Unmasking the structural features and property of lignin from bamboo

Ethanol organosolv lignin separated from bamboo was depolymerized by low-power microwave radiation (~80 W) using ethanol as a swelling agent and formic acid as a hydrogen donor solvent. After increasing the temperature from 100 to 200 °C, the total amount of phenolic compounds in the products increased from 8.1% to 40.8%, and both the weight average molecular weight (Mw) and number average molecular weight (Mn) of the products from the lignin depolymerization decreased. With extended reaction time from 20 to 60 min, the total amount of phenolic compounds and molecular weight did not remarkably change. In addition, Fourier transform infrared (FT-IR) spectroscopy showed that oxidative fracture was the primary way that lignin depolymerized. The severity factor played an important role in converting lignin into small molecular substances, and the evaluation showed that the microwave temperature was more influential on the lignin depolymerization than the reaction time. Because depolymerization and repolymerization of fragments both occurred during the microwave radiation process, it is critical to inhibit repolymerization of degraded fragments for the efficient degradation of lignin. This study not only provides a theoretical basis for studying the mechanism of microwave-assisted lignin degradation but is also important for the determination of a cost-effective lignin depolymerization method.

Section: Ft-ir Spectramentioning

confidence: 99%

Low-Power Microwave Radiation-assisted Depolymerization of Ethanol Organosolv Lignin in Ethanol/Formic Acid Mixtures

Duan

Zhao

et al. 2017

“…In the present study, the four lignin samples were characterized by 2D-HSQC NMR techniques to understand their detailed structures. The signal assignments were made according to previous studies (Wen et al 2013b;Yuan et al 2013). The 2D-HSQC NMR spectrum can be divided into three regions, corresponding to aliphatic, side chain, and aromatic 13 C-1 H correlations.…”

Section: D-hsqc Nmr Spectra Of the Lignin Samplesmentioning

confidence: 99%

“…The C2,6-H2,6 correlations of H units were observed at δC/δH 127.7/6.91-7.23. The esterified ferulic acid and p-coumaric acid at the γ-position of the lignin polymers were cleaved during the alkali treatment (Lu and Ralph 1999;Wen et al 2013b). The typical signals of ferulate (FA) were observed at δC/δH 112.7/7.45, 123.1/7.10, and 117.0/6.42, corresponding to C2-H2, C6-H6, and C8-H8 correlations, respectively.…”

Section: D-hsqc Nmr Spectra Of the Lignin Samplesmentioning

confidence: 99%

Effect of Lignin on Bamboo Biomass Self-Bonding During Hot-Pressing: Lignin Structure and Characterization

Li¹,

Wu²,

Peng³

et al. 2015

Self Cite

To achieve high value-added utilization of lignin extracted from the biorefinery process in the wood composite industry, binderless particle boards were manufactured by bamboo materials combined with alkaline lignin (AL) in various proportions under various hot-pressing conditions. To elucidate the reactivity and chemical transformations of lignin macromolecules during the hot-pressing process, lignin samples were isolated from the corresponding boards and characterized by highperformance anion-exchange chromatography (HPAEC), gel permeation chromatography (GPC), quantitative 31 P-NMR, and 2D-HSQC NMR. The best bonding strength (1.36 MPa) of the binderless particle boards was obtained under the conditions of 180 °C, pressure 5 MPa, and lignin/bamboo mass ratio 0.4. The molecular weight of the lignin samples decreased from 3260 to 1420 g/mol during hot-pressing. The NMR results showed that the contents of β-O-4' and β-β' linkages were reduced and β-5' linkages were increased as the hot-pressing temperature rose. Simultaneously, the percentage of G-type and H-type lignins as well as the content of phenolic OH increased.

“…A 20-mg Lps sample in a 20-mL vial was acetylated with 1 mL of a pyridineacetic anhydride (1:1, v/v) solution at ambient temperature for 24 h. Then, it was added dropwise to an excess amount of cold water with vigorous stirring and the precipitated acetylated Lps were collected by centrifugation, washed with cold water, and freeze-dried (Wen et al 2013).…”

Section: Acetylation Of Lignophenolsmentioning

confidence: 99%

Characterization and Application of Bamboo (Sinocalamus affinis) Lignophenols in Lignophenols-Pulp Sheet Composites

Dai¹,

Qian²,

Ren³

et al. 2015

Bamboo (Sinocalamus affinis) lignophenols (Lps), synthesized using a phase separation system, were used as a natural plasticizing additive to complex with pulp (short fiber and fluffy short fiber) sheets. The structural features of Lps were analyzed by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectroscopy, and proton-nuclear magnetic resonance ( 1 H-NMR). The pulp sheet absorptivity of Lps, as well as the physical properties of complex sheets, were discussed. Results showed that when the concentration of bamboo Lps solution was 10 g/L, the absorption amount of Lps in the sheets made up of short pulp fibers (12%) was slightly higher than that of sheets made of fluffy short pulp fibers (10%), while physical properties, such as tightness, tensile strength, elongation, bursting, and tearing, were improved obviously after the addition of Lps. More obvious improvement in the physical strength was found in sheets made up of fluffy short pulp fibers. Results indicated that the amount of absorbed Lps was of the same importance as the properties of the pulp fibers. It is necessary to adjust the properties of both the Lps and sheets to get the best mechanical strength for the pulp sheets.