Journal articles on the topic 'Modification de lignine'
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1
Chatonnet, Pascal, Jean-Noël Boidron, Denis Dubourdieu, and Monique Pons. "Evolution de certains composés volatils du bois de chêne au cours de son séchage premiers résultats." OENO One 28, no. 4 (December 31, 1994): 359. http://dx.doi.org/10.20870/oeno-one.1994.28.4.1720.
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<p style="text-align: justify;">Pendant le séchage des merrains sur parc à l'air libre, on assiste à une profonde modification de la composition chimique et du profil aromatique du bois de chêne. La teneur en eugénol, en aldéhydes phénols et en Β-méthyl-y-octalactone augmente régulièrement pendant le vieillissement du bois. Principalement sous forme trans au début du séchage, la Β-méthyl-y-octalactone s'accumule finalement sous la forme cis plus aromatique. Dans le même temps, on observe également une accumulation importante du précurseur inodore de Β-méthyl-y-octalactone. L'intervention des micro-organismes fréquemment isolés sur le bois en cours de séchage naturel sur la formation de composés aromatiques a été étudiée. La culture de diverses moisissures isolées de bois en cours de séchage naturel sur extraits de bois et directement sur sciure de chêne aboutit dans tous les cas à une forte diminution des teneurs en aldéhydes phénols, notamment de la vanilline. En effet, tous les micro-organismes étudiés (<em>Penicilium sp., Trichoderma sp., Aureobasidium sp.</em>) sont incapables de dégrader la lignine car ils ne possèdent pas d'activité ligninase. En revanche, ces champignons possèdent une forte activité oxydo-réductase capable de réduire la vanilline en alcool vanillique inodore. En conséquence, les aldéhydes phénols apparaissant au cours du séchage naturel du merrain ne dérivent pas d'une attaque enzymatique mais plus vraisemblablementde l'acidolyse et de l'oxydation chimique de la lignine du bois. Le stockage du bois à l'air libre en présence d'eau et d'oxygène doit permettre une évolution favorable de son potentiel aromatique tant que la vanilline et la cis Β-méthyly-octalactone s'accumulent.</p>
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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.
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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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Suota, Maria Juliane, Débora Merediane Kochepka, Marlon Gualberto Ganter Moura, Cleverton Luiz Pirich, Mailson Matos, Washington Luiz Esteves Magalhães, and Luiz Pereira Ramos. "Lignin functionalization strategies and the potential applications of its derivatives – A Review." BioResources 16, no. 3 (July 12, 2021): 6471–511. http://dx.doi.org/10.15376/biores.16.3.suota.
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Lignin is one of the most important and widespread carbon sources on Earth. Significant amounts of lignin are delivered to the market by pulp mills and biorefineries, and there have been many efforts to develop routes for its valorization. Over the years, lignin has been used to produce biobased chemicals, materials, and advanced biofuels on the basis of its variable functionalities and physicochemical properties. Today, lignin’s applications are still limited by its heterogeneity, variability, and low reactivity. Thus, modification technologies have been developed to allow lignin to be suitable for a wider range of attractive industrial applications. The most common modifications used for this purpose include amination, methylation, demethylation, phenolation, sulfomethylation, oxyalkylation, acylation or esterification, epoxidation, phosphorylation, nitration, and sulfonation. This article reviews the chemistry involved in these lignin modification technologies, discussing their effect on the finished product while presenting some market perspectives and future outlook to utilize lignin in sustainable biorefineries.
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Chatonnet, Pascal, Jean-Noël Boidron, and Monique Pons. "Incidence du traitement thermique du bois de chêne sur sa composition chimique. 2e partie : évolution de certains composés en fonction de l'intensité de brûlage." OENO One 23, no. 4 (December 31, 1989): 223. http://dx.doi.org/10.20870/oeno-one.1989.23.4.1722.
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<p style="text-align: justify;">Au-delà de son action de cintrage, le chauffage du bois de chêne provoque une thermodégradation de certains de ses composants. Les auteurs étudient l'influence de l'intensité de brûlage du bois de chêne sessile <em>Quercus sessilis</em> sur certains composés extractibles. Afin de se rapprocher des conditions d'extraction par un vin, le bois brûlé à différents degrés est placé au contact d'une solution hydroalcoolique modèle.</p><p style="text-align: justify;">La thermolyse des principaux polymères pariétaux du bois, produit de nombreux composés volatils et odorants (aldéhydes furaniques, phénols volatils, aldéhydes phénols, phényl cétones). La concentration en β-méthyl-y-octalactone augmente notablement avec le chauffage du bois et simultanément les tanins hydrolysables sont en partie dégradés.</p><p style="text-align: justify;">La chauffe légère ne produit que de faibles variations. La chauffe moyenne correspond au maximum de synthèse de la majorité des composés aromatiques étudiés. A partir et au-delà de la chauffe forte, les réactions de thermodégradation, mais très vraisemblablement aussi une modification de la structure de la lignine vers une forme moins réactive, entraînent une diminution de l'ensemble des composés extractibles.</p>
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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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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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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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Younesi-Kordkheili, Hamed, and Antonio Pizzi. "A Comparison among Lignin Modification Methods on the Properties of Lignin–Phenol–Formaldehyde Resin as Wood Adhesive." Polymers 13, no. 20 (October 12, 2021): 3502. http://dx.doi.org/10.3390/polym13203502.
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The research aim of this work is to determine the influence of lignin modification methods on lignin–phenol–formaldehyde (LPF) adhesive properties. Thus, glyoxal (G), phenol (P), ionic liquid (IL), and maleic anhydride (MA) were used to modify lignin. The modified lignins were used for phenol substitution (50 wt%) in phenol–formaldehyde adhesives. The prepared resins were then used for the preparation of wood particleboard. These LPF resins were characterized physicochemically, namely by using standard methods to determine gel time, solids content, density, and viscosity, thus the physicochemical properties of the LPF resins synthesized. The panels dimensional stability, formaldehyde emission, bending modulus, bending strength, and internal bond (IB) strength were also measured. MA-modified lignin showed by differential scanning calorimetry (DSC) the lowest temperature of curing than the resins with non-modified lignin and modified with IL, phenolared lignin, and glyoxal. LPF resins with lignin treated with maleic anhydride presented a shorter gel time, higher viscosity, and solids content than the resins with other lignin modifications. Equally, the particleboard panels prepared with LPF resins with maleic anhydride or with ionic liquid had the lowest formaldehyde emission and the highest mechanical strength among all the synthesized resins. The dimensional stability of all panels bonded with modified lignin LPF resins presented no difference of any significance.
10
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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van de Pas, Daniel, Aynsley Hickson, Lloyd Donaldson, Gareth Lloyd-Jones, Tarja Tamminen, Alan Fernyhough, and Maija-Liisa Mattinen. "Characterization of fractionated lignins polymerized by fungal laccases." BioResources 6, no. 2 (February 20, 2011): 1105–21. http://dx.doi.org/10.15376/biores.6.2.1105-1121.
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Lignins are important biopolymers that can be converted into value-added materials by enzymatic treatments. However, the heterogeneity of the lignin polymer makes it a challenging material to modify. Thus, chemical fractionation was used to obtain lignins with high homogeneity in order to assess their biotechnological utilization. Commercial Alcell, birch organosolv lignins, and steam-exploded pine and eucalypt lignins were sequentially fractionated by ether, ether/acetone 4:1 (v:v), and acetone. All fractions were structurally characterized prior to treatments with Thielavia arenaria, Trametes hirsuta, and Melanocarpus albomyces laccases. The reactivities of the enzymes towards the lignins were determined by oxygen consumption measurements, and the degree of polymerization was confirmed by size exclusion chromatography. Field emission scanning electron microscopy revealed that the surfaces of the lignin nanoparticles were dispersed in the enzyme treatment, suggesting an increase in hydrophilicity of the surfaces detected as loosened morphology. Hence, it was concluded that enzyme-aided valorization is an attractive means for lignin modification, provided that optimum reaction conditions are employed.
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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.
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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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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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Zrelli, Adel, Walid Elfalleh, Achraf Ghorbal, and Bechir Chaouachi. "Valorization of Date Palm Wastes by Lignin Extraction to be Used for the Improvement of Polymeric Membrane Characteristics." Periodica Polytechnica Chemical Engineering 66, no. 1 (November 26, 2021): 70–81. http://dx.doi.org/10.3311/ppch.18273.
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This work aimed to valorize Date Palm Wastes (DPW) by the extraction of lignin and its application for polymeric membrane modification. Lignin was extracted from five types of DPW (date palm kernel, leaflet, pedicel, palm frond, and fibrilium) using the Klason method. Following DPW characterization, we remark the highest amount of extractives content in the leaflet sample (10.07 %) and the lowest in the fibrilium sample (6.51 %). The ash content ranged from 1.56 % for fibrilium to 7.96 % for palm frond. After extraction, the lignin yield was in the range of 22–32 %. The extracted lignins were characterized by Infrared and Ultraviolet–visible spectroscopy. All extracted lignins provide a high concentration of (-OH) group. Besides, both syringyl and guaiacyl are present in the extracted lignins with a slightly more syringyl unit. The extracted lignins were added to the polymeric solution, prepared from waste plastic, to produce membranes. These membranes showed improved hydrophilicity marked a decrease in the contact angle of 28 % when the lignin concentration increased from 0.125 to 0.5 %. In addition, the membrane porosity increased with the use of the extracted lignins as an additive.
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Alinejad, Mona, Christián Henry, Saeid Nikafshar, Akash Gondaliya, Sajad Bagheri, Nusheng Chen, Sandip Singh, David Hodge, and Mojgan Nejad. "Lignin-Based Polyurethanes: Opportunities for Bio-Based Foams, Elastomers, Coatings and Adhesives." Polymers 11, no. 7 (July 18, 2019): 1202. http://dx.doi.org/10.3390/polym11071202.
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Polyurethane chemistry can yield diverse sets of polymeric materials exhibiting a wide range of properties for various applications and market segments. Utilizing lignin as a polyol presents an opportunity to incorporate a currently underutilized renewable aromatic polymer into these products. In this work, we will review the current state of technology for utilizing lignin as a polyol replacement in different polyurethane products. This will include a discussion of lignin structure, diversity, and modification during chemical pulping and cellulosic biofuels processes, approaches for lignin extraction, recovery, fractionation, and modification/functionalization. We will discuss the potential of incorporation of lignins into polyurethane products that include rigid and flexible foams, adhesives, coatings, and elastomers. Finally, we will discuss challenges in incorporating lignin in polyurethane formulations, potential solutions and approaches that have been taken to resolve those issues.
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Kačíková, Danica, Ivan Kubovský, Nikoleta Ulbriková, and František Kačík. "The Impact of Thermal Treatment on Structural Changes of Teak and Iroko Wood Lignins." Applied Sciences 10, no. 14 (July 21, 2020): 5021. http://dx.doi.org/10.3390/app10145021.
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Thermal modification is an environmentally friendly method to improve dimensional stability, durability, and aesthetic properties of wood. Changes in lignin as one of the main wood components markedly influence wood product properties and recycling possibilities of thermowood at the end of its life cycle. Teak and iroko wood samples were thermally treated at the temperatures of 160 °C, 180 °C and 210 °C following the Thermowood process. Dioxane lignin was isolated from treated and untreated wood and analysed by nitrobenzene oxidation (NBO), size exclusion chromatography (SEC) and Fourier transform infrared spectroscopy (FTIR). The yields of both acid-insoluble and dioxane lignins increased with an increasing treatment temperature. Dioxane lignins are GS-types containing more guaiacyl units compared to syringyl ones with S/G ratios of 0.91 and 0.84, respectively. In the process of thermal modification, several degradation and condensation reactions were observed. The cleavage of methoxyl groups and side chains, oxidation reactions, cleavage of the β-O-4 ether linkage and cross-linking radicals arising at higher temperatures were all confirmed. However, during the thermal treatment, teak lignin changed in a different way than iroko lignin, e.g., the molecular weight of iroko lignin decreased at all applied temperatures while it increased at 180 °C and 210 °C in teak lignin, and the change in S/G ratio and the cleavage of alkyl-aryl bonds are different in both wood species.
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Li, Suxiang, Chengke Zhao, Fengxia Yue, and Fachuang Lu. "Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment." Polymers 12, no. 1 (January 5, 2020): 116. http://dx.doi.org/10.3390/polym12010116.
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γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.
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Ibarra, David, María Isabel Chávez, Jorge Rencoret, José Carlos del Río, Ana Gutiérrez, Javier Romero, Susana Camarero, María Jesús Martínez, Jesús Jiménez-Barbero, and Ángel T. Martínez. "Structural modification of eucalypt pulp lignin in a totally chlorine-free bleaching sequence including a laccase-mediator stage." Holzforschung 61, no. 6 (November 1, 2007): 634–46. http://dx.doi.org/10.1515/hf.2007.096.
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Abstract Structural modification of eucalypt pulp lignin was investigated in a totally chlorine-free (TCF) bleaching sequence including a laccase-mediator stage. This stage was applied after two oxygen delignification stages, and was followed by an alkaline peroxide stage. After two oxygen delignification stages, two more stages with a laccase mediator and alkaline peroxide were applied. The residual lignins were enzymatically isolated from the different pulps and analyzed by spectroscopic techniques and analytical pyrolysis. The latter revealed high amounts of syringyl units (>70%) in the lignins. 13C-1H heteronuclear single quantum correlation (HSQC) NMR indicated high amounts of β-O-4′ inter-unit linkages (>75% side-chains). Changes in lignin composition and inter-unit linkages were demonstrated in the course of the bleaching sequence. Moreover, oxidative modification of the major syringyl units was shown by C2,6-H2,6 HSQC correlations and by the presence of oxidized pyrolysis markers in pyrograms. The existence of both Cα keto and carboxyl groups in the residual lignin, together with normal (Cα-hydroxylated) units, was revealed by heteronuclear multiple bond correlation (HMBC) between aromatic H2,6 and side-chain carbons. These Cα-oxidized structures represent nearly 60% of total units in the lignin isolated from the enzymatically treated pulp. Analysis of residual lignin after the final peroxide stage compared with a simple alkaline treatment revealed that most of the oxidatively altered lignin was removed by the alkali used in the peroxide stage. Thus, the kappa number decreased and the final residual lignin was more structurally related to that found before the oxidative stages, although it contained less resinols and more carboxyl group-bearing units. However, the action of peroxide is necessary to attain the high brightness required (>90% ISO).
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Lisý, Anton, Aleš Ház, Richard Nadányi, Michal Jablonský, and Igor Šurina. "About Hydrophobicity of Lignin: A Review of Selected Chemical Methods for Lignin Valorisation in Biopolymer Production." Energies 15, no. 17 (August 26, 2022): 6213. http://dx.doi.org/10.3390/en15176213.
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Lignin is the second most abundant renewable natural polymer that occurs on Earth, and as such, it should be widely utilised by industries in a variety of applications. However, these applications and possible research seem to be limited or prevented by a variety of factors, mainly the high heterogeneity of lignin. Selective modifications of the structure and of functional groups allow better properties in material applications, whereas the separation of different qualitative lignin groups permits selective application in industry. This review is aimed at modification of the lignin structure, increasing the hydrophobicity of the produced materials, and focusing on several perspective modifications for industrial-scale production of lignin-based polymers, as well as challenges, opportunities, and other important factors to take into consideration.
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Podkościelna, Beata, Magdalena Sobiesiak, Yadong Zhao, Barbara Gawdzik, and Olena Sevastyanova. "Preparation of lignin-containing porous microspheres through the copolymerization of lignin acrylate derivatives with styrene and divinylbenzene." Holzforschung 69, no. 6 (August 1, 2015): 769–76. http://dx.doi.org/10.1515/hf-2014-0265.
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Abstract A novel method for synthesizing microspheres from lignin or lignin acrylate derivatives through copolymerization with styrene (St) and divinylbenzene (DVB) has been developed. The copolymers were obtained by the emulsion-suspension polymerization with a constant molar ratio of DVB to St of 1:1 (w/w) and different amounts of lignin or its derivatives. The morphologies of the obtained materials were examined by scanning electron microscopy. Two types of lignin modifications were performed to introduce vinyl groups into the lignin molecules: modification with acrylic acid and modification with epichlorohydrin plus acrylic acid. The course of modification was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy. The thermal stability and degradation behavior of the obtained microspheres were investigated by thermogravimetric analysis, and the pore structure was characterized via nitrogen sorption experiments. Owing to the presence of specific functional groups and the well-developed pore structure, the obtained Lignin-St-DVB microspheres may have potential application as specific sorbents for the removal of phenolic pollutants from water, as demonstrated by the solid-phase extraction technique.
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Espinoza-Acosta, José Luis, Evelyn Guadalupe Figueroa-Espinoza, and María de los Ángeles De la Rosa-Alcaraz. "Recent progress in the production of lignin-based sunscreens: A Review." BioResources 17, no. 2 (March 31, 2022): 3674–701. http://dx.doi.org/10.15376/biores.17.2.espinoza.
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Technical lignins are becoming an attractive natural, renewable, and non-toxic ingredient in sunscreens, having the capability for replacing synthetic compounds. Researchers have reported that lignin can increase the solar protection factor (SPF) of sunscreens and provide sun protection to body creams. However, to achieve the valorization of lignin in the fabrication of personal care products, it is necessary to overcome several challenges related to their molecular complexity and unattractive color. Fractionation, chemical modification, whitening, particle size reduction, and the synthesis of nanocomposites and copolymers are strategies reported to overcome the lignin challenges in the development of lignin-based sunscreens. This paper summarizes and analyzes previous research studies and outstanding findings (from 2016 to 2022) directed at the reduction of the problems that limit the extensive applications of lignin in skincare products such as sunscreens.
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Ishak, Nadiah, Angzzas Sari Mohd Kassim, Ashuvila Mohd Aripin, Dayang Norulfairuz Abang Zaidel, and Muhd Hafeez Zainulabidin. "Identification and Expression of Ligninase Enzymes from Tropical Asia Wood Insect for Agro-Pulp Biodelignification: A Theoretical Framework." Applied Mechanics and Materials 773-774 (July 2015): 1380–83. http://dx.doi.org/10.4028/www.scientific.net/amm.773-774.1380.
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Current pulp-processing in pulp and paper based industries are inefficient in removing the lignin as this compound is recalcitrant towards degradation. Transitioning from conventional pulping process into bio-delignification through utilisation of ligninase enzymes is one of the alternatives to improve the ability to fully utilize all components of wood to produce high quality fibres. Extensive research efforts have been focused on increase the production of ligninase enzymes from white rot fungi as a whole organism for industrial applications. However, enzymes activity produced from fungi are rather low as lignin modification is a secondary metabolism in which the enzyme only be expressed under particular conditions. Using genetic manipulations to incorporate genes associate for delignification isolated from different organisms such as tropical Asian wood-feeding insect into bacteria expression system will allow rapid enzyme production. This theoretical framework aims to produce an enzyme with high ligninase activity that will be used for removal of lignin during pulp-processing. These enzymes are thought to be more economically efficient in degrading lignin and involves less use of chemicals thus make this processing more environmentally friendly.Keywords: Biodelignification, Asian wood tropical insect, fungi, ligninase enzyme, bacterial expression system
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Popova, Olga, and Tatyana Finochenko. "Synthesis and properties of ion-exchange materials based on hydrolysis lignins." E3S Web of Conferences 273 (2021): 04011. http://dx.doi.org/10.1051/e3sconf/202127304011.
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Hydrolytic lignin is a large-tonnage waste product of ethyl alcohol production and is a renewable resource. The structure of lignin is characterized by the presence of a large number of hydroxyl groups, which provides the value of lignin as a raw material for synthesis in polymer chemistry. But due to their low chemical stability in dilute alkalis, acids and solvents, lignins are of little use for wide practical use. The introduction of additional functional groups into the lignin maromolecule by oxidative modification with the use of resource-saving technologies makes it possible to obtain new products for the synthesis of composite materials. On the basis of electrochemically modified lignin in polycondensation reactions with phthalic acid, ion-exchange materials have been obtained: weakly acidic cation exchangers with a exchange capacity of 0.1 mol/l NaOH 3.5-3.8 mmol/cm3, capable of sorbing cations in a wide range of pH values, and ampholyte (exchange capacity for sodium cation 6.4-6.6 mmol/cm3, for chlorine anion - 1.1-1.3 mmol/cm3). Ion exchangers synthesized on the basis of chlorine and nitro-containing lignins have been investigated in comparison with generally known industrial ion exchangers; they have high exchange and physic-mechanical characteristics and chemical resistance.
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Wang, Miao, Yadong Zhao, and Jiebing Li. "Demethylation and other modifications of industrial softwood kraft lignin by laccase-mediators." Holzforschung 72, no. 5 (April 25, 2018): 357–65. http://dx.doi.org/10.1515/hf-2017-0096.
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Abstract Substitution of phenol in phenol-formaldehyde (PF) resin preparations by technical lignins is hindered by the inherently lower reactivity of lignin compared to phenol. Demethylation of an industrial softwood kraft lignin (SKL) to improve its reactivity is the focus of this paper. To this purpose, kraft lignin (KL) was treated with two commercial laccases, NS51002 (L1) and NS51003 (L2), for 24 h in combination with three mediators, 2,2′-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 1-hydroxybenzotriazole (HBT) and 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). The characterizations of the reaction solution and the resultant KL showed that methanol was released as a result of the methoxy group splitting from the aromatic rings, while such demethylation was dependent on the laccase-mediator system (LMS). The catechol structures formed, which were further oxidized to a quinone structures prone to polymerization, led to molecular mass increment. Also this reaction was LMS dependent. The same is true to the cleavage of β-O-4′ linkages, which resulted in depolymerization. The L1-ABTS, L1-TEMPO and L2-HBT combinations are the most efficient and the resulting modified lignin would be suitable to phenol substitution. Challenging is the lignin polymerization following the demethylation, especially in case of L1-ABTS, which might inhibit the reactivity of the treated lignin.
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Pan, Xue-Jun, and Yoshihiro Sano. "Atmospheric Acetic Acid Pulping of Rice Straw IV: Physico-Chemical Characterization of Acetic Acid Lignins from Rice Straw and Woods. Part 2. Chemical Structures." Holzforschung 53, no. 6 (November 11, 1999): 590–96. http://dx.doi.org/10.1515/hf.1999.098.
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Summary Acetic acid lignins from rice straw (RLs), birch (BL) and fir (FL) were chemically characterized by means of elementary analysis, functional groups analysis, alkaline nitrobenzene and permanganate oxidation, Mannich reactivity and other techniques. The results showed that RLs had higher contents of residual polysaccharide and protein, and remarkably fewer acetyl groups than BL and FL. Results of nitrobenzene and permanganate oxidation indicated that RLs were remarkably more condensed than the native lignin in rice straw. In addition, the results of Mannich reactivity showed that RLs were more reactive toward modification than BL and FL, and might be a good raw material for lignin derivatives, such as lignin adhesives and chelating resins.
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Popova, Yuliya Aleksandrovna, Semen Leonidovich Shestakov, Aleksandr Yur'yevich Kozhevnikov, Dmitriy Sergeyevich Kosyakov, and Sergey Aleksandrovich Sypalov. "COMPARATIVE ANALYSIS OF LIGNINS OF VARIOUS PLANT FORMS BY 31P-NMR." chemistry of plant raw material, no. 4 (December 27, 2019): 57–64. http://dx.doi.org/10.14258/jcprm.2019045119.
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Lignin is one of the most abundant biopolymers. Information about the functional composition and structure of various lignins may be useful in the study of biosynthesis processes in plants. The subject of the article is the determination of 31P-NMR spectroscopy possibilities to identify lignins obtained from various plant forms. To obtain spectra on 31P nuclei, a modification of the studied samples was applied by phosphitylating their OH-groups with a special reagent. We obtained qualitative and quantitative analysis of samples of softwood and hardwood lignins and herbaceous plants. According to the NMR spectra we noted the differences in composition and structure of the studied lignins. We confirmed that the structure of lignins of softwood and hardwood wood mainly contain guaiacilpropane and syringylpropane structural units, respectively. We found that lignins of herbaceous plants contain all types of OH-groups characteristic for lignins, including p-hydroxyphenyl groups. It was observed that samples of herbaceous plants lignins contain fragments of flavonoid structures in most cases. The 31P-NMR spectrum of quercetin, as the flavonoids representative, was registered and also modeled using the ACDLabs software package to confirm the presence of flavone structures in the macromolecules of the herbaceous lignins.
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Solihat, Nissa Nurfajrin, Fahriya Puspita Sari, Faizatul Falah, Maya Ismayati, Muhammad Adly Rahandi Lubis, Widya Fatriasari, Eko Budi Santoso, and Wasrin Syafii. "Lignin as an Active Biomaterial: A Review." Jurnal Sylva Lestari 9, no. 1 (January 29, 2021): 1. http://dx.doi.org/10.23960/jsl191-22.
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Lignin is the second most naturally abundant biopolymer in the cell wall of lignocellulosic compound (15-35%) after cellulose.Lignin can be generated in massive amounts as by-products in biorefineries and pulp and paper industries through differing processes. Most lignin is utilized as generating energy and has always been treated as waste. Due to the high amount of phenolic compounds in lignin, it is considered as a potential material for various polymers, building blocks, and biomaterials production. Even though lignin can be utilized in the form of isolated lignin directly, the modification of lignin can increase the wide range of lignin applications. Lignin-based copolymers and modified lignin show better miscibility with another polymeric matrix, outstanding to the enhanced performance of such lignin-based polymer composites.This article summarizes the properly updated information of lignin’s potential applications, such as bio-surfactant, active packaging, antimicrobial agent, and supercapacitor.Keywords: active packaging, antimicrobial agent, bio-surfactant, lignin, supercapacitor
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Wang, Yun-Yan, Charles Cai, and Arthur Ragauskas. "Recent advances in lignin-based polyurethanes." April 2017 16, no. 04 (2017): 203–7. http://dx.doi.org/10.32964/tj16.4.203.
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Given the rise in demand for sustainable renewable biofuels and promising developments in cellulosic ethanol, the valorization of lignin has become essential for biorefining operations, especially with today’s low-cost energy production state of affairs. In the past 40 years, numerous efforts have been devoted to incorporate lignin and lignin derivatives into commercial polymeric materials. One of the promising strategies is to utilize multifunctional lignin macromolecules or oligomers as the replacement of polyols during polyurethane synthesis. In this review, recent advances in fabricating polyurethane foams, films, and adhesives with modified or unmodified lignins are examined. The mechanical and thermal properties of these lignin-based polyurethanes were correlated to their formulations, lignin molecular weight, and polydispersity, as well as the structural features of different lignin preparations. Recalcitrance and strong intermolecular interactions of lignin macromolecules are known to prevent them from effective incorporation into other polymeric materials, covalently or noncovalently. Therefore, this review intends to summarize the methods that improve the reactivity of lignin through chemical modification such as depolymerization, demethylation, and chain extension. Future developments and applications will be examined with a special emphasis on tailoring lignin structure to specific applications.
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Daou, Mariane, Clementina Farfan Soto, Amel Majira, Laurent Cézard, Betty Cottyn, Florian Pion, David Navarro, et al. "Fungal Treatment for the Valorization of Technical Soda Lignin." Journal of Fungi 7, no. 1 (January 9, 2021): 39. http://dx.doi.org/10.3390/jof7010039.
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Technical lignins produced as a by-product in biorefinery processes represent a potential source of renewable carbon. In consideration of the possibilities of the industrial transformation of this substrate into various valuable bio-based molecules, the biological deconstruction of a technical soda lignin by filamentous fungi was investigated. The ability of three basidiomycetes (Polyporus brumalis, Pycnoporus sanguineus and Leiotrametes menziesii) to modify this material, the resultant structural and chemical changes, and the secreted proteins during growth on this substrate were investigated. The three fungi could grow on the technical lignin alone, and the growth rate increased when the media were supplemented with glucose or maltose. The proteomic analysis of the culture supernatants after three days of growth revealed the secretion of numerous Carbohydrate-Active Enzymes (CAZymes). The secretomic profiles varied widely between the strains and the presence of technical lignin alone triggered the early secretion of many lignin-acting oxidoreductases. The secretomes were notably rich in glycoside hydrolases and H2O2-producing auxiliary activity enzymes with copper radical oxidases being induced on lignin for all strains. The lignin treatment by fungi modified both the soluble and insoluble lignin fractions. A significant decrease in the amount of soluble higher molar mass compounds was observed in the case of P. sanguineus. This strain was also responsible for the modification of the lower molar mass compounds of the lignin insoluble fraction and a 40% decrease in the thioacidolysis yield. The similarity in the activities of P. sanguineus and P. brumalis in modifying the functional groups of the technical lignin were observed, the results suggest that the lignin has undergone structural changes, or at least changes in its composition, and pave the route for the utilization of filamentous fungi to functionalize technical lignins and produce the enzymes of interest for biorefinery applications.
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Daou, Mariane, Clementina Farfan Soto, Amel Majira, Laurent Cézard, Betty Cottyn, Florian Pion, David Navarro, et al. "Fungal Treatment for the Valorization of Technical Soda Lignin." Journal of Fungi 7, no. 1 (January 9, 2021): 39. http://dx.doi.org/10.3390/jof7010039.
Full textAbstract:
Technical lignins produced as a by-product in biorefinery processes represent a potential source of renewable carbon. In consideration of the possibilities of the industrial transformation of this substrate into various valuable bio-based molecules, the biological deconstruction of a technical soda lignin by filamentous fungi was investigated. The ability of three basidiomycetes (Polyporus brumalis, Pycnoporus sanguineus and Leiotrametes menziesii) to modify this material, the resultant structural and chemical changes, and the secreted proteins during growth on this substrate were investigated. The three fungi could grow on the technical lignin alone, and the growth rate increased when the media were supplemented with glucose or maltose. The proteomic analysis of the culture supernatants after three days of growth revealed the secretion of numerous Carbohydrate-Active Enzymes (CAZymes). The secretomic profiles varied widely between the strains and the presence of technical lignin alone triggered the early secretion of many lignin-acting oxidoreductases. The secretomes were notably rich in glycoside hydrolases and H2O2-producing auxiliary activity enzymes with copper radical oxidases being induced on lignin for all strains. The lignin treatment by fungi modified both the soluble and insoluble lignin fractions. A significant decrease in the amount of soluble higher molar mass compounds was observed in the case of P. sanguineus. This strain was also responsible for the modification of the lower molar mass compounds of the lignin insoluble fraction and a 40% decrease in the thioacidolysis yield. The similarity in the activities of P. sanguineus and P. brumalis in modifying the functional groups of the technical lignin were observed, the results suggest that the lignin has undergone structural changes, or at least changes in its composition, and pave the route for the utilization of filamentous fungi to functionalize technical lignins and produce the enzymes of interest for biorefinery applications.
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Yadav, Virendra Kumar, Nitin Gupta, Pankaj Kumar, Marjan Ganjali Dashti, Vineet Tirth, Samreen Heena Khan, Krishna Kumar Yadav, et al. "Recent Advances in Synthesis and Degradation of Lignin and Lignin Nanoparticles and Their Emerging Applications in Nanotechnology." Materials 15, no. 3 (January 26, 2022): 953. http://dx.doi.org/10.3390/ma15030953.
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Lignin is an important commercially produced polymeric material. It is used extensively in both industrial and agricultural activities. Recently, it has drawn much attention from the scientific community. It is abundantly present in nature and has significant application in the production of biodegradable materials. Its wide usage includes drug delivery, polymers and several forms of emerging lignin nanoparticles. The synthesis of lignin nanoparticles is carried out in a controlled manner. The traditional manufacturing techniques are costly and often toxic and hazardous to the environment. This review article highlights simple, safe, climate-friendly and ecological approaches to the synthesis of lignin nanoparticles. The changeable, complex structure and recalcitrant nature of lignin makes it challenging to degrade. Researchers have discovered a small number of microorganisms that have developed enzymatic and non-enzymatic metabolic pathways to use lignin as a carbon source. These microbes show promising potential for the biodegradation of lignin. The degradation pathways of these microbes are also described, which makes the study of biological synthesis much easier. However, surface modification of lignin nanoparticles is something that is yet to be explored. This review elucidates the recent advances in the biodegradation of lignin in the ecological system. It includes the current approaches, methods for modification, new applications and research for the synthesis of lignin and lignin nanoparticles. Additionally, the intricacy of lignin’s structure, along with its chemical nature, is well-described. This article will help increase the understanding of the utilization of lignin as an economical and alternative-resource material. It will also aid in the minimization of solid waste arising from lignin.
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Zhou, Haizhen, Jingyu Li, and Erni Ma. "Multiscale Modification of Populus cathayana by Alkali Lignin Combined with Heat Treatment." Polymers 10, no. 11 (November 9, 2018): 1240. http://dx.doi.org/10.3390/polym10111240.
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Chemical modification of wood with green modifiers is highly desirable for sustainable development. With the aim of enhancing the water resistance and dimensional stability of fast growing wood, modifications were conducted using renewable and toxicity-free industrial lignin combined with heat treatment. Poplar (Populus cathayana) samples first underwent impregnation with alkali lignin solution and were then subjected to heat treatment at 140–180 °C for two hours. The results indicated that the modified wood showed excellent leaching resistance. The alkali lignin treatment improved surface hydrophobicity and compression strength, and decreased moisture and water uptake, thereby reducing the dimensional instability of modified wood. These changes became more pronounced as the heat-treating temperature increased. Scanning electron microscopy, confocal laser scanning microscopy, and Fourier transform infrared spectroscopy evidenced that a multiscale improvement of the alkali lignin occurred in the cell lumen and cell wall of wood fibers and vessels, with small alkali lignin molecules reacting with the wood matrix. This study paves the way for developing an effective modification approach for fast growing wood, as well as promoting the reuse of industrial lignin for high-value applications, and improves the sustainable development of the forestry industry.
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Jin, Yanhong, Jiaxian Lin, Yu Cheng, and Chunhong Lu. "Lignin-Based High-Performance Fibers by Textile Spinning Techniques." Materials 14, no. 12 (June 18, 2021): 3378. http://dx.doi.org/10.3390/ma14123378.
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As a major component of lignocellulosic biomass, lignin is one of the largest natural resources of biopolymers and, thus, an abundant and renewable raw material for products, such as high-performance fibers for industrial applications. Direct conversion of lignin has long been investigated, but the fiber spinning process for lignin is difficult and the obtained fibers exhibit unsatisfactory mechanical performance mainly due to the amorphous chemical structure, low molecular weight of lignin, and broad molecular weight distribution. Therefore, different textile spinning techniques, modifications of lignin, and incorporation of lignin into polymers have been and are being developed to increase lignin’s spinnability and compatibility with existing materials to yield fibers with better mechanical performance. This review presents the latest advances in the textile fabrication techniques, modified lignin-based high-performance fibers, and their potential in the enhancement of the mechanical performance.
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Karunarathna, Menisha S., and Rhett C. Smith. "Valorization of Lignin as a Sustainable Component of Structural Materials and Composites: Advances from 2011 to 2019." Sustainability 12, no. 2 (January 20, 2020): 734. http://dx.doi.org/10.3390/su12020734.
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Lignin is the most abundant aromatic biopolymer and is the sustainable feedstock most likely to supplant petroleum-derived aromatics and downstream products. Rich in functional groups, lignin is largely peerless in its potential for chemical modification towards attaining target properties. Lignin’s crosslinked network structure can be exploited in composites to endow them with remarkable strength, as exemplified in timber and other structural elements of plants. Yet lignin may also be depolymerized, modified, or blended with other polymers. This review focuses on substituting petrochemicals with lignin derivatives, with a particular focus on applications more significant in terms of potential commercialization volume, including polyurethane, phenol-formaldehyde resins, lignin-based carbon fibers, and emergent melt-processable waste-derived materials. This review will illuminate advances from the last eight years in the prospective utilization of such lignin-derived products in a range of application such as adhesives, plastics, automotive components, construction materials, and composites. Particular technical issues associated with lignin processing and emerging alternatives for future developments are discussed.
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Verdini, Federico, Emanuela Calcio Gaudino, Erica Canova, Silvia Tabasso, Paria Jafari Behbahani, and Giancarlo Cravotto. "Lignin as a Natural Carrier for the Efficient Delivery of Bioactive Compounds: From Waste to Health." Molecules 27, no. 11 (June 3, 2022): 3598. http://dx.doi.org/10.3390/molecules27113598.
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Lignin is a fascinating aromatic biopolymer with high valorization potentiality. Besides its extensive value in the biorefinery context, as a renewable source of aromatics lignin is currently under evaluation for its huge potential in biomedical applications. Besides the specific antioxidant and antimicrobial activities of lignin, that depend on its source and isolation procedure, remarkable progress has been made, over the last five years, in the isolation, functionalization and modification of lignin and lignin-derived compounds to use as carriers for biologically active substances. The aim of this review is to summarize the current state of the art in the field of lignin-based carrier systems, highlighting the most important results. Furthermore, the possibilities and constraints related to the physico–chemical properties of the lignin source will be reviewed herein as well as the modifications and processing required to make lignin suitable for the loading and release of active compounds.
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Meister, John J. "MODIFICATION OF LIGNIN*." Journal of Macromolecular Science, Part C: Polymer Reviews 42, no. 2 (June 27, 2002): 235–89. http://dx.doi.org/10.1081/mc-120004764.
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Gouveia, Júlia Rocha, Cleber Lucius da Costa, Lara Basílio Tavares, and Demetrio Jackson dos Santos. "Synthesis of Lignin-Based Polyurethanes: A Mini-Review." Mini-Reviews in Organic Chemistry 16, no. 4 (March 19, 2019): 345–52. http://dx.doi.org/10.2174/1570193x15666180514125817.
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Lignin is a natural polymer composed primarily of phenylpropanoid structures with an abundance of reactive groups: aliphatic and aromatic hydroxyls, phenols, and carbonyls. Considering the large quantity of hydroxyl groups, lignin has significant potential as a replacement for petroleum-based polyols in polyurethane (PU) synthesis and as a value-added, renewable raw material for this purpose. Several methods of lignin-based polyurethane synthesis are reviewed in this paper for reactive and thermoplastic systems: direct lignin incorporation, chemical lignin modification and depolymerization. Despite the unmodified lignin low reactivity towards diisocyanates, its direct incorporation as polyol generates highly brittle PUs, but with proper performance when applied as adhesive for wood. PU brittleness can be reduced employing polyols obtained from lignin/chain extender blends, in which glass transition temperature (Tg), mechanical properties and PU homogeneity are strongly affected by lignin content. The potential applications of lignin can be enhanced by lignin chemical modifications, including oxyalkylation and depolymerization, improving polyurethanes properties. Another PU category, lignin- based thermoplastic polyurethane (LTPU) synthesis, emerges as a sustainable alternative and is also presented in this work.
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Tanjung, Faisal A., Retna A. Kuswardani, Christopher I. Idumah, Januar P. Siregar, and Abdul Karim. "Characterization of mechanical and thermal properties of esterified lignin modified polypropylene composites filled with chitosan fibers." Polymers and Polymer Composites 30 (January 2022): 096739112210824. http://dx.doi.org/10.1177/09673911221082482.
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A comparative study was performed on the use of esterified alkaline lignin (AAL) and esterified organosolv lignin (AOSL) as the interfacial modifying agent to improve the properties of polypropylene-chitosan composites. Chitosan was chemically modified through a reaction with the esterified lignin in an alcohol medium. The composites were prepared using an internal mixer and hot-pressed method. Both modified chitosan showed a different chemical structure upon modification with the esterified lignins as confirmed by Fourier transform infrared spectroscopy spectra. With a lower molecular weight, the AOSL attachment on the chitosan surface resulted in more efficiency in decreasing hydrophilic characters. Tensile tests showed the increased tensile strength by 32.15% and 26.43% for AOSL-modified composites and AAL-modified composites as compared with the unmodified composites. Overall, the AOSL was superior in improving the mechanical strength and thermal stability of the composites, while the AAL exhibited the most apparent enhancement in ductility and crystallization.
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Goliszek, Marta, Beata Podkościelna, Olena Sevastyanova, Barbara Gawdzik, and Artur Chabros. "The Influence of Lignin Diversity on the Structural and Thermal Properties of Polymeric Microspheres Derived from Lignin, Styrene, and/or Divinylbenzene." Materials 12, no. 18 (September 4, 2019): 2847. http://dx.doi.org/10.3390/ma12182847.
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This work investigates the impact of lignin origin and structural characteristics, such as molecular weight and functionality, on the properties of corresponding porous biopolymeric microspheres obtained through suspension-emulsion polymerization of lignin with styrene (St) and/or divinylbenzene (DVB). Two types of kraft lignin, which are softwood (Picea abies L.) and hardwood (Eucalyptus grandis), fractionated by common industrial solvents, and related methacrylates, were used in the synthesis. The presence of the appropriate functional groups in the lignins and in the corresponding microspheres were investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR/FT-IR), while the thermal properties were studied by differential scanning calorimetry (DSC). The texture of the microspheres was characterized using low-temperature nitrogen adsorption. The swelling studies were performed in typical organic solvents and distilled water. The shapes of the microspheres were confirmed with an optical microscope. The introduction of lignin into a St and/or DVB polymeric system made it possible to obtain highly porous functionalized microspheres that increase their sorption potential. Lignin methacrylates created a polymer network with St and DVB, whereas the unmodified lignin acted mainly as an eco-friendly filler in the pores of St-DVB or DVB microspheres. The incorporation of biopolymer into the microspheres could be a promising alternative to a modification of synthetic materials and a better utilization of lignin.
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Krutov, Stepan M., Dmitry V. Evtuguin, Elena V. Ipatova, Sonia A. O. Santos, and Yurii N. Sazanov. "Modification of acid hydrolysis lignin for value-added applications by micronization followed by hydrothermal alkaline treatment." Holzforschung 69, no. 6 (August 1, 2015): 761–68. http://dx.doi.org/10.1515/hf-2014-0264.
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Abstract Technical hydrolysis lignin (THL) was micronized by grinding in a rotary-jet mill to obtain a fraction of approximately 5 mm. Both initial and milled THLs were liquefied by thermal alkaline treatment at 220°C for 2 h. Upgraded THLs that were nonmilled (L1) and milled (L2) were desalted by treatment with cation-exchanged resin and were dried. Micronization affected the course of hydrothermal alkaline treatment and the structure and composition of the obtained lignin. Thus, L2 contained much less concomitant polysaccharides and extractives than L1 and was more condensed. The molecular weights of L1 and L2 were 1100 and 1000 Da, respectively, as determined by size-exclusion chromatography. Structural characterization carried out by employing tandem electrospray ionization-mass spectrometry and 1D and 2D nuclear magnetic resonance spectroscopy revealed that small amounts of β-O-4 (∼6 mol.%), β-5, and β-β structures still remained in L1 and L2. Overall, upgraded lignins are oligomers (trimers-pentamers) with highly degraded propane chains and possess polyconjugated condensed aromatic structures. Upgraded THL seems to be a promising raw material for polymeric formulations.
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Kovalenko, E. I., O. V. Popova, A. A. Aleksandrov, and T. G. Galikyan. "Electrochemical modification of lignins." Russian Journal of Electrochemistry 36, no. 7 (July 2000): 706–11. http://dx.doi.org/10.1007/bf02757667.
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Hu, Yue, Fangjian Xue, and Zhixiao Zhang. "The influence of thermal modification on lignite structure by FT-IR." Thermal Science and Engineering 5, no. 1 (June 12, 2022): 94. http://dx.doi.org/10.24294/tse.v5i1.1532.
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The modification experiment of Inner Mongolia Baiyinhua lignite by hot air at 200 ℃ for 1 h was carried out. Thestructural changes of Baiyinhua lignite before and after thermal modification were analyzed by infrared spectrum. Theresults show that the moisture and oxygen content in lignite are greatly reduced by thermal modification, and the carboncontent and calorific value are also increased to varying degrees. In the process of thermal modification, variousoxygen-containing functional groups in lignite are reduced in different degrees due to thermal decomposition. Thermalmodification also causes substitution reaction of aromatic hydrocarbons in lignite, CH2 in aliphatic hydrocarbonstructure breaks, but hydroxyl group in lignite does not change significantly before and after thermal modification.
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Kačíková, Danica, Ivan Kubovský, Milan Gaff, and František Kačík. "Changes of Meranti, Padauk, and Merbau Wood Lignin during the ThermoWood Process." Polymers 13, no. 7 (March 24, 2021): 993. http://dx.doi.org/10.3390/polym13070993.
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Thermal modification is an environmentally friendly process in which technological properties of wood are modified using thermal energy without adding chemicals, the result of which is a value-added product. Wood samples of three tropical wood species (meranti, padauk, and merbau) were thermally treated according to the ThermoWood process at various temperatures (160, 180, 210 °C) and changes in isolated lignin were evaluated by nitrobenzene oxidation (NBO), Fourier-transform infrared spectroscopy (FTIR), and size exclusion chromatography (SEC). New data on the lignins of the investigated wood species were obtained, e.g., syringyl to guaiacyl ratio values (S/G) were 1.21, 1.70, and 3.09, and molecular weights were approx. 8600, 4300, and 8300 g·mol−1 for meranti, padauk, and merbau, respectively. Higher temperatures cause a decrease of methoxyls and an increase in C=O groups. Simultaneous degradation and condensation reactions in lignin occur during thermal treatment, the latter prevailing at higher temperatures.
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Ando, Daisuke, Fumiaki Nakatsubo, and Hiroyuki Yano. "Thermal stability of lignin in ground pulp (GP) and the effect of lignin modification on GP’s thermal stability: TGA experiments with dimeric lignin model compounds and milled wood lignins." Holzforschung 73, no. 5 (May 27, 2019): 493–99. http://dx.doi.org/10.1515/hf-2018-0137.
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Abstract For ground pulp (GP) utilization in wood fiber composites as reinforced material, its thermal behavior is relevant. The contribution of lignin to thermal performance of GP from Pinus densiflora was the focus of the present study. Dimeric lignin model compounds and isolated milled wood lignins (MWLs) from three sources were submitted for thermogravimetric analysis (TGA). The temperatures leading to 1% weight loss (T per 1% WL) for the material were determined. The thermal stability of β-O-4 models was the lowest. Among the MWLs, the abaca MWL with its high β-O-4 content was the least thermostable. An acetylated nonphenolic β-O-4 lignin model compound showed that acetylation improves the thermal stability of this type of dimeric models. The acetylation of benzylic OH groups in β-O-4 linkages is especially relevant for the thermal resistance, which was also shown based on pre-acetylated benzylic OH groups in the GP before the total acetylation.
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Dizhbite, Tatiana, Lilija Jashina, Galina Dobele, Anna Andersone, Dmitry Evtuguin, Oskar Bikovens, and Galina Telysheva. "Polyoxometalate (POM)-aided modification of lignin from wheat straw biorefinery." Holzforschung 67, no. 5 (July 1, 2013): 539–47. http://dx.doi.org/10.1515/hf-2012-0193.
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Abstract The oxidative modification of Biolignin (BL) has been investigated to make it more suitable as an adsorbent for transition/heavy metals. BL is a by-product of a wheat straw organosolv process for the production of pulp, ethanol, and pentoses (CIMV S.A. pilot plant, Levallois Perret, France). It was subjected to oxidation by a polyoxometalate (POM) H3[PMo12O40], aiming at the increment of oxygen-containing adsorption-active sites. The POM oxidation of BL was performed under moderate conditions (1 bar, 60–90°C, and 200°C) with the co-oxidants O2 or H2O2. The resulting lignin functionality and structure was evaluated by pyrolysis-gas chromatography/mass spectrometry, solid-state 13C nuclear magnetic resonance, Fourier transform infrared, and chemical analysis. The condensation degree of BL and its COOH and aliphatic OH group contents increased significantly, whereas the polymer structure was maintained. Under optimal conditions with POM/H2O2, the sorption capacity of lignins toward Cd(II) and Pb(II) was increased threefold and twofold, respectively.
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Andersons, Bruno, Guna Noldt, Gerald Koch, Ingeborga Andersone, Anete Meija-Feldmane, Vladimirs Biziks, Ilze Irbe, and Juris Grinins. "Scanning UV microspectrophotometry as a tool to study the changes of lignin in hydrothermally modified wood." Holzforschung 70, no. 3 (March 1, 2016): 215–21. http://dx.doi.org/10.1515/hf-2015-0027.
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Abstract Thermal modification (TM) of wood has occupied a relatively narrow but stable niche as an alternative for chemical wood protection. There are different technological solutions for TM and not all details of their effects on wood tissue have been understood. The one-stage hydrothermal modification (HTM) at elevated vapour pressure essentially changes the wood’s composition and structure. In the present paper, the changes in three hardwood lignins (alder, aspen, and birch) were observed within the cell wall by means of cellular UV microspectrophotometry. The lignin absorbances in the compound middle lamella (CML) of unmodified wood are 1.7- to 2.0-fold higher than those in the fibre S2 layer. The woods were modified in the temperature range from 140 to 180°C, while in the lower temperature range (140°C/1 h), the UV absorbances are little affected. Essential changes occur in the range of 160–180°C and the UV data reflect these by absorbtion changes, while the absorbances at 278 nm rise with factors around 2 more in the S2 layer than in the CML. The absorbance increments are interpreted as polycondensation reactions with furfural and other degradation products of hemicelluloses with the lignin moiety of the cell wall.
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Tita, SPS, R. Medeiros, JR Tarpani, E. Frollini, and V. Tita. "Chemical modification of sugarcane bagasse and sisal fibers using hydroxymethylated lignin: Influence on impact strength and water absorption of phenolic composites." Journal of Composite Materials 52, no. 20 (January 25, 2018): 2743–53. http://dx.doi.org/10.1177/0021998317753886.
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Chemical modification of fiber surfaces can increase wettability of composites reinforced by vegetal fibers and, consequently, the dispersion of the fiber in the matrix and mechanical properties can be improved. Although there are some studies about agents for chemical modifications of vegetal fiber surfaces, there are few data and discussion about the usage of lignin. In the present work, chemical modifications of sugarcane bagasse and sisal fibers using lignin (previously hydroxymethylated) were carried out under different reaction times (15, 30, and 60 min). The composition (holocellulose, hemicelluloses, cellulose, and lignin contents) of the treated and untreated fibers was evaluated. Phenolic composites were prepared using unmodified and modified fibers via compression molding process under temperature. Izod impact, water absorption tests, and scanning electron microscopy were performed to evaluate composite properties. The resin and lignin were characterized by size exclusion chromatography. Results showed that there was a tendency of reducing water absorption for composites prepared from modified fibers. Impact strengths of composites reinforced with sugarcane bagasse with modified fibers were similar to the ones with unmodified fibers (around 20 J/m). However, impact strengths for composites reinforced with modified sisal fibers (around 104 J/m for 15 min of reaction time) were higher than the ones with unmodified fibers (around 95 J/m). Therefore, the usage of lignin as a modifier agent of vegetal fiber surfaces to increase fiber–matrix adhesion for phenolic composites is a strategic alternative for improving products through simple, eco-friendly, and low-cost procedures.
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Loginova, Vera A., Anna V. Cheshkova, and Tatyana S. Frolova. "PREPARATION OF DYED AZOLIGNINS ON LINEN COTTONIN MODIFIED BY ENZYMES." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 2 (February 8, 2020): 64–70. http://dx.doi.org/10.6060/ivkkt.20206302.5970.
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The possibility of using azoreaction for obtaining colored like-cotton flax (cottonin) are evaluated in this article. For the process of disfiling (disfibering, disenchantment) enzymes Pulpzyme HC and Scourzyme L ("Novozymes A/S" (Denmark)) were applied. Diazol scarlet K was used as a diazo component. It is established that the enzymatic modification of ligno-carbohydrate complex promotes opening phenolic hydroxyls. As a result, the reactivity of flax fiber with respect to diazol alum K increases. The spectra of dyed extracted polyphenols of flax were obtained and interpreted for region of 400-700 nm. It was shown that in the spectra of extractive aromatic substances of phenolic nature for the native fiber two maxima at 420-440 nm and 500-520 were appeared nm during the azo coupling reaction. The first maximum corresponds to the compounds formed as a result of the reaction of azo combination with aromatic substances having unexpressed color (chromophore). The long-wave maximum is associated with azo lignins, where the associated and non-associated complexes of aromatic polyphenols of lignin act as the diazocomponent. It is assumed that enzymatic hydrolysis of non-cellulose polysaccharides creates stereo accessibility to the reaction groups of lignin, which is part of the structure of the ligno-carbohydrate complex of flax fiber. The dependence of the function K/S – (K/S)0 for colored flax fibers at different modification methods were obtained and interpreted. The effect of lignin unblocking in after enzymatic cottonization is confirmed. There is a significant increase in the K/S function of colored cottonin in comparison with the results for native short flax fiber. The method of spectrophotometry proved that the maximum effect of color dyeing is provided in the case of the enzymatic modification of Pulpzyme NS if excluded of the washing stage.
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Kocheva, Lyudmila Sergeyevna, Anatoliy Petrovich Karmanov, Alʹbert Vladimirovich Kanarskiy, Zosia Albertovna Kanarskaya, Eduard Ilʹyasovich Semenov, and Nikolay Ivanovich Bogdanovich. "DIATOMITES AND LIGNINS AS MYCOTOXIN ADSORBENTS." chemistry of plant raw material, no. 2 (June 10, 2022): 73–84. http://dx.doi.org/10.14258/jcprm.20220210730.
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Currently, there is a tendency to deepen the mycotoxin problem, which is associated with the global warming and environmental pollution. The results of a study of the sorption capacity of adsorbents samples based on natural materials diatomites and lignins in relation to mycotoxin T-2 are presented. The chemical composition of diatomites of the Inzensk deposit before and after modification is given and the parameters of the surface-porous structure of the samples are established. The isotherms of adsorption and desorption of nitrogen on the surface of diatomites were studied and for the first time it was shown that they belong to the type IV(a) acording to IUPAC classification. The distribution of pores by size was studied and it was established that a significant proportion of the pore space of diatomites are mesopores with an average width of 7–12 nm. The highest adsorption rates of mycotoxin T-2 were established for a diatomite sample subjected to acid modification. Data on the adsorption of mycotoxin T-2 by samples of lignins isolated from the wood of birch Betula verrucosa, stems of rye Secale sp. and cabbage Brassica oleracea are given. The results of the determination of functional groups, elemental and monomeric composition of lignins are presented. It has been established that the adsorption capacity of drugs depends mainly on the peculiarities of the chemical structure of the studied samples. The highest adsorption rates of mycotoxin T-2 are established for lignin isolated from cabbage stems. Comparison of mycotoxin T-2 adsorption, surface porous structure parameters and chemical structure of various samples leads to the conclusion that for both diatomites and lignins, the chemisorption process plays the most important role.
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Ralph, John, and Fachuang Lu. "The DFRC Method for Lignin Analysis. 6. A Simple Modification for Identifying Natural Acetates on Lignins." Journal of Agricultural and Food Chemistry 46, no. 11 (November 1998): 4616–19. http://dx.doi.org/10.1021/jf980680d.
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