Method for functionalizing nitro-oxidized lignin-based composite materials for use in industrial, agricultural, and emerging applications

Abstract

A method for producing an oxidized lignin-based composite material includes subjecting a lignin-containing starting material to a nitro-oxidation-process (NOP) treatment to produce the oxidized lignin-based composite material and recovering a reaction effluent. The oxidized lignin-based composite material includes oxidized lignin that includes at least one reactive functional group, an oxidized carbon component, and a nitrate salt originating from the nitro-oxidation treatment.

Description

Attorney Docket No. 201291.14. PCTMETHOD FOR FUNCTIONALIZING NITRO-OXIDIZED LIGNIN-BASED COMPOSITE MATERIALS FOR USE IN INDUSTRIAL, AGRICULTURAL, AND EMERGING APPLICATIONSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 728,251 filed on December 5, 2024. The entire contents of this application are hereby incorporated by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] The present invention relates to methods for functionalizing oxidized lignin and lignin-based composite materials derived from a nitro-oxidation process (NOP) or related nitro-oxidation treatments of commercial lignin and lignin contained in biomass feedstocks. The present invention specifically encompasses the processes of neutralizing, functionalizing, and customizing the properties of NOP-derived lignin-based composite materials for use in industrial, agricultural, and environmental applications, where such materials can displace or compliment petrochemical polymers, surfactants, dispersants, binders, and other functional additives.2. Description of the Related Art

[0003] The growing demand for sustainable, bio-based materials that can displace or complement petrochemical surfactants, solvents, molecules, compounds, and polymers has led to increasing interest in lignin, a natural biopolymer found in plant biomass, and lignin-based composite materials. The use of these materials as ingredients for agricultural and industrial applications has been limited by their complex structures and poor reactivity even though numerous chemical modification strategies such as sulfonation, carboxymethylation, etherification, esterification, and various oxidative treatments have been explored to improve their solubility and functionality. Existing oxidized lignin technologies, including nitro-oxidation and other nitric acid / nitrogen oxide-based processes, generally focus on delignification, cellulose oxidation, or narrowly defined products and often provide limited control over the degree of oxidation (amount of carboxylic group), and physical form of the resulting lignin.Traditional agricultural and industrial formulations often rely on synthetic surfactants and toxic petroleum solvents to achieve adequate dispersion and suspension of active ingredients. While effective at achieving suspension and delivery, these additives often contribute to significant environmental burdens, including soil and water contamination, toxicity to non-target organisms, and persistence in ecosystems thereby underscoring the need for lignin-based, carboxyl-rich materials that can function as renewable dispersants, adjuvants, and carriers in such formulations.SUMMARY OF THE INVENTION

[0004] To overcome the problems described above, example embodiments of the present invention provide methods for producing functional oxidized lignin and lignin-based composite materials, including providing a lignin-containing starting material selected from lignocellulosic biomass feedstocks and / or known commercial technical lignins, subjecting the starting material to a nitro-oxidation treatment to form oxidized lignin in lignin-rich effluent phase, and recovering the oxidized lignin or oxidized lignin-based composite material. The nitro-oxidation treatment introduces reactive functional groups, including carboxyl (-COOH) and carboxylate (- COO"), hydroxyl (-OH), aldehyde (-CHO), nitroso (-NO), oxime ( = NOH), and nitrate ester (-ONO2) groups, and can generate additional oxidized carbon components derived from cellulose or hemicellulose together with nitrate salts. The oxidized lignin can include molecular fragments, oligomers, or macromolecular species and can be further neutralized and functionalized by physical and chemical techniques to tailor particle size, rheology, and surface chemistry. In some example embodiments, the oxidized lignin has a carboxylate content greater than about 1.0 mmol per gram and forms shear-thinning, non-Newtonian aqueous compositions at high solids content. The resulting oxidized lignin-based materials are suitable for use as, or components of, dispersants; adjuvants; drift control agents; deposition agents; water-holding agents; soil and / or substrate amendments; suspending agents and / or stabilizing agents for agricultural and industrial minerals; rheology modifiers; binders or co-binders in coatings, adhesives, and composite materials; and carrier or matrix materials in formulated products. Such formulations include, but are not limited to, agrochemical compositions (for example pesticides, herbicides, fertilizers, biostimulants), coatings and inks, adhesives andsealants, construction and cementitious products, polymer and composite systems, and other application domains where renewable, functional, lignin-based additives or matrices are desired.

[0005] Example embodiments of the present invention provide versatile and robust methods for producing oxidized lignin and lignin-based composite materials using nitrooxidation processes (NOPs). The lignin and lignin-based composite materials can be sourced from any lignocellulosic biomass feedstocks including natural organic waste, plant-based, synthetic, genetically modified, other lignin-containing materials, or neat lignin derived from industrial pulping treatments. These feedstocks can be oxidized by a NOP into various functionalized forms, ranging from molecular fragments to larger particles, and can retain the carbon inherent as existing functional groups remain (alcohols, ethers, carboxylic acids, phenolic rings etc.) to the lignin, making it suitable for industrial and agricultural applications.

[0006] According to an example embodiment of the present invention, a method for producing an oxidized lignin-based composite material includes subjecting a lignin-containing starting material to a nitro-oxidation-process (NOP) treatment to produce the oxidized ligninbased composite material and recovering a reaction effluent. The oxidized lignin-based composite material includes oxidized lignin that includes at least one reactive functional group, an oxidized carbon component, and a nitrate salt originating from the nitro-oxidation treatment.

[0007] The reactive functional group can includes a carboxyl (COOH) group, a hydroxyl (- OH) group, an aldehyde (-CHO) group, an oxime ( = NOH) group, a nitroso (-NO) group, a nitrate ester (-ONO2) group, or a combination thereof. The oxidized carbon component can be derived from cellulose, hemicellulose, pectin, extractive, simple sugar, starch, organic acid, protein, lipid, wax, or a combination thereof from the lignin-containing starting material. The content of carboxylate groups (-COO") in the oxidized lignin can be greater than about 1.0 mmol -COOH equivalents per gram of oxidized lignin.

[0008] The lignin-containing starting material can includes (i) lignocellulosic biomass selected from organic waste, agricultural residues, forestry residues, industrial by-products, andplant-based materials, and / or (ii) a technical lignin selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof.

[0009] The oxidized lignin and / or the oxidized carbon component can include molecular fragments, oligomers, higher-molecular-weight polymeric species, or a combination thereof.

[0010] The nitrate salt can include sodium nitrate (NaNO3), potassium nitrate (KNO3), ammonium nitrate (NI- NOs), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), barium nitrate (Ba(NO3)2), lithium nitrate (LiNO3), zinc nitrate (Zn(NO3)2), copper(ll) nitrate (CU(NO3)2), silver nitrate (AgNO3), or a combination thereof.

[0011] The method can further include functionalizing the oxidized lignin-based composite material by one or more physical techniques selected from sonication, homogenization, and high-speed shearing. The method can further include functionalizing the oxidized lignin-based composite material by one or more chemical techniques selected from ionic crosslinking with metal ions and covalent crosslinking with an aldehyde, an epichlorohydrin-based resin, citric acid, a polycarboxylic acid, a dialdehyde, a phenolic resin, or a combination thereof.

[0012] According to an example embodiment of the present invention, a pesticidal composition includes a pesticidal active ingredient and the oxidized lignin-based composite material made by a method of another example embodiment of the present invention.

[0013] The pesticidal active ingredient can include one or more compounds selected from the group including glyphosate, 2,4-D, dicamba, atrazine, triclopyr, glufosinate ammonium, paraquat, metolachlor, acetochlor, pendimethalin, sulfentrazone, imidacloprid, clothianidin, thiamethoxam, lambda-cyhalothrin, deltamethrin, permethrin, chlorpyrifos, malathion, fipronil, spinosad, abamectin, azoxystrobin, pyraclostrobin, mancozeb, propiconazole, difenoconazole, tebuconazole, captan, thiophanate-methyl, metalaxyl, sulfur, copper hydroxide, a derivative thereof, or a combination thereof. The pesticidal active ingredient can include a 2,4-D active ingredient, a salt thereof, an ester thereof, or a combination thereof. The pesticidal active ingredient can include isopropylamine, mono-ammonium, di-ammonium, potassium, sodium, dimethylammonium, or trimesium salt of glyphosate, or a combination thereof. The pesticidal active ingredient can be present in a range from about 0.5 wt% to about 1 wt% of the pesticidal composition.

[0014] According to an example embodiment of the present invention, a spray includes water and the pesticidal composition of another example embodiment of the present invention. The oxidized lignin-based composite material is a drift control agent.

[0015] According to an example embodiment of the present invention, an agricultural substrate composition includes a substrate including soil and / or a soilless substrate and the oxidized lignin-based composite material made by a method of another example embodiment of the present invention.

[0016] The oxidized lignin-based composite material can be included in an amount from about 0.1 wt% to about 5.0 wt% based on a total dry weight of the agricultural substrate composition. The agricultural substrate composition can exhibit a water-holding capacity at least about 5% greater than that of an otherwise identical agricultural substrate composition lacking the oxidized lignin-based composite material. The soilless substrate can include an organic component selected from coco coir, wood fiber, wood chips, sawdust, bark, rice hulls, or a mixture thereof and / or includes an inorganic component selected from perlite, vermiculite, rockwool, expanded clay pebbles, pumice, sand, or a mixture thereof. The oxidized lignin-based composite material can be a water-holding agent.

[0017] According to an example embodiment of the present invention, a dispersant composition for stabilizing an aqueous suspension includes solid particulate matter and the oxidized lignin-based composite material made by a method of another example embodiment of the present invention.

[0018] The oxidized lignin-based composite material can be included in an amount from about 0.01 wt% to about 30 wt% of the dispersant composition. The solid particulate matter can include one or more minerals selected from elemental sulfur, gypsum, slaked lime, dolomitic lime, silicate minerals, zeolites, bentonites, or a mixture thereof.

[0019] According to an example embodiment of the present invention, an aqueous suspension includes water and the dispersant composition of another example embodiment of the present invention. The oxidized lignin-based composite material is a dispersant and compatibilizer of the solid particulate matter.

[0020] According to an example embodiment of the present invention, a method of functionalizing a technical lignin includes subjecting a technical lignin to a nitro-oxidation- process (NOP) treatment and a neutralization to obtain an oxidized lignin. The oxidized lignin is water-soluble, has a carboxylate content greater than about 0.8 mmol -COOH equivalents per gram, and has a weight-average molecular weight sufficient to form stable aqueous dispersions.

[0021] The technical lignin can be selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof.

[0022] According to an example embodiment of the present invention, a composition includes oxidized lignin and water at a weight ratio of oxidized lignin to water between about 40:60 and about 60:40. The oxidized lignin is produced by a nitro-oxidation process and has a carboxylate content greater than about 1.0 mmol -COOH equivalents per gram, and the composition is a shear-thinning, non-Newtonian fluid.

[0023] The composition can be a rheology modifier, a carrier, or a matrix.

[0024] The above and other features, elements, characteristics, steps, and advantages of the present invention will become more apparent from the following detailed description of example embodiments of the present invention with reference to the attached drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The patent or application file contains at least one drawing executed in color. The patent or application file also contains a corresponding black and white line drawing for each of the at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0026] Fig. 1A is photograph of NOP-treated jute fibers containing oxidized cellulose, oxidized lignin, and associated constituents.

[0027] Fig. IB is photograph of NOP-derived, lignin-rich oxidized effluents obtained after separation of the oxidized cellulose.

[0028] Fig. 2 shows a1H NMR (DMSO-de) spectrum of Jute NOP lignin isolated via liquid / liquid extraction.

[0029] Fig. 3 shows a1H NMR (DMSO-de) spectrum of Jute NOP lignin isolated via liquid / liquid extraction.

[0030] Fig. 4 shows a13C NMR (D2O) spectrum of Jute NOP lignin isolated via liquid / liquid extraction.

[0031] Figs. 5A and 5B are photographs of NOP-oxidized lignin at high solids content (=95 wt% solids) in water. Fig. 5A is in black and white. Fig. 5B is in color.

[0032] Fig. 6 shows1H NMR spectra comparing NOP effluent extracted lignin and known commercial alkaline lignin (D2O, 400 MHz).

[0033] Fig. 7 shows a1H NMR spectrum of NOP lignin precipitated after neutralization with NaOH (D2O, 400 MHz).

[0034] Fig. 8 is a black and white photograph of lignin precipitated after neutralization with NaOH.

[0035] Fig. 9 is a1H NMR (DMSO-de) spectrum of NOP of known commercial de-alkaline lignin.[°°36] Fig. 10 is a1H NMR (D2O) spectrum of NOP of known commercial de-alkaline lignin.

[0037] Fig. 11A is a black and white photograph of known commercial lignin.

[0038] Fig. 11B is a black and white photograph of NOP-treated lignin.

[0039] Figs. 12A-12E are black and white photographs showing an interaction of NOP lignin with 2,4-D free acid (FA) in water. Fig. 12A shows 1 wt% NOP lignin solution. Fig. 12B shows 1 wt% 2,4-D FA showing poor solubility and precipitation. Fig. 12C shows the mixing of equal volumes of Fig. 12A and Fig. 12B but before sonicating. Fig. 12D shows that, immediately after mixing equal volumes of Fig. 12A and Fig. 12B and sonicating, a smooth turbid 2,4-D-NOP lignin dispersion is formed. Fig. 12E shows that, after standing, partial 2,4-D precipitation occurs, indicating that NOP lignin improves dispersion but does not fully overcome the limited solubility of the free acid.

[0040] Figs. 13A and 13B are photographs showing the dispersion behavior of elemental sulfur particles in water mixed with 1% NOP oxidized lignin, resulting in a stable aqueous suspension. Fig. 13A is in black and white. Fig. 13B is in color.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0041] Example embodiments and specific example of the present invention are disclosed below. These disclosed example embodiments and specific examples are given merely as illustrations and do not constitute a comprehensive compilation. The invention can be implemented in a number of different ways. The drawings may not be accurate to scale, and some aspects may have been emphasized or downplayed to draw attention to particular areas. Thus, the particular structural and functional information provided should not be interpreted as restrictive, but rather as a basis for how to modify the current invention in many ways.

[0042] Nitro-oxidation processes (NOPs) or related NOP treatments can be applied to lignin obtained from known commercial lignin products (e.g., kraft, soda, alkaline, organosolv, lignosulfonate, or hydrolysis lignin) as well as lignin contained in lignocellulosic biomass feedstocks, including but not limited to agricultural residues, industrial biomass streams, forestry by-products, and other plant-based materials. The oxidation processes employ nitric acid and / or nitrogen oxide species, optionally in combination with co-acids and co-oxidants, under controlled conditions to introduce oxygen-containing functional groups, including carboxyl (-COOH), hydroxyl (-OH), aldehyde (-CHO), and nitroso (-NO) functionalities. These reactions produce carboxyl-rich oxidized lignin species and lignin-containing composites that exhibit increased anionic charge density, hydrophilicity, and water-binding capacity and that are especially suitable for use as dispersants, adjuvants, and water-management agents.

[0043] Methods of example embodiment of the present invention can be used to produce an oxidized lignin-based composite material. The method include subjecting a lignin-containing starting material to a nitro-oxidation-process (NOP) treatment to produce the oxidized ligninbased composite material. An effluent can be created during the reactions of the NOP treatment and can be recovered. The resulting oxidized lignin-based composite material can include oxidized lignin that is generated during the NOP treatment. The content of carboxylate groups (-COO") in the oxidized lignin can be greater than about 1.0 mmol -COOH equivalents per gram of oxidized lignin, within manufacturing and / or measurement tolerances. The oxidized lignin-based composite material can be functionalized. For example, the oxidized lignin-based composite material can be functionalized by a physical technique or a chemicaltechnique. Physical techniques can reduce particle size and improve dispersion. Suitable physical techniques include, for example, sonication, homogenization, and high-speed shearing. Chemical techniques include, for example, ionic crosslinking with metal ions and covalent crosslinking. Covalent crosslinking can be used with, for example, an aldehyde, an epichlorohydrin-based resin, citric acid, a polycarboxylic acid, a dialdehyde, a phenolic resin, or a combination thereof.

[0044] Nitro-oxidation processes (NOPs) have been demonstrated as an efficient, low-cost, and environmentally favorable technique of producing carboxylated cellulose nanofibers directly from agricultural residues. The detailed chemistry of the NOP can follow any of the nitro-oxidation schemes disclosed in U.S. Patent No. 10,894,838, PCT Application No.PCT / US2024 / 055838, and PCT Application No. PCT / US2015 / 060261. The entire contents of U.S. Patent No. 10,894,838, PCT Application No. PCT / US2024 / 055838, and PCT Application No.PCT / US2015 / 060261 are hereby incorporated by reference. The lignin may alternatively be oxidized using any other process that yields a lignin fraction having a comparable level of carboxyl and related oxygenated functionality. Some example embodiments of the present invention are directed to oxidized lignin products, their neutralization and functionalization, and their use in formulations.

[0045] In these NOPs, nitric acid serves both as a nitrating and oxidizing agent, simultaneously breaking down lignocellulosic biomass, dissolving macronutrients, micronutrients and degraded lignin / cellulose / hemicellulose components, and introducing functional groups into the residual cellulose fibers and dissolved lignin fragments. Unlike many known nanocellulose production methods that generate chemical wastes requiring disposal or regeneration, the effluents from nitro-oxidation can, after neutralization and functionalization, be repurposed as liquid fertilizers and oxidized lignin and lignin-based composite materials. These lignin-based composite materials typically contain oxidized lignin and other organic compounds, nutrient salts (e.g., nitrates and phosphates) derived from nitric acid solutions and original biomass feedstock.

[0046] NOPs result in lignin-based composite materials in various forms— ranging from molecular fragments, nanoscale, microscale, and larger particle sizes— depending on processparameters such as temperature, pressure, acid concentration, stirring rate, co-oxidizing agents, and reaction time.

[0047] In some example embodiments, a material that includes lignin is subjected to nitrooxidation so that at least a portion of the lignin is converted to oxidized lignin bearing carboxyl and other reactive groups. The oxidized lignin can then be recovered from the reaction effluent or slurry by neutralization, precipitation, membrane separation, extraction, or other separation techniques, and can be isolated as a solid, a concentrated aqueous solution, or a dispersion for subsequent formulation as a dispersant, adjuvant, water-holding agent, or other functional ingredient.

[0048] The oxidized lignin produced through such nitro-oxidation treatments may include molecular fragments, oligomers, and higher-molecular-weight fractions, and may be present as discrete particles, associated clusters, or soluble macromolecules. By appropriate selection of feedstock and oxidation conditions, the resulting oxidized lignin can be designed to provide a desired balance of solubility, viscosity, charge density, and particle size that is advantageous for use in aqueous formulations, including agrochemical sprays, soil treatments, and industrial dispersions, while retaining a substantial portion of the inherent biogenic carbon.

[0049] The nitro-oxidation treatment can be controlled by adjusting temperature, pressure, acid concentration and composition, oxidant dosage, mixing intensity, reaction time, and optional catalysts or promoters. These variables influence the degree of oxidation, the molecular weight distribution, and the physical form of the oxidized lignin.

[0050] In some example embodiments, the reaction temperature is from about 25°C to about 100°C, within manufacturing and / or measurement tolerances. Higher temperatures generally increase oxidation rate and favor formation of lower-molecular-weight, more highly oxidized lignin fragments that exhibit higher dispersing power and water solubility.

[0051] Reaction pressure can be from about 10 psi to about 750 psi, within manufacturing and / or measurement tolerances. Pressure can be used to influence gas-liquid mass transfer and thereby the extent of nitro-oxidation and the resulting particle size distribution.

[0052] Nitric acid concentration can be from about 30 % to about 70 % by w / w, within manufacturing and / or measurement tolerances. In some example embodiments, milder nitricacid concentrations can be used to preserve larger lignin fragments that contribute to rheology modification and water-holding capacity, whereas stronger concentrations may be used when higher carboxyl content and smaller fragments are desired for dispersant and adjuvant performance.

[0053] Nitric acid may be combined with one or more additional acids such as hosphoric acid, trifluoroacetic acid, and oxalic acid. The nitric acid can represent at least about 25% by weight of the acid mixture, within manufacturing and / or measurement tolerances. Such mixtures allow tuning of oxidation strength and selectivity.

[0054] Agitation or mixing can be provided to maintain contact between the lignincontaining phase and the nitro-oxidation medium. Higher agitation rates may lead to finer dispersion of feedstock particles and smaller oxidized lignin particles, which can enhance stability in sprayable formulations and improve uniform coverage of treated surfaces.

[0055] Reaction time can range from about 0.1 hours to about 72 hours, within manufacturing and / or measurement tolerances. Shorter residence times typically favor partial oxidation and larger particles, while longer times produce more extensively oxidized, lower- molecular-weight materials.

[0056] Various oxidizing promoters may optionally be employed, including nitrite and nitrate salts, metal salts or metals, and oxygen-containing oxidants such as oxygen, ozone, nitrogen dioxide, nitrous oxide, sulfur dioxide, or hydrogen peroxide. These additives can be used to tailor the formation of carboxylate and other hydrophilic groups that influence dispersant efficiency, surface activity, and interactions with soil and substrate components.

[0057] The nitro-oxidation process can introduce reactive groups such as carboxyl, hydroxyl, aldehyde, nitrate ester, and other functionalities into the lignin structure. Following oxidation, the lignin is typically neutralized at least partially to form carboxylate salt forms (for example sodium, potassium, ammonium, or organic ammonium salts), which markedly increasing aqueous solubility, dispersing ability, and water-binding capacity.

[0058] In some example embodiments, the neutralized oxidized lignin is further functionalized by reaction with surfactant-forming counter-ions, polymeric cations, or hydrophobic modifying groups to adjust the hydrophilic-lipophilic balance (HLB) and optimizeperformance as an adjuvant, spreader, sticker, drift control agent, or dispersant in formulations containing active ingredients. Additionally, the abundant carboxyl and hydroxyl groups can form coordination complexes with nutrients or metal ions, or can hydrogen-bond with soil and substrate components, thereby enhancing water retention and nutrient availability.

[0059] In example embodiments, any suitable lignin-containing starting material can be used. For example, the lignin-containing starting material can include (i) lignocellulosic biomass selected from organic waste, agricultural residues, forestry residues, industrial by-products, and plant-based materials, and / or (ii) a technical lignin selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof. Any suitable technical lignin can be used, including, for example, known commercial and / or purified technical lignins.

[0060] The oxidized lignin can include at least one reactive functional group, an oxidized carbon component, and nitrate salts originating from the nitro-oxidation treatment. The reactive functional group can include, for example, a carboxyl (-COOH) group, a hydroxyl (-OH) group, an aldehyde (-CHO) group, an oxime ( = NOH) group, a nitroso (-NO) group, a nitrate ester (-ONO2) group, or a combination thereof. The oxidized carbon component can be derived from cellulose, hemicellulose, or other constituent from the lignin-containing starting material (including, for example, pectins, extractives, simple sugars, starches, organic acids, proteins, lipids, waxes), and combinations thereof. The oxidized lignin and / or the oxidized carbon component can be any suitable form, including, for example, molecular fragments, oligomers, higher-molecular-weight polymeric species, or a combination thereof. Higher-molecular-weight polymeric species can have a mass of at least about 500 g / mol, including from about 3,000 g / mol to about 100,000 g / mol, within manufacturing and / or measurement tolerances.Alternatively or additionally, higher-molecular-weight polymeric species can be characterized by at least one of (1) broad aromatic and aliphatic signals in 1H and 13C NMR spectra characteristic of polymeric lignin structures and / or (2) the ability, at solids contents of about 40 wt%-60 wt% in water, to form a shear-thinning, non-Newtonian fluid that flows under low shear stress and exhibits solid-like behavior under higher shear stress.

[0061] The oxidized lignin and oxidized lignin-based composite materials can include, for example, the following groups: carboxyl (-COOH) functional group, hydroxyl (-OH) functional group, aldehyde (-CHO) functional group, oxime (=NOH) functional group, nitroso (-NO) functional group, or nitrate ester (-ONO2). The content of the carboxylate group (-COO-) in the oxidized lignin can be above about 1 mmol / g, within manufacturing and / or measurement tolerances.

[0062] Depending on feedstock and processing conditions, oxidized lignin can be obtained in various physical forms, each offering different advantages for formulation and application.

[0063] Extensive oxidation and depolymerization may generate small molecular fragments, oligomers, or monomeric species, generally below about 1 nm in characteristic size, within manufacturing and / or measurement tolerances. These highly oxidized species exhibit high solubility and chemical reactivity and can function as low-viscosity dispersants, sequestrants, or complexing agents in aqueous systems.

[0064] Under milder conditions, oxidized lignin can be converted into particles smaller than about 100 nm, within manufacturing and / or measurement tolerances. Such nanoscale oxidized lignin exhibits high surface area and excellent dispersibility. These nanoparticles are particularly useful in sprayable agrochemical compositions and industrial dispersions, where the nanoparticles can stabilize suspensions, reduce droplet coalescence, and act as effective adjuvants and drift control agents.

[0065] Microscale oxidized lignin particles, with sizes from about 100 nm to about several microns, within manufacturing and / or measurement tolerances, can provide a balance between structural integrity and functional reactivity. In soil and substrate applications, such particles can occupy pore spaces, interact with soil minerals and organic matter, and contribute to improved water-holding capacity, aggregation, and reduced crusting. In liquid formulations, microscale particles can act as rheology modifiers and stabilizing agents.

[0066] Larger oxidized lignin particles (greater than about several microns, within manufacturing and / or measurement tolerances) and lignin-based composites can be produced when higher molecular-weight structures are preserved or when oxidized lignin is combined with mineral or organic carriers. Such materials can serve as granular soil amendments,controlled-release carriers for nutrients or active ingredients, or bulk fillers that provide carbon content and moisture retention in substrates and growing media.

[0067] The carbon included in the oxidized lignin originates from the lignin itself, a biogenic aromatic polymer. When incorporated into soils, substrates, or durable materials, the oxidized lignin serves both as a functional additive and as a means of retaining biogenic carbon for extended periods.

[0068] Oxidized lignin fractions can thus be used in applications that require carbon retention, such as soil health improvement, erosion control, and long-term carbon storage in agricultural systems.

[0069] In fertilizers and soil amendment products, oxidized lignin can be formulated into liquid or granular compositions that enhance soil organic carbon, improve cation-exchange capacity, increase water-holding capacity, and contribute to carbon sequestration while simultaneously providing dispersant, adjuvant, or carrier functions.

[0070] In industrial materials, oxidized lignin can be incorporated into coatings, composites, or polymer systems, where it supplies biogenic carbon and can reduce the overall carbon footprint of the finished product.

[0071] Oxidized lignin produced via NOPs or related processes can be used in a wide range of formulated products. For example, the oxidized lignin can be used as a multifunctional ingredient providing dispersions, adjuvancy, water-holding capacity, and rheology modification in aqueous systems.

[0072] The carboxyl-rich oxidized lignin can act as an anionic dispersant capable of stabilizing mineral, organic, and biological particles in liquid formulations. It may be employed to disperse active ingredients such as pesticides, herbicides, fertilizers, micronutrients, pigments, clay or gypsum particles, and other solids in water or water-miscible media. The oxidized lignin helps prevent sedimentation, improves redispersibility, and can reduce or replace synthetic petrochemical dispersants.

[0073] Oxidized lignin and its salts can function as spray adjuvants that enhance wetting, spreading, retention, and uptake of agrochemical actives on plant surfaces or soil. In some embodiments, the oxidized lignin serves as a drift control agent by increasing solution viscosityand modifying droplet size distribution, thereby reducing the formation of fine mists and off- target movement.

[0074] When applied to soils, substrates, or growing media, oxidized lignin can increase water-holding capacity and improve soil structure through its hygroscopic nature and interaction with mineral and organic components. It can be used alone or in combination with other amendments to reduce irrigation frequency, buffer against drought stress, and enhance seedling emergence and plant growth.

[0075] In addition to its role in agricultural systems, oxidized lignin can be used as a binder or co-binder in coatings, adhesives, and composite materials, and as a component in construction and cementitious products. In such systems, the same functional groups that provide dispersant and adjuvant performance also contribute to adhesion, film formation, and compatibility with inorganic and organic phases.

[0076] Nitro-oxidation treatments can be applied to known commercial lignin streams and to lignin in diverse biomass feedstocks, allowing the use of regionally available resources and waste streams. Feedstock choice can influence the aromatic unit distribution and residual functionalities in the oxidized product.

[0077] By adjusting oxidation conditions as described herein, oxidized lignin can be produced with targeted ranges of carboxyl content, molecular weight, solubility, and particle size. This tunability allows the material to be customized for specific functions, such as high- efficiency dispersants for concentrated suspensions, adjuvants for foliar sprays, or granular soil amendments with enhanced water-holding capacity.

[0078] Nitro-oxidation treatments are adaptable to both small-scale and large-scale manufacturing. The processes can be integrated with existing pulp, biorefinery, or biomassprocessing operations to recover oxidized lignin from process streams and convert it into value- added dispersant and adjuvant products. By providing multiple processing options and targeted property windows, example embodiments of the present invention enable oxidized lignin to be tailored for a wide range of industrial, agricultural, and environmental applications while supporting carbon-efficient, renewable material use.

[0079] The nitrate salt can include any suitable nitrate salt, including, for example, sodium nitrate (NaNO3), potassium nitrate (KNO3), ammonium nitrate (NH4NO3), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), barium nitrate (Ba(NO3)2), lithium nitrate (LiNO3), zinc nitrate (Zn(NO3)2), copper(ll) nitrate (Cu(NO3)2), silver nitrate (AgNO3), or a combination thereof.

[0080] The lignin containing effluents produced through NOPs can undergo post-reaction refinement and customization to produce lignin-based composite materials with desired functionality, stability, safety, and performance.

[0081] Example embodiments of the present invention provide methods to functionalize these materials, enabling their safe use and transportation while expanding their potential applications.

[0082] Example embodiments of the present invention provide methods for neutralizing and functionalizing NOP-produced lignin-based composite materials to produce tunable, safe, and application-specific products.

[0083] For example, the NOP-produced lignin-based composite materials can be neutralized to a pH of about 5.0 or higher, within manufacturing and / or measurement tolerances, using alkaline agents. Any suitable alkaline agent can be used, including, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxides, ammonium hydroxide, sodium bicarbonate, calcium carbonate, potassium citrate, sodium lactate, calcium, and their mixtures.

[0084] For example, the NOP-produced lignin-based composite materials can be functionalized using a physical or mechanical technique and / or a chemical technique. Physical or mechanical techniques include, for example, sonication, homogenization, and high-speed shearing to reduce precipitate's size and / or to improve dispersion.

[0085] Chemical techniques include ionic crosslinking and covalent crosslinking. Ionic crosslinking can be with metal ions (e.g., calcium, magnesium, aluminum, iron, zinc) to create scaffolds with improved mechanical strength, stability, and slow-release properties.

[0086] Covalent crosslinking can be chemicals such as aldehydes (e.g., glutaraldehyde, melamine formaldehyde), epichlorohydrin (ECH. e.g., polyamide epichlorohydrin resins), citricacid, polycarboxylic acids, multifunctional carboxylic acids (e.g., polycarboxylic acids), dialdehydes (e.g., glyoxal), and phenolic resins to create scaffolds with improved mechanical strength, stability, and slow-release properties.

[0087] The refined and functionalized materials can be used across various industries and different applications. For example, the oxidized lignin-based composite material can be used in different compositions, for example, a pesticidal composition, an agricultural substrate composition, a dispersant composition, a rheology modifier, a carrier, or a matrix. For example, the composition can be a rheology modifier, carrier, or matrix in agricultural, industrial, or construction formulations. In agriculture applications, the refined and functionalized materials can be used as controlled / slow-release fertilizers, soil amendments, water retention agents, and carbon sequestration agents. In industrial applications, the refined and functionalized materials mineral can be used as suspending agents.

[0088] Compositions of example embodiments of the present invention provide a shearthinning, non-Newtonian fluid that flows under low shear stress and exhibits solid-like behavior when subjected to higher shear stress. The compositions can include oxidized lignin and water at a weight ratio of oxidized lignin to water between about 40:60 and about 60:40, within manufacturing and / or measurement tolerances. The oxidized lignin can produced by a nitrooxidation process and can have a carboxylate content greater than about 1.0 mmol -COOH equivalents per gram, within manufacturing and / or measurement tolerances.

[0089] The oxidized lignin-based composite materials derived from a Nitro-Oxidation Process (NOP) used in pesticidal compositions of example embodiments can be effective to reduce spray drift and improve foliar coverage and retention of pesticidal active ingredients.

[0090] The reduce spray drift and retention of pesticidal active ingredients of an example embodiment demonstrates a pesticidal composition includes a pesticidal active ingredient, oxidized lignin-based composite, and water. The oxidized lignin-based composite materials have a carboxylate content greater than 1.0 mmol / g, within manufacturing and / or measurement tolerances, and the pesticidal composition can be deployed through an agricultural spray nozzle under typical operating conditions.

[0091] Pesticidal compositions can include a pesticidal active ingredient and oxidized ligninbased composite material. The pesticidal active ingredient can be present in a range from about0.5 wt% to about 1 wt% of the pesticidal composition, within manufacturing and / or measurement tolerances. Any suitable pesticidal active ingredient can be used. For example, the pesticidal active ingredient can be one or more compounds selected from the group including glyphosate, 2,4-D, dicamba, atrazine, triclopyr, glufosinate ammonium, paraquat, metolachlor, acetochlor, pendimethalin, sulfentrazone, imidacloprid, clothianidin, thiamethoxam, lambda-cyhalothrin, deltamethrin, permethrin, chlorpyrifos, malathion, fipronil, spinosad, abamectin, azoxystrobin, pyraclostrobin, mancozeb, propiconazole, difenoconazole, tebuconazole, captan, thiophanate-methyl, metalaxyl, sulfur, copper hydroxide, a derivative thereof, or a combination thereof. The pesticidal active ingredient can include a 2,4-D active ingredient, a salt thereof, an ester thereof, or a combination thereof. The pesticidal active ingredient can include isopropylamine, mono-ammonium, di-ammonium, potassium, sodium, dimethylammonium, or trimesium salt of glyphosate, or a combination thereof.

[0092] The pesticidal composition can be included in a spray. In the spray, the oxidized lignin-based composite material is a drift control agent.

[0093] Agricultural substrate compositions can include a substrate including soil and / or a soilless substrate and oxidized lignin-based composite material. The oxidized lignin-based composite material can be included in an amount from about 0.1 wt% to about 5.0 wt% based on a total dry weight of the agricultural substrate composition, within manufacturing and / or measurement tolerances. The agricultural substrate composition can exhibit a water-holding capacity at least about 5% greater than a corresponding agricultural substrate composition but without the oxidized lignin-based composite (i.e., an identical agricultural substrate composition but without the oxidized lignin-based composite). The soilless substrate can include an organic component and / or inorganic component. The organic component can be selected from, for example, coco coir, wood fiber, wood chips, sawdust, bark, rice hulls, or a mixture thereof, and the inorganic component can be selected from perlite, vermiculite, rockwool, expanded clay pebbles, pumice, sand, or a mixture thereof. In the agricultural substrate composition, the oxidized lignin-based composite material is a water-holding agent.

[0094] The oxidized lignin-based composite materials derived from a Nitro-Oxidation Process (NOP) used in the agricultural substrate compositions of example embodiments can be effective to increase water-holding capacity of the substrate and extend irrigation intervals, thereby improving overall input efficiency and stress resilience in agricultural or agricultural production systems of example embodiments of the present invention.

[0095] The reduced water loss of the substrate of example embodiments through the addition of oxidized lignin-based composite materials and water holding agents enables longer intervals between irrigations, reduced total water consumption, more stable root-zone moisture conditions, and increased resilience of plants to missed irrigations, equipment malfunctions, labor shortages, or high-heat events.

[0096] The oxidized lignin-based composite materials derived from a Nitro-Oxidation Process (NOP) used as suspending agents, can assist the dispersion of agricultural and industrial minerals, such as elemental sulfur, gypsum, slaked lime, and dolomitic lime in aqueous formulations. In known agricultural and industrial practices, the preparation of stable and homogeneous aqueous suspensions of insoluble particulate solids remains a persistent technical challenge. Mineral powders commonly employed as soil amendments, such as elemental sulfur for acidification, gypsum for sodium mitigation, slaked lime and dolomitic lime for pH correction, and silicate minerals, such as zeolites and bentonites, for nutrient retention, are poorly soluble in water and prone to agglomeration or rapid sedimentation.

[0097] Dispersant compositions can be used to stabilize an aqueous suspension. The dispersant compositions can include solid particulate matter and oxidized lignin-based composite material. The oxidized lignin-based composite material can be included, for example, in an amount from about 0.01 wt% to about 30 wt% of the dispersant composition, within manufacturing and / or measurement tolerances. Any suitable solid particulate matter can be used. For example, the solid particulate matter can include one or more minerals selected from elemental sulfur, gypsum, slaked lime, dolomitic lime, silicate minerals, zeolites, bentonites, or a mixture thereof.

[0098] Aqueous suspensions can include a dispersant composition and water. In the aqueous suspension, the oxidized lignin-based composite material can be a dispersant and compatibilizer of the solid particulate matter.

[0099] Methods of example embodiments of the present invention can functionalize technical lignin. The methods include subjecting a technical lignin to a nitro-oxidation-process (NOP) treatment and a neutralization to obtain an oxidized lignin. The resulting oxidized lignin can be water-soluble, can have a carboxylate content greater than about 0.8 mmol -COOH equivalents per gram, and / or can have a weight-average molecular weight sufficient to form stable aqueous dispersions. Stable aqueous dispersion includes a dispersion that maintains a visually uniform appearance without substantial phase separation under normal handling and use conditions. Any suitable technical lignin can be used. For example, the technical lignin can be selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof.Example 1 - Extraction and Characterization of Oxidized Lignin Obtained by NOP Scaled at 2000-gallon Reactor

[0100] In one example embodiment, the lignin rich NOP effluent was produced at scale using jute fibers as the lignocellulosic raw material. The jute feedstock, having an initial moisture content of approximately 13% by weight, was introduced into a closed 2000-gallon reactor system. Approximately 469 pounds of size-reduced jute fibers (average fiber length of about 80 mm) were charged to the reactor together with about 6123 pounds of 50% (w / w) nitric acid solution. The mixture was maintained under continuous agitation at about 120 rpm and at a controlled reaction temperature of 50 °C. Aliquots of the reaction mixture were withdrawn at predetermined intervals of approximately 4 hours, 5 hours, 6 hours, and 7 hours to monitor the progression of the oxidation process as shown in Figs. 1A and IB. At the conclusion of each reaction interval, the oxidized cellulose fibers were separated from the lignin rich effluent using a Nutsche filter unit (approximately 84-inch diameter x 34-inch height). The recovered effluents were further neutralized to pH of ~5, with NH4OH, where large brown solids precipitated out of solution. These solids were identified as lignin.Proton and Carbon NMR (Nuclear Magnetic Resonance) Analysis[oioi] The 11_| N R spectrum of the jute-derived nitro-oxidized lignin fraction (400 MHz, DMSO-d6) as shown in Fig. 2 is characteristic of a heterogeneous lignin-type material. A broad set of signals is observed in the aromatic region at approximately 6 6.2-8.0 ppm, which is assigned to aromatic protons of guaiacyl and syringyl units and other lignin-derived phenylpropanoid structures. A very intense sharp resonance in the vicinity of 6 3.2-3.4 ppm is attributed primarily to residual water in DMSO-d6, with additional, weaker signals between 6 3.0 and 4.5 ppm corresponding to O-CH and O-CH2protons in etherified benzylic positions, methoxy groups, and oxidized side chains. The region from 6 0.8-2.5 ppm contains a series of broad, low-intensity resonances assigned to aliphatic CH, CH2, and CH3groups of residual lignin side chains and minor low-molecular-weight components. Overall, the spectrum is consistent with a polymeric, lignin-derived material bearing aromatic rings, ether linkages, and oxidized aliphatic side chains, rather than a single discrete small molecule.

[0102] The1H NMR spectrum of the jute-derived nitro-oxidized lignin fraction in D2O (400 MHz) shows in Fig. 3 depicts features of a functionalized lignin-type polymer. A broad envelope in the aromatic region at approximately 6 6.5-8.0 ppm is assigned to aromatic protons of guaiacyl and syringyl units originating from the lignocellulosic feedstock. A very intense sharp resonance at about 64.7-4.8 ppm corresponds to residual HDO in D2O. Additional broad signals between 6 3.0 and 4.5 ppm are attributed to O-CH and O-CH2protons, including etherified benzylic positions, methoxy groups, and methylene groups adjacent to oxygen or carboxylate functionalities (-CH2-O-, -CH2-COO"). The low-field aliphatic region from 6 0.8-2.5 ppm contains weaker, broadened resonances assigned to residual aliphatic CH, CH2, and CH3groups in partially oxidized lignin side chains. The overall pattern is consistent with a water-soluble, carboxyl-rich, lignin-derived material comprising aromatic units connected by ether linkages and bearing oxidized aliphatic side chains rather than discrete small molecules.

[0103] In addition to the broad resonances attributed to lignin-derived aromatic and aliphatic units, minor features are observed in the 3.0-4.5 ppm region that may reflect low levels of carbohydrate- or hemicellulose-derived fragments or other low-molecular-weight species. However, the1H NMR spectra are dominated by broad lignin signals, and any such small-molecule components are not resolved as distinct peaks under these conditions.

[0104] Fig. 4 shows carbon NMR which reveals the sharp aromatic carbon signal. NMR spectra indicate the presence of some aromatic compounds.Titration Analysis

[0105] A dry sample of isolated NOP oxidized lignin was dissolved in water and titrated against NaOH using a potentiometric titrator. The equivalence point was used to determine the degree of oxidation (D.O.) of lignin (mmol of carboxylic acid / gram of lignin). The D.O. was 0.57 mmol / g.Other Physical Properties

[0106] At a w / w% of ~50% in water, the lignin behaves as a non-Newtonian fluid. It exhibits liquid behavior until sheer force is applied, then it behaves as a solid. When dry, the lignin is a dark powder. This lignin is readily soluble in water, forming a dark brown solution when dissolved. A typical photograph of NOP oxidized lignin with higher wt% is shown in Figs. 5A and 5B.Example 2: Extraction and Characterization of NOP Oxidized Lignin from Hardwood

[0107] In another example embodiment, lignin contained in a lignocellulosic feedstock was recovered and characterized following a nitro-oxidation treatment. Hardwood material in the form of a granular powder was employed as the feedstock. The material was contacted with nitric acid (HNO3, 50 w / w%) and potassium nitrite (KNO2, 97 %) under nitro-oxidation conditions generally in accordance with the procedures disclosed in U.S. Patent No. 10,894,838. During the NOP treatment, a substantial portion of the lignin fraction present in the feedstock was depolymerized and oxidized, yielding lignin-derived fragments that were soluble in the acidic reaction liquor. Residual oxidized cellulose fibers were separated from the nitric acid effluent by filtration.

[0108] The clarified effluent, containing dissolved oxidized lignin, was then partially neutralized with sodium hydroxide to a pH of about 2 (within manufacturing and / or measurement tolerances) in order to characterize the oxidized lignin fragments in solution. The aqueous phase was subsequently subjected to liquid-liquid extraction with diethyl ether to isolate an oxidized lignin fraction. Proton nuclear magnetic resonance (1H NMR) and carbon-13 nuclear magnetic resonance (13C NMR) spectra were acquired on a Bruker 400 MHz spectrometer.

[0109] Fig. 6 presents a comparison of the1H NMR spectrum of the NOP-effluent-derived oxidized lignin with that of a commercial alkaline lignin standard (both samples dissolved in D2O and measured at 400 MHz).1H NMR spectra were recorded at 400 MHz in D2O at 25 °C. It shows the spectrum of nitro-oxidized lignin isolated from the aqueous effluent (upper trace) together with a spectrum of a commercial alkaline lignin (lower trace), each normalized to comparable intensity. Chemical shifts are reported in 6 (ppm) relative to residual HDO at 6=4.8 ppm.

[0110] Both spectra exhibit a broad envelope between 6=6.2-8.0 ppm, which is assigned to aromatic protons of guaiacyl, syringyl, and p-hydroxyphenyl units. In the commercial alkaline lignin, the region 6=0.5-2.5 ppm contains several sharp resonances attributable to aliphatic CH3and CH2groups in relatively well-defined side chains and low-molecular-weight impurities. In contrast, the nitro-oxidized lignin shows a greatly reduced and broadened signal in this region, indicating a decrease in unoxidized aliphatic side chains and removal of small aliphatic impurities.

[0111] The nitro-oxidized lignin further displays an increased and broadened signal between 6=3.0-4.5 ppm compared to the commercial alkaline lignin. This region is attributed to O-CH and O-CH2protons, including etherified benzylic protons and methylene groups a to oxygen or carboxylate functions (-CH2-O-, -CH2-COO"). The combination of diminished alkyl proton signals (6=0.5-2.5 ppm), enhanced O-substituted aliphatic signals (6=3.0-4.5 ppm), and a broadened aromatic region is consistent with partial oxidative cleavage and functionalization of lignin side chains, yielding lignin-derived aromatic units bearing oxidized, carboxylated side chains and ether linkages as represented in Formulas (l)-(lll). Carboxylic acid protons are not observed under these conditions due to deprotonation and exchange in D2O, in agreement with the presence of the lignin predominantly in its carboxylate salt form following neutralization with NaOH.

[0112] Fig. 7 shows the1H NMR spectrum of the nitro-oxidized lignin fraction that precipitated upon neutralization with NaOH (D2O, 400 MHz, 25 °C). The spectrum exhibits a broad multiplet at 6=6.5 ppm-8.5 ppm assigned to aromatic protons of guaiacyl and syringyl units, a broad signal between 6=3.0 and 4.5 ppm assigned to O-CH and O-CH2protons associated with etherified benzylic positions and oxidized side chains, and a broad envelope at6=0.5-2.5 ppm attributed to aliphatic CH, CH2, and CH3groups in residual lignin side chains. This pattern is consistent with a polymeric, highly substituted aromatic structure comprising lignin- derived units bearing ether linkages and oxidized, carboxylated side chains, as represented in Formulas (l)-(lll), with carboxylic groups predominantly present in their carboxylate salt form under the NMR conditions.Solubility and Appearance of NOP-Derived Oxidized Lignin

[0113] The oxidized lignin component recovered from the hardwood NOP effluent showed high solubility in strongly acidic aqueous media. At pH values below about 2, the material was soluble in water at concentrations of approximately 0.25 g / mL, within manufacturing and / or measurement tolerances. When the pH was adjusted toward neutrality, the solubility decreased to about 0.02 g / mL, and further addition of NaOH to the NOP effluent resulted in precipitation of an oxidized lignin fraction. Fig. 7 shows the1H NMR spectrum of the oxidized lignin that precipitated upon neutralization with NaOH (sample dissolved in D2O and measured at 400 MHz), confirming that the precipitated material is composed of lignin-derived aromatic and aliphatic units bearing oxygenated functionalities. After removal of salts and low- molecular-weight sugars, the neutralization-precipitated oxidized lignin formed a solid with a characteristic brown coloration, as shown in Fig. 8, typical of lignin-based materials. A similar solubility behavior and visual appearance are observed when the NOP process is applied to purified known commercial lignin sources, demonstrating that both feedstock-derived lignin and pure lignin can be converted into carboxyl-rich oxidized lignin products suitable for use in the compositions and applications described herein.Example 3: NOP Oxidation of Pure Commercial Lignin

[0114] In one example embodiment, the interaction of NOP with only lignin species was evaluated. 5 grams of known commercial dealkaline lignin was added slowly to 100 mL of nitric acid (50%, w / w), at 0°C, and stirred for 2 hours. The lignin was added as a slurry in water and added dropwise, slowly, to prevent exothermic reaction with nitric acid. After 2 hours, the temp was raised to about ambient room temperature of about 25°C for 1 hour. To the solution, lg of KNO2 was added slowly and the flask was sealed with parafilm. Next, the temp was raised to 35°C for 1 hour, followed by stirring at 50°C for 9 hours. After this, the reaction was allowedto cooldown and the excess NOXgases were allowed to escape into the ventilation hood. The reaction mixture was then cooled to 0°C and a solution of 4M KOH is added until a pH of 2 was achieved. Next, excess NaCI is dissolved into the solution. The lignin is extracted by liquid / liquid extraction in a separation funnel, with 50% MeOH / THF. The organic layer was isolated, and the solvent was removed by rotary evaporator, at 40°C under reduced pressure. The lignin was further dried under reduced pressure at 95 mTorr. Similar to NOP oxidized lignin extracted from lignocellulosic materials, the proton NMR in DMSO-de and D2O show a broad signal corresponding to aromatic and methoxy protons, associated with lignin as shown in Figs. 9 and 10.

[0115] A color and odor change occurs after NOP treatment of dealkaline lignin. The known commercial lignin is black and fragrant as shown in Fig. 11A, while the NOP treated pure lignin is less pungent and brown in coloration as shown in Fig. 11B. Additionally, the NOP lignin is water soluble, unlike the de-alkaline lignin.Solubility and Appearance of NOP-Derived Oxidized Lignin

[0116] The oxidized lignin component recovered from the hardwood NOP effluent showed high solubility in strongly acidic aqueous media. At pH values below about 2, the material was soluble in water at concentrations of approximately 0.25 g / mL, within manufacturing and / or measurement tolerances. When the pH was adjusted toward neutrality, the solubility decreased to about 0.02 g / mL, and further addition of NaOH to the NOP effluent resulted in precipitation of an oxidized lignin fraction. Figure 7 shows the1H NMR spectrum of the oxidized lignin that precipitated upon neutralization with NaOH (sample dissolved in D2O and measured at 400 MHz), confirming that the precipitated material is composed of lignin-derived aromatic and aliphatic units bearing oxygenated functionalities. After removal of salts and low- molecular-weight sugars, the neutralization-precipitated oxidized lignin formed a solid with a characteristic brown coloration, as illustrated in Figure 8, typical of lignin-based materials. A similar solubility behavior and visual appearance are observed when the NOP process is applied to purified commercial lignin sources, demonstrating that both feedstock-derived lignin and pure lignin can be converted into carboxyl-rich oxidized lignin products suitable for use in the compositions and applications described herein.Solubility and Appearance of NOP-Derived Oxidized Lignin

[0117] The oxidized lignin component recovered from the hardwood NOP effluent showed high solubility in strongly acidic aqueous media. At pH values below about 2, the material was soluble in water at concentrations of approximately 0.25 g / mL, within manufacturing and / or measurement tolerances. When the pH was adjusted toward neutrality, the solubility decreased to about 0.02 g / mL, and further addition of NaOH to the NOP effluent resulted in precipitation of an oxidized lignin fraction. Fig. 7 shows the1H NMR spectrum of the oxidized lignin that precipitated upon neutralization with NaOH (sample dissolved in D2O and measured at 400 MHz), confirming that the precipitated material is composed of lignin-derived aromatic and aliphatic units bearing oxygenated functionalities. After removal of salts and low- molecular-weight sugars, the neutralization-precipitated oxidized lignin formed a solid with a characteristic brown coloration, as illustrated in Fig. 8, typical of lignin-based materials. A similar solubility behavior and visual appearance are observed when the NOP process is applied to purified commercial lignin sources, demonstrating that both feedstock-derived lignin and pure lignin can be converted into carboxyl-rich oxidized lignin products suitable for use in the compositions and applications described herein.Titration of NOP oxidized Pure Lignin:

[0118] A dry sample of isolated lignin was dissolved in water and titrated against NaOH using a potentiometric titrator. The equivalence point was used to determine the degree of oxidation (D.O.) of lignin (mmol of carboxylic acid / gram of lignin). The D.O. of de-alkaline lignin was 0.31 mmol / g and the D.O. after NOP treatment was 0.89 mmol / g.Example 4: Precipitation Behavior of 2,4-D Free Acid with NOP Oxidized Lignin in Water

[0119] In one example embodiment, the interaction of nitro-oxidized lignin (NOP lignin) with a representative herbicide active ingredient was evaluated in aqueous medium. NOP lignin was prepared as described herein and used as an aqueous solution at 1 wt% as shown in Fig. 12A. Separately, an aqueous 1 wt% solution of 2,4-D free acid (FA) was prepared, noting that the free acid form of 2,4-D exhibits poor solubility in water and tends to precipitate under these conditions (Fig. 12B). Approximately 10 mL of the 1% 2,4-D FA solution was mixed with 10 mL of the 1% NOP lignin solution, and the mixture was subjected to sonication for about 15-30minutes to produce a uniform slurry. Fig. 12C shows the mixing of equal volumes of Fig. 12A and Fig. 12B but before sonicating. Immediately after mixing and sonication, a smooth, turbid 2,4-D-NOP lignin dispersion was obtained, as illustrated schematically in Fig. 12D. Upon standing, partial precipitation of 2,4-D was observed, resulting in a settled phase and a slightly turbid supernatant. This behavior is consistent with the limited intrinsic water solubility of 2,4-D in its free acid form. The presence of NOP lignin increased turbidity and provided some degree of dispersion and stabilization of the herbicide particles, but did not fully overcome the fundamental solubility limitation of the free acid, as indicated in Fig. 12E. This example demonstrates that while NOP lignin alone can aid in dispersing poorly soluble actives, additional formulation strategies (e.g., salt forms, co-adjuvants, or nanocellulosic carriers) may be beneficial for achieving fully stable aqueous systems.Example 5: NOP Oxidized Lignin as Dispersing Agents for Elemental Sulfur

[0120] Fig. 13A and 13B show the dispersion behavior of elemental sulfur in the presence of NOP oxidized lignin. Approximately 1% of elemental sulfur was mixed with an aqueous suspension containing 1 % NOP oxidized lignin for a minute, and the mixture was subsequently monitored for settling behavior. No visible immediate sedimentation of elemental sulfur was observed, demonstrating that the incorporation of NOP oxidized lignin provides excellent dispersion stability and prevents aggregation or settling of the sulfur particles in aqueous media.

[0121] It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the present invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variances that fall within the scope of the appended claims.T1

Claims

WHAT IS CLAIMED IS:

1. A method for producing an oxidized lignin-based composite material, the method comprising: subjecting a lignin-containing starting material to a nitro-oxidation-process (NOP) treatment to produce the oxidized lignin-based composite material; and recovering a reaction effluent, wherein the oxidized lignin-based composite material includes: oxidized lignin that includes at least one reactive functional group; an oxidized carbon component; and a nitrate salt originating from the nitro-oxidation treatment.

2. The method of claim 1, wherein the reactive functional group includes a carboxyl (-COOH) group, a hydroxyl (-OH) group, an aldehyde (-CHO) group, an oxime ( = NOH) group, a nitroso (-NO) group, a nitrate ester (-ONO2) group, or a combination thereof.

3. The method of claim 1 or 2, wherein the oxidized carbon component is derived from cellulose, hemicellulose, pectin, extractive, simple sugar, starch, organic acid, protein, lipid, wax, or a combination thereof from the lignin-containing starting material.

4. The method of one of claims 1-3, wherein a content of carboxylate groups (-COO") in the oxidized lignin is greater than about 1.0 mmol -COOH equivalents per gram of oxidized lignin.

5. The method of one of claims 1-4, wherein the lignin-containing starting material includes:(i) lignocellulosic biomass selected from organic waste, agricultural residues, forestry residues, industrial by-products, and plant-based materials, and / or(ii) a technical lignin selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof.

6. The method of any one of claims 1-5, wherein the oxidized lignin and / or the oxidized carbon component include molecular fragments, oligomers, higher-molecular-weight polymeric species, or a combination thereof.

7. The method of any one of claims 1-6, wherein the nitrate salt includes sodium nitrate (NaNO3), potassium nitrate (KNO3), ammonium nitrate (NH4NO3), calcium nitrate (Ca(NO3)2), magnesium nitrate (Mg(NO3)2), barium nitrate (Ba(NO3)2), lithium nitrate (LiNO3), zinc nitrate (Zn(NO3)2), copper(ll) nitrate (Cu(NO3)2), silver nitrate (AgNO3), or a combination thereof.

8. The method of any one of claims 1-7, further comprising functionalizing the oxidized lignin-based composite material by one or more physical techniques selected from sonication, homogenization, and high-speed shearing.

9. The method of any one of claims 1-8, further comprising functionalizing the oxidized lignin-based composite material by one or more chemical techniques selected from: ionic crosslinking with metal ions; and covalent crosslinking with an aldehyde, an epichlorohydrin-based resin, citric acid, a polycarboxylic acid, a dialdehyde, a phenolic resin, or a combination thereof.

10. A pesticidal composition comprising: a pesticidal active ingredient; and the oxidized lignin-based composite material made by the method of one of claims 1-9.

11. The pesticidal composition of claim 10, wherein the pesticidal active ingredient includes one or more compounds selected from the group including glyphosate, 2,4-D, dicamba, atrazine, triclopyr, glufosinate ammonium, paraquat, metolachlor, acetochlor, pendimethalin, sulfentrazone, imidacloprid, clothianidin, thiamethoxam, lambda-cyhalothrin, deltamethrin, permethrin, chlorpyrifos, malathion, fipronil, spinosad, abamectin, azoxystrobin,pyraclostrobin, mancozeb, propiconazole, difenoconazole, tebuconazole, captan, thiophanate- methyl, metalaxyl, sulfur, copper hydroxide, a derivative thereof, or a combination thereof.

12. The pesticidal composition of claim 10, wherein the pesticidal active ingredient includes a 2,4-D active ingredient, a salt thereof, an ester thereof, or a combination thereof.

13. The pesticidal composition of one of claims 10-12, wherein the pesticidal active ingredient includes isopropylamine, mono-ammonium, di-ammonium, potassium, sodium, dimethylammonium, or trimesium salt of glyphosate, or a combination thereof.

14. The pesticidal composition of any one of claims 10-13, wherein the pesticidal active ingredient is present in a range from about 0.5 wt% to about 1 wt% of the pesticidal composition.

15. A spray comprising water and the pesticidal composition of one of claims 10-14, wherein the oxidized lignin-based composite material is a drift control agent.

16. An agricultural substrate composition comprising: a substrate including soil and / or a soilless substrate; and the oxidized lignin-based composite material made by the method of one of claims 1-9.

17. The agricultural substrate composition of claim 16, wherein the oxidized ligninbased composite material is included in an amount from about 0.1 wt% to about 5.0 wt% based on a total dry weight of the agricultural substrate composition.

18. The agricultural substrate composition of claim 16 or 17, wherein the agricultural substrate composition exhibits a water-holding capacity at least about 5% greater than that of an otherwise identical agricultural substrate composition lacking the oxidized lignin-based composite material.

19. The agricultural substrate composition of one of claims 16-18, wherein the soilless substrate includes an organic component selected from coco coir, wood fiber, wood chips, sawdust, bark, rice hulls, or a mixture thereof and / or includes an inorganic component selected from perlite, vermiculite, rockwool, expanded clay pebbles, pumice, sand, or a mixture thereof.

20. The agricultural substrate composition of one of claims 16-19, the oxidized ligninbased composite material is a water-holding agent.

21. A dispersant composition for stabilizing an aqueous suspension comprising: solid particulate matter; and the oxidized lignin-based composite material made by the method of one of claims 1-9.

22. The dispersant composition of claim 21, wherein the oxidized lignin-based composite material is included in an amount from about 0.01 wt% to about 30 wt% of the dispersant composition.

23. The dispersant composition of claim 21 or 22, wherein the solid particulate matter includes one or more minerals selected from elemental sulfur, gypsum, slaked lime, dolomitic lime, silicate minerals, zeolites, bentonites, or a mixture thereof.

24. An aqueous suspension comprising: the dispersant composition of one of claims 21-23; and water; wherein the oxidized lignin-based composite material is a dispersant and compatibilizer of the solid particulate matter.

25. A method of functionalizing a technical lignin comprising subjecting a technical lignin to a nitro-oxidation-process (NOP) treatment and a neutralization to obtain an oxidized lignin, wherein the oxidized lignin is water-soluble, has a carboxylate content greater than about 0.8 mmol -COOH equivalents per gram, and has a weight-average molecular weight sufficient to form stable aqueous dispersions.

26. The method of claim 25, wherein the technical lignin is selected from kraft lignin, soda lignin, alkaline lignin, organosolv lignin, lignosulfonate, hydrolysis lignin, or a mixture thereof.

27. A composition comprising oxidized lignin and water at a weight ratio of oxidized lignin to water between about 40:60 and about 60:40, wherein the oxidized lignin is produced by a nitro-oxidation process and has a carboxylate content greater than about 1.0 mmol -COOH equivalents per gram, and the composition is a shear-thinning, non-Newtonian fluid.

28. The composition of claim 27, wherein the composition is a rheology modifier, a carrier, or a matrix.

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