Structural changes of poplar wood lignin after supercritical pretreatment using carbon dioxide and ethanol–water as co-solvents

Wang, Xing; Guo, Yanzhu; Zhou, Jinghui; Sun, Guangwei

doi:10.1039/c6ra26122a

Cited by 67 publications

(44 citation statements)

References 41 publications

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“…The percentage of non-volatilized material at 900 • C was higher in the case of PFL (53.0%) than in MWL (35.2%). A greater amount of non-volatile residue was related to a more branched structure (more condensed) which agreed with the spectroscopic data of the lignins studied in this work [45,46].…”

Section: Thermogravimetric Analysis Of Lignins (Tga)supporting

confidence: 89%

“…The most important mass change corresponded to the temperatures between 200 and 500 • C, approximately, which accounted for the additional weight loss values of 32.2% for MWL and 37.5% for PFL. In this stage, the bonds forming the structure of the lignin molecule were progressively modified, starting with the fragmentation of the interunit links [43] that were broken to release volatile oxygen compounds (CO, CO 2 , formaldehyde, formic acid, and some simple ethers and alkanes, among others) leaving a solid with a higher degree of unsaturation [44,45]. In this period, the maximum weight loss rate was located at 291 • C (0.31%/ • C) for MWL and 375 • C (0.29%/ • C) for PFL.…”

Section: Thermogravimetric Analysis Of Lignins (Tga)mentioning

confidence: 99%

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Formosolv Pretreatment to Fractionate Paulownia Wood Following a Biorefinery Approach: Isolation and Characterization of the Lignin Fraction

Domínguez¹,

Río

Romaní

et al. 2020

Agronomy

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Paulownia is a rapid-growth tree with a high biomass production rate per year and low demand of water, which make it very suitable for intercropping systems, as it protects the crops from adverse climatic conditions, benefiting the harvest yields. Moreover, these characteristics make Paulownia a suitable raw material able to be fractionated in an integrated biorefinery scheme to obtain multiple products using a cascade conversion approach. Different delignification pretreatments of biomass have been purposed as a first stage of a lignocellulosic biorefinery. In this study, the formosolv delignification of Paulownia wood was investigated using a second order face-centered factorial design to assess the effects of the independent variables (concentrations of formic and hydrochloric acids and reaction time) on the fractionation of Paulownia wood. The maximum delignification achieved in this study (78.5%) was obtained under following conditions: 60 min, and 95% and 0.05% formic and hydrochloric acid, respectively. In addition, the remained solid phases were analyzed to determine their cellulose content and cooking liquors were also chemically analyzed and characterized. Finally, the recovered lignin by precipitation from formosolv liquor and the pristine lignin (milled wood lignin) in Paulownia wood were characterized and compared by the following techniques FTIR, NMR, high-performance size-exclusion chromatography (HPSEC) and TGA. This complete characterization allowed verifying the capacity of the formosolv process to act on the lignin, causing changes in its structure, which included both phenomena of depolymerization and condensation.

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Section: Thermogravimetric Analysis Of Lignins (Tga)supporting

confidence: 89%

Section: Thermogravimetric Analysis Of Lignins (Tga)mentioning

confidence: 99%

Formosolv Pretreatment to Fractionate Paulownia Wood Following a Biorefinery Approach: Isolation and Characterization of the Lignin Fraction

Domínguez¹,

Río

Romaní

et al. 2020

Agronomy

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“…NMR for PAL, PPAL was performed in a Bruker AVIII 400 MHz spectrometer. 31 P-NMR analysis was according to a previous report with minor modification 35 , 36 . 25 mg lignin samples were dissolved in 0.5 ml anhydrous pyridine/CDCl 3 solvent (1.6:1, v/v) under stirring, 0.1 ml internal standard solution including 10.25 mg/ml cyclohexanol in anhydrous pyridine/CDCl 3 solvent (1.6:1, v/v) and 0.1 ml relaxation reagent solution containing 5.1 mg /ml chromium (III) acetylacetonate in anhydrous pyridine/CDCl 3 solvent (1.6:1 v/v) was added.…”

Section: Methodsmentioning

confidence: 99%

Preparation and characterization of thermo-sensitive gel with phenolated alkali lignin

Jiang

Sheng

Shi

et al. 2018

Sci Rep

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Thermo-sensitive gel exhibits great potential industrial application. It has been widely used in tissue repair, drug release and water purification for its property of phase transition in response to external stimuli, reusability and biocompatibility. In this study, a novel lignin-based thermo-sensitive gel was synthesized with alkali lignin by two steps. Firstly, phenolated lignin (PPAL) was synthesized with purified alkali lignin (PAL) catalyzed by sulfuric acid. Subsequently, thermo-sensitive gel was achieved by thermal polymerization of phenolated alkali lignin and N-isopropylacrylamide (NIPAAm). Furthermore, the prepared hydrogels were characterized in terms of thermal behavior, interior morphology and their swelling behavior. Compared with PAL-based gel, the obtained PPAL-based gel exhibits a higher crosslinking density and lower critical solution temperature (LCST) due to the increase of reaction site and smaller space volume of the hydrophobic side groups grafted on NIPAAm. TGA data revealed that thermal stability of gel was enhanced (50% weight loss at ~380 °C) by using lignin as precursor. SEM images showed that a more regular interior morphology, better compressive strength was also found (PPAL0.05, 11.15 KPa). Furthermore, the swelling ratio of PPAL-based gel was lower than that of PAL-based gel due to its more complex structure.

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“…The 13 C NMR spectra were acquired in the FT mode at 100.6 MHz by employing an inverse-gated decoupling pulse sequence, which was conditioned with the following parameters: a pulse angle of 30°, pulse delay of 2 s, acquisition time of 1.4 s and 30,000 scans at room temperature. The signals in the 13 C NMR spectra were assigned according to the previous literature [26]. The 2D-HSQC NMR determination was carried out according to the recently reported method [23,26] with minor modifications.…”

Section: Methodsmentioning

confidence: 99%

“…The signals in the 13 C NMR spectra were assigned according to the previous literature [26]. The 2D-HSQC NMR determination was carried out according to the recently reported method [23,26] with minor modifications. Briefly, 140 mg of lignin samples were dissolved in 0.5 mL of DMSO- d 6 .…”

Section: Methodsmentioning

confidence: 99%

Lignin Structure and Solvent Effects on the Selective Removal of Condensed Units and Enrichment of S-Type Lignin

et al. 2018

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This study focused on the structural differences of lignin after pyridine–acetic acid–water (PAW) and dioxane–acidic water (DAW) purification processes. These structural differences included the S/G ratio, condensed structure, weight-average (MW) molecular weights, β-O-4 linkages and sugar content. The chemical structure of the isolated crude lignin (CL), PAW purified lignin (PPL) and DAW purified lignin (DPL) was elucidated using quantitative 13C NMR, 2D-HSQC NMR spectra, thermogravimetric analysis (TGA), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The results showed that the PPL fractions contain fewer condensed structures, higher S/G ratios, more β-O-4 linkages, higher average MW and lower thermal degradation properties compared to the CL and DPL fractions. Furthermore, the PAW process was more selective in removing condensed units and enriching S-type lignin from CL compared to the DAW process. These results provide valuable information for understanding which purification process is more suitable to be applied for lignin.

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Structural changes of poplar wood lignin after supercritical pretreatment using carbon dioxide and ethanol–water as co-solvents

Abstract: To delineate structural changes of lignin after SCEP, enzymatic hydrolysis lignin (EHL) in poplar chips, lignin in pretreated residues (SCEP-RL), lignin in liquors (SCEP-DL) were isolated and analyzed by GPC, 13C-, 31P-, 2D-HSQC-NMR and TGA.

Cited by 67 publications

References 41 publications

Formosolv Pretreatment to Fractionate Paulownia Wood Following a Biorefinery Approach: Isolation and Characterization of the Lignin Fraction

Formosolv Pretreatment to Fractionate Paulownia Wood Following a Biorefinery Approach: Isolation and Characterization of the Lignin Fraction

Preparation and characterization of thermo-sensitive gel with phenolated alkali lignin

Lignin Structure and Solvent Effects on the Selective Removal of Condensed Units and Enrichment of S-Type Lignin

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