Characterization of Milled Wood Lignin (MWL) in Loblolly Pine Stem Wood, Residue, and Bark

Huang, Fang; Singh, Preet M.; Ragauskas, Arthur J.

doi:10.1021/jf202701b

Cited by 92 publications

(85 citation statements)

References 24 publications

(69 reference statements)

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“…The significant observation from the reported results is that the S-type compounds increase with an increase in the severity of the wet explosion conditions. This was found to contradict the previous observations made by studying the effect of steam explosion and wet oxidation separately on lignocellulosic biomass [30][31][32][33][34] since these studies indicated that S units after pretreatment are cleaved to produce more G units resulting in a reduction in the S/G ratio and an increase in the lignin surface condensation. However, from both the NMR and the GC-MS analysis, wet explosion pretreatment showed an increase in the S units and decrease of H and G, which could best be explained through a selective methoxylation of H and G lignins during the pretreatment.…”

Section: Lignin-derived Phenolic Compounds As Determined By Gc/mscontrasting

confidence: 70%

“…2. Previous studies have been done for comparing the effect of various pretreatment methods on the loblolly pine lignin structure and are the basis for the discussions on chemical shifts for the 13 C NMR spectra used in this study [28][29][30]. The 13 C NMR spectra of raw biomass showed a typical softwood lignin comprising of G lignin, i.e., it largely comprised the expected prevailing G aromatic ring resonances together with characteristic methoxy (−OMe) group signals (δ C~5 5.8 ppm).…”

Section: One-dimensional 13 C Nuclear Magnetic Resonancementioning

confidence: 99%

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Wet explosion pretreatment of loblolly pine leads to an increase in methoxylation of the lignin

Rana

Laskar

Srinivas

et al. 2015

Bioresour. Bioprocess.

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Background: In biorefineries, various pretreatments traditionally employ hazardous chemicals (ammonia, sulfuric acid, sulfite, etc.) for opening the softwood structure and to facilitate easy accessibility of the cellulose for further downstream processing. The resultant lignin (known as technical lignin) after extraction of the carbohydrate fraction as sugars has been either burned as fuel or used in biochemical or biofuel production. It has been observed that the technical lignin after such biomass pretreatments is often more condensed and, hence, cannot be easily used to produce fine chemicals of high value. In this study, we examine lignin after wet explosion pretreatment where the biomass in subjected to oxygen to understand how these interactions will affect lignin utilization for biochemical production.

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Section: Lignin-derived Phenolic Compounds As Determined By Gc/mscontrasting

confidence: 70%

Section: One-dimensional 13 C Nuclear Magnetic Resonancementioning

confidence: 99%

Wet explosion pretreatment of loblolly pine leads to an increase in methoxylation of the lignin

Rana

Laskar

Srinivas

et al. 2015

Bioresour. Bioprocess.

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“…Clearly, it can be seen that the aliphatic hydroxyl group was the dominant hydroxyl type in these three lignin samples. This finding was consistent with previous study for milled wood lignin (Huang et al 2011). Among them, L1 had the highest content of aliphatic hydroxyl groups, followed by L2, and finally L3.…”

Section: Lignin Structural Analysis Using Quantitative 31 P-nmrsupporting

confidence: 93%

Chemical Structure and Pyrolysis Characteristics of the Soda-Alkali Lignin Fractions

Xiao-hong¹,

Wu²

2014

BioResources

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In the present work, three different kinds of lignin fractions (L1, L2, and L3) were isolated from the alkali black liquor of Cunninghamia lanceolata by selective precipitation at the pH values of 8 (fraction L1), 5 (fraction L2), and 2 (fraction L3). Elemental analysis, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), 31 P nuclear magnetic resonance ( 31 P-NMR), thermal gravimetric analysis (TG), and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) were used to characterize the chemical structure and thermochemical properties of the three lignin fractions. The results showed that L1 presented higher heating value (HHV) and molecular weight compared with L2 and L3. The structures and functional group types were similar for the three lignin grades. However, there was more hydroxyl group in L1 than that in L2 and L3, and the L3 contained a higher amount of carboxylic hydroxyl. L1 exhibited the lowest weight loss value (47.8%) at 200 to 600 o C and the highest amount of charred residue (45.1%), which was exactly the opposite for L3. Phenols, the dominant pyrolysis products, constituted 92.17% of all the pyrolysis products for L1, 93.93% for L2, and 88.09% for L3.

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“…Loblolly pine (P. taeda) has a total lignin content of 28%, and a H/G ratio of 0.01, i.e., guaiacyl units largely predominate over p-hydroxyphenyl units [95].…”

Section: Pinusmentioning

confidence: 99%

“…In Pinus taeda, bark lignin ranged from 32.9 to 43.5% [95,166]. It is mainly constituted by guaiacyl and p-hydroxyphenyl units, with reported H/G ratio values of 0.59 (the value for wood lignin is 0.01) [95] and 0.28 [166].…”

Section: Pinus Barksmentioning

confidence: 99%

Compositional Variability of Lignin in Biomass

Lourenço¹,

Pereira²

2018

Lignin - Trends and Applications

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The objective of this chapter is to provide a concise overview of lignin composition and structure in different species and materials (wood, barks and nonwood plants). It includes a brief review on the lignin precursors and their polymerization as well as of the analytical tools used for lignin characterization from wet chemical to spectroscopic methods. Wood of gymnosperms is characterized by high lignin content (25-35%) and a HG-type of lignin with more guaiacyl (G) units and a small portion of p-hydroxyphenyl (H) units. Wood of angiosperms has a lignin content of 15-28%, with a GS-lignin having different proportions of syringyl (S) units. Nonwoody monocotyledon species have different lignin content (9-20%) and a HGS type of lignin, characterized by a high proportion of H units. Bark lignin content ranges from 13 to 43% and is of HGS-type with species-specific composition and different in the bark components, phloem and cork. Lignin composition and macromolecular structure are key issues to understand the properties of lignocellulosic materials and to design a lignin-based pathway within biomass biorefineries. The available information on lignin composition is still limited to a few species and plant components. This is certainly an area where more research is needed.

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Characterization of Milled Wood Lignin (MWL) in Loblolly Pine Stem Wood, Residue, and Bark

Cited by 92 publications

References 24 publications

Wet explosion pretreatment of loblolly pine leads to an increase in methoxylation of the lignin

Wet explosion pretreatment of loblolly pine leads to an increase in methoxylation of the lignin

Chemical Structure and Pyrolysis Characteristics of the Soda-Alkali Lignin Fractions

Compositional Variability of Lignin in Biomass

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