Journal articles on the topic 'Lignin distribution'
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1
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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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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Damayanti, Damayanti, Yeni Ria Wulandari, and Ho-Shing Wu. "Product Distribution of Chemical Product Using Catalytic Depolymerization of Lignin." Bulletin of Chemical Reaction Engineering & Catalysis 15, no. 2 (May 22, 2020): 432–53. http://dx.doi.org/10.9767/bcrec.15.2.7249.432-453.
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Lignin depolymerization is a very promising process which can generate value-added products from lignin raw materials. The main objective of lignin depolymerization is to convert the complex molecules of lignin into small molecules. Nevertheless, lignin is natural polymer which the molecules of lignin are extremely complicated due to their natural variability, and it will be a big challenge to depolymerize lignin, particularly high water yield. The various technology and methods are developed to depolymerize lignin into biofuels or bio chemical products including acid/base/metallic catalyzed lignin depolymerization, pyrolysis of lignin, hydroprocessing, and gasification. The distribution and yield of chemical products depend on the reaction operation condition, type of lignin and kind of catalyst. The reactor type, product distributions and specific chemicals (benzene, toluene, xylene, terephthalic acid) production of lignin depolymerization are intensive discussed in this review. Copyright © 2020 BCREC Group. All rights reserved
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Thring, Ronald W., Esteban Chornet, and Ralph P. Overend. "Fractionation of woodmeal by prehydrolysis and thermal organosolv. Alkaline depolymerization, chemical functionality, and molecular weight distribution of recovered lignins and their fractions." Canadian Journal of Chemistry 71, no. 6 (June 1, 1993): 779–89. http://dx.doi.org/10.1139/v93-103.
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Thermal organosolv glycol lignins and their fractions have been characterized by means of elemental composition, molecular weight distribution, and 1H and 13C NMR spectroscopy. Fractionation of each lignin by sequential solvent extraction produced fractions of increasing molecular weight and polydispersity. Structures in the highest molecular weight fractions were found to be linked by a high proportion of β-O-4 type bonds, whilst the lowest molecular weight fractions consisted of a high content of saturated aliphatic side-chain structures. A noticeable difference in the content of carbohydrate contaminants in both starting lignins indicated the formation of relatively stable lignin–carbohydrate complexes, especially in the lignin recovered from pretreated wood. In addition, depolymerization of the lignins and their fractions to monomeric compounds was explored using alkaline hydrolytic and nitrobenzene oxidative routes. The highest molecular weight fractions from each lignin were identified as the best candidates for production of useful monomeric phenolic compounds.
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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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Koda, Keiichi, Keiichi Koda, Armindo R. Gaspar, Liu Yu, Liu Yu, Liu Yu, and Dimitris S. Argyropoulos. "Molecular weight-functional group relations in softwood residual kraft lignins." Holzforschung 59, no. 6 (November 1, 2005): 612–19. http://dx.doi.org/10.1515/hf.2005.099.
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Abstract An integrated picture of the distribution of functional groups should be provided as a function of molecular size within residual kraft lignins. With this goal we developed a reliable and reproducible method for determination of the molecular weight and molecular weight distribution of residual kraft lignins (RKLs) over the whole delignification range. In general, our data indicate that for reliable measurement of the molecular weight and its distribution of residual lignin in pulps, the lignin-carbohydrate bonds have to be cleaved prior to size exclusion chromatography. The recently developed method for isolating residual lignins, which involves cellulolytic treatment followed by a mild acid hydrolysis step, was found to be the most suitable approach to achieve this. The molecular weight and polydispersity of all RKLs decreased as a function of delignification. As anticipated, the observed decrease in molecular weight was clearly reflected in the concomitantly decreasing amount of β-O-4 structural linkages present. Similarly, the total phenolic hydroxyl content increased as the molecular weight of the RKLs decreased during kraft pulping. Despite the smaller size of the lignin remaining on the kraft fiber at the end of delignification, the preponderance of condensed phenolic structures within these lignins offers an explanation for delignification problems during bleaching.
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Duarte, A. P., D. Robert, and D. Lachenal. "Eucalyptus globulus Kraft Pulp Residual Lignin. Part 2. Modification of Residual Lignin Structure in Oxygen Bleaching." Holzforschung 55, no. 6 (November 6, 2001): 645–51. http://dx.doi.org/10.1515/hf.2001.105.
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Summary Residual lignins were isolated from unbleached and oxygen-bleached Eucalyptus kraft pulps by acid hydrolysis. The structural changes and degradation of residual lignin occurring during kraft pulping and oxygen bleaching were followed and identified by elemental analysis, residual carbohydrate analysis, molecular mass distribution, as well as qualitative and quantitative solution 13C NMR. The dissolved lignins in the kraft cooked and oxygen bleached liquors were also studied and compared with the corresponding residual lignins. Milled wood lignin treated under acid hydrolysis conditions served as a reference for the structural comparison. The results show that etherified syringyl structures were quite resistant towards degradation in the oxygen bleaching, causing little depolymerisation in residual lignin and a small increase in carboxylic acid content, but producing appreciable amounts of saturated aliphatic methylene groups.
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Thring, R. W., and S. L. Griffin. "The heterogeneity of two Canadian kraft lignins." Canadian Journal of Chemistry 73, no. 5 (May 1, 1995): 629–34. http://dx.doi.org/10.1139/v95-081.
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Two kraft lignins, one precipitated with carbon dioxide and the other with sulphuric acid, have been fractionated into three distinct fractions by sequential extraction using organic solvents of increasing hydrogen-bonding capacity. The lignins and fractions were comparatively characterized in terms of yield, methoxyl group content, molecular weight distribution, and 13C NMR spectroscopy. For a given lignin, the fractions showed differences in yield, composition, and chemical structure. A significant portion (21%) of the carbon dioxide precipitated kraft lignin is composed of ethyl acetate soluble material of low molecular weight. This fraction, which is richer in guaiacyl moieties than the other fractions, is virtually absent in the sulphuric acid precipitated kraft lignin. The occurrence of "tails" in the high molecular weight fraction, especially from the carbon dioxide precipitated kraft lignin, suggests the presence of material of very high molecular weight. Data from 13C NMR spectroscopy does little to elucidate the nature or origin of the material causing these tails. Keywords: kraft lignins, heterogeneity, fractionation, characterization.
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Bergamasco, Sara, Florian Zikeli, Vittorio Vinciguerra, Anatoly Petrovich Sobolev, Luca Scarnati, Giorgio Tofani, Giuseppe Scarascia Mugnozza, and Manuela Romagnoli. "Extraction and Characterization of Acidolysis Lignin from Turkey Oak (Quercus cerris L.) and Eucalypt (Eucalyptus camaldulensis Dehnh.) Wood from Population Stands in Italy." Polymers 15, no. 17 (August 29, 2023): 3591. http://dx.doi.org/10.3390/polym15173591.
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Acidolysis lignins from the species Quercus cerris L. and Eucalyptus camaldulensis Dehnh. were isolated and characterized using high pressure size exclusion chromatography (HP-SEC), Fourier-transform (FTIR) infrared spectroscopy, analytical pyrolysis–gas chromatography–mass spectrometry (Py-GCMS), and two-dimensional heteronuclear single quantum coherence (2D HSQC) NMR spectroscopy. The acidolysis lignins from the two different species varied in chemical composition and structural characteristics, with Q. cerris L. lignin having a higher S/G ratio and higher molar mass averages with a bimodal molar mass distribution. The different analytical techniques FTIR spectroscopy, Py-GCMS, and 2D NMR spectroscopy provided consistent results regarding the S/G ratio of the lignins from the two wood species. Based on the determined high S/G ratio of both oak and eucalypt lignin, the two wood sources could be promoted as substrates for efficient lignin isolation in modern forest biorefineries in order to develop innovative lignin-based value-added biorefinery products.
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Vallejos, María E., Fernando E. Felissia, Aprigio A. S. Curvelo, Marcia D. Zambon, Luis Ramos, and María C. Area. "Chemical and physico-chemical characterization of lignins obtained from ethanol-water fractionation of bagasse." BioResources 6, no. 2 (February 21, 2011): 1158–71. http://dx.doi.org/10.15376/biores.6.2.1158-1171.
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Organosolv lignins can replace petroleum chemicals such as phenol either partially or totally in various applications. Eight lignins, seven of which corresponded to the ethanol-water fractionation of bagasse and the other to a reference lignin (Alcell®) were analyzed with the aim to evaluate their chemical and physicochemical characteristics. The purity of the lignin fractions was determined by high pressure liquid chromatography (HPLC) and by ash content. Fourier Transform-Infrared Spectroscopy (FTIR) techniques and differential UV spectroscopy were applied to identify the chemical groups in the lignin samples. The molecular weight distribution was determined by size exclusion chromatography (HPSEC). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were used to determine the mass loss due to the high temperature treatment. The lignins studied showed the presence of p-hydroxyphenyl (H unit) and a greater proportion of guaiacyl (G unit) moieties, lower purity, similar or greater amount of phenolic hydroxyl groups, and higher degradation temperatures, than the Alcell® lignin.
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Cabrera, Yohanna, Andrés Cabrera, Flemming H. Larsen, and Claus Felby. "Solid-state 29Si NMR and FTIR analyses of lignin-silica coprecipitates." Holzforschung 70, no. 8 (August 1, 2016): 709–18. http://dx.doi.org/10.1515/hf-2015-0165.
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Abstract When agricultural residues are processed to ethanol, lignin and silica are some of the main byproducts. Separation of these two products is difficult and the chemical interactions between lignin and silica are not well described. In the present study, the effect of lignin-silica complexing has been investigated by characterizing lignin and silica coprecipitates by FTIR and solid state NMR. Silica particles were coprecipitated with three different lignins, three lignin model compounds, and two silanes representing silica-in-lignin model compounds. Comparison of 29Si SP/MAS NMR spectra revealed differences in the distribution of silanol hydroxyl groups among different coprecipitates. These differences are dependent on the lignin type. The results are interpreted that the underlying mechanism of the interactions is the formation of hydrogen bonds between lignin aliphatic hydroxyl or carboxyl groups and the silanols, but not a condensation of the silica-in-lignin among the silica particles and not the formation of C-O-Si bonds.
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Tamura, Takashi, Noriyuki Morohoshi, and Seiichi Yasuda. "Suitability of Peroxidase-Suppressed Transgenic Hybrid Aspen (Populus sieboldii X Populus gradidentata) for Pulping." Holzforschung 55, no. 4 (June 21, 2001): 335–39. http://dx.doi.org/10.1515/hf.2001.056.
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Summary Lignin content, lignin composition and lignin removal were investigated in hybrid aspen (Populus sieboldii X Populus gradidentata) with suppressed peroxidase (POX) contents, involved in the dehydrogenative polymerization of monolignols. No significant suppression of the lignin content of the transgenic hybrid aspen was observed, but one (POX 29) of the POX-suppressed hybrid aspen species had a lower lignin content and gave a higher pulp yield at the same lignin content in kraft pulping than the control wild type. The molecular weight distribution of kraft lignins, sugar compositions and yields of nitrobenzene oxidation products of the transgenic woods were not different from those of the wild-type wood. These results indicate that suppression of POX may hold promise for producing woods suited for milder kraft pulping conditions using less chemicals and lower pulping temperature.
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Koch, G., and G. Kleist. "Application of Scanning UV Microspectrophotometry to Localise Lignins and Phenolic Extractives in Plant Cell Walls." Holzforschung 55, no. 6 (November 6, 2001): 563–67. http://dx.doi.org/10.1515/hf.2001.091.
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Summary The localisation of lignin and phenolic extractives in woody tissue was determined using scanning UV microspectrophotometry. This improved cellular analytical technique enabled direct imaging of the topochemical lignin distribution within individual cell wall layers with a resolution of 0.25 μm2. Selected softwood (Picea abies), hardwood (Fagus sylvatica, Entandrophragma cylindricum, Prunus serotina) and monocotyledon (Phyllostachys edulis) sections of 1 μm thickness were scanned at a fixed wavelength and evaluated with the “APAMOS” software. This approach allowed the distribution pattern of lignins and aromatic extractives within the cell wall to be visualised simultaneously. The method was found to be ideally suited to the study of their subcellular distribution in plant cell walls.
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Lauberte, Liga, Gabin Fabre, Jevgenija Ponomarenko, Tatiana Dizhbite, Dmitry V. Evtuguin, Galina Telysheva, and Patrick Trouillas. "Lignin Modification Supported by DFT-Based Theoretical Study as a Way to Produce Competitive Natural Antioxidants." Molecules 24, no. 9 (May 9, 2019): 1794. http://dx.doi.org/10.3390/molecules24091794.
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The valorization of lignins as renewable aromatic feedstock is of utmost importance in terms of the use of sustainable resources. This study provides a deductive approach towards market-oriented lignin-derived antioxidants by ascertaining the direct effect of different structural features of lignin on the reactivity of its phenolic OH groups in the radical scavenging reactions. The antioxidant activity of a series of compounds, modeling lignin structural units, was experimentally characterized and rationalized, using thermodynamic descriptors. The calculated O–H bond dissociation enthalpies (BDE) of characteristic lignin subunits were used to predict the modification pathways of technical lignins. The last ones were isolated by soda delignification from different biomass sources and their oligomeric fractions were studied as a raw material for modification and production of optimized antioxidants. These were characterized in terms of chemical structure, molecular weight distribution, content of the functional groups, and the antioxidant activity. The developed approach for the targeted modification of lignins allowed the products competitive with two commercial synthetic phenolic antioxidants in both free radical scavenging and stabilization of thermooxidative destruction of polyurethane films.
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Esakkimuthu, Esakkiammal Sudha, Nathalie Marlin, Marie-Christine Brochier-Salon, and Gérard Mortha. "Application of a Universal Calibration Method for True Molar Mass Determination of Fluoro-Derivatized Technical Lignins by Size-Exclusion Chromatography." AppliedChem 2, no. 1 (March 3, 2022): 30–47. http://dx.doi.org/10.3390/appliedchem2010002.
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The determination of the true molar mass distribution (MMD) of lignin is highly important to understand the physicochemical characteristics for lignin-based value-added applications. It is imperative to develop a universal method to quantify accurate MMD of lignin using size exclusion chromatography (SEC), as the conventional method with polymer standards provides irregular MMD results. This work aims to evaluate the MMD of five lignin samples (Protobind 1000, Organosolv, Indulin, Pine Kraft and Eucalyptus Kraft) in THF. Different derivatization methods (acetylation, fluorobenzylation and fluorobenzoylation) were performed. FTIR and 19F NMR analyses were used to follow derivatization. The MMDs of derivatized and underivatized lignins were determined by the conventional method and compared with the universal calibration method developed using intrinsic viscosity. The 19F NMR spectra provided the information to quantify the degree of substitution of lignin hydroxyl groups, to calculate the true molar mass of the derivatives of lignin monomers. The obtained MMDs values for all the derivatized lignin by universal calibration were found to be three to five times higher than that of the conventional calibration. The polydispersity values obtained with the acetylation method were higher than the fluoro-derivatives. The results demonstrated that fluoro-derivatization is an appropriate method to apply to higher molar mass technical lignins and lacks solubility and aggregation issues.
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Yuliestyan, Avido, Pedro Partal, Francisco J. Navarro, Raquel Martín-Sampedro, David Ibarra, and María E. Eugenio. "Emulsion Stabilization by Cationic Lignin Surfactants Derived from Bioethanol Production and Kraft Pulping Processes." Polymers 14, no. 14 (July 15, 2022): 2879. http://dx.doi.org/10.3390/polym14142879.
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Oil-in-water bitumen emulsions stabilized by biobased surfactants such as lignin are in line with the current sustainable approaches of the asphalt industry involving bitumen emulsions for reduced temperature asphalt technologies. With this aim, three lignins, derived from the kraft pulping and bioethanol industries, were chemically modified via the Mannich reaction to be used as cationic emulsifiers. A comprehensive chemical characterization was conducted on raw lignin-rich products, showing that the kraft sample presents a higher lignin concentration and lower molecular weight. Instead, bioethanol-derived samples, with characteristics of non-woody lignins, present a high concentration of carbohydrate residues and ashes. Lignin amination was performed at pH = 10 and 13, using tetraethylene pentamine and formaldehyde as reagents at three different stoichiometric molar ratios. The emulsification ability of such cationic surfactants was firstly studied on prototype silicone oil-in-water emulsions, attending to their droplet size distribution and viscous behavior. Among the synthetized surfactants, cationic kraft lignin has shown the best emulsification performance, being used for the development of bitumen emulsions. In this regard, cationic kraft lignin has successfully stabilized oil-in-water emulsions containing 60% bitumen using small surfactant concentrations, between 0.25 and 0.75%, which was obtained at pH = 13 and reagent molar ratios between 1/7/7 and 1/28/28 (lignin/tetraethylene pentamine/formaldehyde).
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Ruel, Katia, Vincent Burlat, and Jean-Paul Joseleau. "Relationship Between Ultrastructural Topochemistry of Lignin and Wood Properties." IAWA Journal 20, no. 2 (1999): 203–11. http://dx.doi.org/10.1163/22941932-90000681.
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The main subunits of lignin could be visualized by transmission electron microscopy (TEM) with antibodies raised against synthetic lignin model polymers. Thus, immunological probes against p-hydroxyphenyl propane, guaiacyl and mixed guaiacyl-syringyl units allowed to specifically localize the qualitative distribution of lignins in plant cell tissues . Depending on the mode of preparation of the synthetic lignin antigens , the corresponding antibodies showed specificity for condensed or noncondensed interunits linkages . This specificity is illustrated with the different labellings provided by the antibodies when applied to various wood and nonwoody materials . The results c1early show the heterogeneity of lignification between tissues but also demonstrate the microheterogeneity of lignin deposition within a a single wood cell wall. Our immunological markers were successfully applied to transgenic plants in which lignin synthesis pathways had been modified, to tissues from reaction wood, as well as to materials degraded by ligninolytic fungi.
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Yanagisawa, Masahiro, and Akira Isogai. "Size exclusion chromatographic and UV-VIS absorption analyses of unbleached and bleached softwood kraft pulps using LiCl/1,3-dimethyl-2-imidazolidinone as a solvent." Holzforschung 61, no. 3 (May 1, 2007): 236–41. http://dx.doi.org/10.1515/hf.2007.046.
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Abstract Unbleached and bleached kraft pulps and holocellulose prepared from softwood were totally soluble in 8% LiCl/1,3-dimethyl-2-imidazolidinone (LiCl/DMI). The solutions were analyzed by size exclusion chromatography with photodiode array and multi-angle laser light scattering detection (SEC-PDA-MALLS). The mobile phase consisted of 1% LiCl/DMI. The degree of polymerization (DP) and DP distribution of the softwood kraft pulps were determined, as well as the DP distribution of residual lignins based on their UV-VIS absorption patterns. Changes in DP for kraft pulps after a conventional bleaching sequence were evaluated, and the residual lignins were analyzed in the same way. Approximately half of the residual lignin in unbleached and bleached kraft pulps was present in polysaccharide fractions with high DP, which represented approximately 90% of the total yield. Some characteristic differences in the UV-VIS absorption pattern were observed between kraft pulps bleached with oxygen and chlorine. DP, DP distribution of polysaccharides, and distribution of residual lignin were clearly different for unbleached kraft pulp, unbleached sulfite pulp, and holocellulose. An unbleached kraft pulp prepared from hardwood showed different properties to the corresponding softwood preparation. The UV-VIS absorption patterns due to residual lignins were also very characteristic for the various pulps and holocellulose.
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Ribeiro, William C. O., Vinícius Lobosco, and Patrícia F. M. Martinez. "Solubility parameters analysis of Eucalyptus urograndis kraft lignin." BioResources 15, no. 4 (September 23, 2020): 8577–600. http://dx.doi.org/10.15376/biores.15.4.8577-8600.
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Lignin has gained momentum as a renewable material because it is the largest natural source that can provide aromatic compounds in a wide range of applications. However, its heterogeneity in terms of high polydispersity molar mass distribution and variety of functional groups has limited the direct production of added-value lignin-derivatives. Among the alternatives to obtain more homogeneous lignin cuts is solvent fractionation. However, it is not well understood how different solvents influence lignin partition, and thus it is difficult to establish a rational solvent order to perform it. Thus, the purpose of this work was to understand Eucalyptus urograndis kraft lignin partition in organic solvents through the application of three solubility parameter theories: Hildebrand, Hansen (HSP), and Functional (FSP). Through the theories studied, FSP provided the best representation of lignin partition in organic solvents. In addition, the influence of solvents’ solubility parameters on lignin solubility was investigated by multiregression analyses, which revealed that only the polar solvent parameter showed statistical relevance to describe lignin solubility. The results of this work may contribute to the effective development of technical lignins’ fractionation, allowing the production of higher-value lignin derivatives, increasing the profitability of biorefineries, and establishing a sustainable bio-based economy.
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Gilarranz, Miguel A., Francisco Rodríguez, and Mercedes Oliet. "Lignin Behavior During the Autocatalyzed Methanol Pulping of Eucalyptus globulus Changes in Molecular Weight and Functionality." Holzforschung 54, no. 4 (July 4, 2000): 373–80. http://dx.doi.org/10.1515/hf.2000.064.
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Summary The molecular weight distribution and functional group contents (phenolic and carbonyl) of lignin samples from the autocatalyzed pulping of Eucalyptus globulus wood were determined. A total of 17 pulping runs were carried out at different conditions according to a surface response design experimental matrix (central composite). The influence of pulping temperature (170–200°C), pulping time (40–120 min) and methanol concentration (30–70%, w/w) on the characteristics of the isolated lignins was studied. Empirical models were developed and used to predict the lignin properties as a function of the cooking conditions. Under high temperature, long cooking time and low alcohol concentration, a rise in functional groups content and a drop in molecular weight of lignin
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Pacheco, Marta, Filomena Pinto, Anders Brunsvik, Rui André, Paula Marques, Ricardo Mata, Joana Ortigueira, Francisco Gírio, and Patrícia Moura. "Effects of Lignin Gasification Impurities on the Growth and Product Distribution of Butyribacterium methylotrophicum during Syngas Fermentation." Energies 16, no. 4 (February 9, 2023): 1722. http://dx.doi.org/10.3390/en16041722.
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This work evaluated the effects of condensable syngas impurities on the cell viability and product distribution of Butyribacterium methylotrophicum in syngas fermentation. The condensates were collected during the gasification of two technical lignins derived from wheat straw (WST) and softwood (SW) at different temperatures and in the presence or absence of catalysts. The cleanest syngas with 169 and 3020 ppmv of H2S and NH3, respectively, was obtained at 800 °C using dolomite as catalyst. Pyridines were the prevalent compounds in most condensates and the highest variety of aromatics with cyanide substituents were originated during WST lignin gasification at 800 °C without catalyst. In contrast with SW lignin-based condensates, the fermentation media supplemented with WST lignin-derived condensates at 1:100 vol. only supported residual growth of B. methylotrophicum. By decreasing the condensate concentration in the medium, growth inhibition ceased and a trend toward butyrate production over acetate was observed. The highest butyrate-to-acetate ratio of 1.3 was obtained by supplementing the fermentation media at 1:1000 vol. with the condensate derived from the WST lignin, which was gasified at 800 °C in the presence of olivine. B. methylotrophicum was able to adapt and resist the impurities of the crude syngas and altered its metabolism to produce additional butyrate.
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Gea, Saharman, Amir Hamzah Siregar, Emma Zaidar, Mahyuni Harahap, Denny Pratama Indrawan, and Yurika Almanda Perangin-Angin. "Isolation and Characterisation of Cellulose Nanofibre and Lignin from Oil Palm Empty Fruit Bunches." Materials 13, no. 10 (May 15, 2020): 2290. http://dx.doi.org/10.3390/ma13102290.
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A study on isolation and characterisation of cellulose nanofibre (CNF) and lignin was conducted to expand the application of CNF and lignin from oil palm biomass. CNF was extracted by steam explosion and the by-product was precipitated to obtain lignin by using the soda-pulping method. The concentrations of NaOH used for CNF by-product precipitation were 2%, 4%, and 6%. The morphology of CNF and lignin was characterised using scanning electron microscopy (SEM). The nanofibre of CNF with dimension between 50 nm and 100 nm was investigated using transmission electron microscopy (TEM). The functional group was observed using Fourier-transform infrared (FTIR) spectroscopy, showing that CNF had the structure of cellulose-I. In addition, the chemical structures of isolated and commercial lignin were analysed using 1H-NMR spectrometry. CNF had a 72% crystallinity index characterised by X-ray diffraction (XRD), while lignin showed an amorphous form. The characterisation of isolated lignin was compared with commercial lignin. The two lignins had similar particle size distribution from 1 to 100 μm. From UV-visible analysis, the lignin had aromatic rings/non-conjugated phenolic groups. The morphology of isolated lignin was rough and flaky. Commercial lignin was in powder form with near-spherical morphology. Thermogravimetric analysis (TGA) of CNF showed 30% of residue at 600 °C. The results showed a simple method to isolate CNF and lignin from oil palm empty fruit bunches.
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Yang, Jie, Mengya Sun, Liang Jiao, and Hongqi Dai. "Molecular Weight Distribution and Dissolution Behavior of Lignin in Alkaline Solutions." Polymers 13, no. 23 (November 28, 2021): 4166. http://dx.doi.org/10.3390/polym13234166.
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Lignin, as the sole renewable aromatic resource in nature, has great potential for replacing fossil resources. However, the complexity of its structure limits its high value utilization, and the molecular weight distribution and dissolution behavior of lignin in alkaline solutions is still unclear. In this study, a conventional lignin separation during the pulping process in an alkaline hydrothermal system was performed by controlling the amount of NaOH, reaction temperature and holding time. Various analysis methods, including GPC, 2D–HSQC NMR and FTIR were used to study the characteristics of lignin fragments dissolved from wood. We were aiming to understand the rule of lignin dissolution and the recondensation mechanism during the process. The results showed dissolution of lignin due to ether bond fracturing by OH− attacking the Cα or Cβ positions of the side chain with penetration of NaOH, and the lignin fragments in solution recondensed into complex lignin with more stable C–C bonds. The experimental results also prove that the average molecular weight increased from 4337 g/mol to 11,036 g/mol and that holding time from 60 min to 120 min at 150 °C with 14 wt% of NaOH.
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LOGAN, KAREN J., and BARRY A. THOMAS. "DISTRIBUTION OF LIGNIN DERIVATIVES IN PLANTS." New Phytologist 99, no. 4 (April 1985): 571–85. http://dx.doi.org/10.1111/j.1469-8137.1985.tb03685.x.
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Donaldson, Lloyd, Jamie Hague, and Rebecca Snell. "Lignin Distribution in Coppice Poplar, Linseed and Wheat Straw." Holzforschung 55, no. 4 (June 21, 2001): 379–85. http://dx.doi.org/10.1515/hf.2001.063.
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Summary Lignin distribution was determined by interference microscopy, and by confocal laser scanning microscopy (CLSM) for a range of agricultural residues including coppice poplar, linseed, and wheat straw. Interference microscopy was used to determine the lignin concentration in the middle lamella at the cell corner, and for the secondary wall of libriform fibres in the secondary xylem of poplar and linseed. Wheat was examined in the same way for cortical fibres. In addition the secondary wall of vessel elements was examined for poplar. Confocal microscopy was used to confirm the results from interference microscopy by providing semiquantitative information based on lignin autofluorescence, and by staining with acriflavine. Wheat had the lowest level of lignification, with 31 % lignin in the middle lamella of cortical fibres and 9% lignin in the secondary wall. Poplar had a lignin concentration of 63% in the middle lamella and 6% in the secondary wall of libriform fibres, while linseed had corresponding values of 69 % and 13 %. The secondary wall of poplar vessel elements had a lignin concentration of 25 %. In all three species most of the stem tissue was lignified except for phloem and bark, where present. In linseed the pith was unlignified. In wheat, most of the parenchyma cells were lignified except for a few cells lining the stem cavity. Libriform fibres in poplar and linseed sometimes had an unlignified gelatinous layer in samples containing tension wood. In linseed, lignification was greater in xylem fibres compared to bast fibres. Ray parenchyma cells of poplar and linseed appeared to be lignified to the same extent as xylem fibres.
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Kanana, Chanon, Doungporn Cresry, and Thirawudh Pongprayoon. "Lignin Particle Production by Spray Dryer with Self-Assembly Technique." Materials Science Forum 1098 (September 29, 2023): 77–82. http://dx.doi.org/10.4028/p-ojpa7w.
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Spry dry and self-assembly techniques was applied to obtain a spherical lignin particle with low particles size distribution. Phase behavior of lignin, ethanol and water ternary system was investigated for spray dry process. Lignin with high solubility in ethanol fraction was used in this research. In the lignin/ethanol/water system, an increase in water content induces the self-assembly of lignin and forms lignin particles colloid. Sedimentation of lignin particles was observed at high lignin and water content. Three different contents of lignin at 1:9 of ethanol:water ratio which were stable colloids in the lignin/ethanol/water ternary system, were selected for spray dry process.,. The result was found that higher content of lignin showed smaller size (5.16 μm). FE-SEM results confirmed a spherical shape and low size distribution of the dried lignin particles. The chemical structure and thermal properties of the lignin particles were also investigated by FT-IR and TGA.
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Zhang, Chun Jing, Yu Liu, and Li Bin Dong. "The Analyses of Lignin Structure and Molecular Distribution of pH6 from Dissolved Kraft Lignin." Advanced Materials Research 550-553 (July 2012): 3311–15. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.3311.
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The Chinese poplar was used as the raw material in this study. Conversational Kraft cooking was carried out. The acid-precipitating method was used to separate the dissolved lignin from the black liquor. The FT-IR spectra was quantitatively analyzed and compared in order to discover the change of lignin structures. The lignin 31P—NMR spectra of pH6 lignin samples was obtained and the functional groups of the lignin was quantitatively analyzed and compared in order to discover the change of lignin structures during Kraft cooking. Syrinl-OH was 50~60 percent, Guaiacyl-OH was 40~50 percent. The pH6 lignin samples of 31P-NMR spectra aliphatic OH was 2.75 m mol/g, COOH was 1.75 m mol/g, total phenolic OH 5.66 m mol/g. The molecular weight distribution curves of lignin samples obtained from gel permeation chromatography analysis system was shown that Mw was 1375g/mol, Mn was 2426 g/mol and polydispersity was 4424 g/mol.
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Zhao, Yadong, Ayumu Tagami, Galina Dobele, Mikael E. Lindström, and Olena Sevastyanova. "The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films." Polymers 11, no. 3 (March 21, 2019): 538. http://dx.doi.org/10.3390/polym11030538.
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Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF)—starch mixture to prepare 100% bio-based composite films. The aim was to investigate the impact of lignin structural diversity on film performance. It was confirmed that lignin’s distribution in the films was dependent on the polarity of solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The –OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to decrease in thermal stability and increase in Young’s modulus of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic –OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol content, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the relationship between the chemical structure of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin’s applications in bio-based materials based on their specific characteristics.
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Pedersen, Nanna Bjerregaard, Uwe Schmitt, Gerald Koch, Claus Felby, and Lisbeth Garbrecht Thygesen. "Lignin distribution in waterlogged archaeological Picea abies (L.) Karst degraded by erosion bacteria." Holzforschung 68, no. 7 (October 1, 2014): 791–98. http://dx.doi.org/10.1515/hf-2013-0228.
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Abstract The lignin distribution in poles of waterlogged archaeological Picea abies (L.) Karst, which was decayed by erosion bacteria (EB) under anoxic conditions for approximately 400 years, was topochemically identified by transmission electron microscopy (TEM) and high resolution UV-microspectrophotometry (UMSP). Lignin rich cell wall compartments such as cell corner (CC), compound middle lamella (CML), torus, initial pit border and mild compression wood (CW) appeared morphologically well preserved together with S1 and S3 layers and epithelial and ray parenchyma cells. Residual material (RM) from degraded S2 showed a varied lignin distribution as evidenced by the different local UV-absorbance intensities. However, evaluation of UV-absorbance line spectra of RM revealed no change in conjugation of the aromatic ring system. Presence of RM with both very low and very high lignin absorbances showed evidence for disassembly of lignin during degradation combined with aggregation of lignin fragments and physical movement of these fractions. In contrast to TEM analysis, locally decreasing lignin content was found by UMSP in CML regions.
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Xu, Jindi, Dongying Hu, Qi Zheng, Qiulu Meng, and Ning Li. "The Distribution and Polymerization Mechanism of Polyfurfuryl Alcohol (PFA) with Lignin in Furfurylated Wood." Polymers 14, no. 6 (March 8, 2022): 1071. http://dx.doi.org/10.3390/polym14061071.
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There is increasing interest in furfurylated wood, but the polymerization mechanism between its internal polyfurfuryl alcohol (PFA) and lignin is still uncertain. This paper investigated the distribution of PFA and the feasibility of the polymerization of PFA with lignin in furfurylated balsa wood. The wood first immersed in the furfuryl alcohol (FA) solution followed by in situ polymerization and the distribution of PFA was characterized by Raman, fluorescence microscopy, SEM, and CLSM. Then, the mill wood lignin (MWL) of balsa wood and lignin model molecules were catalytically polymerized with PFA, respectively, studying the mechanism of interaction between PFA and lignin. It was concluded that PFA was mainly deposited in cell corner with high lignin concentration, and additionally partly deposited in wood cell cavity due to high concentration of FA and partial delignification. TGA, FTIR, and NMR analysis showed that the cross-linked network structure generated by the substitution of MWL aromatic ring free position by PFA hydroxymethyl enhanced the thermal stability. New chemical shifts were established between PFA and C5/C6 of lignin model A and C2/C6 of model B, respectively. The above results illustrated that lignin-CH2-PFA linkage was created between PFA and lignin in the wood cell wall.
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Gindl, W. "The Effect of Varying Latewood Proportion on the Radial Distribution of Lignin Content in a Pine Stem." Holzforschung 55, no. 5 (September 19, 2001): 455–58. http://dx.doi.org/10.1515/hf.2001.075.
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Summary The radial distribution of lignin content in a pine stem was compared to latewood proportion. With the exception of the innermost juvenile growth rings, a strong negative correlation was found. However, the cell-wall lignin content of low lignin growth rings was equal to that of high-lignin growth rings. Therefore, the difference in lignin content between individual growth rings was solely due to varying ratios of high-lignin compound middle lamella to low-lignin secondary wall in thin- and thick-walled tracheids.
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Khalil, H. P. S. Abdul, M. Siti Alwani, and A. K. Mohd Omar. "Chemical composition, anatomy, lignin distribution, and cell wall structure of Malaysian plant waste fibers." BioResources 1, no. 2 (November 4, 2006): 220–32. http://dx.doi.org/10.15376/biores.1.2.220-232.
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The chemical composition, anatomical characteristics, lignin distribution, and cell wall structure of oil palm frond (OPF), coconut (COIR), pine-apple leaf (PALF), and banana stem (BS) fibers were analyzed. The chemical composition of fiber was analyzed according to TAPPI Methods. Light microscopy (LM) and transmission electron microscopy (TEM) were used to observe and determine the cell wall structure and lignin distribution of various agro-waste fibers. The results revealed differences in anatomical characteristics, lignin distributions, and cell wall structure of the different types of fibers investigated. Nevertheless, transmission electron microscopy (TEM) micrographs have confirmed that the well wall structure, in each case, could be described in terms of a classical cell wall structure, consisting of primary (P) and secondary (S 1 , S 2 , and S 3 ) layers.
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Dong, Li Bin, and Yu Liu. "The Analyses of Lignin Structure and Molecular Distribution of pH6 from Dissolved Soda-AQ Lignin." Advanced Materials Research 550-553 (July 2012): 3299–304. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.3299.
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The Chinese poplar was used as the raw material in this study. Conversational Soda-AQ cooking was carried out. The acid-precipitating method was used to separate the dissolved lignin from the black liquor. The FT-IR spectra was quantitatively analyzed and compared in order to discover the change of lignin structures. The lignin 31P—NMR spectra of pH6 lignin samples was obtained and the functional groups of the lignin was quantitatively analyzed and compared in order to discover the change of lignin structures during Soda-AQ cooking. Syrinl-OH was 50~60 percent, Guaiacyl-OH was 40~50 percent. The pH6 lignin samples of 31P-NMR spectra aliphatic OH was 5.93 m mol/g, COOH was 0.99 m mol/g, total phenolic OH 7.07 m mol/g. The molecular weight distribution curves of lignin samples obtained from gel permeation chromatography analysis system was shown that Mw was 1506g/mol, Mn was 2888 g/mol and polydispersity was 5257 g/mol.
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McClelland, Daniel J., Ali Hussain Motagamwala, Yanding Li, Marjorie R. Rover, Ashley M. Wittrig, Chunping Wu, J. Scott Buchanan, et al. "Functionality and molecular weight distribution of red oak lignin before and after pyrolysis and hydrogenation." Green Chemistry 19, no. 5 (2017): 1378–89. http://dx.doi.org/10.1039/c6gc03515a.
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Goto, Masakazu, Keiji Takabe, and Isao Abe. "Histochemistry and UV-microspectrometry of cell walls of untreated and ammonia-treated barley straw." Canadian Journal of Plant Science 78, no. 3 (July 1, 1998): 437–43. http://dx.doi.org/10.4141/p97-013.
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Histochemical staining reactions with acid phloroglucinol and ultraviolet (UV) absorption spectra of the individual cell walls in spring barley straw (Hordeum vulgare L.) were investigated in combination with spectrometric measurements of the dioxane-water soluble lignin. Changes in lignin structure of barley straw with ammonia treatment were also investigated. Parenchyma and metaxylem vessel walls in untreated straw stained red with acid phloroglucinol and had higher absorbances around 550 nm than did epidermis and sclerenchyma cell walls, being consistent with the λmax of coniferylaldehyde. Following a reductive treatment, the lignins isolated from untreated barley straw showed an increase in UV absorbance at 280 nm and a decrease in that around 320 nm. These regions in UV and IR absorption spectra are assigned to conjugated carbonyl groups as shown by the narrowing of the IR absorption band at 1660 cm−1, and this was consistent with the staining observation of the specific tissue walls. UV microspectrometry indicated that parenchyma cell walls were much less lignified tissues than metaxylem and protoxylem vessel walls and probably epidermal cell walls. The lignins isolated from untreated and ammonia-treated straw had similar values for empirical formulae of the C9 units, phenolic hydroxyl and methoxyl group contents, and molecular weight, although the lignin of ammonia-treated straw had a slightly higher contents of nitrogen and hydrogen. The IR bands of 1730–1680 cm−1 in ammonia-treated straw lignin also disappeared. Therefore, ammonia appeared to react with the carbon atoms of the propane side-chain. Key words: Ammonia treatment, barley straw, lignin distribution, lignin structure, staining with acid phloroglucinol, ultraviolet microspectrometry
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Leite, Rogério, Yêda Medeiros B. de Almeida, Sandra Maria Sarmento, Kleber G. B. Alves, Etelino Feijó de Melo, and Rosa Maria Souto-Maior. "Solvent-fractionated sugar cane bagasse lignin: structural characteristics and electro-spinnability." e-Polymers 16, no. 2 (March 1, 2016): 137–44. http://dx.doi.org/10.1515/epoly-2015-0229.
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AbstractLignin is one of the most abundant macromolecules on Earth. Lignins are obtained as by-products from the paper industry and used mostly as fuel. Their diverse composition has limited the development of high added-value applications: however, because of their abundance and sustainable origin, there is a growing interest in using lignins as a raw material and as a replacement for oil derivatives. In order to use lignins in bio-refineries, several processes must be studied and standardized. Lignin fractionation using solvents is a promising process. In this study, lignin from sugar cane bagasse (L1) was fractionated with solvents, and the fractions were characterized to evaluate structural aspects relevant for the production of fibers. L1 was extracted into four fractions with toluene (E1), ethanol (E2), methanol (E3), and dimethyl sulfoxide (DMSO, E4). Fractions E2, E3, and E4, showed only slightly different molar masses and molar mass distribution, but have relevant differences in their structural characteristics and processability. The ethanol extract (E2) provided lignins with a more flexible structure, and electro-spinning resulted in the production of nanofibers with diameters between 60 and 120 nm; the methanol fraction (E3) produced nanospheres with diameters between 90 and 350 nm; the DMSO fraction (E4) covered only a surface with electro-spray. These results show the possibility of developing high added-value applications using fractions of lignin from distinct biomasses or from their combination.
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Li, Tengfei, Xin Jin, Xinyao Shen, Hangdan Liu, Ruiping Tong, Xuzhen Qiu, and Junfei Xu. "Study on the Relationship between the Structure and Pyrolysis Characteristics of Lignin Isolated from Eucalyptus, Pine, and Rice Straw through the Use of Deep Eutectic Solvent." Molecules 29, no. 1 (December 30, 2023): 219. http://dx.doi.org/10.3390/molecules29010219.
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Understanding the pyrolysis product distributions of deep eutectic solvent (DES)-isolated lignins (DESLs) from different types of biomass is of great significance for lignin valorization. The structure and pyrolysis properties of DESLs obtained from eucalyptus (E-DESL), pine (P-DESL), and rice straw (R-DESL) were studied through the use of various methods such as elemental analysis, GPC, HS-GC, and NMR techniques, and the pyrolysis characteristics and product distributions of the DESLs were also further investigated through the use of TGA, Py-GC/MS, and tubular furnace pyrolysis. DESLs with high purity (88.5–92.7%) can be efficiently separated from biomass while cellulose is retained. E-DESL has a relatively low molecular weight, and P-DESL has a relatively higher hydrogen–carbon effective ratio and a lower number of condensation structures. The Py-GC/MS results show that, during DESL pyrolysis, the monomeric aromatic hydrocarbons, p-hydroxyphenyl-type phenols, and catechol-type phenols are gradually released when the guaiacyl-type phenols and syringyl-type phenols decrease with the rising temperature. 4-methylguaiacol and 4-methylcatechol, derived from the guaiacyl-type structural units, are positively correlated with temperature, which causes a significant increase in products with a side-chain carbon number of 1 from P-DESL pyrolysis. 4-vinylphenol, as a representative product of the R-DESL, derived from p-hydroxyphenyl-type structural units, also gradually increased. In addition, the P-DESL produces more bio-oil during pyrolysis, while gases have the highest distribution in E-DESL pyrolysis. It is of great significance to study the characteristic product distribution of lignin isolated through the use of DES for lignin directional conversion into specific high-value aromatic compounds.
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Blumentritt, Melanie, Douglas J. Gardner, Barbara J. W. Cole, and Stephen M. Shaler. "Influence of hot-water extraction on ultrastructure and distribution of glucomannans and xylans in poplar xylem as detected by gold immunolabeling." Holzforschung 70, no. 3 (March 1, 2016): 243–52. http://dx.doi.org/10.1515/hf-2015-0030.
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Abstract Pre-extraction of hemicelluloses from lignocellulosic feedstock has been a research focus during the last decade within the context of lignocellulosic biorefineries. In this study, the effect of hot-water extraction (HWE) on the topochemistry and ultrastructure of poplar wood (Populus sp.) was investigated based on scanning electron microscopy (SEM) and transmission electron microscopy (TEM) paired with immunogold labeling of the hemicelluloses. The cell walls of HWE wood (HWEW) differ significantly in their ultrastructure from neat wood, i.e., there are many distorted cells and agglomerations of lignin and extractives agglomerations in the cell lumina. Results of immunogold labeling indicate that different types of hemicelluloses are extracted at different stages and both their concentration and distribution within the wood cell wall layers are affected by the HWE. Hemicelluloses more closely associated with lignin appear to be more easily removed by HWE. Lignins are also extracted partially and altered. Results provide a holistic view of chemical and ultrastructural changes including the associated changes in hemicelluloses and lignin distribution in HWEW. The obtained data could be helpful to understand better the mechanical properties and adhesion related issues of HWEW for wood composite production.
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More, Ajinkya, Thomas Elder, and Zhihua Jiang. "A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids." Holzforschung 75, no. 9 (March 18, 2021): 806–23. http://dx.doi.org/10.1515/hf-2020-0165.
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Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.
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Nieminen, Kaarlo, and Herbert Sixta. "Comparative evaluation of different kinetic models for batch cooking: A review." Holzforschung 66, no. 7 (October 1, 2012): 791–99. http://dx.doi.org/10.1515/hf-2011-0122.
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Abstract The purpose of this study was to review some of the existing models for delignification in kraft cooking. Data and results from earlier studies were utilized to evaluate the performance of the models of Gustafson (MG), Purdue (MP), Andersson (MA) and Bogren’s method “continuous distribution of reactivity” (MBcdr) in terms of their ability to give a realistic description for delignification of softwood and hardwood. The MG, MP and MBcdr were tested on lignin data obtained from cooks of Eucalyptus globulus. In this case, MP seemed to perform best, whereas the MBcdr failed in the range of low residual lignins. MA considers the lignin subunits with various reaction speeds, and this feature improves the performance in the case of low residual lignins and helps to reflect sudden changes in cooking conditions, but the difference to the ordinary MP is moderate.
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Liu, Bo, Lina Tang, Qian Chen, Liming Zhu, Xianwu Zou, Botao Li, Qin Zhou, Yuejin Fu, and Yun Lu. "Lignin Distribution on Cell Wall Micro-Morphological Regions of Fibre in Developmental Phyllostachys pubescens Culms." Polymers 14, no. 2 (January 13, 2022): 312. http://dx.doi.org/10.3390/polym14020312.
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Bamboo is a natural fibre reinforced composite with excellent performance which is, to a certain extent, an alternative to the shortage of wood resources. The heterogeneous distribution and molecular structure of lignin is one of the factors that determines its performance, and it is the key and most difficult component in the basic research into the chemistry of bamboo and in bamboo processing and utilization. In this study, the distribution of lignin components and lignin content in micro-morphological regions were measured in semi-quantitative level by age and radial location by means of visible-light microspectrophotometry (VLMS) coupled with the Wiesner and Maule reaction. There as guaiacyl lignin and syringyl lignin in the cell wall of the fibre. Lignin content of the secondary cell wall and cell corner increased at about 10 days, reached a maximum at 1 year, and then decreased gradually. From 17 days to 4 years, the lignin content of the secondary cell wall in the outer part of bamboo is higher than that in the middle part (which is, in turn, higher than that in the inner part of the bamboo). VLSM results of the micro-morphological regions showed that bamboo lignification developed by aging. Guaiacyl and syringl lignin units can be found in the cell wall of the fibre, parenchyma, and vessel. There was a difference in lignin content among different ages, different radial location, and different micro-morphological regions of the cell wall. The fibre walls were rich in guaiacyl lignin in the early stage of lignification and rich in syringyl units in the later stage of lignification. The guaiacyl and syringyl lignin deposition of bamboo green was earlier than that of the middle part of bamboo culm, and that of the middle part of bamboo culm was earlier than that of bamboo yellow. The single molecule lignin content of the thin layer is higher than that of thick layers, while the primary wall is higher than the secondary cell wall, showing that lignin deposition is consistent with the rules of cell wall formation. The obtained cytological information is helpful to understand the origin of the anisotropic, physical, mechanical, chemical, and machining properties of bamboo.
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Lybeer, Bieke, and Gerald Koch. "Lignin Distribution in the Tropical Bamboo Species Gigantochloa Levis." IAWA Journal 26, no. 4 (2005): 443–56. http://dx.doi.org/10.1163/22941932-90000126.
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The lignin distribution within the cell walls of Gigantochloa levis was studied topochemically by means of TEM and cellular UV microspectrophotometry. The distribution of lignin structural units in different anatomical regions is described and lignification of the tropical bamboo species Gigantochloa levis is compared with that of the temperate bamboo species Phyllostachys viridiglaucescens. Considerable differences were found in cell wall structure between fibres adjacent to the vascular tissue, fibres of free fibre strands and parenchyma cells. The S2 fibre wall in general has a lamellar structure with an increasing lignin content from the centre towards the compound middle lamella. P-coumaric and ferulic acids are more widely distributed in G. levis and their content depends on the anatomical location. The early maturing fibres adjacent to the vascular tissue and at the outer culm wall reveal a maximum absorbance at 280 nm (guaiacyl peak) whereas the late maturing fibres display a shoulder at 310–320 nm. This is in contrast to P. viridiglaucescens where the late maturing fibres also show a maximum peak at 280 nm. The compound middle lamellae show higher absorbance values and are richer in p-coumaric and ferulic acid esters in comparison to the S2 wall layers. The vessel walls have a lower lignin content. A difference in lignin content between the various ages and between flowering and non-flowering culms could not be observed.
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Ang, Aikfei, Zaidon Ashaari, Edi Suhaimi Bakar, and Nor Azowa Ibrahim. "Characterisation of Sequential Solvent Fractionation and Base-catalysed Depolymerisation of Treated Alkali Lignin." BioResources 10, no. 3 (May 21, 2015): 4137–51. http://dx.doi.org/10.15376/biores.10.3.4137-4151.
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An alkali lignin (OL) with a weight-average molecular weight (Mw) of 11646 g/mol was used to prepare low-molecular weight lignin for resin synthesis. The low-molecular weight lignin feedstock was obtained via base-catalysed depolymerisation (BCD) treatments at different combined severity factors. Sequential fractionation of the OL and BCD-treated lignins using organic solvents with different Hildebrand solubility parameters were used to alter the homogeneity of the OL. The yield and properties of OL itself and OL and BCD-treated OL dissolved in propan-1-ol (F1), ethanol (F2), and methanol (F3) were determined. Regardless of the treatment applied, a small amount of OL was dissolved in F1 and F2. The BCD treatment did not increase the yield of F1 but did increase the yields of F2 and F3. Gel permeation chromatography (GPC) showed that the repolymerization reaction occurred in F3 for all BCD-treated OL, so these lignins were not suitable for use as feedstocks for resin production. The GPC, 13Carbon-nuclear magnetic resonance, and Fourier transform infrared spectroscopy analyses confirmed that the F3 in OL exhibited the optimum yield, molecular weight distribution, and chemical structure suitable for use as feedstocks for resin synthesis.
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Donaldson, Lloyd A., Adya P. Singh, Arata Yoshinaga, and Keiji Takabe. "Lignin distribution in mild compression wood of Pinus radiata." Canadian Journal of Botany 77, no. 1 (June 1, 1999): 41–50. http://dx.doi.org/10.1139/b98-190.
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Lignin distribution in the tracheid cell wall of mild compression wood in Pinus radiata D. Don was examined by interference microscopy, confocal fluorescence microscopy, and ultraviolet (UV) microscopy. Two anatomically different samples of mild compression wood were compared with a sample of normal wood using quantitative interference microscopy and microdensitometry combined with confocal fluorescence microscopy to estimate the quantitative or semiquantitative lignin distribution in the S2 and S2L regions of the secondary cell wall and of the cell corner middle lamella (CCML). One of these samples was briefly examined by UV microscopy for comparison. Quantitative interference microscopy provided information on lignin concentration in different regions of the cell wall with values of 26, 46, and 57%, respectively, for the S2, S2L, and CCML regions of sample 1 and 20, 29, and 46%, respectively, for the same regions of sample 2. Microdensitometry of confocal fluorescence images provided semiquantitative information on the relative lignin distribution based on lignin autofluorescence. Comparison between the two compression wood samples using autofluorescence gave results that were in partial agreement with interference microscopy with respect to the relative lignification levels in the S2, S2L, and CCML regions. Some improvement was achieved by using calibration values for hemicellulose rather than holocellulose for interference data in the S2L region. Results for UV microscopy performed on sample 1 indicated that the lignification of the CCML region was comparable with that of the S2L region in this sample but with some variation among cells. All three techniques indicated significant variation in lignification levels of the S2L and CCML regions among adjacent cells and a significant reduction in the lignification of the CCML region compared to normal wood.Key words: lignin distribution, interference microscopy; confocal fluorescence microscopy, UV microscopy, mild compression wood, Pinus radiata D. Don.
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Ma, Jianfeng, Xia Zhou, Jing Ma, Zhe Ji, Xun Zhang, and Feng Xu. "Raman Microspectroscopy Imaging Study on Topochemical Correlation Between Lignin and Hydroxycinnamic Acids in Miscanthus sinensis." Microscopy and Microanalysis 20, no. 3 (April 15, 2014): 956–63. http://dx.doi.org/10.1017/s1431927614000658.
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AbstractConfocal Raman microspectroscopy (CRM) has emerged as a powerful approach to visualize the compositional distribution in lignocellulosic biomass of cell walls. In this work, the applicability of CRM for imaging the topochemical correlation between lignin and hydroxycinnamic acids (HCA) in the Miscanthus sinensis internode was explored. Model compound [p-coumaric acid (PCA) and ferulic acid (FA)] analysis indicated that the band region from 1,152 to 1,197 cm−1 can be used to characterize the distribution of HCA. Raman images calculated by integrating over the area intensity of characteristic spectral regions showed heterogeneous distribution of lignin and HCA at cellular and sub-cellular level. When overlaying the Raman image of lignin and HCA distribution, it was found that these two polymers were co-located in the middle lamella and secondary wall of corresponding cells. Raman images for the band intensity ratio (1,173 cm−1/1,603 cm−1) indicated a clear association between lignin and HCA distribution within morphologically distinct cell wall layers of sclerenchyma fibers and the parenchyma. This is the first time that the spatial correlation between lignin and HCA concentration has been illustrated by a microspectroscopy imaging approach. The results are of importance in extending the current understanding of lignin and aromatics topochemistry in herbaceous biomass.
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Yones, Tehani A. E., Hai Bin Zhu, Yin Xuan Fu, Yong Mei Chen, and Ping Yu Wan. "The Effects of Catalysts on Pyrolysis Products of Enzymolyzed Straw Lignin." Applied Mechanics and Materials 295-298 (February 2013): 345–50. http://dx.doi.org/10.4028/www.scientific.net/amm.295-298.345.
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Lignin is depolymerized to small molecule aromatic compounds, which is regarded as one of the effective ways to achieve utilization of lignin resource. In this study, Al and Cu catalysts were loaded onto enzymolyzed straw lignin by the immersion method, and the product distribution of the catalytic pyrolysis of lignin was studied by GC-MS after being extracted by solvents. Results show that both Al and Cu catalysts can promote the lignin pyrolysis reaction. Based on the comparison of the product distribution without catalyst, Al catalyst is benefit to the formation of aromatic hydrocarbons, alcohols and phenols, while Cu catalyst contribute to the formation of hydrocarbons, alcohols and ketones.
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Takabe, Keiji, Shigeru Miyauchi, Ryuichi Tsunoda, and Kazumi Fukazawa. "Distribution of Guaiacyl and Syringyl Lignins in Japanese Beech (Fagus Crenata): Variation Within an Annual Ring." IAWA Journal 13, no. 1 (1992): 105–12. http://dx.doi.org/10.1163/22941932-90000561.
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Microspectrometry is the most definitive technique for obtaining both ultraviolet (UV) and visible light absorption spectra from a very limited area, and this technique allows the determination of lignin distribution throughout an individual cell wall. It is generally accepted that hardwood lignin .is composed mainly of guaiacyl and syringyl moieties. Our microspectrometric investigations revealed variation of lignin distribution within an annual ring in beech (Fagus crenata).
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Álvarez-Barajas, Rodrigo, Antonio A. Cuadri, Francisco J. Navarro, Francisco J. Martínez-Boza, and Pedro Partal. "Bioethanol Production and Alkali Pulp Processes as Sources of Anionic Lignin Surfactants." Polymers 13, no. 16 (August 13, 2021): 2703. http://dx.doi.org/10.3390/polym13162703.
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Lignin is an abundant biopolymer with potential value-added applications that depend on biomass source and fractioning method. This work explores the use as emulsifiers of three native lignin-rich product coming from industrial bioethanol production and alkali or Kraft pulping. In addition to their distinctive characteristics, the different molecular organization induced by emulsification pH is expected to interact in various ways at the water-oil interface of the emulsion droplets. Initially, model oil-in-water (O/W) emulsions of a silicone oil will be studied as a function of lignin source, disperse phase concentration and emulsification pH. Once stablished the effect of such variables, emulsion formulations of three potential bitumen rejuvenators (waste vegetable cooking oil, recycled lubricating oil and a 160/220 penetration range soft bitumen). Droplet size distribution, Z-potential and viscous tests conducted on model emulsions have shown that emulsification pH strongly affects stabilization ability of the lignins tested. Regarding bitumen rejuvenators, lignin emulsification capability will be affected by surfactant source, pH and, additionally, by the dispersed phase characteristics. Lower Z-potential values shown by KL at pH 9 and 11 seem to facilitate emulsification of the less polar disperse phases formed by RLUB and bitumen. In any case, lower particle size and higher yield stress values were found for both bioethanol-derived lignins emulsifying RVO and RLUB at pH 13, which are expected to exhibit a longer stability.
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Kiyoto, Shingo, Arata Yoshinaga, Eva Fernandez-Tendero, Arnaud Day, Brigitte Chabbert, and Keiji Takabe. "Distribution of Lignin, Hemicellulose, and Arabinogalactan Protein in Hemp Phloem Fibers." Microscopy and Microanalysis 24, no. 4 (August 2018): 442–52. http://dx.doi.org/10.1017/s1431927618012448.
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AbstractThe distribution of lignin, 8-5′ and 8-8′ linked lignin substructure, and noncellulosic polysaccharides in hemp (Cannabis sativa L.) phloem fibers were explored based on histochemical and immunological methods. Ultraviolet absorption and potassium permanganate staining were observed mainly in the compound middle lamella (CML) and S1 layers, and rarely in the G-layer of phloem fibers, suggesting that lignin concentration is high at the CML and S1 layers, and very low at the G-layer of hemp fibers. Acriflavine staining, uniform KM1 labeling (8-5′ linked lignin substructure), and no KM2 labeling (8-8′ linked structure) were observed in the G-layer, suggesting that there is a small amount of lignin-like compound with 8-5′ linked structure in the G-layer. In addition, some fiber cells showed a multilayered structure. Uniform arabinogalactan protein (AGP) labeling was observed on the S1 layers and G-layers using JIM14, but little appeared in the CML of hemp fibers, indicating that these layers of the phloem fibers contain AGP. Immunogold labeling of xylan (LM11) and glucomannan (LM21) showed that xylan and glucomannan were mainly present in the S1 layers and the G-layers, respectively. In some phloem fibers, LM21 immunofluorescence labeling showed multilayered structure, suggesting the heterogeneous distribution of glucomannan.
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Pylypchuk, Ievgen, Roman Selyanchyn, Tetyana Budnyak, Yadong Zhao, Mikael Lindström, Shigenori Fujikawa, and Olena Sevastyanova. "“Artificial Wood” Lignocellulosic Membranes: Influence of Kraft Lignin on the Properties and Gas Transport in Tunicate-Based Nanocellulose Composites." Membranes 11, no. 3 (March 13, 2021): 204. http://dx.doi.org/10.3390/membranes11030204.
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Nanocellulose membranes based on tunicate-derived cellulose nanofibers, starch, and ~5% wood-derived lignin were investigated using three different types of lignin. The addition of lignin into cellulose membranes increased the specific surface area (from 5 to ~50 m2/g), however the fine porous geometry of the nanocellulose with characteristic pores below 10 nm in diameter remained similar for all membranes. The permeation of H2, CO2, N2, and O2 through the membranes was investigated and a characteristic Knudsen diffusion through the membranes was observed at a rate proportional to the inverse of their molecular sizes. Permeability values, however, varied significantly between samples containing different lignins, ranging from several to thousands of barrers (10−10 cm3 (STP) cm cm−2 s−1 cmHg−1cm), and were related to the observed morphology and lignin distribution inside the membranes. Additionally, the addition of ~5% lignin resulted in a significant increase in tensile strength from 3 GPa to ~6–7 GPa, but did not change thermal properties (glass transition or thermal stability). Overall, the combination of plant-derived lignin as a filler or binder in cellulose–starch composites with a sea-animal derived nanocellulose presents an interesting new approach for the fabrication of membranes from abundant bio-derived materials. Future studies should focus on the optimization of these types of membranes for the selective and fast transport of gases needed for a variety of industrial separation processes.