Journal articles: 'Lignin modification'

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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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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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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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Komisarz, Karolina, Tomasz M. Majka, and Krzysztof Pielichowski. "Chemical and Physical Modification of Lignin for Green Polymeric Composite Materials." Materials 16, no. 1 (December 20, 2022): 16. http://dx.doi.org/10.3390/ma16010016.

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Lignin, a valuable polymer of natural origin, displays numerous desired intrinsic properties; however, modification processes leading to the value-added products suitable for composite materials’ applications are in demand. Chemical modification routes involve mostly reactions with hydroxyl groups present in the structure of lignin, but other paths, such as copolymerization or grafting, are also utilized. On the other hand, physical techniques, such as irradiation, freeze-drying, and sorption, to enhance the surface properties of lignin and the resulting composite materials, are developed. Various kinds of chemically or physically modified lignin are discussed in this review and their effects on the properties of polymeric (bio)materials are presented. Lignin-induced enhancements in green polymer composites, such as better dimensional stability, improved hydrophobicity, and improved mechanical properties, along with biocompatibility and non-cytotoxicity, have been presented. This review addresses the challenges connected with the efficient modification of lignin, which depends on polymer origin and the modification conditions. Finally, future outlooks on modified lignins as useful materials on their own and as prospective biofillers for environmentally friendly polymeric materials are presented.

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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.

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Bujanovic, Biljana, Sally A. Ralph, Richard S. Reiner, and Rajai H. Atalla. "Lignin modification in the initial phase of softwood kraft pulp delignification with polyoxometalates (POMs)." Holzforschung 61, no. 5 (August 1, 2007): 492–98. http://dx.doi.org/10.1515/hf.2007.102.

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Abstract Commercial softwood kraft pulp with kappa number 30.5 (KP30.5) was delignified with polyoxometalates (POM, Na5(+2)[SiV1(-0.1)MoW10(+0.1)O40]), and POM-treated kraft pulp of kappa number 23.6 was obtained (KPPOM,23.6). Residual lignin from pulps was isolated by mild acid hydrolysis and characterized by analytical and spectral methods to gain insight into lignin reactions taking place during the initial delignification phase. Lignin from POM-delignified pulp was isolated in lower yield. Comparative analysis of residual lignins (RL-KP30.5, RL-KPPOM,23.6) showed that POM leads to products enriched in carbonyl/carboxyl groups and carbohydrates. POM lignins have a lower molecular mass and a lower content of phenolic hydroxyl and methoxyl groups. Based on these results and FTIR spectra, we suggest that aromatic ring cleavage and quinone formation occur during POM delignification. The degree of lignin-cellulose association increases after POM delignification. Lignin-cellulose association was found to be partially unstable under mild alkaline conditions, as residual lignin isolated after alkaline extraction of KPPOM,23.6 pulp (RL-KPPOM/NaOH) exhibited lower glucose content, higher Klason lignin content, and less extraneous material.

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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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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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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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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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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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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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Popp, Janet L., and Jonathan S. Dordick. "Enzymatic modification of lignin: Synthesis of lignin-phenol copolymers." Enzyme and Microbial Technology 13, no. 6 (June 1991): 522. http://dx.doi.org/10.1016/0141-0229(91)90029-a.

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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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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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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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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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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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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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Pupart, Hegne, Piia Jõul, Melissa Ingela Bramanis, and Tiit Lukk. "Characterization of the Ensemble of Lignin-Remodeling DyP-Type Peroxidases from Streptomyces coelicolor A3(2)." Energies 16, no. 3 (February 3, 2023): 1557. http://dx.doi.org/10.3390/en16031557.

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Lignin is Nature’s major source of aromatic chemistry and is by many seen as the green entry-point alternative to the fossil-based chemical industry. Due to its chemically recalcitrant structure, the utilization of lignin is challenging, wherein enzymes might be the key to overcome this challenge. Here, we focus on the characterization of dye-decolorizing peroxidases from Streptomyces coelicolor A3(2) (ScDyPs) in the context of enzymatic modification of organosolv lignins from aspen and Miscanthus × giganteus. In this study, we show that the ScDyPB can remodel organosolv lignins from grassy biomass, leading to higher molecular weight species, while ScDyPAs can deconstruct hardwood lignin, leading to an overall reduction in its molecular weight. Additionally, we show that ScDyPB is effective in polymerizing low-molecular-weight phenolics, leading to their removal from the solution.

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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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Hu, Lihong, Hui Pan, Yonghong Zhou, and Meng Zhang. "Methods to improve lignin’s reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review." BioResources 6, no. 3 (May 17, 2011): 3515–25. http://dx.doi.org/10.15376/biores.6.3.3515-3525.

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Lignin is readily available as a by-product from the pulp and paper industry. It is considered to be a promising substitute for phenol in phenol-formaldehyde (PF) resin synthesis, given the increasing concerns of the shortage of fossil resources and the environmental impact from petroleum-based products. One hurdle that prevents the commercial utilization of lignin is its low reactivity due to its chemical structure. Many efforts have been made to improve its reactivity by modification and/or depolymerization of lignin molecules. Methylolation and phenolation are the two most studied modification approaches aimed at introducing reactive functional groups to lignin molecules. Modified lignin from these two methods could partially replace phenol in PF resin synthesis. Demethylation of lignin could effectively increase the reactivity of lignin by forming catechol moieties in the lignin macromolecule. Other methods, including reduction, oxidation, and hydrolysis, have also been studied to improve the reactivity of lignin as well as to produce phenolic compounds from lignin. Most current methods of lignin modification are not economically attractive. One can expect that efforts will be continued, aimed at improving the utilization of lignin for value-added products.

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Hu, Lihong, Hui Pan, Yonghong Zhou, and Meng Zhang. "Methods to improve lignin’s reactivity as a phenol substitute and as replacement for other phenolic compounds: A brief review." BioResources 6, no. 3 (May 17, 2011): 3515–25. http://dx.doi.org/10.15376/biores.6.3.hu.

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Lignin is readily available as a by-product from the pulp and paper industry. It is considered to be a promising substitute for phenol in phenol-formaldehyde (PF) resin synthesis, given the increasing concerns of the shortage of fossil resources and the environmental impact from petroleum-based products. One hurdle that prevents the commercial utilization of lignin is its low reactivity due to its chemical structure. Many efforts have been made to improve its reactivity by modification and/or depolymerization of lignin molecules. Methylolation and phenolation are the two most studied modification approaches aimed at introducing reactive functional groups to lignin molecules. Modified lignin from these two methods could partially replace phenol in PF resin synthesis. Demethylation of lignin could effectively increase the reactivity of lignin by forming catechol moieties in the lignin macromolecule. Other methods, including reduction, oxidation, and hydrolysis, have also been studied to improve the reactivity of lignin as well as to produce phenolic compounds from lignin. Most current methods of lignin modification are not economically attractive. One can expect that efforts will be continued, aimed at improving the utilization of lignin for value-added products.

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Ibarra, David, Luisa García-Fuentevilla, Gabriela Domínguez, Raquel Martín-Sampedro, Manuel Hernández, María E. Arias, José I. Santos, and María E. Eugenio. "NMR Study on Laccase Polymerization of Kraft Lignin Using Different Enzymes Source." International Journal of Molecular Sciences 24, no. 3 (January 25, 2023): 2359. http://dx.doi.org/10.3390/ijms24032359.

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The usage of laccases is a sustainable and environmentally friendly approach to modifying the Kraft lignin structure for use in certain applications. However, the inherent structure of Kraft lignin, as well as that resulting from laccase modification, still presents challenges for fundamental comprehension and successful lignin valorization. In this study, bacterial and fungal laccases were employed to modify eucalypt Kraft lignin. To evaluate the type and range of the chemical and structural changes of laccase-treated lignins, different NMR techniques, including solution 1H and 2D NMR (heteronuclear single quantum correlation (HSQC)), and solid-state 13C NMR, were applied. Size exclusion chromatography and infrared spectroscopy were also used. Interestingly, HSQC analysis showed substantial changes in the oxygenated aliphatic region of lignins, showing an almost complete absence of signals corresponding to side-chains due to laccase depolymerization. Simultaneously, a significant loss of aromatic signals was observed by HSQC and 1H NMR, which was attributed to a deprotonation of the lignin benzenic rings due to polymerization/condensation by laccase reactions. Then, condensed structures, such as α-5’, 5-5´, and 4-O-5´, were detected by HSQC and 13C NMR, supporting the increment in molecular weight, as well as the phenolic content reduction determined in lignins.

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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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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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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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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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29

Paulsson, Magnus, Rune Sirnonson, and Ulla Westerrnark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 9, no. 4 (December 1, 1994): 232–36. http://dx.doi.org/10.3183/npprj-1994-09-04-p232-236.

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30

Paulsson, Magnus, Rune Sirnonson, and Ulla Westermark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 10, no. 1 (January 1, 1995): 62–67. http://dx.doi.org/10.3183/npprj-1995-10-01-p062-067.

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Paulsson, Magnus, Shiming Li, Knut Lundquist, Rune Simonson, and Ulla Westermark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 11, no. 2 (May 1, 1996): 109–14. http://dx.doi.org/10.3183/npprj-1996-11-02-p109-114.

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32

Paulsson, Magnus, Shiming Li, Rune Simonson, and Ulla Westermark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 11, no. 4 (December 1, 1996): 220–26. http://dx.doi.org/10.3183/npprj-1996-11-04-p220-226.

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33

Paulsson, Magnus, Rune Simonson, and Ulla Westermark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 11, no. 4 (December 1, 1996): 227–33. http://dx.doi.org/10.3183/npprj-1996-11-04-p227-233.

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34

Paulsson, Magnus, Rune Simonson, and Ulla Westermark. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 11, no. 4 (December 1, 1996): 234–38. http://dx.doi.org/10.3183/npprj-1996-11-04-p234-238.

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35

Paulsson, Magnus, and Arthur J. Ragauskas. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 13, no. 2 (May 1, 1998): 124–31. http://dx.doi.org/10.3183/npprj-1998-13-02-p124-131.

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36

Paulsson, Magnus, and Arthur J. Ragauskas. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 13, no. 2 (May 1, 1998): 132–42. http://dx.doi.org/10.3183/npprj-1998-13-02-p132-142.

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37

Paulsson, Magnus, and Arthur J. Ragauskas. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 13, no. 3 (August 1, 1998): 191–97. http://dx.doi.org/10.3183/npprj-1998-13-03-p191-197.

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38

Paulsson, Magnus, and Arthur J. Ragauskas. "Chemical modification of lignin-rich paper." Nordic Pulp & Paper Research Journal 13, no. 3 (August 1, 1998): 198–205. http://dx.doi.org/10.3183/npprj-1998-13-03-p198-205.

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39

Li, Xu, Jing-Ke Weng, and Clint Chapple. "Improvement of biomass through lignin modification." Plant Journal 54, no. 4 (May 2008): 569–81. http://dx.doi.org/10.1111/j.1365-313x.2008.03457.x.

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40

Umezawa, Toshiaki. "Lignin modification in planta for valorization." Phytochemistry Reviews 17, no. 6 (January 8, 2018): 1305–27. http://dx.doi.org/10.1007/s11101-017-9545-x.

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Nada, Abda‐Alla M. A., Hussein Abou‐Youssef, and Souad E. M. El‐Gohary. "Phenol Formaldehyde Resin Modification with Lignin." Polymer-Plastics Technology and Engineering 42, no. 4 (January 9, 2003): 689–99. http://dx.doi.org/10.1081/ppt-120023103.

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Karthäuser, Johannes, Vladimirs Biziks, Carsten Mai, and Holger Militz. "Lignin and Lignin-Derived Compounds for Wood Applications—A Review." Molecules 26, no. 9 (April 26, 2021): 2533. http://dx.doi.org/10.3390/molecules26092533.

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Improving the environmental performance of resins in wood treatment by using renewable chemicals has been a topic of interest for a long time. At the same time, lignin, the second most abundant biomass on earth, is produced in large scale as a side product and mainly used energetically. The use of lignin in wood adhesives or for wood modification has received a lot of scientific attention. Despite this, there are only few lignin-derived wood products commercially available. This review provides a summary of the research on lignin application in wood adhesives, as well as for wood modification. The research on the use of uncleaved lignin and of cleavage products of lignin is reviewed. Finally, the current state of the art of commercialization of lignin-derived wood products is presented.

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Komisarz, Karolina, Tomasz M. Majka, Monika Kurczab, and Krzysztof Pielichowski. "Synthesis and Characterization of Thermally Stable Lignosulfonamides." Molecules 27, no. 21 (October 25, 2022): 7231. http://dx.doi.org/10.3390/molecules27217231.

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Lignin, a highly aromatic macromolecule building plant cells, and cellulose are two of the most commonly occurring natural polymers. Lignosulfonate is a grade of technical lignin, obtained as a by-product in the paper and wood pulping industries, a result of the used lignin isolation method, i.e., sulfite process. In this work, sodium lignosulfonate is used as a starting material to manufacture sulfonamide derivatives of lignin in a two-step modification procedure. Since this direction of the lignin modification is rather rarely investigated and discussed, it makes a good starting point to expand the state of knowledge and explore the properties of lignosulfonamides. Materials obtained after modification underwent characterization by FTIR, SS-NMR, WAXD, SEM, and TGA. Spectroscopic measurements confirmed the incorporation of dihexylamine into the lignin structure and the formation of lignosulfonamide. The crystalline structure of the material was not affected by the modification procedure, as evidenced by the WAXD, with only minute morphological changes of the surface visible on the SEM imaging. The obtained materials were characterized by improved parameters of thermal stability in relation to the raw material. As-prepared sulfonamide lignin derivatives with a potential application as a filler in biopolymeric composites may become a new class of functional, value-added, sustainable additives.

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Luo, Xue Gang, Xiao Yan Lin, and Feng Liu. "Key Technology for Extraction, Thermoplastic Modification and Application of Lignin." Materials Science Forum 620-622 (April 2009): 241–46. http://dx.doi.org/10.4028/www.scientific.net/msf.620-622.241.

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New technique has been used to extract of lignin by adding carboxylic acid derivates and organic solvent to precipitate and extract lignin from black liquor (pulp wastewater). Through this new treatment process, new carboxylate which is decomposed to carbondioxide, water and metal oxide at the high temperature was formed. The process of using organic carboxylic acid and organic solvent to precipitate and extract lignin is low-cost and can not cause second pollution. The lignin obtained through this new process is water insoluble and thermoplastic. Its weigh average molecular weight, purity, and glass transition temperature are higher than 2000, 90% and 150°C, respectively. Through the methods of thermoplastic modification, the thermoplastic properties for high purity lignin-based composite materials are improved significantly. Its melt flow ratio, tensile strength and elongation at break are 0.73 g/10 min, 11.8 MPa, and 21%, respectively. Thermoplastic lignin-based composite materials have good processing properties as well as synthetic polymers for extruding, injection molding, and blowing processes. Lignin, as a kind of natural thermoplastic polymers with good processing properties, can be carried out to process for film, foam, and thermoplastic composite.

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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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Pinto, Patricia I. F., Sandra Magina, Sara Fateixa, Paula C. R. Pinto, Falk Liebner, and Dmitry V. Evtuguin. "Modification of Paper Surface by All-Lignin Coating Formulations." Materials 15, no. 22 (November 8, 2022): 7869. http://dx.doi.org/10.3390/ma15227869.

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All-lignin coating formulations were prepared while combining water-soluble cationic kraft lignin (quaternized LignoBoost®, CL) and anionic lignosulphonate (LS). The electrostatic attraction between positively charged CL and negatively charged LS led to the formation of insoluble self-organized macromolecule aggregates that align to films. The structures of the formed layers were evaluated by atomic force microscopy (AFM), firstly on glass lamina using dip-coating deposition and then on handsheets and industrial uncoated paper using roll-to-roll coating in a layer-by-layer mode. Coated samples were also characterized by optical microscopy, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (SEM/EDS), and contact angle measurements. It was suggested that the structure of all-lignin aggregates is the result of the interaction of amphiphilic water-soluble lignin molecules leading to their specifically ordered mutual arrangement depending on the order and the mode of their application on the surface. The all-lignin coating of cellulosic fiber imparts lower air permeability and lower free surface energy to paper, mainly due to a decrease in surface polarity, thus promoting the paper’s hydrophobic properties. Moderate loading of lignin coating formulations (5–6 g m−2) did not affect the mechanical strength of the paper.

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47

Yue, Xiaopeng, Fangeng Chen, and Xuesong Zhou. "Improved interfacial bonding of PVC/wood-flour composites by lignin amine modification." BioResources 6, no. 2 (April 21, 2011): 2022–34. http://dx.doi.org/10.15376/biores.6.2.2022-2034.

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Soda lignin was divided into two fractions with different molecular weights by methanol extraction. Lignin amine was synthesized from the low-molecular-weight lignin fraction via Mannich reaction and was used for interfacial modification of poly-(vinylchloride) (PVC)/wood-flour composites. The PVC/wood-flour composites were prepared from surface-treated wood flour and PVC by melt compounding. The lignin amine treatment provided almost equivalent improvement in mechanical performances of composites as aminosilane treatment does. The tensile and impact strengths of composites prepared from 30phr of wood flour treated with 2wt% lignin amine were increased by 21.0% and 43.9%, respectively, compared to those prepared from untreated wood flour. Furthermore, lignin amine treatment could also significantly reduce the water absorption of composites. A significant increase in storage modulus (E’) was observed upon incorporation of wood flour with lignin amine treatment. The improved dispersion of wood flour in polymer matrix was observed by SEM images when the wood flour was treated by lignin amine. The experimental data indicate that the polymer-wood interfacial combination is strengthened.

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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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49

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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Wan, Xue, Fengpei Yao, Dong Tian, Fei Shen, Jinguang Hu, Yongmei Zeng, Gang Yang, Yanzong Zhang, and Shihuai Deng. "Pretreatment of Wheat Straw with Phosphoric Acid and Hydrogen Peroxide to Simultaneously Facilitate Cellulose Digestibility and Modify Lignin as Adsorbents." Biomolecules 9, no. 12 (December 8, 2019): 844. http://dx.doi.org/10.3390/biom9120844.

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Effective valorization of lignin is crucial to achieve a sustainable, economic and competitive biorefinery of lignocellulosic biomass. In this work, an integrated process was proposed based on a concentrated phosphoric acid plus hydrogen peroxide (PHP) pretreatment to simultaneously facilitate cellulose digestibility and modify lignin as adsorbent. As a dominant constitutor of PHP pretreatment, H2O2 input and its influence on the overall fractionation/lignin modification performance was thoroughly investigated. Results indicated that wheat straw was fractionated more efficiently by increasing the H2O2 input. H2O2 input had a significant influence on the digestibility of the obtained cellulose-rich fraction whereby almost 100.0% cellulose-glucose conversion can be achieved even with only 0.88% H2O2 input. Besides, the adsorption capacity of lignin on MB was improved (74.3 to 210.1 mg g−1) due to the oxidative-modification in PHP pretreatment with H2O2 inputs. Regression analysis indicated that –COOH groups mainly governed the lignin adsorption (R2 = 0.946), which displayed the considerable adsorption capacities for typical cationic substances. This work shows a promising way to integrate the lignin modification concept into the emerging PHP pretreatment process with the dual goal of both cellulose utilization and lignin valorization.

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Journal articles on the topic 'Lignin modification'

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