Lignin transformations for high value applications: towards targeted modifications using green chemistry

Valorization of lignin in polymer and composite systems for advanced engineering applications – A review

Factors governing dissolution process of lignocellulosic biomass in ionic liquid: current status, overview and challenges.

Current advancement on the isolation, characterization and application of lignin.

Cellulose, in addition to hemicellulose and lignin, makes the major fraction of lignocellulosic biomass – the only sustainable feedstock to meet the long-term sustainable energy need of the world. Cellulose is soluble in a number of solvents, e.g., concentrated phosphoric acid (CPA), N-methylmorpholine-N-oxide (NMMO), and ionic liquids (ILs), and can be regenerated by an anti-solvent without major derivatization for various applications. For one, the regenerated and much less crystalline cellulose is highly reactive for its biological conversion to sugars, fuels, and chemicals mediated by enzymes and/or microbes. This ability can be used as a core pretreatment step for improved bioprocessing of lignocelluloses. In this comprehensive review, cellulose solvent-based lignocellulosic fractionation technologies for enhanced enzymatic hydrolysis to improve biofuel and renewable chemical production are reviewed. The first part is focused on the background information of lignocellulosic biomass, lignocellulosic derived biogas, biohydrogen, and ethanol as well as acetone, butanol, and ethanol (ABE) production, and enzymatic hydrolysis. In the second part, the conditions for pretreatments applying CPA, NMMO, and IL solvents, improvements in enzymatic hydrolysis rates and yields for solids resulting from application of these pretreatments, and the features of the lignocellulosic structure affecting the improved bioprocessing have been thoroughly reviewed.

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Cellulose solvent-based pretreatment for enhanced second-generation biofuel production: a review

In this paper, the depolymerization of lignin was successfully achieved by the thermal treatment of kraft lignin in butyl-1,8-diazabicyclo[5.4.0]undec-7-enium chloride ([DBUC4+][Cl-]) without a catalyst. The thermal treatment experiments were performed in an oven at 150, 200, and 250 °C for 1 h. The changes in kraft lignin structure over the course of depolymerization were characterized by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and 1H / 31P NMR analyses. GPC chromatograms indicated that the retention time of the original kraft lignin had shifted toward higher values after the thermal treatment, which indicated lignin depolymerization. The average molecular weight of the lignin obtained after 1 h reaction time decreased by 23, 70, and 58 wt% for the treatment at 150, 200, and 250 °C, respectively. FTIR spectra indicated the cleavage of β-O-4 bonds of kraft lignin. The 1H NMR spectra showed demethylation of all treated kraft lignins. Moreover, the 31P NMR analysis demonstrated that the demethylation phenomenon of the treated kraft lignin contributed to the formation of catechol groups.

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_10_3_4933_Diop_Kraft_Lignin_Depolymerization/3652

Kraft Lignin Depolymerization in an Ionic Liquid without a Catalyst

This work aims to develop a new ionic liquid, used as an aprotic green a solvent, to dissolve kraft lignin from black liquor The kraft lignin was extracted through precipitation with carbon dioxide at atmospheric pressure 1,8-Diazabicyclo[540]undec-7-ene-based ionic liquids were obtained by quaternization of the nitrogen atom with a hydrogen atom or an alkyl chain The yields of the synthesis of the ionic liquids varied between 76 and 80% Dissolving experiments were carried out using the lignin isolated from the black liquor of a kraft process Up to 20% (w/w) of the lignin can be dissolved in butyl-1,8 diazabicyclo[540] undec-7-enium chloride ([DBUC4]+Cl-]), hexyl-1,8 diazabicyclo[540] undec-7-enium chloride [DBUC6]+[Cl-], and octyl-1,8 diazabicyclo[540] undec-7-enium chloride [DBUC8]+[Cl-] The time it takes to dissolve the lignin in these three liquids shows that its solubility is influenced mostly by the nature of the cations The lignin solubility was reduced in relation to the increased length of the grafted carbon chain The thermogravimetric analysis (TGA) showed these liquids can be used as lignin solvents from room temperature up to 300 °C (onset of degradation) Steric exclusion chromatography showed a slight decrease (6%) in the molecular weight of the lignin dissolved in these ionic liquids

https://ojs.cnr.ncsu.edu/index.php/BioRes/article/download/BioRes_08_3_4270_Diop_Ionic_Liquid_Dissolution_Lignin/2221

New Ionic Liquid for the Dissolution of Lignin

Fiber treatments to enhance interfacial adhesion in natural fiber-reinforced composites generally induce the use of many chemicals. To address this issue, the present work aimed to develop innovati...

PLA/flax fiber bio-composites: effect of polyphenol-based surface treatment on interfacial adhesion and durability

A maximum of 20% (w/w) lignin was used as a filler in low-density polyethylene (LDPE), together with 3–6% maleic anhydride-grafted LDPE as compatibilizer and 3–10% copper(II) sulphate pentahydrate (CuSO4·5H2O) as lignin’s dispersing agent. The resulting composites were investigated for both their mechanical properties and their melting point following the ASTM standards as well as their behaviour was compared with neat LDPE. The results reveal that addition of compatibilizer significantly improved the mechanical properties of lignin, yielding closer values to those of neat LDPE. In fact, the addition of 3% maleated polyethylene induced a 37% increase of the Young’s modulus, whilst 3% CuSO4·5H2O provides a good lignin dispersion. The above observations are further supported by the scanning electron micrographs of the blend specimens. Finally, the differential scanning calorimetry analysis revealed that the melting temperature and the crystallinity of LDPE slightly increase with the addition of 3% CuSO4·5H2O.

Study of lignin dispersion in low-density polyethylene

Developing innovative industries in rural communities requires researching valuable finished products using local natural resources and feasible equipment and technology. Resources like se...

Amadou Diop

Papers

Kraft Lignin Depolymerization in an Ionic Liquid without a Catalyst

New Ionic Liquid for the Dissolution of Lignin

PLA/flax fiber bio-composites: effect of polyphenol-based surface treatment on interfacial adhesion and durability

Study of lignin dispersion in low-density polyethylene

Bioextracting Polyphenols from the Brown Seaweed Ascophyllum nodosum from Québec's North Shore Coastline