An uncondensed lignin depolymerized in the solid state and isolated from lignocellulosic biomass: a mechanistic study

Li, Ning; Li, Yanding; Yoo, Chang Geun; Yang, Xiaohui; Lin, Xuliang; Ralph, John; Pan, Xuejun

doi:10.1039/c8gc00953h

Cited by 146 publications

(99 citation statements)

References 48 publications

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“…L-M T110 and L-M T120 retained more than 60 %and 40 %ofthe b-O-4 linkages, respectively,whereas AHL L-P T85 lost almost 95 % b-O-4 ( Figure 2a nd Table 2). L-P T85 also has am uch darkerc olor than MWL, L-M T110 ,a nd L-M T120 ( Figure 2) because of condensation and the formation of chromophore groups.T he pinkish color of the AHL is attributed to the conjugatedd ouble bond and aldehyde auxochrome group in coniferyl aldehyde and the ketone auxochrome group in 1-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-2-propanone (HHMP) [31] ,b oth formed by depolymerization of Hibbert's ketones( HK), which are observed at Figure 2B-D. [32] The S/G ratio increased after AHF (Table 2) but much more significantly with the use of p-TsOH mainly because of the de-creasedGsignal upon condensation. The decrease in the amount of Gs ubunits in L-P T85 compared with MWL, as measured by G 2 signal, was 90 %, in contrast to the decrease of 56 %and 33 %inL-M T110 and L-M T120 ,respectively.This suggests that MAHF more effectively dissolves Gs ubunits than does p-Ts OH fractionation at equivalent levels of delignification.…”

Section: Chemical and Physical Properties Of Lignin From Ahfmentioning

confidence: 99%

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Comparison of Two Acid Hydrotropes for Sustainable Fractionation of Birch Wood

Cai

Hirth

et al. 2020

ChemSusChem

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This study reports on a comparative study of acid hydrotropic fractionation (AHF) of birch wood using maleic acid (MA) and p‐toluenesulfonic acid (p‐TsOH). Under the same level of delignification, lignin dissolved by MA is much less condensed with a higher content of ether aryl β‐O‐4 linkages. Lignin depolymerization dominated in MA hydrotropic fractionation (MAHF) and resulted in a single lower molecular weight peak, in contrast to the competitive depolymerization and repolymerization in p‐TsOH AHF with a bimodal distribution. The less condensed MA‐dissolved lignin facilitated catalytic conversion to monophenols. Carboxylation of residual lignin in fractionated cellulosic water‐insoluble solids (WISs) enhanced enzymatic saccharification by decreasing nonproductive cellulase binding to lignin. At a low cellulase loading of 10 FPU g−1 glucan, saccharification of WIS‐MT120 from MAHF at 120 °C was 95 % compared with 48 % for WIS‐PT85 from p‐TsOH AHF at 85 °C under the same level of delignification of 63 %. Residual lignin carboxylation also facilitated nanofibrillation of WIS for producing lignin‐containing cellulose nanofibrils (LCNFs) through an enhanced lignin lubrication effect, which substantially decreases fibrillation energy. LCNFs from only one pass of microfluidization of WIS‐MT120 have the same morphology as those from WIS‐PT85 after three passes. MA also has a lower solubility and higher minimal hydrotropic concentration, which facilitated acid recovery. MA is U.S. Food and Drug Administration (FDA)‐approved as an indirect food additive, affording significant advantages compared with p‐TsOH for biorefinery applications.

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Section: Chemical and Physical Properties Of Lignin From Ahfmentioning

confidence: 99%

“…The procedure described by Li et al [32] was followed for sample preparation. 0.05 gl ignin was first acetylated by dissolving in 2mL of pyridine-acetic anhydride (1:1 by volume) solution and later added dropwise into 100 mL of ice-cold DI water for precipitation.…”

Section: Lignin Molecular Weightb Yg El Permeation Chromatographymentioning

confidence: 99%

Comparison of Two Acid Hydrotropes for Sustainable Fractionation of Birch Wood

Cai

Hirth

et al. 2020

ChemSusChem

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“…14,15 However, lignin is truly not waste without any application value; in contrast, it has great potential for use as feedstock to produce aromatic monomers. 16 Lignin from different biomass species is considered to have different structures and application values. 15 Lignin from gymnosperms is thought to lack a syringyl unit and, thus, shows a higher branching degree and a less active b-O-4 ether bond, resulting in more difficulties to be degraded.…”

Section: Introductionmentioning

confidence: 99%

Effluent of biomass cooking with active oxygen and solid alkali (CAOSA): component separation, recovery and characterization

et al. 2020

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“…Several preparation techniques are available to obtain CNWs from ligno-cellulosic residues. Various mechanical or chemical approaches can be undertaken to obtain the nanocellulose having various morphological and chemical properties [8][9][10][11][12][13]. Usually preliminary treatment of raw biomass substrates is carried out using alkali treatment and bleaching first to separate the lignin and hemicellulose fraction to obtain crude cellulose.…”

Section: Introductionmentioning

confidence: 99%

Extraction of Cellulose Nano-Whiskers Using Ionic Liquid-Assisted Ultra-Sonication: Optimization and Mathematical Modelling Using Box–Behnken Design

et al. 2019

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This study focuses on the extraction of cellulose nano-whiskers (CNWs) from the leaves of Adansonia kilima (AK), usually known as African baobab, using a combination of a microwave-assisted alkali (KOH) pre-treatment with subsequent bleaching process prior to ultra-sonication. Ultra-sonication was carried out using the ionic liquid (IL) 1-butyl-3-methylimidazolium hydrogen sulfate (Bmim-HSO4). Process parameters for ultra-sonication were optimized using a two-level factorial Box–Behnken design (BBD). Process variables such as ultra-sonication power (x1), hydrolysing time (x2) and temperature (x3) were varied. Responses selected were percentage crystallinity index, CrI% (y1) and yield% (y1) for the finally procured CNWs sample. Regression analysis was carried out to develop quadratic model to analyze the effect of process variables on IL-assisted ultra-sonication process. Analysis of variance (ANOVA) showed that ultra-sonication power was the most influential aspect for hydrolyzing the amorphous segments of crude cellulose extracted from baobab leaves. A relative study of the physio-chemical properties of the starting lignocellulosic substrate (AK), KOH pre-treated, bleached and IL-assisted ultra-sonicated CNWs was conducted. The synthesized samples were characterized using Fourier transform infrared spectroscopy, Scanning electron microscopy, atomic force microscopy, high resolution transmission electron microscopy, X-ray diffraction and thermo-gravimetric and zeta potential analysis. Under optimum condition, the extracted CNWs showed an average width of 15–20 nm; with high crystallinity index of 86.46%. This research provides an insight about the delignification of Adansonia kilima (AK) leaves and its effective conversion to CNWs having high crystallinity.

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An uncondensed lignin depolymerized in the solid state and isolated from lignocellulosic biomass: a mechanistic study

Abstract: Lignin was depolymerized in the solid state and separated from lignocellulosic biomass in high-purity and in a less condensed form for valorization.

Cited by 146 publications

References 48 publications

Comparison of Two Acid Hydrotropes for Sustainable Fractionation of Birch Wood

Comparison of Two Acid Hydrotropes for Sustainable Fractionation of Birch Wood

Effluent of biomass cooking with active oxygen and solid alkali (CAOSA): component separation, recovery and characterization

Extraction of Cellulose Nano-Whiskers Using Ionic Liquid-Assisted Ultra-Sonication: Optimization and Mathematical Modelling Using Box–Behnken Design

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