Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Lu, Yao; Lu, Yang; Hong-qin, HU; Xie, Feng-Jin; Wei, Xian‐Yong; Fan, Xing

doi:10.1155/2017/8951658

Cited by 255 publications

(124 citation statements)

References 95 publications

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“…Furthermore, the intense bands around 1455 and 1457 cm −1 are due to aromatic methyl group vibrations. 27 Nevertheless, there exist absorptions that are clearly different in these lignins. For instance, peaks between 1263 and 1282 cm −1 are indicative of guaiacyl rings, and these are present only in lignin recovered when solution S1 was used.…”

Section: Resultsmentioning

confidence: 99%

Optimization of ethyl lactate‐based organosolv process for lignin recovery from the solid waste of a wheat straw biorefinery

Valdespino‐Rodríguez

Pérez-Martín

González‐Barajas

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND: The organosolv process promotes biomass delignification at relatively high temperatures using a wide variety of organic solvent solutions. Nevertheless, previous studies on organosolv processes have not dealt with the use of ethyl lactate as organic solvent. Thus the aim of the present contribution was to determine and to validate if the use of ethyl lactate has a positive influence on lignin recovery for organosolv processes whose feedstock is the solid waste from a wheat straw-based biorefinery. The effect of operating conditions (temperature and time) on lignin recovery was also studied. RESULTS: A mixed design of experiments was proposed as the strategy to maximize lignin recovery. The mathematical model derived from a multiple linear regression applied to the mixed design results indicates that 190 ∘ C and a non-aqueous solution containing ethyl lactate and ethanol (81.2% w/w ethyl lactate) could provide a maximum lignin recovery of 75.9% w/w. This theoretical maximum was validated. Thus the proposed model adequately describes the behavior of lignin recovery. Moreover, Fourier transform infrared (FTIR) characterization of the resultant lignin suggested that its structure is a function of the organic solvent solution used during the organosolv process.CONCLUSION: The evidence from this study indicates that lignin recovery from the solid waste of a wheat straw-based biorefinery in an organosolv process depends on temperature and ethyl lactate presence in the reaction medium. These findings enhance the understanding of organosolv processes and could be applied if eventual lignin valorization is desired.Corrections added on 24 January 2020, after first online publication: the second occurrence of the term "m residue " in Equation 1 has been changed to "m sample ". Also the term "m sample " has been included in the sentence "In summary, 300.0 ± 10.0 mg of the solid waste was weighed in a pressure tube" under the section "Washings and lignin content quantification in solid waste".

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Section: Resultsmentioning

confidence: 99%

Optimization of ethyl lactate‐based organosolv process for lignin recovery from the solid waste of a wheat straw biorefinery

Valdespino‐Rodríguez

Pérez-Martín

González‐Barajas

et al. 2019

J of Chemical Tech & Biotech

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“…Methoxyl groups: the methoxyl groups are 0.92 and 0.94 per one phenyl propane unit in softwoods and hardwoods, respectively (Bykov 2008; Davis et al 2016;Lu et al 2017).…”

Section: Constituents Of Various Biomass Materialsmentioning

confidence: 99%

Interaction of enzymes with lignocellulosic materials: causes, mechanism and influencing factors

Baig

2020

Bioresour. Bioprocess.

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For the production of biofuel (bioethanol), enzymatic adsorption onto a lignocellulosic biomass surface is a prior condition for the enzymatic hydrolysis process to occur. Lignocellulosic substances are mainly composed of cellulose, hemicellulose and lignin. The polysaccharide matrix (cellulose and hemicellulose) is capable of producing bioethanol. Therefore, lignin is removed or its concentration is reduced from the adsorption substrates by pretreatments. Selected enzymes are used for the production of reducing sugars from cellulosic materials, which in turn are converted to bioethanol. Adsorption of enzymes onto the substrate surface is a complicated process. A large number of research have been performed on the adsorption process, but little has been done to understand the mechanism of adsorption process. This article reviews the mechanisms of adsorption of enzymes onto the biomass surfaces. A conceptual adsorption mechanism is presented which will fill the gaps in literature and help researchers and industry to use adsorption more efficiently. The process of enzymatic adsorption starts with the reciprocal interplay of enzymes and substrates and ends with the establishment of molecular and cellular binding. The kinetics of an enzymatic reaction is almost the same as that of a characteristic chemical catalytic reaction. The influencing factors discussed in detail are: surface characteristics of the participating materials, the environmental factors, such as the associated flow conditions, temperature, concentration, etc. Pretreatment of lignocellulosic materials and optimum range of shear force and temperature for getting better results of adsorption are recommended.

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“…Due to the very complex nature of lignins, it is challenging to unambiguously identify the exact origin of all the signals in the 13 C spectra [46]. Generally, signals around 140-155 ppm arise from aromatic C Ar -O carbons and those around 120-139 ppm from C Ar -C [47,48]. In Fig.…”

Section: Nmr Analysis Of Upscaled Reactor Samplesmentioning

confidence: 99%

Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

Goldmann

Anthonykutty

Ahola

et al. 2019

Waste Biomass Valor

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Lignin modification opens the possibility of using it in polyol bio-based polymers, such as phenol-formaldehyde resins, polyurethanes, composites, and binders. Pine kraft lignin Indulin AT was partially depolymerized and the resulting products analyzed to determine their degree of valorization. Depolymerized lignin products were analyzed by GPC-SEC (molar mass), ∆ε-IDUS (phenolic hydroxyls), HACL (formaldehyde uptake), 13 C-NMR (hydroxyl and methoxyl groups), and 1 H-DOSY (molar mass distribution). The dominant parameter in lignin depolymerization by solvolysis was reaction temperature. According to the results, a higher reaction temperature decreases the average molar masses and PDI of lignin as well as the primary and secondary aliphatic hydroxyls, while simultaneously increasing the phenolic hydroxyls and formaldehyde uptake of lignin. Other variables (time, formic acid wt %, ethanol wt %, lignin load) had lesser effects. Partial depolymerization by solvolysis in mild conditions without catalyst is a viable valorization route for lignin, by which lignin properties can be significantly improved.

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Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Cited by 255 publications

References 95 publications

Optimization of ethyl lactate‐based organosolv process for lignin recovery from the solid waste of a wheat straw biorefinery

Optimization of ethyl lactate‐based organosolv process for lignin recovery from the solid waste of a wheat straw biorefinery

Interaction of enzymes with lignocellulosic materials: causes, mechanism and influencing factors

Effect of Process Variables on the Solvolysis Depolymerization of Pine Kraft Lignin

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