Milled Wood Lignin: A Linear Oligomer

Crestini, Claudia; Melone, Federica; Sette, Marco; Saladino, Raffaele

doi:10.1021/bm200948r

Cited by 263 publications

(222 citation statements)

References 45 publications

(123 reference statements)

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“…The understanding of the molar mass of lignin has changed over the last few decades from the concept of a very large molecule2, 3, 4, 5, 6, 7 providing three‐dimensional support for the comparatively flexible cellulose molecule, to the theory of a very low molar mass lignin, where some evidence suggests it consists merely of linear oligomers with not more than approximately ten monomeric units 8. Besides the difficulty of isolating unaltered lignin from lignocellulosic biomass, the correct analysis of the absolute molar mass is the second problem, which has not yet been solved in a general way for most lignins.…”

Section: Introductionmentioning

confidence: 99%

Getting Closer to Absolute Molar Masses of Technical Lignins

et al. 2018

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Determination of molecular weight parameters of native and, in particular, technical lignins are based on size exclusion chromatography (SEC) approaches. However, no matter which approach is used, either conventional SEC with a refractive index detector and calibration with standards or multi‐angle light scattering (MALS) detection at 488 nm, 633 nm, 658 nm, or 690 nm, all variants can be severely erroneous. The lack of calibration standards with high structural similarity to lignin impairs the quality of the molar masses determined by conventional SEC, and the typical fluorescence of (technical) lignins renders the corresponding MALS data rather questionable. Application of MALS detection at 785 nm by using an infrared laser largely overcomes those problems and allows for a reliable and reproducible determination of the molar mass distributions of all types of lignins, which has been demonstrated in this study for various and structurally different analytes, such as kraft lignins, milled‐wood lignin, lignosulfonates, and biorefinery lignins. The topics of calibration, lignin fluorescence, and lignin UV absorption in connection with MALS detection are critically discussed in detail, and a reliable protocol is presented. Correction factors based on MALS measurements have been determined for commercially available calibration standards, such as pullulan and polystyrene sulfonate, so that now more reliable mass data can be obtained also if no MALS system is available and these conventional calibration standards have to be resorted to.

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Section: Introductionmentioning

confidence: 99%

Getting Closer to Absolute Molar Masses of Technical Lignins

et al. 2018

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“…Lignin is poorly understood in terms of chemistry and structure compared with other wood compounds such as cellulose. The knowledge of this complex biopolymer is still delayed due to its various covalent bonds, resistance to degradation, heterogeneous nature, the absence of selective and convenient analysis methods and the lack of efficient isolation methods [2,3]. The control and tailoring of lignin multifunctional nature is the basis for the exploitation of this fascinating still under exploration material.…”

Section: Introductionmentioning

confidence: 99%

Obtaining lignin nanoparticles by sonication

Gilca

Popa

Crestini

2015

Ultrasonics Sonochemistry

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a b s t r a c tLignin, the main natural aromatic polymer was always aroused researchers interest. Currently around 90% of this biomaterial is burned for energy. It has a very complex and complicated structure which depends on the separation method and plant species, what determine difficulties to use as a raw material widely. This research presents a physical method to modify lignin by ultrasonic irradiation in order to obtain nanoparticles. The nanoparticles synthesized were dimensionally and morphologically characterized. At the same time the preoccupations were to determine the structural and compositional changes that occurred after sonication. To achieve this, two types of commercial lignins (wheat straw and Sarkanda grass) were used and the modifications were analyzed by FTIR-spectroscopy, GPC-chromatography, 31 P-NMR-spectroscopy and HSQC0. The results confirm that the compositional and structural changes of nanoparticles obtained are not significantly modified at the intensity applied but depend on the nature of lignin.

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“…Presumably, strongly interactive in such a way that traditional analyses of the molecular weights are biased, thus, a suggestion of the existence of higher molecular weight polymeric units [184]. Apparently and to the best of the current knowledge, these lignin oligomers lack a defined primary structure, but rather represent random phenylpropanoid (C 9 ) polyphenols, mainly linked by arylglycerol ether bonds between phenolic para-coumaryl alcohol (2) (H-type), coniferyl alcohol (3) (G-type) and sinapyl alcohol (4) (S-type) units [185,186].…”

Section: Lignin Oligomersmentioning

confidence: 99%

Utilisation of Lignins in the Bioeconomy: Projections on Ionic Liquids and Molecularly Imprinted Polymers for Selective Separation and Recovery of Base Metals and Gold

Ndibewu¹,

Tchieta²

2018

Lignin - Trends and Applications

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A brief review has been herein done of technologies involved in the exploitation of lignin, in order to provide an introduction to the subject from the perspective of a fast technologically advancing economy. Lignocellulosic materials and biomass have historically been utilised from since time memorial, but a new conversation is emerging on the role of these materials in modern bioeconomies. This new discourse needs to help us understand how technologies for managing and processing lignocellulosic materials both as biosynthetic moieties, biogenic wastes or simply renewable biopolymer-both established and novel-should be deployed and integrated (or not) to meet developmental requirements of the sustainability paradigm. The world is caught in the middle of green technology advocating for more and more focus on renewable sources of manufacturing raw materials and that of the molecularly imprinted/synthesised or genetically engineered ones. The utilisation of lignins (from renewable sources) in both the industry as the base for the formulation of ionic liquids (with yet a wider industrial applications), and also is a potential scaffold material for functionally modified imprinted polymers (LCIPS) for the selective recovery of base metals and gold, respectively, evidently incorporates the bioeconomy aspirations.

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Milled Wood Lignin: A Linear Oligomer

Cited by 263 publications

References 45 publications

Getting Closer to Absolute Molar Masses of Technical Lignins

Getting Closer to Absolute Molar Masses of Technical Lignins

Obtaining lignin nanoparticles by sonication

Utilisation of Lignins in the Bioeconomy: Projections on Ionic Liquids and Molecularly Imprinted Polymers for Selective Separation and Recovery of Base Metals and Gold

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