Lignin Extraction Research Articles

Study on the green extraction of lignin and its crosslinking and solidification properties by geopolymer pretreatment.

Different delignification processes lead to significant differences in the structure and activity of lignin. Consequently, complex modifications are necessary before lignin to be applied. In this paper, a green process for the selective catalytic extraction of lignin by geopolymer is proposed based on biomass refining. This process can obtain lignin with ideal performance on activity, crosslink ability and curability. Taking eucalyptus, fir and bagasse as examples, the optimal lignin yields reach 46.5 %, 34.8 % and 48.7 % respectively (mFiber/mGeopolymer = 3, 120 min, and 130 °C). Moreover, lignin isolated with geopolymer (GL) shows a similar narrow molecular weight distribution range to that of Milled Wood Lignin (MWL). Studies on crosslinking solidification mechanisms have demonstrated that the phenolic hydroxyl groups of GL participate in the formation of a multi-stage amine crosslinking and solidification network structure. GL does not rely on flexible chains in the crosslinking and solidification of wood adhesives. Since highly active lignin can condense with phenolic hydroxyl groups on the surface of wood, it provides the adhesive with higher bonding strength (3.8 MPa). This study presents a novel approach to fabricating lignin-based formaldehyde-free wood adhesives.

Lignin extraction from lignocellulosic biomass and its valorization to therapeutic phenolic compounds

Lignin extraction from lignocellulosic biomass and its valorization to therapeutic phenolic compounds

Influence of the Conditions of Alkaline Pretreatment of Vegetable Raw Material before Hydrolysis in a Rotor Pulsation Device on the Cellulose Conversion

Introduction. The growing global energy demand, limited fossil fuel resources, and increasing greenhouse gasemissions highlight the need for expanded use of renewable energy sources, particularly biomass.Problem Statement. A significant drawback in the production of bioethanol is its high cost, primarily due tothe presence of hemicellulose and lignin.Purpose. This study aims to determine the effect of treating an alkaline suspension of wheat straw in a rotary pulsation device on the degree of cellulose conversion during enzymatic hydrolysis, a critical step in the productionof fuel ethanol.Materials and Methods. The raw material is pre-crushed wheat straw. The experiments have been conductedwith the use of a rotary pulsation device in an experimental plant.Results. It has been found that the combined physical effects of the discrete pulse energy input method andreduced straw particle size significantly increase the lignin extraction, from 40.0% at an average particle size of2—1 mm to 62.0% at an average particle size of 0.4—0.1 mm. Additionally, the treatment of an alkaline suspension of wheat straw at 90 оC for one hour, at alkali concentrations ranging from 1 to 4% (wt./wt.), results in anincrease in the cellulose conversion during enzymatic hydrolysis from 38% to 65.8%. Additionally, a corresponding decrease in the lignin content, from 17.1% to 3.16% has been reported.Conclusions. Increasing alkali concentration during the alkaline pretreatment of wheat straw using the discrete-pulse energy input method in a rotary pulsation device enhances the rate of cellulose conversion duringsubsequent enzymatic hydrolysis.

Isolation of β-O-4-Rich Lignin From Birch in High Yields Enabled by Continuous-Flow Supercritical Water Treatment.

The continuous flow supercritical water (scH2O) treatment of Birch wood (T=372-382 °C; t=0.3-0.7 s; p=260 bar) followed by alkali extraction of lignin allowed for the isolation of lignin and lignin carbohydrate complexes (LCCs) with a high number of β-O-4 moieties in the range 29-57/100 Ar (evaluated by quantitative 13C NMR analysis) in yields ranging between 13-19 wt % with respect to the initial wood. A "lightning rod effect" of carbohydrates has been claimed to explain the low degradation of β-O-4 bonds during the process. The structure of the isolated lignin was thoroughly elucidated via comprehensive NMR studies (HSQC, 13C and 31P). A low degree of condensation (DC)<5 % was found for all the lignin samples, which was only slightly dependent on the reaction severity. The number of aliphatic -OH, phenolic -OH, and -COOH groups was in the range 3.37-5.25, 1.41-2.31 and 0.39-0.73 mmol/g, respectively. The number of -COOH groups increased with increased severity, suggesting that oxidation can occur during the scH2O treatment. Furthermore, by simply varying the reaction severity, it was possible to tune important lignin properties, like the molar mass and the glass transition temperature (Tg).

Optimizing corncob pretreatment with eco-friendly deep eutectic solvents to enhance lignin extraction and cellulose-to-glucose conversion

Deep eutectic solvents (DES) are an eco-friendly, cost-effective alternative to traditional ionic liquids for biomass pretreatment, with unique characteristics encompassed by hydrogen bond donor (HBD), the molar ratio of hydrogen bond acceptor (HBA) to HBD, temperature, and time affecting efficiency. Despite its potential, a comprehensive study exploring the interplay of these factors is limited. This study explores the optimization of pretreatment variables using choline chloride/lactic acid (1:5) via the response surface method (RSM). It aims to evaluate the effects of time and temperature on lignin extraction, cellulose-to-glucose conversion, and hemicellulose removal. Employing a 22 central composite design with temperature (80–140 °C) and time (2–6 h) as variables, optimal conditions were 123 °C for 6 h. Results include 90.08±1.42 % lignin extraction, 68.77±6.9 % cellulose-to-glucose conversion, and 77.34±0.85 % hemicellulose removal, with 52.52±8.07 % lignin recovery. The fractions of pretreated CC and lignin recovered in the optimal condition found were characterized by X-ray diffraction (XDR), Fourier transform infrared spectroscopy (FTIR), 1H, 13C, 2D-HSQC NMR spectroscopy, Thermogravimetric analysis (TGA/DTG), Gel Permeation Chromatography (GPC) to elucidate chemical characteristics of the materials obtained and facilitate downstream valorization. High efficiency was achieved in lignin extraction and cellulose conversion, and addressing solvent viscosity and DES recycling will further enhance the potential for industrial scalability.

High acetone soluble organosolv lignin extraction and its application towards green antifouling and wear-resistant coating

Marine fouling poses significant challenges to the efficiency and longevity of marine engineering equipment. To address this issue, developing effective marine antifouling coatings is critical to ensure the economic viability, environmental sustainability, and safety of offshore operations. In this study, we developed an innovative green antifouling and wear-resistant coating based on lignin, a renewable and sustainable resource. Lignin is considered environmentally friendly because it is abundant, biodegradable, and reduces reliance on petroleum-based materials. The coating was formulated with a controlled hydrophilic-to-hydrophobic ratio of 2:8, leveraging lignin's unique properties. Applying lignin increased the water contact angle by 14.5 %, improving surface hydrophobicity and contributing to the coating's antifouling efficacy. Moreover, the mechanical strength of the coating was enhanced by approximately 200 %, significantly boosting its durability in harsh marine environments. Additionally, the friction coefficient was reduced by about 85 %, further preventing organism adhesion. These results demonstrate that lignin-based coatings offer a greener alternative to traditional antifouling solutions. The results of this study not only help advance antifouling coating technology but are also consistent with the broader goal of promoting environmental responsibility in marine engineering practice.

Utilization of benzoic acid–based green deep eutectic solvents for the fractionation of lignocellulosic biomass

The fractionation of lignocellulose utilizing green solvents is essential for the effective operation of biorefineries. In this study, a deep eutectic solvent (DES) system composed of benzoic acid (BA, hydrogen bond donor) and choline chloride (ChCl, hydrogen bond acceptor) was fabricated and successfully applied to the lignocellulose fractionation. The DES has low toxicity and little pollution. In this system, 67.8 % of lignin and 91.2 % of hemicellulose in poplar were removed, leaving 95.8 % of cellulose intact as solid residue. Due to the removal of the amorphous components, crystallinity of cellulose-rich water-insoluble solid (CIS) substantially increased from 55.6 % to 68.6 %, and CIS was used as feedstock for nanocrystalline cellulose preparation with excellent properties. The results showed that the obtained lignin had similar properties to CEL by GPC, FT-IR, 2D-NMR and TGA. A high-purity lignin rich in G units was recovered with a well-preserved structure, which has β–O–4 linkage content up to 53.01 %, low molecular weight, low polydispersity (1.99). Finally, the hydrolyzate can be used for fermentation. This study demonstrated that BA is suitable for DES design with excellent properties on lignin extraction, and this promising DES enable efficient pretreatment for economically feasible biomass conversion. This ChCl-BA DES facilitates environmentally friendly production of functional materials derived from cellulose and lignin under mild conditions.

Multispecies Trichoderma in Combination with Hydrolyzed Lignin Improve Tomato Growth, Yield, and Nutritional Quality of Fruits

The application of biological pesticides as alternatives to chemical phytosanitary products is a natural and innovative method to improve environmental protection and sustainable agricultural production. In this work, the compatibility between Trichoderma spp. and a commercial lignin extract was assessed in vitro and in vivo. The beneficial effects of lignin in combination with different Trichoderma consortia were evaluated in terms of improved growth and quantitative and qualitative tomato productivity. T. virens GV41 + T. asperellum + T. atroviride + lignin formulation was the most effective in growth promotion and increased root and stem dry weight compared to control (45.4 and 43.9%, respectively). This combination determined a 63% increase in tomato yield compared to the control, resulting in the best-performing treatment compared to each individual constituent. Consistent differences in terms of lycopene, GABA, ornithine, total, essential, and branched-chain amino acids were revealed in fruits from tomato plants treated with Trichoderma–lignin formulations (T. asperellum + T. virens GV41 + lignin) or with the microbial consortia (T. asperellum + T. virens GV41, T. atroviride + T. virens GV41). The developed bioformulations represent a sustainable biological strategy to increase yield and produce nutritional compound-enriched vegetables.

Efficient Extraction and Analysis of Wheat Straw Lignin by Response Surface Methodology

To enhance the high-value utilization of straw waste and achieve efficient lignin extraction, wheat straw was selected as the feedstock for investigating the effects of reaction temperature, reaction time, solid–liquid ratio, and formic acid concentration on lignin yield using a formic acid/acetic acid solvent system. A single-factor experimental design was initially employed, followed by optimization using the response surface methodology. Additionally, a kinetic model was developed to describe lignin extraction kinetics in the formic acid/acetic acid system. The structural characteristics and thermal stability of the extracted lignin were analyzed via FTIR, UV spectroscopy, and TGA. The findings indicate that increasing reaction temperature, reaction time, solid–liquid ratio, and formic acid content all significantly enhanced lignin extraction yield from wheat straw, with the primary influencing factors being reaction temperature &gt; solid–liquid ratio &gt; reaction time &gt; formic acid content. The optimal extraction conditions were identified at a reaction temperature of 90 °C, a reaction time of 3.5 h, a solid–liquid ratio of 1:16.5, and a formic acid content of 86.2 wt.%, yielding a lignin content of 79.83%. The analytical results demonstrated that the extracted lignin preserved the structural integrity of the original lignin and exhibited good thermal stability.

Retraction Note: Microwave-ultrasonic assisted extraction of lignin to synthesize new nano micellar organometallic surfactants for refining oily wastewater

Retraction Note: Microwave-ultrasonic assisted extraction of lignin to synthesize new nano micellar organometallic surfactants for refining oily wastewater

Characterization of sugar maple and red oak bark: Efficient lignin extraction via the Organosolv and acidic dioxane process

The barks of two wood species, sugar maple (SM) and red oak (RO), were investigated to characterize their chemical composition and isolate the lignins they contain, representing relatively underexplored and underutilized polymers. Characterizing these two barks involved assessing extractive components, Klason and acid-soluble lignin, ash content, and sugars. It was observed that RO bark had a higher concentration of extractive substances and a lower Klason lignin content compared to SM bark. The Klason lignin content in the barks of the SM and RO bark was measured at 35.0% and 26.4%, respectively, higher than values reported for corresponding to wood of the same species, 21.8% and 22.2%, respectively, for RO and SM. Lignin isolation from bark was achieved by utilizing Organosolv catalytic and acid dioxane processes. Notably, the Organosolv process yielded lignins of considerably higher purity. The structural analysis of the bark lignins was peformed by combination of spectroscopic methods: FTIR,13P NMR, and solid-state NMR. Compared to dioxane lignins, a higher concentration of OH bound to syringyl and guayacyl units were found in Organosolv lignins. In contrast, aliphatic OH units are more important in dioxane lignins than in Organosolv lignins. Furthermore, sugar analysis was conducted via HPLC, thermal analysis was conducted through DSC and TGA, and ash composition identification was done using ICP-OES. Notably, higher Mw and Mn values are determined by GPC for dioxane lignins than for Organosolv lignins.

Solubility effect of deep eutectic solvent and ethanol concentration on corncob lignin extraction

This research investigates the solubility effect of deep eutectic solvent (DES) mass ratio and ethanol–water solution concentration on corncob lignin extraction. The objective is to propose a solubility matching technique based on like-dissolves-like theory to optimize lignin extraction conditions. The choline chloride (ChCl):lactic acid (LA) mass ratio that maximized lignin extraction was determined by varying DES mass ratio between 1:2 and 1:5, and ethanol–water solution (5–95 % (v/v)) was added to precipitate lignin. By using the solubility matching technique, the maximum lignin extraction was achieved at 1:4 ChCl:LA mass ratio, and 70 % (v/v) ethanol–water concentration yielded the highest lignin precipitation. Lignin is highly soluble where the solubility (δ-values) of lignin, DES, and precipitant are similar. Unlike conventional trial-and-error methods, the solubility matching technique relies on δ-values calculated by the Hildebrand and Scott equation. The proposed technique can also be applied to optimize the extraction conditions of other biomass materials.

The effect of agro-ecological zone on the chemical composition of feed resources in the Gera district, southwest Ethiopia

The poor quality of available feed resources is the major limiting factor for livestock production in Ethiopia. The aim of this study was to determine and compare the chemical composition of major feed resources in three agro-ecological zones (AEZs) of the Gera District, southwest Ethiopia. Three representative samples of natural pasture (Cynodon dactylon, Pavonia schimperiana Hochst and Rhynchosia ferruginea), three indigenous fodder trees and shrubs (IFTSs) (Erythrina abyssinica, Vernonia amygdalina and Maytenus undat), two cultivated forages (Pennisetum purpureum and Pennisetum pedicellatum) and five crop residues (Hordeum vulgare (barley), Zea mays (maize), Sorghum bicolor (sorghum), Triticum aestivum (wheat) and Eragrostis tef (Teff)) were randomly and separately collected from the Highland (HL), midland (ML) and lowland (LL) AEZs. The samples were analyzed for ash, dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), and acid detergent lignin (ADL) content using standard analytical methods. The results showed that AEZ significant (P < 0.05) affected the chemical composition parameters of most of the feed samples. Regardless of the feed sample and AEZs, the mean DM, CP, ash, EE, NDF, ADF, ADL and CF content varied from 89.17% in Pennisetum purpureum to 92.22 ± 0.51 in Erythrina abyssinica, 2.90 ± 0.22% in Triticum aestivum to 10.70 ± 0.52 in Vernonia amygdalina, 7.24 ± 0.19% in Sorghum bicolor to 13.25 ± 0.51% in Pavonia Schimperiana Hochst, 1.33 ± 0.04% in Triticum aestivum to 2.39 ± 0.15% in Maytenus undata, 57.65 ± 1.19% in Erythrina Abyssinica to 79.16 ± 1.04% in Triticum aestivum, 34.57% in Pennisetum purpureum to 59.41 ± 0.98% in Sorghum bicolor, 8.15 ± 0.62% in Rhynchosia ferruginea to 12.65 ± 0.57% in Triticum aestivum and 37.51% in Pennisetum pedicelatum to 69.93 ± 0.65% DM in Triticum aestivum, respectively. It was observed that IFTSs had the highest CP and the lowest NDF, implying their potential for protein supplement, whereas crop residues had the lowest CP and the highest NDF, indicating the need for their treatment using urea or supplementing animals with protein source feeds, especially during the dry season. In conclusion, AEZ has an influence on the chemical composition traits of feed resources attributed to its effects on the microclimate conditions that affect plant growth and maturation in the study sites.

Efficient extraction of light-colored lignin from bamboo by p-toluenesulfonic acid assisted tetrahydrofurfuryl alcohol aqueous solution

Acidic hydrotropes exhibit effective performance in fractionating the constituents of lignocellulosic biomass owing to their amphiphilic characteristics. However, the requirement for excessively high concentrations may lead to the condensation and aggregation of lignin. In this case, bamboo was extracted with 70 % (w/v) tetrahydrofurfuryl alcohol (THFA) aqueous solution containing 5–20 % (w/v) p-toluenesulfonic acid (pTsOH) at 90–120 °C for 1–4 h. Results indicated that 91 % of lignin was efficiently removed from bamboo, with subsequent recovery of 73.5 % achieved through extraction with 10 % pTsOH at 110 °C for 4 h. Furthermore, the resulting lignin exhibited a relative content of β-O-4 bonds of 64.1 %, displayed a light color (L*: 70.48), boasted a purity of 99.64 %, and possessed a moderate molecular weight. These attributes position it as a valuable candidate in functional material production. The aqueous solution provides an ideal medium for efficient extraction of uncondensed, light-colored lignin, thereby furnishing insights for advancing the utilization.

Isolation and Structural Characterization of Natural Deep Eutectic Solvent Lignin from Brewer's Spent Grains.

Brewer's spent grains (BSG) offer valuable opportunities for valorization beyond its conventional use as animal feed. Among its components, lignin-a natural polymer with inherent antioxidant properties-holds significant industrial potential. This work investigates the use of microwave-assisted extraction combined with acidic natural deep eutectic solvents (NaDESs) for efficient lignin recovery, evaluating three different NaDES formulations. The results indicate that choline chloride-lactic acid (ChCl-LA), a NaDES with superior thermal stability as confirmed via thermogravimetric analysis (TGA), is an ideal solvent for lignin extraction at 150 °C and 15 min, achieving a balance of high yield and quality. ChCl-LA also demonstrated good solubility and cell disruption capabilities, while microwaves significantly reduced processing time and severity. Under optimal conditions, i.e., 150 °C, 15 min, in the presence of ChCl-LA NaDES, the extracted lignin achieved a purity of up to 79% and demonstrated an IC50 (inhibitory concentration 50%) of approximately 0.022 mg/L, indicating a relatively strong antioxidant activity. Fourier transform infrared (FTIR) and 2D-HSQC NMR (heteronuclear single quantum coherence nuclear magnetic resonance) spectroscopy confirmed the successful isolation and preservation of its structural integrity. This study highlights the potential of BSG as a valuable lignocellulosic resource and underscores the effectiveness of acidic NaDESs combined with microwave extraction for lignin recovery.

Sustainable Lignin Extraction Using a Mild Acidic γ-Valerolactone Process for the Identification of White and Red Oaks.

Current wood identification struggles to differentiate white and red oak (Quercus alba and Quercus rubra) due to highly similar microstructures, as demonstrated by morphological microscope analysis. The present research explores lignin composition as a potential discriminating factor. Here, a rapid and sustainable method for extracting high-quality lignin from oak samples using acidic γ-valerolactone (GVL) under mild conditions is described. As-extracted lignin is thoroughly characterized using various analytical methods, and results reveal a distinct structural difference between the lignin from the two species. White oak lignin possesses a unique "Hibbert ketone" unit detectable by nuclear magnetic resonance spectroscopy (NMR), which is absent in red oak lignin. In addition, infrared spectroscopy differentiates the species based on specific carbonyl groups present in their lignin. These findings suggest that identifying the presence of the Hibbert ketone unit in lignin may offer a highly efficient and reliable method for differentiating white and red oak, opening new avenues for wood identification.

One Pot Synthesis of Thiopyrimidine Derivatives from Lignin Reproductions by Microwave-Assisted Ultrasonic Microscopy with DFT Description for Clarifying the Mass Spectrum

In this work, an efficient and sustainable procedure for the one-pot synthesis of thiopyrimidine derivatives starting 1,3-diketone cut off β-O-4 lignin precursors to create anticancer agents. Microwave-ultrasonic assisted lignin extract in accessing various heterocyclic precursors such as pyrimidine, pyridine, and thiophene moieties. The results designated the ultrasonic-assisted microwave significantly accelerated synthesis with reduced time. We have diversely prolonged to tight-binding approaches to the electron ionization mass spectrometry with quantum stimulation (DFT/EIMS) to examine electron ionization mass spectra correlated to the experiment. Moreover, DFT/EIMS provides into the mechanism of the reaction of mass spectra trials. It cabins on the fragmentation method to raise the challenging bond breaking and structural rearrangements. The quantum chemical process for effective precursors of a mass spectrum is exactness required and discussed. Foremost fragmentation designs are studied and related to experimental data of the pyrimidin-thione derivatives and their glycosides.

Enhancing reed cellulose conversion to glucose with octyl glucoside and tea saponin pretreatment

Low pretreatment temperatures are beneficial for enhancing the activity of both soluble lignin and lignin in pretreated solids. To achieve high-activity lignin and a higher glucose yield at a lower lignin removal rate and reduced enzymatic loading, the synergistic effects of octyl glucoside and tea saponin during low-temperature ammonia‑oxygen pretreatment and enzymatic hydrolysis were explored. Utilizing a moderated lignin extraction at 38 %, with pretreatment at 110 °C, and enriched with 1 % octyl glucoside and 0.06 g/g tea saponin, the biochemical conversion was galvanized. This manifested in an enzymatic hydrolysis efficiency of 96 % and a glucose yield in excess of 85 % at an enzyme loading of 5 FPU/g of pretreated-solids. Conversely, the lignin removal rate without surfactants was 26 %, resulting in 70 % hydrolysis efficiency even at a higher enzyme loading of 15 FPU/g of pretreated-solids. In order to minimize the pretreatment temperature and enzyme load as much as possible without affecting the efficiency of enzymatic hydrolysis and glucose yield, the goal of this research is to investigate the roles of octyl glucoside in the pretreatment process and tea saponin in the enzymatic hydrolysis process. This study provides a new approach for refining lignocellulosic biomass.

Preparation of Alkali-Resistant Lignin Nanospheres Loaded with Silver Nanoparticles and Their Applications Toward Antibiosis and Printing.

Lignin nanoparticles (LNPs) loaded with silver nanoparticles have exhibited significant application potential in antibacterial and catalytic fields. However, the high solubility of LNPs in silver ammonia solution makes it difficult to achieve the reduction of Ag+ and the adsorption of silver nanoparticles. In this study, a protecting agent, terephthalic aldehyde (TA) is used to block lignin condensation and introduce aldehyde groups onto the lignin molecular backbone during lignin extraction. Furthermore, the TA stabilized lignin (TASL) is cross-linked with bisphenol A diglycidyl ether (BADGE) to enhance its alkali resistance performance and subsequently prepared into alkali-resistance BADGE- TASL hybrid LNPs (BADGE- TASL hy-LNPs) by anti-solvent precipitation and self-assembly. Because the presence of a large number of aldehyde groups in TASL compensates for the loss of phenolic hydroxyl groups caused by crosslinking reactions, a high loading of silver nanoparticles of 54.00% is obtained after redox reaction and adsorption in silver ammonia solution. When the BADGE-TASL hy-LNPs@Ag is used as an antibacterial agent, its inhibition efficiency reached ≈99%. Besides, the BADGE-TASL hy-LNPs@Ag can serve as a printing material for the preparation of conductive printing ink. Therefore, this study provides a strategy for lignin functionalization and application in printed electronics and antimicrobial fields.

Effects of partial lignin extraction on rheological characteristics and combustion performance of high solids bamboo kraft black liquor

Effects of partial lignin extraction on rheological characteristics and combustion performance of high solids bamboo kraft black liquor