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1
Sujan, SMA, MA Kashem, and ANM Fakhruddin. "Lignin: a valuable feedstock for biomass pellet." Bangladesh Journal of Scientific and Industrial Research 55, no. 1 (April 21, 2020): 83–88. http://dx.doi.org/10.3329/bjsir.v55i1.46735.
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Pelletization and briquettization have been extensively used for mass and energy densification of biomass. As the demand for pellets increases, the biorefinery waste lignin can be used with the conventional raw materials for pellet preparation. Sugarcane bagasse (20-40 mesh) is treated with NaOH (8% & 16%) for bioethanol production and obtained lignin is used to prepare pellet along and with sugarcane bagasse (SB). SB, Lignin1 (8% NaOH treated SB), Lignin2 (16% NaOH treated SB) and various composition of SB and Lignin1 were used to produce pelletswith different applied pressures (5kN, 10kN, 15kN and 20kN). Pellet density and heating value were gradually increase with the applied pelletization pressure. Among the samples Lignin1 showed highest heating value at 20kN (3581.54 kcal/kg). Results revealed that 5kN is enough to produce pellet from different composition of SB and Lignin1 and the pellet composition of SB (40%) and Lignin1(60%) showed the highest heating value (3456.21 kcal/kg).
Bangladesh J. Sci. Ind. Res.55(1), 83-88, 2020
2
Vikman, Minna, Olesya Fearon, and Anna Kalliola. "Biodegradation of alkali-O2 oxidized lignins used as dispersants." BioResources 17, no. 4 (September 13, 2022): 6079–93. http://dx.doi.org/10.15376/biores.17.4.6079-6093.
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Large quantities of lignin are produced as by-streams via chemical pulping and emerging biorefinery processes. These lignins are typically water-insoluble; however, they can be converted into a water-soluble form by chemical modifications. A novel LigniOx technology solubilizes lignin using alkali-O2 oxidation. The product can be used for bio-based dispersants. This study evaluated the biodegradability of alkali-O2 oxidized kraft, organosolv, and hydrolysis lignin. The oxidized lignins exhibited higher biodegradation in soil and in aquatic environments in comparison to a commercial kraft lignin and a commercial lignosulfonate. In soil, the biodegradabilities of oxidized lignins were 19 to 44%, whereas the reference lignins exhibited only 5 to 12% conversion to CO2. Biodegradation of the oxidized lignins and references in the aquatic environment increased in a similar order as in the soil environment, although the degradation in each sample was slightly smaller than in the soil. The improved biodegradability of the oxidized lignins was due to the altered chemical structure of lignin. Compared to the untreated lignin, the oxidized lignin contained structures formed in aromatic ring opening reactions, making the lignin more accessible to microbial degradation. In addition, the oxidized lignin contained carbon originating from small organic compounds, which are easily biodegradable.
3
Markovic, Jordan, Jasmina Radovic, Ratibor Strbanovic, Danica Bajic, and Miroslav Vrvic. "Changes in the infrared attenuated total reflectance (ATR) spectra of lignins from alfalfa stem with growth and development." Journal of the Serbian Chemical Society 74, no. 8-9 (2009): 885–92. http://dx.doi.org/10.2298/jsc0909885m.
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Lignin is a poorly characterized polymer and its exact properties vary depending on both the species of the plant and its location within the plant. Three classes of lignins taken from alfalfa stem were examined. The investigation was concentrated on the determination of chemical changes in the lignins during growth and development by the attenuated total reflectance (ATR) infrared (IR) spectrometric technique. The spectrum of permanganate lignin was comparable to that of acid detergent lignin. The main differences were in the different relative absorbance of the peaks. The predominant component of acid detergent lignin and permanganate lignin was guaiacyl-type lignin. The predominant component of Klason lignin was syringyl-type lignin. A comparison between the signals from lignin in different development stages revealed the appearance of new peaks, which are indications of new bonds and changes in the structure of the lignins.
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Capanema, Ewellyn A., Mikhail Yu Balakshin, Chen-Loung Chen, Josef S. Gratzl, and Hanna Gracz. "Structural Analysis of Residual and Technical Lignins by 1H-13C Correlation 2D NMR-Spectroscopy." Holzforschung 55, no. 3 (April 25, 2001): 302–8. http://dx.doi.org/10.1515/hf.2001.050.
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Summary Structural analysis was conducted on residual lignin from pine Kraft AQ pulp, Eucalyptus Kraft lignin from Eucalyptus globulus and Repap Organosolv lignin by 2D 13C-1H correlation NMR spectroscopic techniques such as HMQC sequence. These lignins contain a rather wide variety of saturated aliphatic groups. The HMQC NMR spectra of the lignins do not verify the presence of diarylmethane moieties in any lignin investigated. The type and amount of other condensed structures depend on the nature of lignin preparation. All the lignins investigated still contained β-O-4′, pino- and syringayresinol (β-β′) and phenylcoumarane (β-5′) structures. Stilbene structures were also identified. Vinyl ether structures were present only in Eucalyptus Kraft lignin. All the lignins contain α-carbonyl groups conjugated to aromatic moieties as terminal side chains rather than involving β-O-4′ structures. No coniferyl alcohol and coniferyl aldehyde type structures are detected in the lignins after pulping. The spectra of kraft lignins show some new signals, the origin of which is discussed.
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Jahan, M. Sarwar, and Sung Phil Mun. "Isolation and Characterization of Lignin from Tropical and Temperate Hardwood." Bangladesh Journal of Scientific and Industrial Research 44, no. 3 (February 15, 2010): 271–80. http://dx.doi.org/10.3329/bjsir.v44i3.4399.
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Dioxane and milled wood lignins (MWL) were isolated from tropical hardwood, Nalita (Trema orientalis) and temperate hardwood, aspen. These lignins were characterized by UV, FTIR, 1H-NMR and 13C-NMR spectroscopy, alkaline nitrobenzene oxidation, molecular weight determination, elemental and methoxyl analysis. The structural analysis revealed that Nalita and aspen lignin is syringyl-guaiacyl type. Aspen lignin had higher syringyl unit than Nalita lignin. The β-O-4 type linkages are the main interunit linkages and more abundant in aspen than Nalita. Dioxane lignin showed higher free phenolic hydroxyl group than MWL in both species. The weight average molecular weight of aspen lignin was lower than that of Nalita lignin. Nalita and aspen lignins contained both erythro and threo configuration, but erythro proton gave stronger peak. A UV absorption maximum of aspen lignin was at 274 nm, whereas it was shifted to 280 nm for Nalita lignin. Keywords: Trema orientalis, Aspen, Dioxane lignin, Milled wood lignin, Syringyl-guaiacyl, β-O-4 linkages DOI: 10.3329/bjsir.v44i3.4399 Bangladesh J. Sci. Ind. Res. 44(3), 271-280, 2009
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El Mansouri, Nour-Eddine, Qiaolong Yuan, and Farong Huang. "Synthesis and characterization of kraft lignin-based epoxy resins." BioResources 6, no. 3 (May 10, 2011): 2492–503. http://dx.doi.org/10.15376/biores.6.3.2492-2503.
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Epoxidization is an interesting way to develop a new application of lignin and therefore to improve its application potential. In this work, kraft lignin-based epoxy resins were obtained by the epoxidization reaction, using the kraft lignin recovered directly from pulping liquor and modified by a methylolation reaction. The methylolated lignins were obtained by the reaction of original kraft lignin with formaldehyde and glyoxal, which is a less volatile and less toxic aldehyde. 1H-NMR spectroscopy showed that methylolated kraft lignin has more hydroxymethyl groups than glyoxalated kraft lignin. For the epoxidization reaction we studied the influence of the lignin:NaOH (w/w) ratio, temperature, and time of the reaction on the properties of the prepared epoxidized lignins. The structures of lignin-based epoxy resins were followed by epoxy index test and FTIR spectroscopy. Optimal conditions were obtained for lignin-based epoxy resin produced at lignin/NaOH = 1/3 at 70 ºC for 3h. Thermogravimetry analysis (TGA) revealed that the epoxidization enhances the thermal stability of lignins and may allow a wider temperature range for applications with lignin epoxy-PF blends.
7
Beis, Sedat H., Saikrishna Mukkamala, Nathan Hill, Jincy Joseph, Cirila Baker, Bruce Jensen, Elizabeth A. Stemmler, et al. "Fast pyrolysis of lignins." BioResources 5, no. 3 (May 14, 2010): 1408–24. http://dx.doi.org/10.15376/biores.5.3.1408-1424.
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Three lignins: Indulin AT, LignoboostTM, and Acetocell lignin, were characterized and pyrolyzed in a continuous-fed fast pyrolysis process. The physical and chemical properties of the lignins included chemical composition, heat content, ash, and water content. The distributed activation energy model (DAEM) was used to describe the pyrolysis of each lignin. Activation energy distributions of each lignin were quite different and generally covered a broad range of energies, typically found in lignins. Process yields for initial continuous-fed fast pyrolysis experiments are reported. Bio-oil yield was low, ranging from 16 to 22%. Under the fast pyrolysis conditions used, the Indulin AT and LignoboostTM lignin yielded slightly more liquid product than the Acetocell lignin. Lignin kinetic parameters and chemical composition vary considerably and fast pyrolysis processes must be specified for each type of lignin.
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Liu, Zhichang, Ziwei Wang, Yichen Li, Wanxia Wang, Xiongbin Liu, Hao Shu, and Jungang Jiang. "Comparison of the Effects of NaOH and Deep Eutectic Solvent Catalyzed Tobacco Stock Lignin Isolation: Chemical Structure and Thermal Characteristics." Catalysts 14, no. 11 (October 23, 2024): 744. http://dx.doi.org/10.3390/catal14110744.
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Uncovering the structure of lignin from biorefinery has an important effect on lignin catalytic depolymerization and the production of bioenergy. In this study, two biorefinery lignins were isolated from tobacco stalks via alkaline and deep eutectic solvent (DES) catalyzed delignification processes, and the lignin heterogeneity structural characteristics were elucidated by gel permeation chromatography, 2D-HSQC, FT-IR, etc., to understand the relationship between the structure and the thermal characteristics of lignin. It was found that the lignins presented various structural characteristics and components, in which the predominant interunit linkages of black liquor lignin are β-O-4 and β-β linkages, and the β-O-4 linkages disappeared by DES treatment. DES lignins exhibited lower molecular weights and yields than black liquor lignin. Thermogravimetric analysis and fixed-bed pyrolysis were also performed to investigate the lignin thermal behavior. The results show that the DES approach can improve the bio-oil production from lignin and highlight the potential of DES lignin as a promising feedstock in the lignin pyrolysis process. This work provides a valuable example of the conversion of biorefinery lignin into pyrolysis products.
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Jardim, Juliana M., Peter W. Hart, Lucian A. Lucia, Hasan Jameel, and Hou-min Chang. "The Effect of the Kraft Pulping Process, Wood Species, and pH on Lignin Recovery from Black Liquor." Fibers 10, no. 2 (February 9, 2022): 16. http://dx.doi.org/10.3390/fib10020016.
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Lignin has shown a great potential to produce fuels, value-added chemicals, and functional materials due to its high-energy density and intrinsic aromatic-based structure. Yet, the lignin precipitation of different biomasses needs investigation because most of the work has been performed on softwood and much less is known about hardwoods. In fact, the lignin from these two wooden biomasses vary in composition and pulping performance, which can reflect on lignin precipitation. Therefore, the present study investigated the precipitation and composition of 40 distinct kraft lignins obtained from pine, acacia, sweetgum, and eucalyptus black liquors. Two lignin fractions were precipitated at different pHs, according to known industrial lignin separation practices (pH = 9.5 and 2.5) from black liquors taken at different levels of pulping. Overall, lignin recovery increased with increasing lignin concentration in the black liquor, i.e., higher amounts of lignin were obtained at higher levels of delignification. In addition, pine lignins showed superior yields than the hardwoods and were around five times purer. Among the hardwoods, lignin recovery increased with the S–G ratio of the native lignin, and eucalyptus showed the best performance by achieving the highest yields and purities. Finally, the present work compared the lignin recovery yield and the purity of softwood and different hardwood lignins in a systematic way, which will increase awareness of this underutilized green material and could potentially increase the interest in establishing new lignin plants across the globe.
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Fu, Shiyu, and Lucian A. Lucia. "TMAH-pyrolysis gas chromatography mass spectrometry analysis of residual lignin changes in softwood kraft pulp during oxygen delignification." Canadian Journal of Chemistry 82, no. 7 (July 1, 2004): 1197–202. http://dx.doi.org/10.1139/v04-085.
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The residual lignins from pulps and effluent lignins from oxygen delignification effluents were characterized using pyrolysis gas chromatography mass spectrometry in the presence of tetramethylammonium hydroxide. The results indicated that oxidation under alkali oxygen conditions can induce fragmentation in lignin and produce more acid groups, but the lignin maintains most of its C6C3 units. Oxygen delignification also led to a decrease in diphenyl structures in the residual lignin and an enrichment in concentration of lignin carbohydrate complex structures.Key words: residual lignin, pyrolysis, oxygen delignification.
11
ROUHI, A. MAUREEN. "LIGNIN AND LIGNAN BIOSYNTHESIS." Chemical & Engineering News 78, no. 46 (November 13, 2000): 29–32. http://dx.doi.org/10.1021/cen-v078n046.p029.
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Nada, A. M. A., Nesrine F. Kassem, and Samar H. Mohamed. "Characterization and properties of ion exchangers produced from lignin precipitated after peroxyacid pulping." BioResources 3, no. 2 (April 17, 2008): 538–48. http://dx.doi.org/10.15376/biores.3.2.538-548.
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Pulping of bagasse by one-stage and three-stage peroxyacetic acid was carried out. Characterization of the precipitated lignin from the waste liquor of the pulping process was studied using infrared spec-troscopy. Comparison between the molecular structure of peroxyacid lignin and kraft lignin was investigated. Different lignins were applied to phosphorylation reaction. The sodium binding capacity and metal ions absorption by these lignins were taken into consideration. Infrared spectroscopy of the produced phosphorylated lignin was investigated. The peroxyacid lignin was found to have lower OH, higher COOH, a higher level of phosphate groups, and a higher binding capacity for sodium compared to kraft lignin.
13
Kondo, Tsuneo, Tomoko Ohshita, and Tadashi Kyuma. "Characteristics of dioxane-soluble lignins from corn and sorghum silages and feces of sheep fed on them." Canadian Journal of Animal Science 73, no. 3 (September 1, 1993): 661–64. http://dx.doi.org/10.4141/cjas93-071.
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Dioxane-soluble lignin fractions were isolated from corn and sorghum silages, and the feces of sheep fed on them and their properties were examined. The lignin fractions were composed chiefly of soluble lignin fragments with different molecular weights and contained phenolic acid esters as non-core lignin components. A comparison of the analytical data showed that the soluble lignins from the silages had different properties from those of corresponding feces, suggesting structural changes of lignins in the digestive tract of sheep. Key words: Dioxane-soluble lignin, silage, corn, sorghum, sheep digestion
14
Parkås, Jim, Gosta Brunow, and Knut Lundquist. "Quantitative lignin analysis based on permanganate oxidation." BioResources 2, no. 2 (March 9, 2007): 169–78. http://dx.doi.org/10.15376/biores.2.2.169-178.
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Qualitative lignin analysis relies rather much on studies of lignin degradation products. As concerns precise quantification of lignin’s composition such studies in general have obvious limitations. Aromatic acids obtained on permanganate oxidation of pretreated lignins (cleavage of ethers and alkylation of phenolic groups) offer a possibility to estimate the amounts of differently substituted aromatic units in lignins. An equation is derived for the calculation of the gross composition of lignins based on the yields of methoxy-substituted aromatic acids obtained on permanganate oxidation of lignins with methylated phenolic groups. The equation could also be used for the calculation of the phenolic content in a lignin sample based on permanganate oxidation data, provided that such data are available for a similar lignin sample with known phenolic content. Literature data for milled wood lignin from spruce are used to exemplify the calculations.
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Wang, Yun-Yan, Xianzhi Meng, Yunqiao Pu, and Arthur J. Ragauskas. "Recent Advances in the Application of Functionalized Lignin in Value-Added Polymeric Materials." Polymers 12, no. 10 (October 3, 2020): 2277. http://dx.doi.org/10.3390/polym12102277.
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The quest for converting lignin into high-value products has been continuously pursued in the past few decades. In its native form, lignin is a group of heterogeneous polymers comprised of phenylpropanoids. The major commercial lignin streams, including Kraft lignin, lignosulfonates, soda lignin and organosolv lignin, are produced from industrial processes including the paper and pulping industry and emerging lignocellulosic biorefineries. Although lignin has been viewed as a low-cost and renewable feedstock to replace petroleum-based materials, its utilization in polymeric materials has been suppressed due to the low reactivity and inherent physicochemical properties of lignin. Hence, various lignin modification strategies have been developed to overcome these problems. Herein, we review recent progress made in the utilization of functionalized lignins in commodity polymers including thermoset resins, blends/composites, grafted functionalized copolymers and carbon fiber precursors. In the synthesis of thermoset resins such as polyurethane, phenol-formaldehyde and epoxy, they are covalently incorporated into the polymer matrix, and the discussion is focused on chemical modifications improving the reactivity of technical lignins. In blends/composites, functionalization of technical lignins is based upon tuning the intermolecular forces between polymer components. In addition, grafted functional polymers have expanded the utilization of lignin-based copolymers to biomedical materials and value-added additives. Different modification approaches have also been applied to facilitate the application of lignin as carbon fiber precursors, heavy metal adsorbents and nanoparticles. These emerging fields will create new opportunities in cost-effectively integrating the lignin valorization into lignocellulosic biorefineries.
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Quintana, Germán C., George J. M. Rocha, Adilson R. Gonçalves, and Jorge A. Velásquez. "Evaluation of heavy metal removal by oxidised lignins in acid media from various sources." BioResources 3, no. 4 (September 16, 2008): 1082–102. http://dx.doi.org/10.15376/biores.3.4.1092-1102.
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The capacity for removal of heavy metals from liquid streams by formation of complexes with lignins oxidized by acid treatment was studied. Lignins were obtained from different sources: sulfuric acid pre-treated cane bagasse, soda pulping bagasse, eucalypt Kraft lignin, and commercial Kraft lignin. These lignins were characterized using different techniques to determine Klason lignin, carbohydrates, total acids, ashes, and their main functional groups: phenolic-OH, carbonyls, etc. The studied lignins were determined spectroscopically using FTIR. In order to increase the metal adsorption capacity, lignins were oxidized at 100°C during 2 h, using aqueous solutions of H2O2 in distilled water solvent and HCl catalyst. Some lignin adsorption isotherms were constructed before and after the oxidation process to define Cd(II) ion removal capacity.
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Akpakpan, Aniekan E., Edu J. Inam, Basil N. Ita, and Ukana D. Akpabio. "Physicochemical Properties of Soda and Kraft Lignin Extracted from Gmelina arborea Wood." International Research Journal of Pure and Applied Chemistry 24, no. 4 (July 27, 2023): 9–19. http://dx.doi.org/10.9734/irjpac/2023/v24i4816.
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Lignin, an amorphous biopolymer is one of the major components of wood. In this study, lignin was extracted from Gmelina arborea wood using Soda and Kraft pulping processes. The lignin was characterized using Fourier Transformed Infrared Spectrometer (FTIR), UV/visible spectrometer, electrospray ionization mass spectrometer and scanning electron microscope (SEM). Results revealed that G. arborea wood lignins contained several chemical functional groups. Kraft lignin (KL) contain carboxyl and thiol group in addition to other functional groups such as methoxyl, alcohols and phenolic. UV/ visible spectroscopy results revealed that Soda lignin (SL) absorbed at higher wavelength than Kraft lignin. The concentrations of both conjugated and non-conjugated phenolic group were higher in Kraft lignin than Soda lignin. ESI-MS spectra revealed that the composition of the monomers was higher in Kraft lignin while dimers composition was higher in Soda lignin. The surface morphology of both lignins were heterogeneous with uneven particle size. These physicochemical properties of lignin will enhance their applications as adsorbents, corrosion inhibitors and in the production of some industrial chemical intermediates.
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Martínková, Ludmila, Michal Grulich, Miroslav Pátek, Barbora Křístková, and Margit Winkler. "Bio-Based Valorization of Lignin-Derived Phenolic Compounds: A Review." Biomolecules 13, no. 5 (April 22, 2023): 717. http://dx.doi.org/10.3390/biom13050717.
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Lignins are the most abundant biopolymers that consist of aromatic units. Lignins are obtained by fractionation of lignocellulose in the form of “technical lignins”. The depolymerization (conversion) of lignin and the treatment of depolymerized lignin are challenging processes due to the complexity and resistance of lignins. Progress toward mild work-up of lignins has been discussed in numerous reviews. The next step in the valorization of lignin is the conversion of lignin-based monomers, which are limited in number, into a wider range of bulk and fine chemicals. These reactions may need chemicals, catalysts, solvents, or energy from fossil resources. This is counterintuitive to green, sustainable chemistry. Therefore, in this review, we focus on biocatalyzed reactions of lignin monomers, e.g., vanillin, vanillic acid, syringaldehyde, guaiacols, (iso)eugenol, ferulic acid, p-coumaric acid, and alkylphenols. For each monomer, its production from lignin or lignocellulose is summarized, and, mainly, its biotransformations that provide useful chemicals are discussed. The technological maturity of these processes is characterized based on, e.g., scale, volumetric productivities, or isolated yields. The biocatalyzed reactions are compared with their chemically catalyzed counterparts if the latter are available.
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Mattinen, Maija-Liisa, Tapani Suortti, Richard Gosselink, Dimitris S. Argyropoulos, Dmitry Evtuguin, Anna Suurnäkki, Ed de Jong, and Tarja Tamminen. "Polymerization of different lignins by laccase." BioResources 3, no. 2 (April 23, 2008): 549–65. http://dx.doi.org/10.15376/biores.3.2.549-565.
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In this study the oxidative polymerization of different lignins, i.e. Flax Soda lignin, Spruce EMAL, and Eucalyptus Dioxane lignin by Trametes hirsuta laccase was compared. Initially the structures of the different lignins were compared by Fourier transform infrared spectroscopy. The reactivity of laccase with the different types of lignins in the absence of mediators was examined and verified by oxygen consumption measurements. The molecular weight distributions of treated and untreated lignins were determined by two different size exclusion chromatography methods. Furthermore, the potential of matrix-assisted laser desorption/ionisation-time of flight-mass spectroscopy for determination of the absolute molecular weights of the different lignins was evaluated. The data showed that all the technical lignins could be activated and polymerized by laccase to different degrees. The efficiency as indicated by measurements of the degree of polymerization was found to increase in the order of Spruce EMAL < Eucalyptus Dioxane lignin < Flax Soda lignin. Overall, this data supplies foundations for using enzymes more efficiently in the enzymatic upgrading of lignin.
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Bhattacharyya, Shubhankar, Leonidas Matsakas, Ulrika Rova, and Paul Christakopoulos. "Melt Stable Functionalized Organosolv and Kraft Lignin Thermoplastic." Processes 8, no. 9 (September 5, 2020): 1108. http://dx.doi.org/10.3390/pr8091108.
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A shift towards an economically viable biomass biorefinery concept requires the use of all biomass fractions (cellulose, hemicellulose, and lignin) for the production of high added-value products. As lignin is often underutilized, the establishment of lignin valorization routes is highly important. In-house produced organosolv as well as commercial Kraft lignin were used in this study. The aim of the current work was to make a comparative study of thermoplastic biomaterials from two different types of lignins. Native lignins were alkylate with two different alkyl iodides to produce ether-functionalized lignins. Successful etherification was verified by FT-IR spectroscopy, changes in the molecular weight of lignin, as well as 13C and 1H Nuclear Magnetic Resonance (NMR). The thermal stability of etherified lignin samples was considerably improved with the T2% of organosolv to increase from 143 °C to up to 213 °C and of Kraft lignin from 133 °C to up to 168 °C, and glass transition temperature was observed. The present study shows that etherification of both organosolv and Kraft lignin with alkyl halides can produce lignin thermoplastic biomaterials with low glass transition temperature. The length of the alkyl chain affects thermal stability as well as other thermal properties.
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Ház, Aleš, Michal Jablonský, Igor Šurina, František Kačík, Tatiana Bubeníková, and Jaroslav Ďurkovič. "Chemical Composition and Thermal Behavior of Kraft Lignins." Forests 10, no. 6 (June 3, 2019): 483. http://dx.doi.org/10.3390/f10060483.
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Lignin has great potential for utilization as a green raw material or as an additive in various industrial applications, such as energy, valuable chemicals, or cost-effective materials. In this study, we assessed a commercial form of lignin isolated using LignoBoost technology (LB lignin) as well as three other types of lignin (two samples of non-wood lignins and one hardwood kraft lignin) isolated from the waste liquors produced during the pulping process. Measurements were taken for elemental analysis, methoxyl and ash content, higher heating values, thermogravimetric analysis, and molecular weight determination. We found that the elemental composition of the isolated lignins affected their thermal stability, activation energies, and higher heating values. The lignin samples examined showed varying amounts of functional groups, inorganic component compositions, and molecular weight distributions. Mean activation energies ranged from 93 to 281 kJ/mol. Lignins with bimodal molecular weight distribution were thermally decomposed in two stages, whereas the LB lignin showing a unimodal molecular weight distribution was decomposed in a single thermal stage. Based on its thermal properties, the LB lignin may find direct applications in biocomposites where a higher thermal resistance is required.
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Olgun, Çağrı, and Saim Ateş. "Characterization and Comparison of Some Kraft Lignins Isolated from Different Sources." Forests 14, no. 5 (April 25, 2023): 882. http://dx.doi.org/10.3390/f14050882.
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Lignin characteristics are significantly affected by kraft processing and isolation conditions. In the studies carried out in this context, commercial lignins or isolated lignins from industrial black solutions are generally preferred. In this study, in order to conduct more comprehensive research, three lignin samples were isolated from kraft black liquor obtained from laboratory cooking trials of pine, poplar, and wheat straw chips, representing softwoods, hardwoods, and annual plants, respectively, according to efficient pulping studies. In addition, another lignin-containing industrial waste was provided from a pulp mill (OBL). The acidification method was applied for isolating lignin from black liquor samples. After isolating the lignin samples from different sources, they were characterized and compared with the commercially available kraft lignin sample (Indulin AT). Total phenolic groups, carboxyl groups, purity, functional groups, nitrobenzene oxidation products, molecular weight, thermal stability, and element contents were analyzed. The isolated lignin samples (except wheat straw) were as pure as commercial lignin. Since the wheat straw was agricultural waste and an annual plant, inorganic elements such as P, K, and Si were more abundant than in the other samples. However, the polydispersity and molecular weight of all of the isolated lignin samples were higher than those of commercial lignin. Because the ash contents of the lignin samples for pine, poplar, OBL, and indulin AT were between 1 and 3%, they can be used for high-value applications. In particular, despite some disadvantages, wheat straw lignin has greater potential for use in extruders than softwood lignins due to their syringyl content.
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Cachet, Nadja, and Bouchra Benjelloun-Mlayah. "Comparison of organic acid-based organosolv lignins extracted from the residues of five annual crops." BioResources 16, no. 4 (October 14, 2021): 7966–90. http://dx.doi.org/10.15376/biores.16.4.7966-7990.
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Organosolv lignins were extracted from corn stover, wheat, rice straw, reed straw, and sugarcane bagasse using a mixture of acetic and formic acids, at relatively low temperature and atmospheric pressure. Lignin content, residual carbohydrates, ash levels, proteins, and molecular weights were determined in each extracted lignin. The lignin content of all samples was relatively high, confirming the performance of the pretreatment process. The low molecular weights were in a narrow range, in accordance with the organosolv lignin molar masses. However, some differences between studied lignins were highlighted, in particular in rice straw lignin, which contained the highest silica, calcium, and nitrogen contents. Nuclear magnetic resonance spectroscopies (31P and semi-quantitative Heteronuclear Single Quantum Correlation) underlined the structural similarities and differences between these organosolv lignins. Corn stover and sugarcane bagasse lignins were rich in non-methoxylated (H-Unit) or mono-methoxylated (G-Unit) phenolic units, making them the best promising candidates for production of phenolic resins. Wheat straw lignin was richer in aliphatic OH than in phenolic OH. This is an advantage for use as polyol substitute in polyurethane synthesis. Reed straw lignin was less specific, with a balanced content of OH groups. However, it contained a high concentration of β-O-4 linkages, which is favorable for depolymerization.
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Zhu, Weizhen, Gunnar Westman, and Hans Theliander. "The molecular properties and carbohydrate content of lignins precipitated from black liquor." Holzforschung 69, no. 2 (February 1, 2015): 143–52. http://dx.doi.org/10.1515/hf-2014-0062.
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Abstract Precipitation and utilization of lignin from black liquor (BL) offers many promising advantages to modern kraft pulp mills. A novel process, known as “LignoBoost”, has recently been introduced as a process for separating lignin from BL; it results in lignins with a low ash and high dry solid content. There is a lack of knowledge regarding the influences of process parameters on the behavior of lignin in the precipitation step. In this study, the yield of precipitated lignin and its average molecular weight (MWt) and carbohydrate content were the focus. Nuclear magnetic resonance (NMR) analysis showed that the lignin yield increased at lower pH and temperatures or when the ion strength of BL was elevated. High yield lignins contained more low MWt components and such lignins have more phenolic OH and methoxy groups. Xylan content of the lignins decreased with decreasing pH and increasing temperature, but glucomannan content was virtually unaffected by the conditions of precipitation.
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Sutton, Jordan T., Kalavathy Rajan, David P. Harper, and Stephen C. Chmely. "Improving UV Curing in Organosolv Lignin-Containing Photopolymers for Stereolithography by Reduction and Acylation." Polymers 13, no. 20 (October 10, 2021): 3473. http://dx.doi.org/10.3390/polym13203473.
Full textAbstract:
Despite recent successes in incorporating lignin into photoactive resins, lignin photo-properties can be detrimental to its application in UV-curable photopolymers, especially in specialized engineered resins for use in stereolithography printing. We report on chemical modification techniques employed to reduce UV absorption by lignin and the resulting mechanical, thermal, and cure properties of these modified lignin materials. Lignin was modified using reduction and acylation reactions and incorporated into a 3D printable resin formulation. UV–Vis absorption at the 3D printing range of 405 nm was reduced in all modified lignins compared to the unmodified sample by 25% to ≥ 60%. Resins made with the modified lignins showed an increase in stiffness and strength with lower thermal stability. Studying these techniques is an important step in developing lignin for use in UV-curing applications and further the effort to valorize lignin towards commercial use.
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Ahmad, Zaid, Waleed Wafa Al Dajani, Michael Paleologou, and Chunbao (Charles) Xu. "Sustainable Process for the Depolymerization/Oxidation of Softwood and Hardwood Kraft Lignins Using Hydrogen Peroxide under Ambient Conditions." Molecules 25, no. 10 (May 16, 2020): 2329. http://dx.doi.org/10.3390/molecules25102329.
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The present study demonstrated a sustainable and cost-effective approach to depolymerize/oxidize softwood (SW) and hardwood (HW) kraft lignins using concentrated hydrogen peroxide at temperatures ranging from 25 to 35 °C, in the absence of catalysts or organic solvents. The degree of lignin depolymerization could be simply controlled by reaction time, and no further separation process was needed at the completion of the treatment. The obtained depolymerized lignin products were comprehensively characterized by GPC–UV, FTIR, 31P-NMR, TGA, Py-GC/MS and elemental analysis. The weight-average molecular weights (Mw) of the depolymerized lignins obtained from SW or HW lignin at a lignin/H2O2 mass ratio of 1:1 after treatment for 120 h at room temperature (≈25 °C) were approximately 1420 Da. The contents of carboxylic acid groups in the obtained depolymerized lignins were found to significantly increase compared with those of the untreated raw lignins. Moreover, the depolymerized lignin products had lower thermal decomposition temperatures than those of the raw lignins, as expected, owing to the greatly reduced Mw. These findings represent a novel solution to lignin depolymerization for the production of chemicals that can be utilized as a bio-substitute for petroleum-based polyols in polyurethane production.
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Niksa, Stephen. "Simulating the Rapid Devolatilization of Mineral-Free Lignins." Polymers 15, no. 20 (October 10, 2023): 4043. http://dx.doi.org/10.3390/polym15204043.
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Lig-FC is a network depolymerization mechanism for the rapid primary devolatilization of mineral-free lignins that has already been validated with test data on 16 lignin samples. This paper expands the validation with an additional 13 lignins, including cases that applied different lignin preparations to the same feedstock. The validations reported here cover 27 mineral-free lignins for temperatures to 1150 °C, heating rates from 30 to 8000 °C/s, contact times after heatup to 90 s, and pressures from vacuum to 0.13 MPa. Lig-FC accurately depicts the impacts of lignin quality, heating rate, temperature, contact time, and pressure on the major products and oils’ molecular weight distributions (MWDs). All raw lignins contain abundant oil precursors that are released as oils via flash distillation as soon as a flow of noncondensables carries them into the free stream. Consequently, lignin MWD is an essential aspect of lignin constitution because it determines the inventory of inherent volatile chains subject to unhindered flash distillation. Lighter lignin MWDs have larger inherent inventories and therefore produce more oils than heavier MWDs at the onset of devolatilization. Oil yields diminish and char yields increase for progressively heavier MWDs and heavier mean monomer weights and for lignins with relatively less H and more O compared to C.
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Widsten, P., B. Hortling, and K. Poppius-Levlin. "Ozonation of conventional kraft and SuperBatch residual lignins in methanol/water and water." Holzforschung 58, no. 4 (July 7, 2004): 363–68. http://dx.doi.org/10.1515/hf.2004.055.
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Abstract The chemistry of ozone bleaching of chemical pulps was explored by ozonating residual lignins isolated from conventional kraft and SuperBatch pulps in methanol/water medium to detect possible differences in the reactivity of the two types of lignin. SuperBatch lignin was ozonated also in water to study the effect of ozonation medium on the lignin reactivity. The residual lignins were found to display similar reactivities in methanol/water, implying that ozonation should result in equal delignification rates for both conventional kraft and SuperBatch pulps unless the rates of reagent diffusion in the pulps are different. The lignins were partly oxidized to volatile and nonvolatile low-molecular weight oxidation products by the so-called “peeling mechanism”, according to which oxidation products go into solution and insoluble reaction products resemble the starting lignins. The reaction products obtained upon ozonation of SuperBatch lignin in neutral water resembled those formed in methanol/water, but their yield was much lower. This is probably due to the better solubility of lignin in methanol/water than in water and/or higher degradability of lignin by ozone than by radicals formed as ozone decomposition products.
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Fox, S. Carter, and Armando G. McDonald. "Chemical and thermal characterization of three industrial lignins and their corresponding lignin esters." BioResources 5, no. 2 (April 2, 2010): 990–1009. http://dx.doi.org/10.15376/biores.5.2.990-1009.
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Corn stover and rice straw lignin samples received from ethanol pilot plants, along with softwood kraft lignin samples, were characterized using pyrolysis GC-MS, 13C CP/MAS NMR spectroscopy, and permanganate oxidation degradation. The lignins were then esterified using 1-methylimidazole as a catalyst in a pyridine-free reaction, and the thermal properties of the products were evaluated. Solid state NMR showed the rice straw lignin contained 18% residual polysaccharides. Pyrolysis GC-MS showed the softwood kraft, corn stover, and rice straw lignins to be G – type, H/G/S – type, and G/S – type, respectively. However, some discrepancy was apparent between the pyrolysis and permanganate oxidation studies as to the ratios of the monomeric make-up of the lignins. The kraft and rice straw lignins were determined to have high degrees of condensation, while the corn stover lignin was uncondensed. Little to no increase in solubility was noticed for corn stover or rice straw lignin esters in organic solvents. Glass transition temperatures (Tg) of the lignin derivatives were determined by a combination of differential scanning calorimetry, dynamic mechanical analysis, and parallel plate rheometry.
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Nguyen, Ngoc, Christopher Bowland, Peter Bonnesen, Kenneth Littrell, Jong Keum, and Amit Naskar. "Fractionation of Lignin for Selective Shape Memory Effects at Elevated Temperatures." Materials 13, no. 8 (April 20, 2020): 1940. http://dx.doi.org/10.3390/ma13081940.
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We report a facile approach to control the shape memory effects and thermomechanical characteristics of a lignin-based multiphase polymer. Solvent fractionation of a syringylpropane-rich technical organosolv lignin resulted in selective lignin structures having excellent thermal stability coupled with high stiffness and melt-flow resistance. The fractionated lignins were reacted with rubber in melt-phase to form partially networked elastomer enabling selective programmability of the material shape either at 70 °C, a temperature that is high enough for rubbery matrix materials, or at an extremely high temperature, 150 °C. Utilizing appropriate functionalities in fractionated lignins, tunable shape fixity with high strain and stress recovery, particularly high-stress tolerance were maintained. Detailed studies of lignin structures and chemistries were correlated to molecular rigidity, morphology, and stress relaxation, as well as shape memory effects of the materials. The fractionation of lignin enabled enrichment of specific lignin properties for efficient shape memory effects that broaden the materials’ application window. Electron microscopy, melt-rheology, dynamic mechanical analysis and ultra-small angle neutron scattering were conducted to establish morphology of acrylonitrile butadiene rubber (NBR)-lignin elastomers from solvent fractionated lignins.
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Kozhevnikov, Aleksandr Yur'yevich, Semen Leonidovich Shestakov, and Yuliya Aleksandrovna Sypalova. "ISSUES OF THE STRUCTURAL ORGANIZATION OF LIGNIN AND PROSPECTS FOR ITS PROCESSING." chemistry of plant raw material, no. 2 (June 26, 2023): 5–26. http://dx.doi.org/10.14258/jcprm.20230211737.
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In this article, we represented the review of literature data about the study of lignin as one of the most abundant biopolymers. The review is based on the articles published in the most quoted world publishing. It is noted that already nowadays the lignin is considered as a powerful renewable source of valuable organic raw materials, also it’s pointed that potential possibilities of lignin valorization are much wider than those are used in present times. The special attention is paid to the structure and molecular organization of birch lignin, which wood is actively utilized in chemical industry, meanwhile the hardwood lignins are less studied in literature than softwood lignins. The authors touched the most basic methods of research of such complex and irregular polymer as lignin, methods’ advantages, disadvantages and perspectives are analyzed. It is noted that nowadays the most effective methods of lignin structure units study are pyrolisys gas chromatography and nuclear magnetic resonance. The article describes various ways of lignins isolation from the wood, and influence of the isolation way on the structure of isolated substance. Also, the structural features of birch lignin and its differences from other species are shown.
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Pu, Yunqiao, and Arthur J. Ragauskas. "Structural analysis of acetylated hardwood lignins and their photoyellowing properties." Canadian Journal of Chemistry 83, no. 12 (December 1, 2005): 2132–39. http://dx.doi.org/10.1139/v05-231.
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Lignin was isolated from aspen bleached chemithermomechanical pulp by employing a mild acid hydrolysis procedure, and the extracted material was acetylated with acetic anhydride. Nuclear magnetic resonance analyses indicated that the relative ease of acetylating lignin hydroxyl groups was phenolic >> γ-side chain > α-side chain. Non-acetylated and acetylated lignins were impregnated onto cellulosic test sheets, and the photo-behavior of the lignins was examined under irradiation with two light sources, a fluorescent lamp and a black lamp. Optical reflective studies indicated acetylation efficiently inhibited the photodiscoloration of aspen bleached chemithermomechanical pulp lignin under visible and near-UV light irradiation. The photostability of the lignin was correlated to the extent of lignin acetylation. The observed photo-stabilization of acetylated lignin during light irradiation was attributed to the acetylation of phenoxy and aliphatic hydroxyl groups in lignin.Key words: green chemistry, hardwood lignin, acetylation, photo-stabilization, photoyellowing, NMR.
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Wang, Yihan, Shihao Su, and Guoyong Song. "Lignin Extracted from Various Parts of Castor (Ricinus communis L.) Plant: Structural Characterization and Catalytic Depolymerization." Polymers 15, no. 12 (June 19, 2023): 2732. http://dx.doi.org/10.3390/polym15122732.
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Castor is an important non-edible oilseed crop used in the production of high-quality bio-oil. In this process, the leftover tissues rich in cellulose, hemicellulose and lignin are regarded as by-products and remain underutilized. Lignin is a crucial recalcitrance component, and its composition and structure strongly limit the high-value utilization of raw materials, but there is a lack of detailed studies relating to castor lignin chemistry. In this study, lignins were isolated from various parts of the castor plant, namely, stalk, root, leaf, petiole, seed endocarp and epicarp, using the dilute HCl/dioxane method, and the structural features of the as-obtained six lignins were investigated. The analyses indicated that endocarp lignin contained catechyl (C), guaiacyl (G) and syringyl (S) units, with a predominance of C unit [C/(G+S) = 6.9:1], in which the coexisted C-lignin and G/S-lignin could be disassembled completely. The isolated dioxane lignin (DL) from endocarp had a high abundance of benzodioxane linkages (85%) and a low level of β-β linkages (15%). The other lignins were enriched in G and S units with moderate amounts of β-O-4 and β-β linkages, being significantly different from endocarp lignin. Moreover, only p-coumarate (pCA) incorporated into the epicarp lignin was observed, with higher relative content, being rarely reported in previous studies. The catalytic depolymerization of isolated DL generated 1.4–35.6 wt% of aromatic monomers, among which DL from endocarp and epicarp have high yields and excellent selectivity. This work highlights the differences in lignins from various parts of the castor plant, providing a solid theory for the high-value utilization of the whole castor plant.
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Yevstigneyev, Eduard Ivanovich. "What is lignin - the evolution of views (review)." chemistry of plant raw material, no. 1 (February 6, 2024): 57–81. http://dx.doi.org/10.14258/jcprm.20240112046.
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The review considers changes in ideas about the biosynthesis, structure and functions of lignin in plants, starting from early mentions and up to the present. Alternative points of view on the process of lignin biosynthesis, its spatial and supramolecular structure, and the nature of lignincarbohydrate bonds are presented.
A special place in the review is occupied by the results of studies of lignin modification with the aim of reducing the content and changing the composition of monomer units by genetic engineering methods. Comparison of the structure of lignins isolated from transgenic and mutant trees, as well as herbaceous plants, showed that lignin biosynthesis is plastic and, in addition to canonical monolignols (coniferyl, synapic, and coumaric alcohols), other phenolic compounds can also participate in it.
The study of the so-called "stress lignins" showed that lignin plays an important role in protecting plants from adverse environmental influences: mechanical damage, drought, low temperatures, pathogens, etc.
The results of studies of the genetic modification of lignin made it possible to outline a program for directed modification of the biosynthesis process in order to obtain designer lignins, i.e. lignins with desired properties. This group also includes the so-called zip-lignins. They are distinguished by the presence of ester bonds between phenylpropane units.
It is noted that, when conducting research in the field of genetic engineering, it is necessary to find a compromise between improving the processing of plant materials due to the modification of lignin and the viability of transgenic plants.
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Huang, Yang, Chenhuan Lai, Shaolong Sun, Qiang Yong, Brian K. Via, and Maobing Tu. "Organosolv lignin properties and their effects on enzymatic hydrolysis." BioResources 15, no. 4 (October 12, 2020): 8909–24. http://dx.doi.org/10.15376/biores.15.4.8909-8924.
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Lignin plays a crucial role in enzymatic hydrolysis of lignocellulosic biomass. To evaluate the correlation between lignin properties and its effects on enzymatic hydrolysis, five organosolv lignins (OLs) were isolated from woody biomass, and their physico-chemical properties and structural features were characterized. The effects of OL addition on enzymatic hydrolysis of microcrystalline cellulose (pure cellulose) were assessed first, which showed their disparate effects. The addition of three OLs increased the 72 h hydrolysis yield by 7.4% to 10.1%, while the addition of other two OLs reduced the 72 h hydrolysis yield by 3.2% to 20.4%. A strong correlation between the enzyme distribution coefficient on lignins and the 72 h hydrolysis yields indicated that the enzyme-lignin interaction played a significant role in determining the lignin effects. More importantly, a correlation between lignin properties (hydrophobicity, zeta potential, and particle size) and the enzyme distribution coefficient was established. Identifying the key lignin properties will give insights to reduce the lignin inhibition by altering the lignin properties, thereby promoting enzymatic hydrolysis of lignocellulose.
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Santos, José I., Raquel Martín-Sampedro, Úrsula Fillat, José M. Oliva, María J. Negro, Mercedes Ballesteros, María E. Eugenio, and David Ibarra. "Evaluating Lignin-Rich Residues from Biochemical Ethanol Production of Wheat Straw and Olive Tree Pruning by FTIR and 2D-NMR." International Journal of Polymer Science 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/314891.
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Lignin-rich residues from the cellulose-based industry are traditionally incinerated for internal energy use. The future biorefineries that convert cellulosic biomass into biofuels will generate more lignin than necessary for internal energy use, and therefore value-added products from lignin could be produced. In this context, a good understanding of lignin is necessary prior to its valorization. The present study focused on the characterization of lignin-rich residues from biochemical ethanol production, including steam explosion, saccharification, and fermentation, of wheat straw and olive tree pruning. In addition to the composition and purity, the lignin structures (S/G ratio, interunit linkages) were investigated by spectroscopy techniques such as FTIR and 2D-NMR. Together with the high lignin content, both residues contained significant amounts of carbohydrates, mainly glucose and protein. Wheat straw lignin showed a very low S/G ratio associated withp-hydroxycinnamates (p-coumarate and ferulate), whereas a strong predominance of S over G units was observed for olive tree pruning lignin. The main interunit linkages present in both lignins wereβ-O-4′ethers followed by resinols and phenylcoumarans. These structural characteristics determine the use of these lignins in respect to their valorization.
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El Mansouri, Nour-Eddine, Qiaolong Yuan, and Farong Huang. "Characterization of alkaline lignins for use in phenol-formaldehyde and epoxy resins." BioResources 6, no. 3 (May 19, 2011): 2647–62. http://dx.doi.org/10.15376/biores.6.3.2647-2662.
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Besides polyurethanes and polyesters, phenolic and epoxy resins are the most prominent applications for technical lignins in thermosetting materials. To evaluate the potential application of lignin raw materials in phenol formaldehyde and epoxy resins, three types of alkaline lignins were characterized in terms of their structures and thermal properties. The lignin samples analyzed were kraft lignin (LIG-1), soda–rice straw lignin (LIG-2), and soda-wheat straw lignin (LIG-3). FTIR and 1H-NMR methods were used to determine their structure. Gel permeation chromatography (GPC) was used to determine the molecular weight distribution (MWD). Differential scanning calorimetry (DSC) was used to measure the glass transition temperature (Tg), and thermogravimetric analysis (TGA) to determine the thermal stability of lignin samples. Results showed that kraft lignin (LIG-1) has moderate hydroxyl-group content, is rich in G-type units, and has good thermal stability. These properties make it more suitable for direct use in phenol formaldehyde resins, and it is therefore a good raw material for this purpose. The alkaline soda-rice straw lignin (LIG-2) with a high hydroxyl-group content and excellent thermal stability is most suited to preparing lignin-based epoxy resins.
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Nadányi, Richard, Aleš Ház, Anton Lisý, Michal Jablonský, Igor Šurina, Veronika Majová, and Andrej Baco. "Lignin Modifications, Applications, and Possible Market Prices." Energies 15, no. 18 (September 7, 2022): 6520. http://dx.doi.org/10.3390/en15186520.
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Lignin is the second most abundant biopolymer in the world. Due to its complex structure, lignin can be considered a valuable source of energy and different chemicals. In addition, using different reactive sites on lignin, it is possible to prepare different value-added products, such as resins, polyurethanes, and many more. Different functional groups are presented on the lignin macromolecule and can be modified via different pathways. Hydroxyl groups are the most promising reactive sites for lignin modifications. Both modified and unmodified lignins could be used for preparing different biomaterials. This paper shows several possible applications of lignin. The main goal of this publication is to show the possible valorization of lignin in different value-added products throughout the actual market prices of non-biobased materials. This review proves that lignin has unquestionable advantages in material technology and can replace different substances which will lead to a higher potential market value of lignins and could create new bio-based materials compared with the actual prices of commercially available materials. Nowadays, it is easier to use lignin as an energy source even though a lot of lignin modifications and conversion processes are still under development and need more time to become more relevant for industrial applications. Information in the presented paper should reveal to the reader the importance and economic benefits of using lignin as a value-added compound in different applications.
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Ortiz, Martha L. "Aproximaciones a la comprensión de la degradación de la lignina." Orinoquia 13, no. 2 (September 1, 2009): 137–44. http://dx.doi.org/10.22579/20112629.208.
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Titulo en ingles: Approaches to understanding lignin degradation.RESUMEN: El objetivo de esta revisión es reunir los hallazgos más recientes que aportan a la comprensión de las rutas metabólicas que intervienen en la degradación del biopolímero más recalcitrante del planeta: la lignina. Esta le proporcionó a las plantas resistencia mecánica en sus tejidos para colonizar la tierra y una barrera fisicoquímica ante la infección microbiana. Debido a su naturaleza recalcitrante, la lignina es el precursor principal para la síntesis de la reserva de materia orgánica del suelo, regulando el ciclo del carbono. Adicionalmente, el sistema enzimático extracelular inespecífico que usan los microorganismos para degradar la lignina, ofrece un sinnúmero de moléculas con potencial biotecnológico. Este trabajo pretende estimular la investigación en la degradación de lignina, especialmente en ambientes poco explorados como la Amazorinoquía para el desarrollo de la bioprospección en nuestro país.Palabras clave: Lignina, enzimas, microorganismos, biotecnología.ABSTRACT: This work was aimed at summarising our current knowledge regarding understanding the metabolic routes intervening in lignin degradation, this being the most recalcitrant biopolymer on earth. Lignin provides plant tissues with mechanic resistance for colonising the earth and represents a physicochemical barrier to microbial infection. Lignin is the main precursor for synthesising the reserve of soil organic matter due to its recalcitrant nature, thereby regulating the carbon cycle. The unspecific extracellular enzymatic system used by microorganisms for lignin degradation offers a large number of molecules having biotechnological poten- tial. This work tries to stimulate research into lignin degradation, especially in little-explored environments such as the Amazon-Orinoquía region for developing bioprospecting in Colombia.Key words: Lignin, enzyme, microorganism, biotechnology.
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Evstigneyev, Eduard Ivanovich. "LIGNIN VALORIZATION PROBLEMS." chemistry of plant raw material, no. 1 (March 10, 2022): 11–33. http://dx.doi.org/10.14258/jcprm.2022019211.
Full textAbstract:
The review considers two directions of lignin valorization: valorization of technical lignins, as such, without preliminary depolymerization, and valorization through monomeric compounds formed as a result of their selective destruction. The first area includes the production of lignin hydrogels, the use of lignin in medicine and pharmacology, 3D printing, as well as in the production of carbon fibers and biofuels.
Lignin hydrogels are distinguished by a high sorption capacity with respect to heavy metals such as lead, iron and copper, which, depending on the content of acidic groups in lignin and the molar mass of sorbate, is ~ 25-50% of the mass of lignin, and therefore they can be used for the purification of waste waters of chemical enterprises. Lignin has high biological activity against various pathogens, including viruses, which makes research in this area very relevant, especially against the backdrop of the COVID-19 pandemic. The use of lignin in some composites for 3D printing can increase the mechanical strength of finished products. The industrial implementation of the technology for the production of carbon fibers from lignin will ensure a twofold reduction in the mass of vehicles.
The second direction of lignin valorization - hydrogenolysis and selective oxidation - allows one to obtain monomeric compounds with a yield close to the theoretical one. The economic aspects of valorization are also considered. In addition, based on a comparison of the results of valorization of coniferous and deciduous lignins, a hypothesis on the structure of native lignin was proposed.
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Evstigneyev, Eduard Ivanovich. "LIGNIN VALORIZATION PROBLEMS." chemistry of plant raw material, no. 1 (March 10, 2022): 11–33. http://dx.doi.org/10.14258/jcprm.2022019211.
Full textAbstract:
The review considers two directions of lignin valorization: valorization of technical lignins, as such, without preliminary depolymerization, and valorization through monomeric compounds formed as a result of their selective destruction. The first area includes the production of lignin hydrogels, the use of lignin in medicine and pharmacology, 3D printing, as well as in the production of carbon fibers and biofuels.
Lignin hydrogels are distinguished by a high sorption capacity with respect to heavy metals such as lead, iron and copper, which, depending on the content of acidic groups in lignin and the molar mass of sorbate, is ~ 25-50% of the mass of lignin, and therefore they can be used for the purification of waste waters of chemical enterprises. Lignin has high biological activity against various pathogens, including viruses, which makes research in this area very relevant, especially against the backdrop of the COVID-19 pandemic. The use of lignin in some composites for 3D printing can increase the mechanical strength of finished products. The industrial implementation of the technology for the production of carbon fibers from lignin will ensure a twofold reduction in the mass of vehicles.
The second direction of lignin valorization - hydrogenolysis and selective oxidation - allows one to obtain monomeric compounds with a yield close to the theoretical one. The economic aspects of valorization are also considered. In addition, based on a comparison of the results of valorization of coniferous and deciduous lignins, a hypothesis on the structure of native lignin was proposed.
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Davidson, Daniel J., Aidan P. McKay, David B. Cordes, J. Derek Woollins, and Nicholas J. Westwood. "The Covalent Linking of Organophosphorus Heterocycles to Date Palm Wood-Derived Lignin: Hunting for New Materials with Flame-Retardant Potential." Molecules 28, no. 23 (December 1, 2023): 7885. http://dx.doi.org/10.3390/molecules28237885.
Full textAbstract:
Environmentally acceptable and renewably sourced flame retardants are in demand. Recent studies have shown that the incorporation of the biopolymer lignin into a polymer can improve its ability to form a char layer upon heating to a high temperature. Char layer formation is a central component of flame-retardant activity. The covalent modification of lignin is an established technique that is being applied to the development of potential flame retardants. In this study, four novel modified lignins were prepared, and their char-forming abilities were assessed using thermogravimetric analysis. The lignin was obtained from date palm wood using a butanosolv pretreatment. The removal of the majority of the ester groups from this heavily acylated lignin was achieved via alkaline hydrolysis. The subsequent modification of the lignin involved the incorporation of an azide functional group and copper-catalysed azide–alkyne cycloaddition reactions. These reactions enabled novel organophosphorus heterocycles to be linked to the lignin. Our preliminary results suggest that the modified lignins had improved char-forming activity compared to the controls. 31P and HSQC NMR and small-molecule X-ray crystallography were used to analyse the prepared compounds and lignins.
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JARDIM, JULIANA M., PETER W. HART, LUCIAN LUCIA, and HASAN JAMEEL. "Probing the molecular weights of sweetgum and pine kraft lignin fractions." June 2021 20, no. 6 (July 1, 2021): 381–91. http://dx.doi.org/10.32964/tj20.6.381.
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The present investigation undertook a systematic investigation of the molecular weight (MW) of kraft lignins throughout the pulping process to establish a correlation between MW and lignin recovery at different extents of the kraft pulping process. The evaluation of MW is crucial for lignin characterization and utilization, since it is known to influence the kinetics of lignin reactivity and its resultant physicochemical properties. Sweetgum and pine lignins precipitated from black liquor at different pHs (9.5 and 2.5) and different extents of kraft pulping (30–150 min) were the subject of this effort. Gel permeation chromatography (GPC) was used to deter- mine the number average molecular weight (Mn), mass average molecular weight (Mw), and polydispersity of the lignin samples. It was shown that the MW of lignins from both feedstocks follow gel degradation theory; that is, at the onset of the kraft pulping process low molecular weightlignins were obtained, and as pulping progressed, the molecular weight peaked and subsequently decreased. An important finding was that acetobromination was shown to be a more effective derivatization technique for carbohydrates containing lignins than acetylation, the technique typically used for derivatization of lignin.
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Jahan, M. Sarwar, D. Alam, M. Mostafzur Rahman, and MA Quaiyyum. "Isolation and characterization of lignin from okra (Abelmoschus esculentus) fibre and stick." Bangladesh Journal of Scientific and Industrial Research 50, no. 4 (December 11, 2015): 257–62. http://dx.doi.org/10.3329/bjsir.v50i4.25834.
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The okra (Abelmoschus esculentus) plant consists of bast fiber and core (stick). The bast fibre of okra plant was characterized with high ?-cellulose (56.7%) and low lignin (12.6%) and stick withlow ?-cellulose (34.3%) and high lignin (25.2%) content. Lignin was isolated from the fiber and stick by acidolytic dioxane method and characterized for elemental analysis, methoxyl analysis and FTIR and 1H-NMR spectroscopy. The C9 formulas for okra stick and fibre lignin were C9H9.61O4.63(OCH3)1.24 and C9H8.61O4.66(OCH3)1.49, respectively. Both of the lignins were of the guaiacyl-syringyl type. The bands of FT-IR spectrum at 1327 cm-1, 1122 cm-1 and 837 cm-1 associated with syringyl unit was higher in okra fibre lignin than in the okra stick lignin. The structural analysis revealed that the average numbers of proton of ?-O-4 (H? & H?) per C9 unit in okra stick and fibre lignin were 1.53 and 1.20, respectively. The ?-O-4 units in these lignins had predominately erythro stereochemistry type.Bangladesh J. Sci. Ind. Res. 50(4), 257-262, 2015
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Budnyak, Tetyana, Selda Aminzadeh, Ievgen Pylypchuk, Anastasia Riazanova, Valentin Tertykh, Mikael Lindström, and Olena Sevastyanova. "Peculiarities of Synthesis and Properties of Lignin–Silica Nanocomposites Prepared by Sol-Gel Method." Nanomaterials 8, no. 11 (November 18, 2018): 950. http://dx.doi.org/10.3390/nano8110950.
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The development of advanced hybrid materials based on polymers from biorenewable sources and mineral nanoparticles is currently of high importance. In this paper, we applied softwood kraft lignins for the synthesis of lignin/SiO2 nanostructured composites. We described the peculiarities of composites formation in the sol-gel process through the incorporation of the lignin into a silica network during the hydrolysis of tetraethoxysilane (TEOS). The initial activation of lignins was achieved by means of a Mannich reaction with 3-aminopropyltriethoxysilane (APTES). In the study, we present a detailed investigation of the physicochemical characteristics of initial kraft lignins and modified lignins on each step of the synthesis. Thus, 2D-NMR, 31P-NMR, size-exclusion chromatography (SEC) and dynamic light scattering (DLS) were applied to analyze the characteristics of pristine lignins and lignins in dioxan:water solutions. X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) were used to confirm the formation of the lignin–silica network and characterize the surface and bulk structures of the obtained hybrids. Termogravimetric analysis (TGA) in nitrogen and air atmosphere were applied to a detailed investigation of the thermal properties of pristine lignins and lignins on each step of modification. SEM confirmed the nanostructure of the obtained composites. As was demonstrated, the activation of lignin is crucial for the sol-gel formation of a silica network in order to create novel hybrid materials from lignins and alkoxysilanes (e.g., TEOS). It was concluded that the structure of the lignin had an impact on its reactivity during the activation reaction, and consequently affected the properties of the final hybrid materials.
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Guo, Tian, Shen, Yang, Long, He, Song, et al. "Transparent Cellulose/Technical Lignin Composite Films for Advanced Packaging." Polymers 11, no. 9 (September 5, 2019): 1455. http://dx.doi.org/10.3390/polym11091455.
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Although recent work has shown natural lignin products are promising to fabricate various polymer based functional composites, high-value applications were challenged by their structural complexity and inhomogeneity. This work specially assessed the potential of four technical lignins for cellulose based functional films production. These four technical lignins were obtained by emerging pretreatment systems, i.e., lactic acid-betaine deep eutectic solvent (DES), ethanol organosolv, soda/anthraquinone (Soda/AQ) and the sodium salicylate hydrotrope, and their phenolic substructures were comparatively identified by prevalent 31P NMR technique. The influence of lignin chemical structure on the antioxidant potential and UV-shielding performance of the prepared cellulose/technical lignin composite films were assessed. Results showed severe organosolv and soda/AQ pretreatment produced technical lignins with higher total phenolic hydroxyl groups (3.37 and 3.23 mmol g-1 respectively), which also exhibited higher antioxidant activities. The composite films could effectively block the ultraviolet lights especially for UVB region (ultraviolet B, 280–315 nm) at only 5 wt.% lignin content. The contribution of lignin phenolic substructures to both antioxidant activity and UV-shielding property from high to low was syringyl > guaiacyl > p-hydroxyphenyl phenolic hydroxyl groups. This work provided some useful information that could facilitate upstream lignin extraction or downstream value-added applications.
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Lourençon, Tainise V., Sami Alakurtti, Tommi Virtanen, Anna-Stiina Jääskeläinen, Tiina Liitiä, Mark Hughes, Washington L. E. Magalhães, Graciela I. B. Muniz, and Tarja Tamminen. "Phenol-formaldehyde resins with suitable bonding strength synthesized from “less-reactive” hardwood lignin fractions." Holzforschung 74, no. 2 (February 25, 2020): 175–83. http://dx.doi.org/10.1515/hf-2018-0203.
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AbstractThe substitution of phenol by lignin in phenol-formaldehyde (PF) resins is one of the most promising end uses of lignin valorization. Lignin from grasses and softwood has been the focus of the studies in this field as they present a higher number of theoretical reactive sites for resin synthesis. Herein we examined the composition and chemical reactivity of “less-reactive” hardwood lignin fractions and their performance in PF resins, synthesized by substituting 50 wt% of the phenol with lignin. Before resin synthesis, the samples were hydroxymethylated and the maximum formaldehyde consumption was recorded. By doing so, we observed that hardwood fractions consumed formaldehyde close to the theoretical calculation, whereas the reference softwood lignin consumed only about ¼ of the theoretical value. In the resin synthesis, we added formaldehyde to the formulation according to the measured maximum formaldehyde consumption. Thus, low values of free formaldehyde in lignin-PF (LPF) resins were achieved (<0.23%). Moreover, the resin bonding strength displayed similar performance irrespective of whether the LPF resins were made with softwood or hardwood lignin (range of 3.4–4.8 N mm−2 at 150°C and 45–480 s of press time). Furthermore, we concluded that hardwood kraft lignins present no disadvantage compared to softwood lignins in PF resin applications, which have significant practical implications.
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Lam, Pui Ying, Lanxiang Wang, Andy C. W. Lui, Hongjia Liu, Yuri Takeda-Kimura, Mo-Xian Chen, Fu-Yuan Zhu, et al. "Deficiency in flavonoid biosynthesis genes CHS, CHI, and CHIL alters rice flavonoid and lignin profiles." Plant Physiology 188, no. 4 (December 28, 2021): 1993–2011. http://dx.doi.org/10.1093/plphys/kiab606.
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Abstract Lignin is a complex phenylpropanoid polymer deposited in the secondary cell walls of vascular plants. Unlike most gymnosperm and eudicot lignins that are generated via the polymerization of monolignols, grass lignins additionally incorporate the flavonoid tricin as a natural lignin monomer. The biosynthesis and functions of tricin-integrated lignin (tricin-lignin) in grass cell walls and its effects on the utility of grass biomass remain largely unknown. We herein report a comparative analysis of rice (Oryza sativa) mutants deficient in the early flavonoid biosynthetic genes encoding CHALCONE SYNTHASE (CHS), CHALCONE ISOMERASE (CHI), and CHI-LIKE (CHIL), with an emphasis on the analyses of disrupted tricin-lignin formation and the concurrent changes in lignin profiles and cell wall digestibility. All examined CHS-, CHI-, and CHIL-deficient rice mutants were largely depleted of extractable flavones, including tricin, and nearly devoid of tricin-lignin in the cell walls, supporting the crucial roles of CHS and CHI as committed enzymes and CHIL as a noncatalytic enhancer in the conserved biosynthetic pathway leading to flavone and tricin-lignin formation. In-depth cell wall structural analyses further indicated that lignin content and composition, including the monolignol-derived units, were differentially altered in the mutants. However, regardless of the extent of the lignin alterations, cell wall saccharification efficiencies of all tested rice mutants were similar to that of the wild-type controls. Together with earlier studies on other tricin-depleted grass mutant and transgenic plants, our results reflect the complexity in the metabolic consequences of tricin pathway perturbations and the relationships between lignin profiles and cell wall properties.
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Bujanovic, Biljana, Sally A. Ralph, Richard S. Reiner, and Rajai H. Atalla. "Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)." Holzforschung 61, no. 5 (August 1, 2007): 492–98. http://dx.doi.org/10.1515/hf.2007.102.
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Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.
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Qian, Yong, Hongming Lou, Weifeng Liu, Dongjie Yang, Xinping Ouyang, Yuan Li, and Xueqing Qiu. "Lignin — a promising biomass resource." March 2018 17, no. 03 (April 1, 2018): 125–41. http://dx.doi.org/10.32964/tj17.03.125.
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Lignin, the second most abundant component in plants, is a class of complex aromatic polymer. Industrial lignin is a major byproduct of pulp and paper production and biorefineries, with more than 50 megatons generated annually. However, more than 98% of industrial lignin is either burned as fuel or discharged as wastewater, causing serious environmental pollution. From a sustainable feedstock perspective, finding additional high-volume and high-value applications for lignin is an extremely important and long-term pursued objective. Thus, lignin resources deserve to be further exploited as biorenewable raw materials for energy-saving and lowcarbon polymer production. Inspired by the natural three-dimensional structure, excellent ultraviolet-blocking and antioxidant properties of lignins, the authors have focused their research on lignin-based biorenewable resources. This review summarizes research achievements of the recent decade. Progress has been made in several aspects, such as nonionic and amphoteric lignin-based surfactants, lignin-based functional materials, lignin-based photoelectric materials, lignin-based resins and polymer composites, and catalytic depolymerization of lignin.