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Mun JS, Mun SP. Structural and Thermal Characterization of Milled Wood Lignin from Bamboo ( Phyllostachys pubescens) Grown in Korea. Molecules 2023; 29:183. [PMID: 38202765 PMCID: PMC10780058 DOI: 10.3390/molecules29010183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 12/22/2023] [Accepted: 12/26/2023] [Indexed: 01/12/2024] Open
Abstract
The structural and thermal characterization of milled wood lignin (MWL) prepared from bamboo (Phyllostachys pubescens) grown in Korea was investigated, and the results were compared with bamboo MWLs from other studies. The C9 formula of the bamboo MWL was C9H7.76O3.23N0.02 (OCH3)1.41. The Mw and Mn of MWL were 13,000 and 4400 Da, respectively, which resulted in a polydispersity index (PDI) of 3.0. The PDI of the prepared MWL was higher than other bamboo MWLs (1.3-2.2), suggesting a broader molecular weight distribution. The structural features of MWL were elucidated using FT-IR spectroscopy and NMR techniques (1H, 13C, HSQC, 31P NMR), which indicate that MWL is of the HGS-type lignin. The major lignin linkages (β-O-4, β-β, β-5) were not different from other bamboo MWLs. The syringyl/guaiacyl ratio, determined from 1H NMR, was calculated as 0.89. 31P NMR revealed variations in hydroxyl content, with a higher aliphatic hydroxyl content in MWL compared to other bamboo MWLs. Thermal properties were investigated through TGA, DSC, and pyrolysis-GC/MS spectrometry (Py-GC/MS). The DTGmax of MWL under inert conditions was 287 °C, and the Tg of MWL was 159 °C. Py-GC/MS at 675 °C revealed a syringyl, guaiacyl, p-hydroxyphenyl composition of 17:37:47.
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Affiliation(s)
- Ji-Sun Mun
- Department of Carbon Materials and Fiber Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea;
| | - Sung-Phil Mun
- Department of Wood Science and Technology, Jeonbuk National University, Jeonju 54896, Republic of Korea
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Zhu X, Sipilä J, Potthast A, Rosenau T, Balakshin M. Exploring Alkyl-O-Alkyl Ether Structures in Softwood Milled Wood Lignins. J Agric Food Chem 2023; 71:580-591. [PMID: 36542797 PMCID: PMC9837880 DOI: 10.1021/acs.jafc.2c06375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 06/17/2023]
Abstract
Recent studies have suggested that there are significant amounts of various alkyl ether (Alk-O-Alk; Alk = alkyl) moieties in a spruce native lignin preparation, milled wood lignin (SMWL). However, the comprehensive NMR assignment to these moieties has not been addressed yet. This study focused on investigating different types of Alk-O-Alk structures at the α- and γ-positions of the lignin side chain in an heteronuclear single-quantum coherence (HSQC) spectrum of SMWL using experimental NMR data of lignin and synthesized model compounds. Ambiguous structural features were predicted by computer simulation of 1H and 13C NMR spectra to complement the experimental NMR data. As a result, specific regions in the HSQC spectrum were attributed to different Alk-O-Alk moieties of Alk-O-Alk/β-O-4 and Alk-O-Alk/β-β' structures. However, the differences between the specific regions were rather subtle; they were not well separated from each other and some major lignin moieties. Furthermore, SMWL contained a large variety of Alk-O-Alk moieties but in minute individual amounts, resulting in rather broad, superimposing resonances. Thus, evaluation did not allow assigning individual types of Alk-O-Alk moieties from the HSQC spectra; instead, they were quantified as total (α- and γ-linked) Alk-O-Alk based on the balance of structural units in the 13C NMR spectra. At last, potential formation mechanisms of various Alk-O-Alk ether structures in lignin biosynthesis, lignin aging, and during ball milling of wood were hypothesized and discussed.
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Affiliation(s)
- Xuhai Zhu
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo 02150, Finland
| | - Jussi Sipilä
- Laboratory
of Organic Material Chemistry, Department of Chemistry, University of Helsinki, P.O. 55 (A. I. Virtasen Aukio 1), Helsinki 00014, Finland
| | - Antje Potthast
- Department
of Chemistry, Institute for Chemistry of Renewable Resources, University of Natural Resources and Life Sciences
(BOKU), Muthgasse 18, Vienna 1190, Austria
| | - Thomas Rosenau
- Department
of Chemistry, Institute for Chemistry of Renewable Resources, University of Natural Resources and Life Sciences
(BOKU), Muthgasse 18, Vienna 1190, Austria
| | - Mikhail Balakshin
- Department
of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo 02150, Finland
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Yang G, An X, Yang S. The Effect of Ball Milling Time on the Isolation of Lignin in the Cell Wall of Different Biomass. Front Bioeng Biotechnol 2022; 9:807625. [PMID: 34970536 PMCID: PMC8713889 DOI: 10.3389/fbioe.2021.807625] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 11/15/2021] [Indexed: 12/02/2022] Open
Abstract
Ball milling technology is the classical technology to isolate representative lignin in the cell wall of biomass for further investigation. In this work, different ball milling times were carried out on hardwood (poplar sawdust), softwood (larch sawdust), and gramineous material (bamboo residues) to understand the optimum condition to isolate the representative milled wood lignin (MWL) in these different biomass species. Results showed that prolonging ball milling time from 3 to 7 h obviously increased the isolation yields of MWL in bamboo residues (from 39.2% to 53.9%) and poplar sawdust (from 15.5% to 35.6%), while only a slight increase was found for the MWL yield of larch sawdust (from 23.4% to 25.8%). Importantly, the lignin substructure of ß-O-4 in the MWL samples from different biomasses can be a little degraded with the increasing ball milling time, resulting in the prepared MWL with lower molecular weight and higher content of hydroxyl groups. Based on the isolation yield and structure features, milling time with 3 and 7 h were sufficient to isolate the representative lignin (with yield over 30%) in the cell wall of bamboo residues and poplar sawdust, respectively, while more than 7 h should be carried out to isolate the representative lignin in larch sawdust.
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Affiliation(s)
- Guangrong Yang
- College of Furniture and Industrial Design, Nanjing Forestry University, Nanjing, China.,School of Landscape Architecture, Jiangsu Vocational College of Agriculture and Forestry, Jurong, China
| | - Xueying An
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Sports Medicine and Adult Reconstructive Surgery, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | - Shilong Yang
- Advanced Analysis and Testing Center, Nanjing Forestry University, Nanjing, China
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Mun JS, Pe JA 3rd, Mun SP. Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods. Molecules 2021; 26:4861. [PMID: 34443450 DOI: 10.3390/molecules26164861] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/06/2021] [Accepted: 08/07/2021] [Indexed: 11/17/2022] Open
Abstract
Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C9 formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C9 formula of KL was determined to be C9H7.29O2.26N0.07S0.12(OCH3)1.24. The Mw of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (1H, 13C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH- and OH- during pulping.
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Wan G, Zhang Q, Li M, Jia Z, Guo C, Luo B, Wang S, Min D. How Pseudo-lignin Is Generated during Dilute Sulfuric Acid Pretreatment. J Agric Food Chem 2019; 67:10116-10125. [PMID: 31442037 DOI: 10.1021/acs.jafc.9b02851] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pseudo-lignin is generated from lignocellulose biomass during pretreatment with dilute sulfuric acid and has a significant inhibitory effect on cellulase. However, the mechanism of pseudo-lignin generation remains unclear. The following main points have been addressed to help elucidate the pseudo-lignin generation pathway. Cellulose and xylan were pretreated with sulfuric acid at different concentrations; aliquots were periodically collected; and the changes in the byproducts of the prehydrolysate were quantified. Milled wood lignin (MWL) mixed with cellulose and xylan was pretreated to evaluate the impact of lignin on pseudo-lignin generation. Furfural, 5-hydroxymethylfurfural, and MWL were pretreated as model compounds to investigate pseudo-lignin generation. The result indicated that the increasing acid concentration significantly promoted the generation of pseudo-lignin. When the acid concentration was increased from 0 to 1.00 wt %, pseudo-lignin was increased from 1.36 to 4.05 g. In addition, lignin promoted the pseudo-lignin generation through the condensation between lignin and the generated intermediates.
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Affiliation(s)
- Guangcong Wan
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Qingtong Zhang
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Mingfu Li
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Zhuan Jia
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Chenyan Guo
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Bin Luo
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Shuangfei Wang
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Douyong Min
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
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Zinovyev G, Sumerskii I, Rosenau T, Balakshin M, Potthast A. Ball Milling's Effect on Pine Milled Wood Lignin's Structure and Molar Mass. Molecules 2018; 23:molecules23092223. [PMID: 30200441 PMCID: PMC6225492 DOI: 10.3390/molecules23092223] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 08/25/2018] [Accepted: 08/29/2018] [Indexed: 11/16/2022] Open
Abstract
The effect of ball milling expressed as the yield of milled wood lignin (MWL) on the structure and molar mass of crude milled wood lignin (MWLc) preparation is studied to better understand the process' fundamentals and find optimal conditions for MWL isolation (i.e., to obtain the most representative sample with minimal degradation). Softwood (loblolly pine) MWLc preparations with yields of 20⁻75% have been isolated and characterized based on their molar mass distribution (by Size Exclusion Chromatography (SEC)), hydroxyl groups of different types (31P NMR), methoxyl groups (HS-ID GC-MS), and sugar composition (based on methanolysis). Classical MWL purification is not used to access the whole extracted lignin. The results indicate that lignin degradation during ball milling occurs predominantly in the high molar mass fraction and is less pronounced in the low molar mass fraction. This results in a significant decrease in the Mz and Mw of the extracted MWLc with an increase in the yield of MWLc, but has only a very subtle effect on the lignin structure if the yield of MWLc is kept below about 55%. Therefore, no tedious optimization of process variables is necessary to achieve the required MWLc yield in this range for structural studies of softwood MWL. The sugar composition shows higher amounts of pectin components in MWLs of low yields and higher amounts of glucan and mannan in high-yield MWLs, confirming that lignin extraction starts from the middle lamella in the earlier stages of MWL isolation, followed by lignin extraction from the secondary wall region.
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Affiliation(s)
- Grigory Zinovyev
- Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
| | - Ivan Sumerskii
- Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
| | - Thomas Rosenau
- Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
| | - Mikhail Balakshin
- Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland.
| | - Antje Potthast
- Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, A-3430 Tulln, Austria.
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Abstract
Chinese quince (Chaenomeles sinensis) is used in food and pharmaceutical products, but it is seldom eaten as a raw fruit due to its astringent, woody flesh. The structural characterization of lignin fractions from Chinese quince was very important to investigate the structure-activity relationships of lignin. In this investigation, to characterize the structure of lignin in Chinese quince fruits, the milled wood lignin sample was isolated from the fruits (FMWL) and the chemical structure of FMWL was investigated by sugar analysis, FT-IR, GPC, pyrolysis-GC/MS analysis, UV spectra analysis, thermogravimetric analysis (TGA), and advanced NMR spectroscopic techniques. In addition, the lignin fraction from the stalk of Chinese quince (SMWL) was also prepared for comparison to obtained more information of lignin structure in the fruits. The results showed that the two lignin fractions isolated from fruit and stalk of Chinese quince exhibited different structural features. The two MWL samples were mainly composed of β-O-4 ether bonds, β-5 and β-β' carbon-carbon linkages in the lignin structural units. Compared to the SMWL, the FMWL fraction had the higher S/G ratio and more carbohydrates linkages. The predominant carbohydrates associated with FMWL and SMWL fractions were glucans-type hemicelluloses and xylan-type hemicelluloses, respectively. Understanding the structure of lignin could give insight into the properties of the lignin and enable the food processing industry to separate lignin more efficiently.
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Affiliation(s)
- Hui-Shuang Yin
- Department of Oil Engineering, College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China.
| | - Hua-Min Liu
- Department of Oil Engineering, College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China.
| | - Yu-Lan Liu
- Department of Oil Engineering, College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China.
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Wu JQ, Wen JL, Yuan TQ, Sun RC. Integrated hot-compressed water and laccase-mediator treatments of Eucalyptus grandis fibers: structural changes of fiber and lignin. J Agric Food Chem 2015; 63:1763-1772. [PMID: 25639522 DOI: 10.1021/jf506042s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Eucalyptus grandis fibers were treated with hot-compressed water (HCW) and laccase mediator to enhance the fiber characteristics and to produce an active lignin substrate for binderless fiberboard production. The composition, morphology, and crystallinity index (CrI) analysis of fibers showed that the HCW treatment increased the CrI and lignin content of the treated fibers through partial removal of hemicelluloses. Simultaneously, the HCW treatment produced some granules and holes on the surface of the fibers, which possibly facilitated the accessibility of the laccase mediator. Milled wood lignins and enzymatic hydrolysis lignins isolated from the control and treated fibers were comparatively characterized. A reduction of molecular weight was observed, which indicated that a preferential degradation of lignin occurred after exposure to the laccase mediator. Quantitative (13)C, 2D-HSQC and (31)P NMR characterization revealed that the integrated treatment resulted in the cleavage of β-O-4' linkages, removal of G' (oxidized α-ketone) substructures, and an increase in the S/G ratio and free phenolic hydroxyls.
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Affiliation(s)
- Jian-Quan Wu
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University , Beijing, China
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