References of "Jacquet, Nicolas"
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See detailCan Lignin Wastes Originating From Cellulosic Ethanol Biorefineries Act as Radical Scavenging Agents?
Vanderghem, Caroline ULg; Jacquet, Nicolas ULg; Richel, Aurore ULg

in Australian Journal of Chemistry (in press)

Lignin is a co-product from the biorefinery and paper industry. Its non-energetic valorization remains a field of extensive R&D developments. In this perspective, this study is undertaken to evaluate the ... [more ▼]

Lignin is a co-product from the biorefinery and paper industry. Its non-energetic valorization remains a field of extensive R&D developments. In this perspective, this study is undertaken to evaluate the radical scavenging ability of some herbaceous lignins. These lignins, extracted from Miscanthus (Miscanthus x giganteus) or Switchgrass (Panicum Virgatum L.), are selected as benchmarks for this study as a function of their chemical structure and average molecular weight. These technical lignins, side-products in the bioethanol production process, are found to display a moderate antioxidant activity as evaluated by the DPPH (1,1-diphenyl-2-picrylhydrazil) free radical scavenging test system. A correlation between the radical scavenging properties and the molecular features is proposed and discussed. Infrared spectroscopy is evaluated as a straightforward qualitative prediction tool for the radical scavenging capacity. [less ▲]

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See detailMicrowave-assisted thermochemical and primary hydrolytic conversions of lignocellulosic resources: a review
Richel, Aurore ULg; Jacquet, Nicolas ULg

in Biomass Conversion and Biorefinery (in press)

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as promising renewable alternatives. Particularly, the conversion of lignocellulosic materials has ... [more ▼]

Faced with the inevitable depletion of fossil resources, agricultural productions have rapidly emerged as promising renewable alternatives. Particularly, the conversion of lignocellulosic materials has nowadays opened new vistas for the production of energy, biofuels and chemicals. In this literature review, microwave technology is described as an original heating source either for the thermochemical conversions (at temperatures up to 400°C) of lignocellulose into biofuels or the pretreatment (below 400°C) and further hydrolysis of lignocellulose into bioethanol and other valuable chemicals. Advantages of microwave approaches include a commonly observed acceleration in reaction rate and improved selectivities and yields. [less ▲]

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See detailInfluence of Homogenization Treatment on Physicochemical 4 Properties and Enzymatic Hydrolysis Rate of Pure 5 Cellulose Fibers
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

in Applied Biochemistry and Biotechnology (in press)

The aim of this study is to compare the effect of different homogenization treat- 12 ments on the physicochemical properties and the hydrolysis rate of a pure bleached 13 cellulose. Results obtained show ... [more ▼]

The aim of this study is to compare the effect of different homogenization treat- 12 ments on the physicochemical properties and the hydrolysis rate of a pure bleached 13 cellulose. Results obtained show that homogenization treatments improve the enzymatic 14 hydrolysis rate of the cellulose fibers by 25 to 100 %, depending of the homogenization 15 treatment applied. Characterization of the samples showed also that homogenization had an 16 impact on some physicochemical properties of the cellulose. For moderate treatment inten- 17 sities (pressure below 500 b and degree of homogenization below 25), an increase of water 18 retention values (WRV) that correlated to the increase of the hydrolysis rate was highlighted. 19 Result also showed that the overall crystallinity of the cellulose properties appeared not to be 20 impacted by the homogenization treatment. For higher treatment intensities, homogenized 21 cellulose samples developed a stable tridimentional network that contributes to decrease 22 cellulase mobility and slowdown the hydrolysis process. [less ▲]

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See detailINFLUENCE OF STEAM EXPLOSION ON THECRYSTALLINITY OF CELLULOSE FIBER
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

Poster (2014, February 07)

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct ... [more ▼]

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct stages: vapocracking and explosive decompression. The treatment intensities is determined by a severity factor, established by a correlation between temperature process and retention time. The results show that steam explosion treatment has an impact on the crystallinity properties of pure cellulose fiber. When the severity factor is below 5.2, an increase of the overall crystallinity of the samples is observed with the treatment intensities. For higher intensities, a significant thermal degradation of cellulose lead to an important change in substrate composition, which lead to a further decrease of cellulose crystallinity. [less ▲]

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See detailLignin as a raw material for industrial materials applications
Richel, Aurore ULg; Vanderghem, Caroline ULg; Jacquet, Nicolas ULg et al

Poster (2014)

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl ... [more ▼]

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl, syringyl or p-hydroxyphenyl) linked together by a panel of specific ether or carbon-carbon bonds.[1] Nowadays, large amounts of lignins and lignin-based wastes are available and originate either from the pulp and paper manufacturing or from the production of bioethanol from lignocellulose. [2] Typically, these lignins are dedicated to energetic purposes by combustion. In recent years however, novel axes for high added value applications have emerged and concern, notably, the use of lignin as performance products (e.g. polymer additives, binders) or specialty chemicals (e.g. surface-active agents) for materials applications.[3] Herein, several applications of lignin in materials sciences with industrial issues are presented. A correlation is established between the extraction processes from lignocellulosic materials and the chemical structure and physico-chemical properties of lignins.[4] Our research group has also developed new methodologies for the extraction of highly pure lignins from several starting materials, including food wastes, herbaceous raw materials and wood biomass. These methodologies include microwave-assisted extraction and two-step conventional pretreatment involving steam explosion. These methodologies are described in this presentation. [less ▲]

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See detailLignin as a raw material for industrial materials applications
Richel, Aurore ULg; Vanderghem, Caroline ULg; Jacquet, Nicolas ULg et al

Poster (2013, October)

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl ... [more ▼]

Native lignin is an abundant biopolymer on earth and represents 15-30% by weight of the lignocellulosic biomass. Lignin is a heterogeneous cross-linked polymer composed of phenylpropane units (guaiacyl, syringyl or p-hydroxyphenyl) linked together by a panel of specific ether or carbon-carbon bonds.[1] Nowadays, large amounts of lignins and lignin-based wastes are available and originate either from the pulp and paper manufacturing or from the production of bioethanol from lignocellulose. [2] Typically, these lignins are dedicated to energetic purposes by combustion. In recent years however, novel axes for high added value applications have emerged and concern, notably, the use of lignin as performance products (e.g. polymer additives, binders) or specialty chemicals (e.g. surface-active agents) for materials applications.[3] Herein, several applications of lignin in materials sciences with industrial issues are presented. A correlation is established between the extraction processes from lignocellulosic materials and the chemical structure and physico-chemical properties of lignins.[4] Our research group has also developed new methodologies for the extraction of highly pure lignins from several starting materials, including food wastes, herbaceous raw materials and wood biomass. These methodologies include microwave-assisted extraction and two-step conventional pretreatment involving steam explosion. These methodologies are described in this presentation. [less ▲]

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See detailThe swelling behaviour of wheat starch granules during isothermal and non-isothermal treatments
Malumba Kamba, Paul ULg; Jacquet, Nicolas ULg; Delimme, Guy ULg et al

in Journal of Food Engineering (2013), 114(2), 199-206

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling ... [more ▼]

The size of wheat starch granules was measured during isothermal and non-isothermal treatments and fitted using mathematical models in order to elucidate the time–temperatures dependence of the swelling phenomenon and to improve our understanding of the mechanism followed by granules during gelatinization. Upon the onset temperature of gelatinization, starch granules size increase rapidly and tend to reach equilibrium values that depend on the temperature and heating rate applied. The most accurate fitting of granule size observed overall isothermal treatments was obtained with the third-order kinetic and the Weibull empirical models. The activation energy of swelling calculated for isothermal treatment varied between 41 and 318 kJ mol 1, depending on the mathematical model considered. Therefore, without a consensus on the mechanism and order of reaction followed during gelatinization, the meaningful of kinetic parameters calculated using mathematical models seems highly questionable. During non-isothermal treatments at lower heating rate, it seems like a limitation of the swelling capacity of granules was induced. This phenomenon was attributed to restructuration occurred inside of granules. So, forecasting the swelling behaviour of starch granules during non-isothermal treatment has to consider both the time–temperature and the heating rate applied. [less ▲]

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See detailCharacterization of sugar beet pectic-derived oligosaccharides obtained by enzymatic hydrolysis.
Combo, Agnan Marie Michel ULg; Aguedo, Mario ULg; Quiévy, N et al

in International Journal of Biological Macromolecules (2013), 52(1), 148-156

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See detailIMPACT DE LA STEAM EXPLOSION ET DE L’HOMOGENEISATION SUR LES PROPRIETES PHYSICOCHIMIQUES ET L’HYDROLYSE ENZYMATIQUE DE LA CELLULOSE
Jacquet, Nicolas ULg

Doctoral thesis (2012)

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is ... [more ▼]

In the economic and energetic context of our society, it is universally recognized that an alternative to fossil fuels and oil based product will be needed in the nearest future. A potential solution is to develop second generation biofuel and biobased product that utilizes non-food plant materials. The major component of these materials is lignocellulose, which is a complex composed by widely available biological polymers such as cellulose, hemicelluloses and lignin. This thesis is a part of this approach and is focused on a well-define part of these materials: the cellulose. The first part of this work was focused on the impact of two pretraitements (steam explosion and homogenization) on physico-chemical properties and hydrolysis yield of pure cellulose fiber. In contrast with literature, results obtained showed that moderate steam explosion treatments did not appear to improve the enzymatic hydrolysis yield of the cellulose fibers. In Parralel, a model that predicts the effect of the intensity of the steam explosion treatment in correlation with temperature and time was assessed. Links between this model and the evolution physico-chemical properties of the cellulose during pretreatment and cellulose hydrolysis yield were established In a second way, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. Regarding the homogenization, it was shown that homogenization increase significatively the cellulose hydrolysis (from 25 to 100%). Results highlights potential of this technology to be used as a pretreatment Finally, enzymatic hydrolysis step has been studied in order to improve cellulose hydrolysis and to obtain high concentrated hydrolysate. In this way, two methods based on successive addition of enzyme and substrate were assessed [less ▲]

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See detailInfluence of steam explosion on physico-chemical properties and hydrolysis rate of pure cellulose fibers
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

in Bioresource Technology (2012), 121(221-227),

The aim of the present study is to compare the effect of different steam explosion treatments on physicochemical properties and hydrolysis rate of a pure bleached cellulose. The results showed that ... [more ▼]

The aim of the present study is to compare the effect of different steam explosion treatments on physicochemical properties and hydrolysis rate of a pure bleached cellulose. The results showed that moderate steam explosion treatments (severity factor below 5.2) did not improve the enzymatic hydrolysis rate of the cellulose fibers. The characterization of the obtained samples showed an increase of the cellulose accessibility coupled with an increase of the overall crystallinity of the substrate. In these conditions, the higher accessibility is counterbalanced by the increased crystallinity. Indeed, a greater proportion of the substrat is accessible by only a fraction of the enzymatic complex (exo-glucanases) activities. When the severity factor reached 5.2, a decrease of the cellulose enzymatic hydrolysis rate was observed. In this case, TGA analysis showed an increase of the char level at the end of the pyrolysis which traduced an important thermal degradation of the samples. The thermal degradation of cellulose lead to an important change in substrate composition, which induced a decrease of the cellulose ratio available for hydrolysis and caused a decrease of the hydrolysis yields. [less ▲]

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See detailImprovement of the cellulose hydrolysis yields and hydrolysate concentration by management of enzymes and substrate input
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Cerevisia : Belgian Journal of Brewing and Biotechnology (2012), 37

In order to improve the hydrolysis of cellulose fiber and to obtain highly concentrated hydrolysate, two methods based on successive addition of enzyme and substrate were assessed. The first method, which ... [more ▼]

In order to improve the hydrolysis of cellulose fiber and to obtain highly concentrated hydrolysate, two methods based on successive addition of enzyme and substrate were assessed. The first method, which required only substrate addition, allowed to increase by 50% the hydrolysate concentration and to decrease by 30% enzyme units needed. The second method highlighted the ability to reach very high concentrated hydrolysate (up to 170 g/l) by simultaneous addition of enzyme and substrate. In parallel, relationships between some limiting factors and the yields of hydrolysis were investigated. In conclusion, viscosity evolution of cellulose suspension during hydrolysis step was investigated with an aim to improve the management of enzyme and substrate addition. [less ▲]

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See detailSTEAM EXPLOSION : PROCESS AND IMPACT ON LIGNOCELLULOSIC MATERIAL
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

Poster (2012, March 01)

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the ... [more ▼]

Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural components by steam heating, hydrolysis of glycosidic bonds by organic acid formed during the process and shearing forces due to the expansion of the moisture. The process is composed of two distinct stages: vapocracking and explosive decompression. Cumul effects of both phases include modification of the physical properties of the material (specific surface area, water retention capacities, color, cellulose crystallinity rate,…), hydrolysis of hemicellulosic components (mono and oligosaccharides released) and modification of the chemical structure of lignin. These effects permit the opening of lignocellulosic structures and increase the enzymatic hydrolysis rate of cellulose components in the aim to obtain fermentable sugars used in second generation biofuels process. [less ▲]

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See detailINFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER INFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER INFLUENCE OF STEAM EXPLOSION ON CRYSTALLINITY PROPERTIES OF PURE CELLULOSE FIBER
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

Poster (2012, March 01)

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct ... [more ▼]

The aim of the present study is to compare the effect of different steam explosion treatments on crystallinity properties of a pure bleached cellulose. Steam explosion process is composed of two distinct stages: vapocracking and explosive decompression. The treatment intensities is determined by a severity factor, established by a correlation between temperature process and retention time. The results show that steam explosion treatment has an impact on the crystallinity properties of pure cellulose fiber. When the severity factor is below 5.2, an increase of the overall crystallinity of the samples is observed with the treatment intensities. For higher intensities, a significant thermal degradation of cellulose lead to an important change in substrate composition, which lead to a further decrease of cellulose crystallinity [less ▲]

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See detailEffect of physicochemical characteristics of cellulosic substrates on enzymatic hydrolysis by means of a multi-stage process for cellobiose production
Vanderghem, Caroline ULg; Jacquet, Nicolas ULg; Danthine, Sabine ULg et al

in Applied Biochemistry and Biotechnology (2012), 166(6), 1423-1432

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and ... [more ▼]

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and the water retention value were determined for both celluloses. A previously studied multistage hydrolysis process that proved to enhance the cellobiose production was studied with both types of celluloses. The cellobiose yield exhibited a significant improvement (120% for the microcrystalline cellulose and 75% for the paper pulp) with the multistage hydrolysis process compared to continuous hydrolysis. The conversion of cellulose to cellobiose was greater for the microcrystalline cellulose than for the paper pulp. Even with high crystallinity, microcrystalline cellulose achieved the highest cellobiose yield probably due to its highest specific surface area accessible to enzymes and quantity of adsorbed protein. [less ▲]

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See detailOptimization of formic/acetic acid delignification of Miscanthus ×giganteus for enzymatic hydrolysis using response surface methodology
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

in Industrial Crops & Products (2012), 35

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for ... [more ▼]

A Box–Behnken experimental design and response surface methodology were employed to optimize the pretreatment parameters of a formic/acetic acid delignification treatment of Miscanthus ×giganteus for enzymatic hydrolysis. The effects of three independent variables, namely cooking time (1, 2 and 3 h), formic acid/acetic acid/water ratio (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107 ◦C) on pulp yield, residual Klason lignin content, concentration of degradation products (furfural and hydroxymethylfurfural) in the black liquor, and enzymatic digestibility of the pulps were investigated. The major parameter influencing was the temperature for pulp yield, delignification degree, furfural production and enzymatic digestibility. According to the response surface analysis the optimum conditions predicted for a maximum enzymatic digestibility of the glucan (75.3%) would be obtained using a cooking time of 3 h, at 107 ◦C and with a formic acid/acetic acid/water ratio of 40/40/20%. Glucan digestibility was highly dependent on the delignification degree. [less ▲]

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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy; Vanderghem, Caroline ULg et al

Poster (2011, December)

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités ... [more ▼]

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités des traitements appliqués ont été définies sur base d’un facteur de sévérité (SF), établi par une corrélation entre le temps de séjour et la température du process. Les résultats obtenus montrent que la dégradation thermique des fibres de cellulose reste limitée lorsque la valeur du facteur de sévérité est inférieure à 4.0. Aux intensités supérieures, le dosage des produits de dégradation montre une croissante importante des concentrations en hydroxyméthylfurfurals (5-HMF) dans les phases liquides issues des différents traitements. Lorsque la valeur du facteur de sévérité dépasse 5.2, les analyses TGA indiquent que l’augmentation des produits de dégradation est couplée à une croissance importante du taux de résidus carbonés, indiquant une forte dégradation thermique de la cellulose [less ▲]

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See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Récents Progrès en Génie des Procédés (2011), 101

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor ... [more ▼]

The aim of this study is to identify the impact of different steam explosion treatments on the thermal degradation of cellulose fibers. The intensities of the treatments were defined by a severity factor (SF), based on the residence time and the process temperature. The results obtained show that thermal degradation of cellulose fibers is limited when the severity factor value is below 4.0. At higher intensities, determination of thermal degradation products shows a significant increase of the hydroxymethylfurfural (5-HMF) amount when increasing the intensity of the treatment. When the severity factor reached 5.2, TGA analysis shows that the increase of degradation products is coupled to an increase of the char level meaning a strong degradation of the cellulose. [less ▲]

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See detailEffect of steam explosion pre-treatment on enzymatic saccharification of lignocellulosic material
Meyer, Laurence ULg; Jacquet, Nicolas ULg; Vanderghem, Caroline ULg et al

Poster (2011, September 08)

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to ... [more ▼]

Taking into account the sharp rise in prices and the depletion of resources of petroleum, an alternative to fossil resources is needed. A probable alternative is the use of lignocellulosic raw material to produce biofuels. The “first generation” biofuels are highly controversial because of the use of food plant material. The aim of the “second generation” biofuels is to take lignocellulosic non-food plant material as raw material. Lignocellulosic biomass has a very complex structure made of linkages between lignins, cellulose and hemicelluloses. The saccharification of these lignocellulosic materials requires the fractionation of its constituents. Research has lead to many lignocellulosic biomass fractionation pre-treatments. This study particularly focuses on the steam explosion pretreatment followed by an enzymatic saccharification. Steam explosion is a thermomechanical process which allows the breakdown of the lignocellulosic material structure by the combined action of steam heating, hydrolysis induced by the organic acids formed during the process and shear stress resulting from the pressure rough drop. This treatment leads to modification of the physical parameters such as water retention capacity, cristallinity rate of the cellulosic fraction, hydrolysis of the hemicellulosic fraction and rearrangement in the lignin structure. Such modifications are supposed to make cellulose enzymatic hydrolysis from complex lignocellulosic material easier. In order to verify this hypothesis, different lignocellulosic raw materials have been pre-treated by steam explosion. These materials were sugar beet pulp, corn straw and miscanthus. In order to check the effect of steam explosion pre-treatment on cellulose, a microcrystalline cellulose was also treated. Steam explosion was performed at a vapor pressure of 18 bars and with a retention time of 2 minutes. The steam exploded lignocellulosic materials and the untreated one were submitted to a hydrolysis with a mixture of enzymes composed of cellulases and cellobiase activities during 24 hours. The quantification of glucose in the hydrolysates at different times was performed by HPAEC-PAD. Rate of cellulose converted into glucose were better with steam exploded raw material showing that steam explosion allows improvement of lignocellulosic material for enzymatic saccharification. [less ▲]

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See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

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