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International Journal of Biological... Oct 2021The production of low-cost and high-quality carbon fibers (CFs) from biorenewable lignin precursors has been of worldwide interest for decades. Although numerous works... (Review)
Review
The production of low-cost and high-quality carbon fibers (CFs) from biorenewable lignin precursors has been of worldwide interest for decades. Although numerous works have been reported and the proposed "1.72 GPa/172 GPa" target set by the Department of Energy (DOE) has been closely met in a few studies, most lignin-based CFs (LCFs) have poor strength properties compared to industrial PAN (polyacrylonitrile)-based CFs. The production of LCFs involves several steps, and the final quality of LCFs is governed by both lignin's properties and the manufacturing processes. Therefore, understanding the key factors of producing high quality LCF is of high importance. In this review, we firstly outlined several lignin's properties (e.g., impurities, thermal properties, molecular structure) that may play important role in determining its processability and suitability as carbon fiber precursor. Secondly, conversion strategies include spinning, stabilization and carbonization, and corresponding parameters influencing the final quality of LCF are comprehensively analyzed. Last, additional characterization methods are proposed as a means to facilitate analyzing of lignin and LCF. This review attempts to provide insights towards high-quality LCF production from both material and manufacturing aspects.
Topics: Acrylic Resins; Calorimetry, Differential Scanning; Carbon Fiber; Lignin; Molecular Weight; Transition Temperature
PubMed: 34464641
DOI: 10.1016/j.ijbiomac.2021.08.187 -
International Journal of Biological... Sep 2022Lignin, as the most abundant aromatic biopolymer, is being widely studied to replace phenol and some other petroleum-based materials in the polymer industry. However,...
Lignin, as the most abundant aromatic biopolymer, is being widely studied to replace phenol and some other petroleum-based materials in the polymer industry. However, the low substitution of lignin and high levels of additives greatly limited the applications of lignin-based materials. Herein, we first propose a simple but effective hydrothermal method assisted synthesis for the fabrication of self-crosslinked lignin-based hydrogels (Lig-Scgel) with super-high-contents (75 wt%) of lignin and controllable mechanical properties. The self-crosslink mechanism was inspired by the repolymerization of lignins under a hydrothermal environment. The employment of self-condensation of lignin subunits in the synthesis of Lig-Scgel can significantly improve the degree of crosslinking, thereby greatly reducing the addition of toxic crosslinkers. The appearances, microstructures, crosslink densities, and mechanical properties of Lig-Scgels can be well controlled by simply altering the hydrothermal temperatures. This strategy not only promotes green and large-scale applications of lignin but also provides insights in the development of environment-friendly polymeric materials.
Topics: Biopolymers; Chemical Phenomena; Hydrogels; Lignin; Polymers
PubMed: 35817238
DOI: 10.1016/j.ijbiomac.2022.07.003 -
International Journal of Biological... Mar 2022The application of industrial kraft lignin is limited by its low molecular weight, dark color, and low solubility. In this work, an efficient crosslinking reaction with...
The application of industrial kraft lignin is limited by its low molecular weight, dark color, and low solubility. In this work, an efficient crosslinking reaction with N,N-Dimethylformamide (DMF) and 1,6-dibromohexane was proposed for adjusting the molecular weight and color of lignin. The chemical structure of alkylation lignin was systematically investigated by gel permeation chromatography (GPC), ultraviolet spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and 2D heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR) spectra. After the alkylation modification, the molecular weights of the lignin were increased to 1643%. The resinol (β-β), β-aryl ether (β-O-4), and phenylcoumaran (β-5) linkages were still the main types of the linkages. The formation of β-β linkage would be inhibited at high temperatures. The color reduction of lignin can be attributed to the low content of chromophores and low packing density. This alkylation lignin will be a new and general approach for developing molecular weight-controlled and light-colored lignins, which can find more applications in cosmetics, packing, and other fields.
Topics: Alkylation; Chromatography, Gel; Lignin; Molecular Structure; Molecular Weight; Spectroscopy, Fourier Transform Infrared
PubMed: 34995668
DOI: 10.1016/j.ijbiomac.2021.12.162 -
ChemSusChem Aug 2022The amphiphilic chemical structure of native lignin, composed by a hydrophobic aromatic core and hydrophilic hydroxy groups, makes it a promising alternative for the...
The amphiphilic chemical structure of native lignin, composed by a hydrophobic aromatic core and hydrophilic hydroxy groups, makes it a promising alternative for the development of bio-based surface-active compounds. However, the severe conditions traditionally needed during biomass fractionation make lignin prone to condensation and cause it to lose hydrophilic hydroxy groups in favour of the formation of C-C bonds, ultimately decreasing lignin's abilities to lower surface tension of water/oil mixtures. Therefore, it is often necessary to further functionalize lignin in additional synthetic steps in order to obtain a surfactant with suitable properties. In this work, multifunctional aldehyde-assisted fractionation with glyoxylic acid (GA) was used to prevent lignin condensation and simultaneously introduce a controlled amount of carboxylic acid on the lignin backbone for its further use as surfactant. After fully characterizing the extracted GA-lignin, its surface activity was measured in several water/oil systems at different pH values. Then, the stability of water/mineral oil emulsions was evaluated at different pH and over a course of 30 days by traditional photography and microscopy imaging. Further, the use of GA-lignin as a surfactant was investigated in the formulation of a cosmetic hand cream composed of industrially relevant ingredients. Contrary to industrial lignins such as Kraft lignin, GA-lignin did not alter the color or smell of the formulation. Finally, the surface activity of GA-lignin was compared with other lignin-based and fossil-based surfactants, showing that GA-lignin presented similar or better surface-active properties compared to some of the most commonly used surfactants. The overall results showed that GA-lignin, a biopolymer that can be made exclusively from renewable carbon, can successfully be extracted in one step from lignocellulosic biomass. This lignin can be used as an effective surfactant without further modification, and as such is a promising candidate for the development of new bio-based surface-active products.
Topics: Glyoxylates; Lignin; Surface-Active Agents; Water
PubMed: 35532091
DOI: 10.1002/cssc.202200270 -
Bioresource Technology Sep 2023Utilizing lignocellulosic biomass wastes to produce bioproducts is essential to address the reliance on depleting fossil fuels. However, lignin is often treated as a... (Review)
Review
Utilizing lignocellulosic biomass wastes to produce bioproducts is essential to address the reliance on depleting fossil fuels. However, lignin is often treated as a low-value-added component in lignocellulosic wastes. Valorization of lignin into value-added products is crucial to improve the economic competitiveness of lignocellulosic biorefinery. Monomers obtained from lignin depolymerization could be upgraded into fuel-related products. However, lignins obtained from conventional methods are low in β-O-4 content and, therefore, unsuitable for monomer production. Recent literature has demonstrated that lignins extracted with alcohol-based solvents exhibit preserved structures with high β-O-4 content. This review discusses the recent advances in utilizing alcohols to extract β-O-4-rich lignin, where discussion based on different alcohol groups is considered. Emerging strategies in employing alcohols for β-O-4-rich lignin extraction, including alcohol-based deep eutectic solvent, flow-through fractionation, and microwave-assisted fractionation, are reviewed. Finally, strategies for recycling or utilizing the spent alcohol solvents are also discussed.
Topics: Biomass; Ethanol; Lignin; Solvents; Waste Management
PubMed: 37245662
DOI: 10.1016/j.biortech.2023.129238 -
Biomacromolecules Sep 2023The bioconversion of homogeneous linear catechyl lignin (C-lignin) to polyhydroxyalkanoates (PHA) was examined for the first time in this study. C-lignins from vanilla,...
The bioconversion of homogeneous linear catechyl lignin (C-lignin) to polyhydroxyalkanoates (PHA) was examined for the first time in this study. C-lignins from vanilla, euphorbia, and candlenut seed coats (denoted as C1, C2, and C3, respectively) varied in their molecular structures, which showed different molecular weight distributions, etherification degrees, and contents of hydroxyl groups. A notable amount of nonetherified catechol units existed within C1 and C2 lignins, and these catechol units were consumed during fermentation. These results suggested that the nonetherified catechol structure was readily converted by KT2440. Since the weight-average molecular weight of C2 raw lignin was 26.7% lower than that of C1, the bioconversion performance of C2 lignin was more outstanding. The KT2440 cell amount reached the maximum of 9.3 × 10 CFU/mL in the C2 medium, which was 37.9 and 82.4% higher than that in the C1 and C3 medium, respectively. Accordingly, PHA concentration reached 137 mg/L within the C2 medium, which was 41.2 and 149.1% higher than the C1 and C3 medium, respectively. Overall, C-lignin, with a nonetherified catechol structure and low molecular weight, benefits its microbial conversion significantly.
Topics: Lignin; Polyhydroxyalkanoates; Fermentation; Pseudomonas putida
PubMed: 37555845
DOI: 10.1021/acs.biomac.3c00288 -
International Journal of Biological... Nov 2021In this study, electrospray deposition has been used as a method to prepare lignin submicron spherical particles. Regularities of electrospraying of lignin solutions in...
In this study, electrospray deposition has been used as a method to prepare lignin submicron spherical particles. Regularities of electrospraying of lignin solutions in DMSO were revealed. The influence of voltage, distance between electrodes, feed rate, temperature and concentration of lignin solution on the morphology, size and polydispersity of the obtained particles was determined. SEM, IR, TG-DSC, elemental analysis, dynamic light scattering, Zeta potential and nitrogen sorption were used to characterize the particles and to determine their properties. The aqueous colloidal solutions of the submicron particles of lignins from various plant sources were stabilized by preparing the lignin/polyvinylpyrrolidone polymeric complexes.
Topics: Betula; Calorimetry, Differential Scanning; Colloids; Electricity; Electrochemistry; Elements; Lignin; Particle Size; Povidone; Solutions; Spectroscopy, Fourier Transform Infrared; Surface Properties; Thermogravimetry; Water
PubMed: 34509517
DOI: 10.1016/j.ijbiomac.2021.09.013 -
ChemSusChem Oct 2022A laccase-Lig multienzymatic multistep system for lignin depolymerization was designed and developed. Studies were performed on pristine and fractionated lignins (Kraft...
A laccase-Lig multienzymatic multistep system for lignin depolymerization was designed and developed. Studies were performed on pristine and fractionated lignins (Kraft and Organosolv) using a specific cascade of enzymes, that is, laccases from Bacillus licheniformis and from Funalia trogii, respectively for Kraft and Organosolv lignin, followed by the Lig system from Sphingobium sp. SYK-6 (β-etherases Lig E and Lig F, glutathione lyase Lig G). Careful elucidation of the structural modifications occurring in the residual lignins associated with the identification and quantification of the generated low-molecular-weight compounds showed that (i) the laccase-Lig system cleaves non-phenolic aryl glycerol β-O-4 aryl ether bonds, and (ii) the overall reactivity is heavily dependent on the individual lignin structure. More specifically, samples with low phenolic/aliphatic OH groups ratio undergo net depolymerization, while an increased phenolic/aliphatic OH ratio results in the polymerization of the residual lignin irrespective of its botanical origin and isolation process.
Topics: Lignin; Laccase; Glycerol; Lyases; Ethers; Glutathione
PubMed: 35917230
DOI: 10.1002/cssc.202201147 -
Bioresource Technology May 2022To elucidate the structure-activity relationship between lignin and various cellulase domains, four lignin fractions with specific structures and molecular weight were...
To elucidate the structure-activity relationship between lignin and various cellulase domains, four lignin fractions with specific structures and molecular weight were prepared from bamboo kraft lignin (BKL) and used to investigate the adsorption mechanism between different cellulase domains by fluorescence spectroscopy and SDS-PAGE. Endo-cellulase 6B exhibited a higher affinity to BKL fractions than the carbohydrate-binding module (CBM4A) of cellulase, which is positively correlated to molecular weight. The thermodynamic mechanism showed that the adsorption between BKL fractions and endo-cellulase 6B was dominated by van der Waals and electrostatic forces, while hydrophobic force is the driver for BKL fractions to adsorb CBM4A. Structure-activity relationship between lignin fractions and cellulase domain revealed that thermodynamics and interaction forces were more easily affected by the structure of BKL, including S/G ratio, molecular weight and hydrophobicity. The aforementioned results demonstrated that lignin's structure plays a critical role in its adsorption with various cellulase domains.
Topics: Adsorption; Cellulase; Hydrolysis; Hydrophobic and Hydrophilic Interactions; Lignin
PubMed: 35318146
DOI: 10.1016/j.biortech.2022.127042 -
Journal of Agricultural and Food... Dec 2020A high-throughput agarose gel electrophoresis (AGE) analytical method has been developed to separate lignin fractions according to their molecular weight (), charge, and...
A high-throughput agarose gel electrophoresis (AGE) analytical method has been developed to separate lignin fractions according to their molecular weight (), charge, and shape. Operating conditions to effect separation of species have been evaluated along with imaging parameters. Kraft, soda (Protobind), and Organosolv lignins showed distinct differences in migration. Bands were cut, extracted, and cross-analyzed by gel permeation chromatography (GPC), H NMR, and pyrolysis GC/MS to confirm their identity as lignin. The band intensity was correlated with lignin concentration by running serially diluted samples and imaging each lane to produce a precise calibration curve. The AGE technique was used to monitor and compare enzymatic, bacterial, chemical, and hydrothermal lignin digestions. Each method showed changes in lignin migration and band intensities over time. Low species were seen in samples collected from the anode buffer tank. Though requiring further development, the AGE method can provide structural information about the lignin and is accessible to biological and chemistry laboratories.
Topics: Electrophoresis, Agar Gel; High-Throughput Screening Assays; Lignin; Molecular Weight
PubMed: 33200936
DOI: 10.1021/acs.jafc.0c06308