References of "Jacquet, Nicolas"
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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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See detailImpact of formic/acetic acid and ammonia pre-treatments on chemical structure and physico-chemical properties of Miscanthus x giganteus lignins
Vanderghem, Caroline ULg; Richel, Aurore ULg; Jacquet, Nicolas ULg et al

in Polymer Degradation & Stability (2011), 96(10), 1761-1770

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these ... [more ▼]

Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these fractionation processes on chemical structure, physico-chemical properties and antioxidant activity of extracted lignins were investigated. Lignins were characterized by their purity, carbohydrate composition, thermal stability, molecular weight and by Fourier transform infrared (FTIR), 1H and quantitative 13C nuclear magnetic resonance (NMR), adiabatic broadband {13C-1H} 2D heteronuclear (multiplicity edited) single quantum coherence (g-HSQCAD). The radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) was also investigated. Formic/acetic acid pretreatment performed in milder conditions (80° C for 3 h) gave a delignification percentage of 44.7% and soaking in aqueous ammonia 36.3%. Formic/acetic acid pretreatment performed in harsh conditions (107°C for 3 h) was more effective for extensive delignification (86.5%) and delivered the most pure lignin (80%). The three lignin fractions contained carbohydrate in different extent: 3% for the lignin obtained after the formic/acetic acid pretreatment performed at 107 C (FAL-107), 5.8% for the formic/acetic acid performed at 80°C (FAL-80) and 13.7% for the ammonia lignin (AL). The acid pretreatment in harsh conditions (FAL-107) resulted in cleavage of b-O-4' bonds and aromatic C-C. Repolymerisation was thought to originate from formation of new aromatic C-O linkages. Under milder conditions (FAL-80) less b-O-4' linkages were broken and repolymerisation took place to a lesser extent. Ammonia lignin was not degraded to a significant extent and resulted in the highest weight average 3140 g mol -1. Despite the fact of FAL-107 repolymerisation, significant phenolic hydroxyls remained free, explaining the greater antioxidant activity. [less ▲]

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See detailPretreatment And Enzymatic Hydrolysis Of Miscanthus x giganteus: Influence Of Process Parameters
Vanderghem, Caroline ULg; Brostaux, Yves ULg; Jacquet, Nicolas ULg et al

Poster (2010, September 21)

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and ... [more ▼]

Miscanthus x giganteus is a perennial grass which grows rapidly and gives high yields of biomass per hectare. It can be grown in poor quality soil and is non invasive. Due to its high cellulose and hemicellulose content, it has attracted considerable attention as a possible energy crop to produce bioethanol. Pretreatment of lignocellulosic biomass is a key step to unlocking the protective structures so that the enzymatic hydrolysis of the carbohydrate fraction to monosugars can be achieved more easily and with greater yield. In this study, Miscanthus x giganteus was delignified by a chemical pre-treatment process using a mixture of formic acid/acetic acid (1). The treated material was then hydrolyzed. By means of Box-Behnken experimental design and response surface methodology we investigated the effect of cooking time (60, 120 and 180 min), formic acid/acetic acid/water concentration (20/60/20, 30/50/20 and 40/40/20) and temperature (80, 90 and 107°C) on the residual Klason lignin content and the % of digestibility. The optimal pretreatment process parameters were identified. [less ▲]

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See detailInfluence of steam explosion and thermal degradation of cellulose
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Poster (2010, August 20)

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have ... [more ▼]

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have already been removed by acid and alkaline treatments. The results of this study show that thermal degradation of cellulose fibres, studied by TGA, is still limited for a temperature process below 240 °C. However, derivative TGA show that thermal stability of cellulose obtained by these conditions decreases with the increase of temperature. For temperatures above 250°C, char level is higher at the end of the pyrolysis. According to the literature, the increase of the char level is correlated to an increase of the degradation product1. Determination of the degradation products in the liquor obtained after the pretreatment show an important increase of furfural and 5-hydroxymethylfurfural concentration with the temperature in agreement with the increase of the char level. These results confirm the important degradation of the cellulose fibres. [less ▲]

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See detailSteam explosion pretreatment and thermal degradation of cellulose fibers
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Conference (2010, August 20)

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See detailPretreatments and enzymatic hydrolysis of Miscanthus x giganteus for oligosaccharides production: delignification degree and characterisation of the hydrolysis products
Vanderghem, Caroline ULg; Jacquet, Nicolas ULg; Blecker, Christophe ULg et al

Poster (2010, February 04)

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose ... [more ▼]

The aim of the present study is to compare two delignification methods (formic/acetic acid1 and soaking in aqueous ammonia) on Miscanthus x giganteus and to assess the suitability to produce cellobiose and other oligosaccharides after enzymatic hydrolysis. Oligosaccharides have recently gotten attention for their health benefits. Two methods were compared in order to quantify lignin: the acid detergent lignin method (procedure of Van Soest most commonly employed by animal scientist and agronomists for analysis of forages) and the Klason lignin procedure. Lignin concentrations in raw material determined by both methods were different; Klason lignin value (23.5%) was greater than the acid detergent lignin concentration (12.9%). Possible reasons of these results will be discussed. Pretreatment by the formic/acid mixture showed a better deliginification rate compared to the soaking in aqueous ammonia method. Results were based on Klason lignin. Analysis of the structural carbohydrates revealed that untreated miscanthus was mainly composed of glucose and xylose. Extracted pulps by both delignification methods were hydrolysed by commercial cellulases and hemicellulases. A major challenge is the characterisation of complex mixtures of lignocellulosic hydrolysates. In this study, the hydrolysis products were separated and quantified by highperformance anion exchange chromatography with pulsed amperometric detection (HPAECPAD). This method was successfully applied to the quantitative analysis of monosaccharides (glucose and xylose) and disaccharides (cellobiose and xylobiose) formed by the enzymatic hydrolysis of pretreated miscanthus. The influence of the pretreatments on the oligosaccharides yields will be presented. [less ▲]

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See detailApplication of steam explosion for the pretreatment of the lignocellulosic raw materials
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(2), 561-566

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. Steam explosion is a thermomechanochemical process which allows the breakdown of lignocellulosic structural ... [more ▼]

Application of steam explosion for the pretreatment of the lignocellulosic raw materials. 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 cristallinity 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 or high value-added molecules process. [less ▲]

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See detailInfluence of homogenization and drying on the thermal stability of microfibrillated cellulose
QUIEVY, N.; Jacquet, Nicolas ULg; SCLAVONS, M. et al

in Polymer Degradation and Stability (2010), 95

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See detailInfluence of homogenization and drying on the thermal stability of microfibrillated cellulose
QUIEVY, N.; Jacquet, Nicolas ULg; SCLAVONS, M. et al

in Polymer Degradation and Stability (2010), 95

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See detailLa steam explosion : application en tant que prétraitement de la matière cellulosique
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Blecker, Christophe ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2010), 14(Spécial N°2),

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 cristallinity 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 or high value-added molecules process. [less ▲]

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See detailLA STEAM EXPLOSION : PRINCIPE ET ACTION SUR LES MATERIAUX LIGNOCELLULOSIQUES
Jacquet, Nicolas ULg; Blecker, Christophe ULg; Paquot, Michel ULg

Poster (2009, December 16)

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites ... [more ▼]

La steam explosion est un procédé thermomécanochimique qui va permettre la déstructuration de la matière lignocellulosique par l’action combinée de la chaleur issue de la vapeur, des hydrolyses induites par la formation d’acides organiques et du cisaillement résultant de la chute brutale de pression. Le procédé est composé de deux phases distinctes. D’une part, le vapocraquage qui consiste à faire pénétrer par diffusion, puis à condenser, la vapeur sous haute pression à l’intérieur de la structure du matériau. L’eau condensée à température élevée va initier l’hydrolyse des groupements acétyles contenus dans les xylanes et induire la formation d’acides organiques. Selon la sévérité des conditions (pression, température), les acides vont catalyser l’hydrolyse des fractions hémicellulosiques, induire des modifications dans la structure des lignines et modifier le degré de cristallinité de la fraction cellulosique. D’autre part, la décompression explosive. Cette phase est provoquée par une chute brutale de pression qui va entraîner la revaporisation d’une partie de l’eau condensée. L’expension brutale de la vapeur va induire des forces de cisaillement qui vont modifier les propriétés physiques (granulométrie, surface spécifique, rétention d’eau…) du matériau. [less ▲]

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See detailVapocraquage et Steam Explosion
Jacquet, Nicolas ULg; Paquot, Michel ULg

Conference (2009, October 21)

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See detailIsothermal titration calorimetry as a tool for improving enzymatic lignocellulose hydrolysis
Razafindralambo, Hary ULg; Boquel, Pascal; Jacquet, Nicolas ULg et al

Conference (2008, December)

Detailed reference viewed: 21 (9 ULg)