of OBFLCF increased 41 .6% compared to BFLCF and the tensile strength of OAFLCF increased 47.7% compared to OAFLCF, while the MOE of OBFLCF increased 41.6% compared to the BFLCF and MOE of OAFLCF increased 47.7% compared to OBFLCF. Interestingly, the tensile strength and MOE of OAFLCF were 47.7% and 84.6% higher compared to OBFLCF, respectively.

[0074] These results indicated that the disclosed processes can improve the carbon fiber performance, and the higher molecular weight and more uniform lignin after fermentation also improves significantly the carbon fiber performance. Remarkably, both tensile strength and MOE of OAFLCF at 1221.3MPa and 85.3GPa are significantly higher than that of pure PAN-derived carbon fiber (1148.6MPa and 65.6 GPa, respectively). The substantial changes in lignin molecular structure after PHA fermentation allows better inter-molecular strength to drastically improve carbon fiber performance.

[0075] The elongation data is also consistent with the mechanism of lignin optimal molecular structure. Optimized lignin-based carbon fibers have lower elongation compared to the untreated lignin-based carbon fiber or pure PAN carbon fiber. The large molecular lignin precursor derived a higher strength carbon fiber and the disclosed treatment allowed the lignin precursor to have a better interaction between the lignin and PAN, which significantly improve the MOE.

[0076] The lignin molecular structure and functional groups also improved the electrical conductivity of carbon fiber. The electroconductivity of OAFLCF is 37337 Snr ¹ , which is around two times higher than that of the BFLCF at 19507 Srrr¹. [0077] The fermentation process and the lignin chemical structural optimization had significant impacts on the electroconductivity of the resultant carbon fiber. AFLCF increased its electronegativity from 27175 to 37337 Snr¹, while BFLCF increased from 19507 to 35153 Snr¹. Furthermore, the electroconductivity of OAFLCF reached the similar values than PANCF.

[0078] In order to further explore how carbon fiber microstructure impact properties, the morphologies of lignin-based carbon fiber was analyzed by SEM to identify the improvement of carbon fiber properties. The morphology and diameter distribution of the carbon fibers are shown in. The improved mechanical properties and electroconductivity are reflected in the lignin-based carbon fiber with excellent morphology. The PANCF, OAFLCF and OBFLCF display smooth and homogeneous structures in both fiber axial direction and cross section except for the carbon fiber without optimization treatment, which has some voids on the cross section. This indicates that the functional group optimization can improve the spinnability and miscibility, which can reduce the carbon fiber diameter and improve the distribution. The diameter of OAFLCF was 7.388pm followed by OBFLCF at 8.628pm, which has a similar diameter to PANCF (9.688 pm) and smaller than AFLCF (12.240 pm) and BFLCF (1 1.021 pm). Thus, even though the mechanical properties and electroconductivity can be improved by using lignin after PHA fermentation, the generation of as-spun fibers with more uniform and smaller diameters requires more processing of functional groups through optimization treatment with guest polymer PAN.

[0079] In order to further establish the relationship between the microstructure and lignin-based carbon fiber properties, materials were examined by XRD spectroscopy and correlated with Raman analysis. The XRD analysis revealed that OAFLCF obtained the highest crystalline size (Lhkl) followed by OBFLFC,2.356nm and 1.866nm, respectively. The crystalline size of PANCF resulted also lower than the optimized lignin-base carbon fibers, 1 ,665nm. The distance of crystallite lattices (dhkl) resulted consistent among all the samples. The XRD spectroscopy in was well correlated with the Raman analysis in. The content of crystalline vs. amorphous carbon in carbon fibers. The D/G ratios were calculated from the intensity of the disordered sp² D band (around 1326cm^-1) and the area of the graphite sp³ G band (around 1586cm^-1) of the Raman spectroscopy. OAFLCF achieved the lowest D/G ratio of 1 .44, which resulted even lower than PANCF at 1 .67. OBFLCF had higher D/G ratio at 1.67, whereas AFLCF had slightly lower D/G ratio at 1.54 and BFLCF hasd significantly higher D/G ratio at 1 .93. This result highlighted that PHA fermentation not only improved the economy of biorefineries and utilization efficiency, but also facilitates the formation of pre-graphite turbostratic carbon in lignin-based carbon fiber. [0080] The rheology tests also highlight the unique features of the PIL. As The biorefined lignin/PAN precursor dopes displayed a decreased in the shear viscosity and poor interaction in comparison with PAN dope only. A non-Newtonian behavior of the shear thinning fluid appeared for the optimized biorefined lignin/PAN precursor dopes. The results implied a strong attraction between the optimized lignin and PAN molecules for OAFLCF and OBFLCF precursor dopes. The interaction could also help producing improved as-spun fibers with smaller diameters, more uniform structures, and fewer defects.

[0081] Overall, the testing and characterization results highlight that both the fermentation process and optimization treatment promote a better interaction with PAN and better miscibility and spinnability, subsequently enabling the formation of more pre-graphite turbostratic carbon during carbonization. Eventually, the improved microstructure and crystallite carbon content lead to a much higher tensile strength and elastic modulus.

Development of carbon fiber reinforced composite films from the multi-stream integrated biorefinery wastes.

[0082] Herein, we presented an integrated biorefinery to fully utilize the biomass components and generate both PHA and lignin-based carbon fiber, significantly improving the economy and sustainability of the biorefinery industry. To demonstrate the versatility of these products, we furthervdeveloped a derived carbon fiber reinforced cellulose-based plastic composites for high-value packaging applications. Although a portion of crystalline cellulose residues cannot be converted to biofuel in the current biorefinery process, this waste can be repurposed to develop packaging materials.

[0083] To meet the required specifications for packaging applications, the cellulose residues undergoes hydrophobic treatment. To achieve this, we used the lignin- derived PHA, to change the natural properties of cellulose residues. T rad itional ly , PHA with long carbon chains exhibits hydrophobic properties that is not compatible with the hydrophilic cellulose. However, the PHA synthesized from lignin waste has a unique molecular structure (mainly composed of 3 hydroxydecanoate and other medium chain length PHA monomers) with a small molecular weight (Mn=341 ). This structure exposes hydroxyl groups that facilitate hydrogen bonding between PHA and cellulose. Nevertheless, the PHA does not disperse well in the cellulose matrix due to the hydrophobicity of the carbon chains, resulting in aggregation in the composite. To address this issue, the carbon fiber produced from lignin was used to reinforce the composites, as the carbon chain of PHA is compatible with carbon fiber hydrophobic properties. PHA encapsulated CF was prepared to enhance the performance of cellulose microfiber (CMP).

[0084] Although the PHA could interact with cellulose through hydrogen bonds, the carbon-chain of PHA aggregated affecting its dispersion in the cellulose matrix. In comparison to the CMF/PHA composites, PHA encapsulated CF composites first dispersed the PHA on the surface of carbon fiber using the carbon-chain interaction to prevent the aggregation. Then the carbonyl groups and hydroxyl groups of the PHA crosslinked with the CMF, creating an integrated structure. The unique short chain structure of PHA connected CF through hydrophobic interaction and crosslinked cellulose by hydrogen bonds.

[0085] FTIR spectra of CF, PHA, CMF, CMF/PHA, and CMF/PHA/CF reveal that the C=O band in CMF/PHA/CF is sharper than the C=O band in PHA alone, indicating that the C=O groups interact with the hydrogen group of cellulose to form hydrogen bonds. On the other hand, the water surface contact angle analysis demonstrates that the PHA significantly enhances the hydrophobicity of this composite, with contact angles increasing from 40.34° for CMF to 102.33° for CMF/PHA and 104.26° for CMF/PHA/CF. We believe that CF improved the dispersion of PHA and further enhances the hydrophobicity. Although the PHA component improved the hydrophobicity of the composite, it also caused a decrease in the tensile strength of the CMF composite. The tensile strength of the CMF/PHA composite decreased from 32.8 MPa in the CMF composite to 21.4 MPa. However, the incorporation of just 1 % of CF into the CMF/PHA/CF composite has a great impact on its tensile strength, increasing it from 21 4MPa of CMF/PHA to 35.8MPa of CMF/PHA/CF.

[0086] Overall, it was demonstrated that the lignin waste generated by biorefineries can be utilized to create bioplastics and carbon fiber, which can be subsequently employed to manufacture environmentally-friendly products to replace traditional petroleum-based plastics in various applications.

Claims

CLAIMS What is claimed is:

1 . A method of producing a lignin composition comprising: contacting a lignin obtained from a renewable resource with an aqueous fluid a plurality of times to produce a washed lignin; contacting the washed lignin with an acid under conditions suitable for formation of an acid washed lignin; contacting the acid washed lignin with one or more cellulases to form a pretreated lignin; and fermenting the pretreated lignin to form a crosslinked high molecular weight lignin.

2. The method of claim 1 , wherein the renewable resource comprises corn stover, corn cobs, corn kernels, corn fibers, straw, banana plantation waste, rice straw, rice hull, oat straw, oat hull, corn fiber, cotton stalk, cotton gin, wheat straw, sugar cane bagasse, sugar cane trash, sorghum residues, sugar processing residues, barley straw, cereal straw, wheat straw, canola straw, soybean stover, or combinations thereof.

3. The method of claim 1 , wherein the crosslinked high molecular weight lignin has a weight average molecular weight (M_w ) of from about 5000 grams/mole (g/mol) to about 50000 g/mol.

4. The method of claim 1 , further comprising esterifying crosslinked high molecular weight lignin.

5. The method of claim 4, wherein esterification comprises contacting of the crosslinked high molecular weight lignin with an organic anhydride suitable selected from the group consisting of acetic anhydride, octanoic acid anhydride, n-octanoic anhydride, caprylic anhydride, n-caprylic anhydride, propionic anhydride, crotonic anhydride and combinations thereof.

6. The method of claim 1 , wherein the fermenting is carried out in the presence of Psuedomonas putida.

7. The method of claim 1 , wherein the acid comprises sulfuric acid, phosphoric acid, nitric acid or combinations thereof.

8. A composite material, comprising: a high molecular weight crosslinked lignin and at least one material selected from the group consisting of carbon fiber, polymers, a precursor for carbon-based materials, nanomaterials, cement, concrete and combinations thereof.

9. The composite material of claim 8, wherein the polymer comprises wherein the polymeric material comprises low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polytetrafluoroethylene, thermoplastic polyurethanes (TPU), polyacrylonitrile or combinations thereof.

10. The composite material of claim 9, wherein the material comprises a carbon fiber.

11. The composite material of claim 10, wherein the polymer comprises polyacrylonitrile.

12. The composite material of claim 9, wherein the high molecular weight crosslinked lignin is present in amounts ranging from about 1 wt.% to about 50 wt.% based on the total weight of the material.

13. The composite material of claim 9, wherein the tensile strength of the material is increased by from about 10% to about 100% when compared to the tensile strength of the material when compared to the tensile strength in the absence of the high molecular weight crosslinked lignin.

14. The composite material of claim 9, wherein the elastic modulus of the material is increased by from about 10% to about 100% when compared to the tensile strength of the material when compared to the tensile strength in the absence of the high molecular weight crosslinked lignin.

15. A method of producing a lignin composition, comprising: contacting a lignin obtained from a renewable resource with an aqueous fluid a plurality of times to produce a washed lignin; contacting the washed lignin with an acid under conditions suitable for formation of an acid washed lignin; esterifying the acid washed lignin to form an esterified lignin; contacting the esterified lignin with one or more cellulases to form a pretreated lignin; and fermenting the pretreated lignin to form a crosslinked high molecular weight lignin.

16. The method of claim 15, further comprising recovering the high molecular weight lignin.

17. The method of claim 15, wherein esterification comprises contacting of the acid washed lignin with an organic anhydrides suitable selected from the group consisting of acetic anhydride, octanoic acid anhydride, n-octanoic anhydride, caprylic anhydride, n-caprylic anhydride, propionic anhydride, crotonic anhydride and combinations thereof.

18. The method of claim 15, wherein the renewable resource comprises corn stover, corn cobs, corn kernels, corn fibers, straw, banana plantation waste, rice straw, rice hull, oat straw, oat hull, corn fiber, cotton stalk, cotton gin, wheat straw, sugarcane bagasse, sugar cane trash, sorghum residues, sugar processing residues, barley straw, cereal straw, wheat straw, canola straw, soybean stover, or combinations thereof.

19. The method of claim 16, wherein the recovered high molecular weight esterified lignin has a weight average molecular weight (M_w ) of from about 5000 grams/mole (g/mol) to about 50000 g/mol.

20. The method of claim 15, wherein the acid comprises sulfuric acid, phosphoric acid, nitric acid, or combinations thereof.