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.

scholarly journals Size-exclusion chromatography of cellulose: observations on the low-molar-mass fraction

Cellulose ◽  
2020 ◽  
Vol 27 (16) ◽  
pp. 9217-9225
Author(s):  
Leena Pitkänen ◽  
Herbert Sixta
Keyword(s):  
Mass Distribution ◽  
Size Exclusion Chromatography ◽  
Mass Fraction ◽  
Molar Mass ◽  
Accurate Determination ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
Universal Method ◽  
Exclusion Chromatography

AbstractAccurate determination of molar mass distribution for disperse cellulose samples has proved to be a challenging task. While size-exclusion chromatography coupled to multi-angle light scattering (MALS) and differential refractive index (DRI) detectors has become the most commonly used method for molar mass determination of celluloses, this technique suffers low sensitivity at the low-molar mass range. As discussed here, the universal method for accurate molar mass distribution analysis of cellulose samples not exists and thus thorough understanding on the differences of the various methodological approaches is important. In this study, the focus is in the accurate determination of the low-molar mass fraction. The results obtained by combining the two calibration strategies, MALS/DRI for polymeric region of a cellulose sample and conventional calibration for oligomeric region, was compared to the results obtained using only MALS/DRI (with extrapolation of the curve where signal-to-noise of MALS is low). For birch pulp sample, the results from the two approaches were comparable; it should be highlighted, however, that MALS/DRI slightly overestimates the molar masses at the low-molar-mass region.

scholarly journals Temperature Gradient Interaction Chromatography: A Perspective

2021 ◽  
Author(s):  
Lian R. Hutchings ◽  
Antonella Pagliarulo
Keyword(s):  
Liquid Chromatography ◽  
Temperature Gradient ◽  
Molar Mass ◽  
Reversed Phase ◽  
Normal Phase ◽  
Branched Polymers ◽  
Size Exclusion ◽  
Advanced Technique ◽  
High Molar Mass ◽  
Exclusion Chromatography

AbstractThe application of temperature gradient interaction chromatography (TGIC) as an advanced technique for the characterisation of polymers is discussed, in comparison to other liquid chromatography techniques and in particular the ubiquitous size exclusion chromatography. Specifically, the use of reversed-phase TGIC for the interrogation of complex branched polymers and normal-phase TGIC for characterisation of high-molar mass end-functionalised polymers is highlighted.

scholarly journals The Effect of Ball Milling Time on the Isolation of Lignin in the Cell Wall of Different Biomass

2021 ◽  
Vol 9 ◽  
Author(s):  
Guangrong Yang ◽  
Xueying An ◽  
Shilong Yang
Keyword(s):  
Molecular Weight ◽  
Cell Wall ◽  
Optimum Condition ◽  
Ball Milling ◽  
Milling Time ◽  
Lower Molecular Weight ◽  
Hydroxyl Groups ◽  
Milled Wood Lignin ◽  
Ball Milling Time ◽  
Poplar Sawdust

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.

scholarly journals A branched structure provides kraft lignins a denser morphology and a high molar mass for a given hydrodynamic radius

Holzforschung ◽  
2020 ◽  
Vol 74 (6) ◽  
pp. 551-558
Author(s):  
Linping Wang ◽  
Kengo Shigetomi ◽  
Keiichi Koda ◽  
Aori Gele ◽  
Yasumitsu Uraki
Keyword(s):  
Retention Time ◽  
Hydrodynamic Radius ◽  
Molar Mass ◽  
Size Exclusion ◽  
Compact Structure ◽  
High Molar Mass ◽  
H Nmr ◽  
Exclusion Chromatography ◽  
Lignin Model ◽  
Branched Structure

AbstractSize exclusion chromatography with multi-angle laser light-scattering detectors was applied for acetylated softwood and hardwood kraft lignins (Ac-SKL and Ac-HKL) and 8-O-4′ type of linear polymeric lignin model (Ac-M-8O4′) to compare their swelling behaviors. The plot of molar mass (MM) vs. retention time for Ac-M-8O4′ was similar to that of polystyrene, which revealed that Ac-M-8O4′ exhibited swelling behavior that was similar to that of polystyrene. However, the MM values of both Ac-KLs were larger than those of polystyrene standards at any retention time. This difference indicated that both Ac-KLs had a more compact structure than those of polystyrene and Ac-M-8O4′. One hypothesis is that the larger MM of both Ac-KLs stems from their branched structures. To verify this hypothesis, the frequency of 5-5′ interunit linkage in lignin samples was determined by 1H NMR after nitrobenzene oxidation. A linear relationship between MM and 5-5′ abundance was observed in the high MM region.

Molar mass determination of lignins by size-exclusion chromatography: towards standardisation of the method

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 459-468 ◽  
Author(s):  
Stéphanie Baumberger ◽  
Alfred Abaecherli ◽  
Mario Fasching ◽  
Gäoran Gellerstedt ◽  
Richard Gosselink ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Size Exclusion Chromatography ◽  
Molar Mass ◽  
Size Exclusion ◽  
Molar Mass Distribution ◽  
High Molar Mass ◽  
Wide Range ◽  
Exclusion Chromatography ◽  
Technical Lignins

Abstract The reactivity and physicochemical properties of lignins are partly governed by their molar mass distribution. The development of reliable standard methods for determination of the molar mass distribution is not only relevant for designing technical lignins for specific applications, but also for monitoring and elucidating delignification and pulping processes. Size-exclusion chromatography (SEC) offers many advantages, such as wide availability, short analysis time, low sample demand, and determination of molar mass distribution over a wide range. A collaborative study has been undertaken within the “Eurolignin” European thematic network to standardise SEC analysis of technical lignins. The high-molar-mass fraction of polydisperse lignins was shown to be the main source of intra- and interlaboratory variations, depending on the gel type, elution solvent, detection mode, and calculation strategy. The reliability of two widespread systems have been tested: one based on alkali and a hydrophilic gel (e.g., TSK Toyopearl gel) and the other based on THF as solvent and polystyrene-based gels (e.g., Styragel). A set of practical recommendations has been deduced.

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