Comparative study of stone-ground wood pulp and native wood 2. Comparison of the fluorescence of stone-ground wood pulp and native wood

Castellan, Alain; Choudhury, Hasneen; Davidson, R. S.; Grelier, Stéphane

doi:10.1016/1010-6030(94)03783-3

Cited by 33 publications

(6 citation statements)

References 8 publications

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“…The broad emission spectrum evaluated at a position (yellow circle) on the cell wall is basically due to lignin excited by continuous wave (CW) 1P illumination at 405 nm. This wavelength corresponds to optical transitions involving the low energy tail of the absorption band states that do persist over a wide spectral range (much higher than 400 nm) [25,26], due to the great inhomogeneity of lignin in the complex sugarcane structure.…”

Section: Resultsmentioning

confidence: 99%

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

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et al. 2013

Biotechnol Biofuels

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BackgroundDelignification pretreatments of biomass and methods to assess their efficacy are crucial for biomass-to-biofuels research and technology. Here, we applied confocal and fluorescence lifetime imaging microscopy (FLIM) using one- and two-photon excitation to map the lignin distribution within bagasse fibers pretreated with acid and alkali. The evaluated spectra and decay times are correlated with previously calculated lignin fractions. We have also investigated the influence of the pretreatment on the lignin distribution in the cell wall by analyzing the changes in the fluorescence characteristics using two-photon excitation. Eucalyptus fibers were also analyzed for comparison.ResultsFluorescence spectra and variations of the decay time correlate well with the delignification yield and the lignin distribution. The decay dependences are considered two-exponential, one with a rapid (τ1) and the other with a slow (τ2) decay time. The fastest decay is associated to concentrated lignin in the bagasse and has a low sensitivity to the treatment. The fluorescence decay time became longer with the increase of the alkali concentration used in the treatment, which corresponds to lignin emission in a less concentrated environment. In addition, the two-photon fluorescence spectrum is very sensitive to lignin content and accumulation in the cell wall, broadening with the acid pretreatment and narrowing with the alkali one. Heterogeneity of the pretreated cell wall was observed.ConclusionsOur results reveal lignin domains with different concentration levels. The acid pretreatment caused a disorder in the arrangement of lignin and its accumulation in the external border of the cell wall. The alkali pretreatment efficiently removed lignin from the middle of the bagasse fibers, but was less effective in its removal from their surfaces. Our results evidenced a strong correlation between the decay times of the lignin fluorescence and its distribution within the cell wall. A new variety of lignin fluorescence states were accessed by two-photon excitation, which allowed an even broader, but complementary, optical characterization of lignocellulosic materials. These results suggest that the lignin arrangement in untreated bagasse fiber is based on a well-organized nanoenvironment that favors a very low level of interaction between the molecules.

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Section: Resultsmentioning

confidence: 99%

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

Coletta

Rezende

Conceição

et al. 2013

Biotechnol Biofuels

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“…The observed fluorescence properties of jute are found to be similar to those of cotton cellulose fibers. − Tylli et al observed a shaped peak with a maximum at 455 nm for pure cotton filter paper excited at 350 nm, which is in good agreement with our results. The assignments of fluorescence emission of other lignocellulose such as wood are well-documented, − although the source of the fluorescence emission has not been unequivocally identified. Oldstead and co-workers 19,20 have suggested that the observed fluorescence emission originates from the cellulose and the spectral characteristics are influenced by lignin acting as an inner filter.…”

Section: Resultsmentioning

confidence: 99%

γ-Radiation Induced Changes in the Physical and Chemical Properties of Lignocellulose

2006

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gamma-radiation induced effects on the physical and chemical properties of natural lignocellulose (jute) polymer were investigated. Samples were irradiated to required total doses at a particular dose rate. The changes in the parameters such as the tensile strength, elongation at break, and work done at rupture for the lignocellulose samples on irradiation with the gamma-rays from a cobalt-60 source were measured. The mechanical properties were found to have nonlinear relations with the radiation doses. The chemical stability of irradiated fibers was found to degrade progressively with the increase of radiation dose. Additionally, other chemical changes of the samples due to exposure to high-energy radiation were also investigated using fluorescence and infrared spectroscopic analysis. Differential scanning calorimetry and thermogravimetric studies showed a significant reduction in thermal stability. The wide-angle X-ray diffraction study showed that structural changes of cellulose appeared due to the radiation-induced chemical reaction of lignocellulose.

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“…This approach of relating optical properties with structural properties is based on the idea that the lignin polymer is a collection of weakly interacting chromophores (in a uniform dielectric medium) analogous to a dilute solution of a limited number of different types of chromophores, where the term “chromophore” denotes a set of electronic states with well-defined properties. Thus, each type of chromophore corresponds to a definite type of chemical substructure, an approach that has been used previously in the interpretation of plant fiber fluorescence. ,− It is, for example, a common approach to compare emission spectra of plant fiber or paper pulp samples to those of lignin model compounds. The model compounds are then assigned as the possible cause of the emission by comparing, for example, excitation and emission peak positions.…”

Section: Introductionmentioning

confidence: 99%

Lignin−Quinone Interactions: Implications for Optical Properties of Lignin

2003

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Charge transfer (CT) excited states are well-known and examined for artificial solution and solid-state donor-acceptor systems. Their possible existence in lignin has, however, not been considered before. In the present work we have studied the optical modifications resulting from the co-adsorption of the acceptor p-benzoquinone with selected donor compounds, some of which are related to lignin, onto filter paper. The quinone was also incorporated into the lignin of beech and spruce thermomechanical pulp fibers, and their optical absorption and emission properties were then examined. Evidence for the formation of CT states of donor compounds-quinone or (wood fiber) lignin-quinone is presented. Most notable is the formation of a broad-band visible absorption, at lower energies than what can be explained by quinone absorption alone, and the significant wood fiber emission quenching caused by these CT states. Since quinones commonly occur in various lignin types (e.g., wood pulps), this has the implication that lignin photo-oxidation may proceed via such CT states.

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Comparative study of stone-ground wood pulp and native wood 2. Comparison of the fluorescence of stone-ground wood pulp and native wood

Cited by 33 publications

References 8 publications

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

Mapping the lignin distribution in pretreated sugarcane bagasse by confocal and fluorescence lifetime imaging microscopy

γ-Radiation Induced Changes in the Physical and Chemical Properties of Lignocellulose

Lignin−Quinone Interactions: Implications for Optical Properties of Lignin

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