scholarly journals Correction: Spruce milled wood lignin: linear, branched or cross-linked?

2020 ◽  
Vol 22 (22) ◽  
pp. 8046-8046
Author(s):  
Mikhail Balakshin ◽  
Ewellyn Augsten Capanema ◽  
Xuhai Zhu ◽  
Irina Sulaeva ◽  
Antje Potthast ◽  
...  
Keyword(s):  
Milled Wood Lignin

Correction for ‘Spruce milled wood lignin: linear, branched or cross-linked?’ by Mikhail Balakshin et al., Green Chem., 2020, 22, 3985–4001, DOI: 10.1039/D0GC00926A.

scholarly journals Understanding the effects of different residual lignin fractions in acid-pretreated bamboo residues on its enzymatic digestibility

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Wenqian Lin ◽  
Jinlai Yang ◽  
Yayue Zheng ◽  
Caoxing Huang ◽  
Qiang Yong
Keyword(s):  
Enzymatic Hydrolysis ◽  
Negative Impact ◽  
Dilute Acid Pretreatment ◽  
Residual Lignin ◽  
Dilute Acid ◽  
Enzymatic Digestibility ◽  
Acid Pretreatment ◽  
Organic Reagents ◽  
Milled Wood Lignin ◽  
Affinity Constants

Abstract Background During the dilute acid pretreatment process, the resulting pseudo-lignin and lignin droplets deposited on the surface of lignocellulose and inhibit the enzymatic digestibility of cellulose in lignocellulose. However, how these lignins interact with cellulase enzymes and then affect enzymatic hydrolysis is still unknown. In this work, different fractions of surface lignin (SL) obtained from dilute acid-pretreated bamboo residues (DAP-BR) were extracted by various organic reagents and the residual lignin in extracted DAP-BR was obtained by the milled wood lignin (MWL) method. All of the lignin fractions obtained from DAP-BR were used to investigate the mechanism for interaction between lignin and cellulase using surface plasmon resonance (SPR) technology to understand how they affect enzymatic hydrolysis Results The results showed that removing surface lignin significantly decreased the yield for enzymatic hydrolysis DAP-BR from 36.5% to 18.6%. The addition of MWL samples to Avicel inhibited its enzymatic hydrolysis, while different SL samples showed slight increases in enzymatic digestibility. Due to the higher molecular weight and hydrophobicity of MWL samples versus SL samples, a stronger affinity for MWL (KD = 6.8–24.7 nM) was found versus that of SL (KD = 39.4–52.6 nM) by SPR analysis. The affinity constants of all tested lignins exhibited good correlations (r > 0.6) with the effects on enzymatic digestibility of extracted DAP-BR and Avicel. Conclusions This work revealed that the surface lignin on DAP-BR is necessary for maintaining enzyme digestibility levels, and its removal has a negative impact on substrate digestibility.

scholarly journals Structural Changes in Milled Wood Lignin (MWL) of Chinese Quince (Chaenomeles sinensis) Fruit Subjected to Subcritical Water Treatment

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 398
Author(s):  
Wen-Yue Wang ◽  
Zhao Qin ◽  
Hua-Min Liu ◽  
Xue-De Wang ◽  
Jing-Hao Gao ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Water Treatment ◽  
Quantum Coherence ◽  
Structural Changes ◽  
31P Nmr ◽  
Subcritical Water ◽  
Water Extraction ◽  
Subcritical Water Extraction ◽  
Milled Wood Lignin ◽  
Chinese Quince

Subcritical water treatment has received considerable attention due to its cost effectiveness and environmentally friendly properties. In this investigation, Chinese quince fruits were submitted to subcritical water treatment (130, 150, and 170 °C), and the influence of treatments on the structure of milled wood lignin (MWL) was evaluated. Structural properties of these lignin samples (UL, L130, L150, and L170) were investigated by high-performance anion exchange chromatography (HPAEC), FT-IR, gel permeation chromatography (GPC), TGA, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), 2D-Heteronculear Single Quantum Coherence (HSQC) -NMR, and 31P-NMR. The carbohydrate analysis showed that xylose in the samples increased significantly with higher temperature, and according to molecular weight and thermal analysis, the MWLs of the pretreated residues have higher thermal stability with increased molecular weight. The spectra of 2D-NMR and 31P-NMR demonstrated that the chemical linkages in the MWLs were mainly β-O-4′ ether bonds, β-5′ and β-β′, and the units were principally G- S- H- type with small amounts of ferulic acids; these results are consistent with the results of Py-GC/MS analysis. It is believed that understanding the structural changes in MWL caused by subcritical water treatment will contribute to understanding the mechanism of subcritical water extraction, which in turn will provide a theoretical basis for developing the technology of subcritical water extraction.

Characterization of autohydrolysis aspen (P. tremuloides) lignins. Part 4. Residual autohydrolysis lignin

1979 ◽  
Vol 57 (19) ◽  
pp. 2612-2616 ◽  
Author(s):  
Morris Wayman ◽  
Miranda G. S. Chua
Keyword(s):  
Enzymatic Hydrolysis ◽  
Time Varying ◽  
Residual Lignin ◽  
Aspen Wood ◽  
Milled Wood Lignin ◽  
Wood Meal ◽  
Nitrobenzene Oxidation ◽  
Infrared Studies ◽  
Lignocellulosic Residue

Lignocellulosic residue remaining after autohydrolysis of extractive-free aspen wood meal at 195 °C for periods of time varying from 5 to 120 min followed by extraction with 90% dioxane was subjected to enzymatic hydrolysis to obtain residual lignin. Infrared studies indicated that in the early stages of autohydrolysis residual lignin resembles protolignin, but as autohydrolysis proceeds it changes to resemble more and more the extracted lignin. Residual lignin was found to be higher in carbon but lower in hydrogen and oxygen than aspen milled wood lignin. The methoxyl content was also lower than the reference lignin. From alkaline nitrobenzene oxidation, residual lignin is seen to become more condensed with increasing autohydrolysis time. The insolubility of residual lignin is attributed to the existence of strong bonds between this lignin and carbohydrate.

Stabilization of Cotton Fibers during Mechanical Cutting

1988 ◽  
Vol 58 (10) ◽  
pp. 575-580 ◽  
Author(s):  
David N.-S. Hon
Keyword(s):  
Loblolly Pine ◽  
Oxidative Degradation ◽  
Degree Of Polymerization ◽  
Electron Spin Resonance Study ◽  
Red Oak ◽  
White Oak ◽  
Milled Wood Lignin ◽  
Subsequent Decrease ◽  
Mechanical Cutting ◽  
Oxidative Ageing

The mechanical stress energy used to process cotton in a cutter is sufficient to induce homolytic scission of C2 and C3 bonds and chain scission of C1—O—C4 glycosidic bonds, i.e., to reduce the degree of polymerization (DP), of cellulose molecules. The formation of carbon and alkoxy mechanoradicals at these locations was identified by an electron spin resonance study. The incorporation of nonylated phenol phosphite, hindered amine, and milled wood lignins of red oak and white oak was effective in inhibiting the reduction of the DP of cellulose. In addition, the incorporation of an alkylary phosphite mixture, hindered phenol, ditridecyl thiodipropionate and dialutyl thiodipropionate, milled wood lignin of loblolly pine and white oak, and lignosulfonate of spruce and red oak was useful in inhibiting the oxidative ageing of cut cotton fiber. Of the stabilizers used, only milled wood lignin of red oak was the most effective in preventing loss of the DP of cellulose during mechanical cutting and oxidative ageing. Termination of primary mechanoradicals at C2 and C3 by stabilizers appeared to eliminate secondary reactions that led to a subsequent decrease in the DP. Termination of alkoxy and carbon radicals at C4 and C1 positions appeared to eliminate oxidative degradation.

scholarly journals Structural Characterization and Antioxidant Activity of Milled Wood Lignin from Xylose Residue and Corncob

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2092 ◽  
Author(s):  
Miaomiao Xu ◽  
Chao Wang ◽  
Gaojin Lyu ◽  
Lei Zhong ◽  
Liyuan Yang ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Structural Changes ◽  
Food Additives ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Gel Permeation Chromatography ◽  
Structural Features ◽  
2D Nmr Spectroscopy ◽  
Milled Wood Lignin ◽  
Xylose Residue

Xylose residue (XR), after diluted acid treatment of corncob, consists of cellulose and lignin. However, structural changes of XR lignin have not been investigated comprehensively, and this has seriously hindered the efficient utilization of lignin. In this study, corncob milled wood lignin (CC MWL), and xylose residue milled wood lignin (XR MWL) were isolated according to the modified milled wood lignin (MWL) method. The structural features of two lignin fractions were thoroughly investigated via fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and two dimensional nuclear magnetic resonance (2D NMR) spectroscopy techniques. XR MWL with higher yield and lower bound carbohydrate contents presented more phenolic OH contents than CC MWL due to partial cleavage of β-O-4. Furthermore, the molecular weights of XR MWL were increased, possibly because of condensation of the lignin during the xylose production. A study on antioxidant activity showed that XR lignin had better radical scavenging ability than that of 2,6-Di-tert-butyl-4-methyl-phenol (BHT) and CC MWL. The results suggested that the lignin in xylose residue, showing great antioxidant properties, has potential applications in food additives.

scholarly journals Ball Milling’s Effect on Pine Milled Wood Lignin’s Structure and Molar Mass

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2223 ◽  
Author(s):  
Grigory Zinovyev ◽  
Ivan Sumerskii ◽  
Thomas Rosenau ◽  
Mikhail Balakshin ◽  
Antje Potthast
Keyword(s):  
Ball Milling ◽  
Mass Fraction ◽  
Molar Mass ◽  
Size Exclusion ◽  
Hydroxyl Groups ◽  
Wall Region ◽  
Sugar Composition ◽  
High Molar Mass ◽  
Milled Wood Lignin ◽  
Lignin Extraction

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.

Acid Reactions of Lignin Models of β-5 Type

Holzforschung ◽  
1999 ◽  
Vol 53 (1) ◽  
pp. 39-42 ◽  
Author(s):  
S. Li ◽  
K. Lundquist
Keyword(s):  
Sulfonic Acid ◽  
Starting Material ◽  
Acid Catalysts ◽  
Reaction Products ◽  
Milled Wood Lignin ◽  
H Nmr ◽  
Stilbene Derivative ◽  
Trifluoromethane Sulfonic Acid ◽  
Spectrometric Measurements ◽  
Adjacent Unit

Summary Refluxing of trans–2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]furan with dioxane-water (9 : 1) in the presence of various acid catalysts led to the formation of 2-(3,4-dimethoxyphenyl)- 7-methoxy-3-methylbenzo[b]furan, the trans and cis forms of 2-hydroxy-3,3′4′-trimethoxystilbene and cis–2-(3,4-dimethoxyphenyl)-3-hydroxymethyl-7-methoxy-2,3-dihydrobenzo[b]furan. The proportions of the products were strongly dependent on the particular acid used as catalyst. HCl and to a greater extent HBr favored the formation of the 2-arylbenzofuran (phenylcoumarone) while the trans-stilbene derivative predominated in reaction products from the experiments with trifluoromethane sulfonic acid as the catalyst. Isomerization of the starting material occurred, regardless of the nature of the catalyst (small amounts of the cis-isomer formed). The number of phenylpropane units in spruce lignin attached to an adjacent unit by a β−5 linkage was estimated to be 6–9% on the basis of 1H NMR spectrometric measurements of the formation of phenylcoumarone structures on refluxing of milled wood lignin from spruce with 0.1M HBr in dioxane-water (9 : 1).

Lignin-Polyphenol Interaction in Azobe (Lophira alata) Heartwood. A Study on Milled Wood Lignin (MWL) and Klason Residues

Holzforschung ◽  
1999 ◽  
Vol 53 (5) ◽  
pp. 519-524 ◽  
Author(s):  
Werner Lange ◽  
Oskar Faix
Keyword(s):  
Cell Wall ◽  
Degradation Products ◽  
Oxidation Products ◽  
Hydroxyl Groups ◽  
Milled Wood Lignin ◽  
Permanganate Oxidation ◽  
Methods Of Determination ◽  
Step Procedure ◽  
Acid Type

Summary Findings about anomalous high Klason residues of azobe (Lophira alata) heartwood prompted a search for methods of determination of non lignin-type polyphenols in lignin preparations. A four step procedure was performed: (1) ethylation of milled wood lignins (MWLs) from azobe and beech heartwood, (2) permanganate oxidation, (3) methylation, and (4) GC analysis of the oxidation products. Besides the well known degradation products of hemipinic, iso-hemipinic, and meta-hemipinic acid type, methyl-3,4-diethoxy-benzoate (compound I) has also been detected among the oxidation products. The oxidation of beech MWL gave rise only to 0.4 mol % of I but azobe MWL yielded the remarkably high amount of 10.7 mol % of I. As lignins do not contain two adjacent aromatic hydroxyl groups, we concluded that I is of polyflavonoid origin. Hence the extraordinarily high Klason residues of azobe heartwood can be rationalized with large amounts of acid insoluble polyphenols which are an integral part of the azobe cell wall and which is also closely associated to MWLs. Ethylation followed by KMnO4 oxidation is an effective tool to detect polyflavonoids in lignins.

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