On the effect of hemicellulose removal on cellulose-lignin interactions. - OPEN ACCESS

Giummarella, Nicola; Henriksson, Gunnar; Salmén, Lennart; Lawoko, Martin

doi:10.3183/npprj-2017-32-04-p542-549

Cited by 3 publications

(2 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The maximum temperature of degradation of the cellulose (peak II) was 362.7 °C for the water-soaked fibres against 308.2 °C for the raw fibres ubH, as shown in Figure 6, so it was necessary to bring more thermal energy to degrade the cellulose. According to a study on wood conducted by Giummarella et al (2017), it would seem that the extraction of hemicelluloses on the surface of cellulose microfibrils is in favour of stronger interaction between lignin and cellulose. Even if hemp fibres have a lower lignin content compared to wood, it is arguable that new interactions between macromolecules of the cell wall involving cellulose were formed, resulting in a higher thermostability, as shown experimentally in Figure 6, where we observed a shift of temperature from 354.5°C to 484.4°C for hydro-treated fibres bH_10 compared to ubH at the maximum temperature of degradation of peak III.…”

Section: Thermal Stability Evolutionmentioning

confidence: 99%

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

et al. 2019

View full text Add to dashboard Cite

In this study, a gradually increased hydro-mechanical treatments duration were applied to native hemp bast fibres with a traditional pulp and paper beating device (laboratory Valley beater). There is often a trade-off between the treatment applied to the fibres and the effect on their integrity. The multimodal analysis provided an understanding of the beating impact on the fibres at multiple scales and the experimental design made it possible to distinguish the effects of hydro-and hydromechanical treatment. Porosity analyses showed that beating treatment doubled the macroporosity and possibly reduced nanoporosity between the cellulose microfibrils. The beating irregularly extracted the amorphous components known to be preferentially located in the middle lamellae and the primary cell walls rather than in the secondary walls, the overall increasing the crystallinity of cellulose from 49.3 % to 59.1 %, but a non-significant change in the indentation moduli of the cell wall was observed. In addition, beating treatments with two distinct mechanical severities showed a disorganization of the cellulose conformation, which significant dropped the indention moduli by 11.2 GPa and 8.4 GPa for 10 and 20 minutes of Valley beater hydromechanical treatment, respectively, compared to hydro-treated hemp fibres (16.6 GPa). Pearson's correlation coefficients between physicochemical features and the final indentation moduli were calculated. Strong positive correlations were highlighted between the cellulose crystallinity and rhamnose, galactose and mannose as non-cellulosic polysaccharide components of the cell wall.

show abstract

Section: Thermal Stability Evolutionmentioning

confidence: 99%

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Several factors can affect hydrolysis efficiency, such as chemical composition, polymer distribution, accessible surface, lignin composition and structure, cellulose fibers length and size, cellulose degree of polymerization, and cellulose degree of crystallinity. , Among them, lignin is recognized as having a dual negative effect by limiting accessibility of enzymes to polysaccharides and by sticking them through nonspecific interactions . The recalcitrance of lignocellulosic biomass can be overcome by optimizing enzyme efficiency through synergistic combination , and engineered enzymes , and by making substrates more accessible to enzymes by adapting pretreatments or by designing genetically modified plants. , In particular, following the steam explosion pretreatment, which is believed to be one of the most efficient processes, , hemicelluloses are hydrolyzed, leading to a relocation and an enrichment in lignin that can contribute significantly to recalcitrance. − Thus, a better understanding of the reactivity of such pretreated substrates is necessary.…”

Section: Introductionmentioning

confidence: 99%

Real Time and Quantitative Imaging of Lignocellulosic Films Hydrolysis by Atomic Force Microscopy Reveals Lignin Recalcitrance at Nanoscale

et al. 2018

View full text Add to dashboard Cite

Lignocellulosic biomass is considered as a sustainable source of energy and chemicals, but its recalcitrance to bioconversion still limits its use. In this paper, a strategy based on two aspects was developed to improve our knowledge on the lignin recalcitrance to enzymatic hydrolysis. First, lignocellulosic films of cellulose nanofibrils (CNFs) with increasing content of lignin (up to 40%) were prepared. Thanks to in situ real time Atomic Force Microscopy (AFM) measurements during the hydrolysis and by comparison with biochemical assays, the use of such films allows to fully assess the importance of the lignin content and of the arrangement between CNFs and lignin on the hydrolysis efficiency. In a second time, contrary to other studies by AFM which only followed a specific structure during enzymatic processes mostly on simple systems (CNFs or cellulose nanocrystals), a quantitative analysis of in-situ time-lapse measurements was developed. It enables to accurately address lignocellulosic biomass recalcitrance mechanisms mediated by lignin at nanoscale. Such analysis could pave the way for the use of a quantitative criteria to visualize in situ deconstruction of complex lignocellulosic substrates. Coupling the use of lignocellulosic films and dynamical AFM quantitative analysis to follow the evolution of the structure at nanoscale might lead to an effective targeting of new promising bioconversion strategies.

show abstract

Changes in wheat straw cell walls during ozone pretreatment

2020

View full text Add to dashboard Cite

Treatment of plant biomass with ozone is a promising delignification method. It was shown that lignin removal from the cell wall during ozonation was limited by topochemical reactions and toke place in the secondary rather in the primary cell wall. The separation of cellulose microfibrils, the loss of cell wall stiffness and complete removal of intercellular substance during the delignification process were visualized by SEM. The dependence of the average diameter of the cellulose microfibril aggregates in the cell wall of ozonized straw on ozone consumption was studied. Lignin removal caused an increase of size of cellulose microfibrils aggregates. It was demonstrated that there was an optimal degree of delignification, at which cellulose became more accessible to enzymes in the subsequent bioconversion processes. The data on the ozone consumption, residual lignin content, and sugars yield in the enzymatic hydrolysis of ozonized wheat straw were obtained. It was also found that the optimum delignification degree for sugars yield was ≈10% of residual lignin content and optimum ozone consumption was 2 mol·О3/mol C9PPU (phenylpropane structural unit) of lignin in raw straw.

show abstract

On the effect of hemicellulose removal on cellulose-lignin interactions. - OPEN ACCESS

Cited by 3 publications

References 17 publications

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

Beating of hemp bast fibres: an examination of a hydro-mechanical treatment on chemical, structural, and nanomechanical property evolutions

Real Time and Quantitative Imaging of Lignocellulosic Films Hydrolysis by Atomic Force Microscopy Reveals Lignin Recalcitrance at Nanoscale

Changes in wheat straw cell walls during ozone pretreatment

Contact Info

Product

Resources

About