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L'état actuel de l'art lié à la technologie de conversion de la biomasse a, jusqu'à présent,principalement concerné les méthodes enzymatiques, éventuellement couplées à des prétraitements thermomécaniques ; les biomasses concernées sont généralement riches en cellulose, mais le matériel à haute teneur en amidon brut est également important des deux points stratégique et économique. Notre nouvelle stratégie est une contribution à l’étude de ce dernier type de biomasses riches en amidon, en vue d’une conversion comportant une seule étape de transformation en oligosaccharide et en glucose, à l’aide de la technologie thermo-mécanique de Détente Instantanée Contrôlée DIC. Cette opération a été étudiée,analysée, modélisée et optimisée. Contrairement à un traitement thermique conventionnel,la technologie DIC comporte deux étapes incluant l’instauration d’un vide capable d'accroître l'accessibilité de la vapeur dans la biomasse, puis d’une étape de vide final en vue de réduire la génération de molécules de dégradation thermique du glucose. L’analyse des composés (oligosaccharides, glucose…) a été réalisée ; elle a pu démontrer que le process était étroitement associée à la sévérité du traitement brut. Le prétraitement DIC de faible sévérité mène à des rendements élevés en fractions oligo saccharidiques avec une petite fraction de glucose. Par contre, le traitement DIC de haute sévérité permet d’accéder au glucose comme principal produit final. Au cours de l'étude exploratoire, le cycle de vide et de haute pression d'humidité a été établi, avec comme facteur de réponse le taux de conversion de l'amidon en glucose brut. Les deux facteurs de pression de vapeur d’eau et de vide ont été combinés ensemble afin d'optimiser trois autres facteurs opératoires : la concentration d'acide, le couple de pression/température et le temps de traitement. Le traitement DIC de haute sévérité a été démontré comme étant capable de convertir près de50% d'amidon brut en glucose à l'étape du simple et unique traitement thermomécanique.Une autre étape du processus a été impliquée : il s’agit de l'hydrolyse à l’acide dilué, souvent à la suite du prétraitement DIC. Au cours de l’étape d'optimisation du prétraitement DIC, la méthodologie de surface de réponse a été utilisée pour aider au développement de modèles cinétiques auto-hydrolysés DIC. D'autre part, les modèles empiriques de la cinétique ont été développés. Dans le cas de faible sévérité, le modèle aboutit à des réponses étroitement associées aux deux limites inférieures et supérieures de la concentration acide et du temps de traitement. Par contre, ces modèles quand ils sont obtenus à de niveaux de traitement grande sévérité, ont été jugés seulement associés aux valeurs supérieures de ces paramètres opératoires. Cette observation a été déduite de l’équation polynomiale utilisée, tandis que les modèles cinétiques ont été basés sur une série exponentielle. Une série polynomiale de plus grand ordre serait donc nécessaire pour pouvoir explorer avec précision les données de la surface de réponse pour ce genre d'analyse approfondie à tous les niveaux des facteurs.Lors de l'étape d'optimisation de l’hydrolyse dans une solution d'acide dilué, le premier modèle cinétique consécutive a été développé pour étudier les mécanismes de conversion des polysaccharides totale en glucose et en ses produits de dégradation. Le modèle empirique de surface de réponse a été utilisé pour étudier les effets de facteurs pendant le processus opératoire. La teneur en humidité et le cycle de vide ont été des facteurs communs. Plus le temps de traitement est court et plus la température est élevée, et plus la génération du glucose est importante. Cette étude montre que le traitement DIC de haute sévérité est capable de convertir les polysaccharides totaux en glucose avec une faible dégradation du glucose. Les produits solides résiduels pourraient également faire l’objet d'un traitement enzymatique. / Present state of art related to biomass conversion technology so far was found to concentrate on an enzymatic process, coupled with thermal pretreatment on biomass rich in cellulose. Biomass that rich in crude starch is also important in terms of strategic and economic point of view. The main objective of this study is to adopt a new strategy for a single step conversion of a crude starch material into oligosaccharide and glucose utilizing DIC technology. In contrast to existing thermal based pretreatment, DIC technology involves two vacuum cycles; first vacuum cycle was to increase steam accessibility on biomass and to reduce generation of steam condensate thus avoid losing of monosaccharide and hemicelluloses, while second vacuum cycle was to reduce potential thermal degradation of glucose. Distributions of products formed were found to be closely associated with severity of treatment on crude starch material. At lower DIC severity, pretreatment favors the formations of high oligosaccharide composition with small fraction of glucose; while at high DIC severity, pretreatment favors formation of high glucose as a major end product. During an exploratory study to establish the relevant reaction factors; vacuum cycle and moisture content were the two main factors influencing the conversion of crude starch into glucose.DIC starch conversion into glucose was found to be moisture dependent. Both factors were combined together to optimize the other three factors: pressure/temperature, treatment times, and acid concentration. High DIC severity treatment alone could convert nearly 50% of crude starch into glucose. During DIC optimization, an experimental design was developed and tested with DIC pretreatment in order to obtain a second order polynomial mathematical model that was then applied for response surface methodology (RSM). The interaction nature of above factors was examined and was found they depend on DIC treatment severity. Two experimental designs with low and high DIC severity were developed; Low DIC severity (acid: 0.01-0.05 molar, time: 0.5-3.0 min) and High DIC severity (acid: 0.05-0.20 molar, time: 3.0-10.0 min) with similar temperature range (144-165oC) were used. Data mining operation was done on RSM model to develop a kinetic model at both treatment severities. Kinetic data, including rate constant and activation energy were calculated from kinetic models of both severities to compare with actual dilute acidhydrolysis kinetic studies on two DIC treated samples. It was found that activation energy (Ea)for glucose generation at High DIC severity (Ea: 59.44 kJ/mol) was lower than at optimum dilute acid hydrolysis (Ea: 91.30 kJ/mol); while for glucose degradation, Ea was higher with High DIC severity (Ea: 144.12 kJ/mol) if compared to dilute acid hydrolysis (Ea: 45.14 kJ/mol).This indicates that glucose generation with DIC requires less energy while its degradation needs high energy. This combination was required to maximize glucose generation and minimize glucose degradation. Further studies with non-isothermal state during DIC and dilute acid hydrolysis support this finding. In normal polysaccharide conversion to low molecular weight (LMW) oligosaccharides and glucose procedures; two process steps were involved, namely the first process involved thermal pretreatment followed by a second process with dilute acid hydrolysis. In the present work, attempt was made to exclude dilute acid hydrolysis stage in order to establish that DIC process alone is sufficient for total polysaccharides conversion into LMW mainly glucose fraction. Information gathered from quantitative and statistical analysis on (i) exploratory studies, (ii) kinetic models from RSM of DIC process and (iii) kinetic data based on experimental works during dilute acid hydrolysis study; support the assumption that DIC treatment alone is sufficient for the total conversion required.

O presente trabalho teve como objetivo, a caracterizacao da composicao quimica de diferentes variedades de bagaco de cana-de-acucar (CTC-9; CT99-1906; SP81-3250; RB86-7515 e CT99-1902), e posterior hidrolise enzimatica para averiguacao de acucares redutores e sacarificacao da biomassa. As analises composicionais foram realizadas utilizando biomassa nas condicoes in natura, celulignina e polpa celulosica. As condicoes de pre-tratamento das amostras para hidrolise com acido sulfurico diluido (relacao s/l: 1,5:10; temperatura: 150 °C; concentracao acida: H2SO4 2% m/v; tempo: 30 minutos); e deslignificacao com hidroxido de sodio (1:10 s/l; 100 °C; 1% NaOH; 30 minutos) foram pre-estabelecidas de modo a determinar uma analise comparativa das diferentes variedades de bagaco de cana-de-acucar estudadas. A hidrolise enzimatica das amostras obtidas apos os pre-tratamento foram realizadas em frascos Erlenmeyers de 125 mL, contendo tampao citrato (50 mM; pH 5; 1:20 s/l) e carga enzimatica (Celluclast 1.5 L - 75 FPU/mL e 13,5 UI/mL de ?-glicosidase; e Novozym 188 - 65 UI/mL de ?-glicosidase), e surfactante Tween 20 (0,15 g/g de bagaco). A composicao quimica das variedades de bagaco de cana-de-acucar, acucares redutores e sacarificacao da biomassa foram determinados por metodos cromatograficos, espectrofotometricos e gravimetricos tradicionais. Quanto a analise das variedades de cana tratada, a media dos valores observados: in natura - celulose (40,84%), hemicelulose (24,07%), lignina (33,7%) e cinzas (0,68%); extraido - celulose (38,83%), hemicelulose (27,32%), lignina (25,92), cinzas (0,32%) e extrativos (10,24%); celulignina - celulose (54,17%), hemicelulose (5,3%), lignina (37,28%), cinzas (0,54%) e polpa celulosica - celulose (77,48%), hemicelulose (6,07%), lignina (15,4%) e cinzas (0,32%). Os processos de hidrolise acida e deslignificacao demonstraram remocao eficaz da hemicelulose e da lignina (80% e 58%, respectivamente), e solubilizacao da biomassa (45% e 14%, em media). Os percentuais de sacarificacao da celulose das amostras apos 24 horas de reacao foram de 9,7% para bagaco extraido, 50,4% para celulignina e 72,87% para polpa celulosica. Nao foram observadas variacoes significativas na composicao quimica das cinco amostras estudadas, bem como diferenciacao na sacarificacao das mesmas. Evidenciou-se que emprego de variedades de bagaco de cana-de-acucar distintas utilizando pre-tratamentos em condicoes fixas nao alteram os percentuais quimico-estruturais do vegetal, bem como a recuperacao da glicose e dos acucares redutores presente na celulose. / The present work had as objective the chemical characterization of different varieties of sugarcane bagasse (CTC-9; CT99-1906; SP81-3250; RB86-7515 e CT99-1902) in different pretreatment conditions and the influence of pretreatments concerning varieties, reducing sugars recovery and biomass saccharification. Different pretreated biomass were obtained from in natura bagasse as it follows: extracted bagasse (24 hours/24 hours water/ethanol extraction in Sohxlet equipment), cellulignin (solid/liquid ratio: 1.5/10; temperature: 150 °C; acid concentration: H2SO4 2% w/v; residence time: 30 minutes); and cellulose pulp (1:10 solid/liquid ratio; 1% NaOH w/v; 100°C; 30 minutes). Enzymatic hydrolysis experiments were performed in 125 mL Erlenmeyers containing citrate buffer (50 mM; pH 5; 1:20 solid/liquid ratio), Tween 20 surfactant (0.15 g/g of bagasse) and commercial enzymatic loads of Celluclast 1.5 L (75 FPU/mL and 13,5 IU/mL of ?- glicosidase) and Novozym 188 (65 IU/mL of ?-glucosidase). Chemical composition of varieties, reducing sugars and biomass saccharification were determined by chromatographic, spectrometric and gravimetric traditional methods. Biomass presented an average composition in each condition as it follows: In natura - cellulose (40.84%), hemicellulose (24.07%), lignin (33.7%) and ashes (0.68%); Extracted - cellulose (38.83%), hemicellulose (27.32%), lignin (25.92), ashes (0.32%) and extractives (10.24%); Cellulignin - cellulose (54.17%), hemicellulose (5.3%), lignin (37.28%) and ashes (0.54%). Cellulose pulp - cellulose (77.48%), hemicellulose (6.07%), lignin (15.4%) and ashes (0.32%). Acid and alkaline hydrolysis presented effective removal of hemicellulose and lignin (80% and 58% respectively), showing as average biomass solubilization 45% and 14%. Saccharification after 24 hours of reaction presented 9,7% for extracted bagasse, 50.4% for cellulignin and 72.87% for cellulose pulp. There were no significant observations in chemical-structural composition and at cellulose saccharification of the five studied samples, showing that the variety did not present any relevant influence on pretreated sugarcane bagasse.

O presente trabalho teve como objetivo, a caracterizacao da composicao quimica de diferentes variedades de bagaco de cana-de-acucar (CTC-9; CT99-1906; SP81-3250; RB86-7515 e CT99-1902), e posterior hidrolise enzimatica para averiguacao de acucares redutores e sacarificacao da biomassa. As analises composicionais foram realizadas utilizando biomassa nas condicoes in natura, celulignina e polpa celulosica. As condicoes de pre-tratamento das amostras para hidrolise com acido sulfurico diluido (relacao s/l: 1,5:10; temperatura: 150 °C; concentracao acida: H2SO4 2% m/v; tempo: 30 minutos); e deslignificacao com hidroxido de sodio (1:10 s/l; 100 °C; 1% NaOH; 30 minutos) foram pre-estabelecidas de modo a determinar uma analise comparativa das diferentes variedades de bagaco de cana-de-acucar estudadas. A hidrolise enzimatica das amostras obtidas apos os pre-tratamento foram realizadas em frascos Erlenmeyers de 125 mL, contendo tampao citrato (50 mM; pH 5; 1:20 s/l) e carga enzimatica (Celluclast 1.5 L - 75 FPU/mL e 13,5 UI/mL de ?-glicosidase; e Novozym 188 - 65 UI/mL de ?-glicosidase), e surfactante Tween 20 (0,15 g/g de bagaco). A composicao quimica das variedades de bagaco de cana-de-acucar, acucares redutores e sacarificacao da biomassa foram determinados por metodos cromatograficos, espectrofotometricos e gravimetricos tradicionais. Quanto a analise das variedades de cana tratada, a media dos valores observados: in natura - celulose (40,84%), hemicelulose (24,07%), lignina (33,7%) e cinzas (0,68%); extraido - celulose (38,83%), hemicelulose (27,32%), lignina (25,92), cinzas (0,32%) e extrativos (10,24%); celulignina - celulose (54,17%), hemicelulose (5,3%), lignina (37,28%), cinzas (0,54%) e polpa celulosica - celulose (77,48%), hemicelulose (6,07%), lignina (15,4%) e cinzas (0,32%). Os processos de hidrolise acida e deslignificacao demonstraram remocao eficaz da hemicelulose e da lignina (80% e 58%, respectivamente), e solubilizacao da biomassa (45% e 14%, em media). Os percentuais de sacarificacao da celulose das amostras apos 24 horas de reacao foram de 9,7% para bagaco extraido, 50,4% para celulignina e 72,87% para polpa celulosica. Nao foram observadas variacoes significativas na composicao quimica das cinco amostras estudadas, bem como diferenciacao na sacarificacao das mesmas. Evidenciou-se que emprego de variedades de bagaco de cana-de-acucar distintas utilizando pre-tratamentos em condicoes fixas nao alteram os percentuais quimico-estruturais do vegetal, bem como a recuperacao da glicose e dos acucares redutores presente na celulose. / The present work had as objective the chemical characterization of different varieties of sugarcane bagasse (CTC-9; CT99-1906; SP81-3250; RB86-7515 e CT99-1902) in different pretreatment conditions and the influence of pretreatments concerning varieties, reducing sugars recovery and biomass saccharification. Different pretreated biomass were obtained from in natura bagasse as it follows: extracted bagasse (24 hours/24 hours water/ethanol extraction in Sohxlet equipment), cellulignin (solid/liquid ratio: 1.5/10; temperature: 150 °C; acid concentration: H2SO4 2% w/v; residence time: 30 minutes); and cellulose pulp (1:10 solid/liquid ratio; 1% NaOH w/v; 100°C; 30 minutes). Enzymatic hydrolysis experiments were performed in 125 mL Erlenmeyers containing citrate buffer (50 mM; pH 5; 1:20 solid/liquid ratio), Tween 20 surfactant (0.15 g/g of bagasse) and commercial enzymatic loads of Celluclast 1.5 L (75 FPU/mL and 13,5 IU/mL of ?- glicosidase) and Novozym 188 (65 IU/mL of ?-glucosidase). Chemical composition of varieties, reducing sugars and biomass saccharification were determined by chromatographic, spectrometric and gravimetric traditional methods. Biomass presented an average composition in each condition as it follows: In natura - cellulose (40.84%), hemicellulose (24.07%), lignin (33.7%) and ashes (0.68%); Extracted - cellulose (38.83%), hemicellulose (27.32%), lignin (25.92), ashes (0.32%) and extractives (10.24%); Cellulignin - cellulose (54.17%), hemicellulose (5.3%), lignin (37.28%) and ashes (0.54%). Cellulose pulp - cellulose (77.48%), hemicellulose (6.07%), lignin (15.4%) and ashes (0.32%). Acid and alkaline hydrolysis presented effective removal of hemicellulose and lignin (80% and 58% respectively), showing as average biomass solubilization 45% and 14%. Saccharification after 24 hours of reaction presented 9,7% for extracted bagasse, 50.4% for cellulignin and 72.87% for cellulose pulp. There were no significant observations in chemical-structural composition and at cellulose saccharification of the five studied samples, showing that the variety did not present any relevant influence on pretreated sugarcane bagasse.

Este trabalho avaliou a extração de xilose da palha de cana-de-açúcar sob diferentes condições de hidrólise por ácido sulfúrico diluído visando à obtenção de um hidrolisado hemicelulósico rico em xilose e ainda a fermentabilidade deste para a bioconversão a etanol por Pichia stipitis Y-7124. Inicialmente caracterizou-se a palha de cana e a fração hemicelulósica representou 30,79% da massa seca da palha, enquanto que a celulose representou 40,84% e a lignina 25,80%. Verificou-se ainda que 26,57% da palha corresponde à xilose, representando 86,27% de sua fração hemicelulósica. As hidrólises ácidas foram realizadas de acordo com um planejamento experimental fatorial fracionado 24-1 visando-se à resposta concentração de xilose (g/L) no hidrolisado hemicelulósico. Levou-se em consideração os fatores: tempo, temperatura, concentração da solução ácida e a relação sólido:líquido. A melhor resposta para a concentração de xilose foi encontrada nas condições do ponto central, com a média da concentração igual a 31,70 g/L. A análise de variância foi realizada para um screening do planejamento e observou-se que apenas os fatores concentração da solução ácida e temperatura foram significativos ao nível de 95% de confiança. Em seguida realizou-se ensaios para otimização da hidrólise ácida considerando os fatores temperatura e concentração da solução ácida. As condições de ótimo encontradas foram 130 ºC e a solução de ácido sulfúrico em 2,9% m/v, empregadas com uma relação sólido:líquido igual a 1:4 (g/mL) por 30 minutos de reação. Estas condições de ótimo permitiram a obtenção de um hidrolisado hemicelulósico com concentração igual a 56,5 g/L de xilose, correspondendo à extração de 85,1% da xilose da palha. Posteriormente, ensaios de fermentação foram conduzidos com o hidrolisado hemicelulósico obtido, visando à produção de etanol por P. stipitis em frascos Erlenmeyer de 250 mL com 100 mL de meio hidrolisado para avaliar a fermentabilidade do hidrolisado obtido bem como a necessidade de suplementação nutricional e utilizou-se um planejamento experimental fatorial 23 de face centrada para verificar a influência dos fatores: concentração de ureia, concentração de MgSO4*7H2O e concentração de extrato de levedura. Os ensaios foram conduzidos a 200 rpm e 30 ºC. Verificou-se que o extrato de levedura (5 g/L) exerceu maior influência sobre o processo fermentativo e que o MgSO4*7H2O (0,5 g/L) não apresentou significância estatística. A melhor condição na fermentação para produção de etanol por P. stipitis encontrada foi empregando-se extrato de levedura (5 g/L), ureia (5 g/L) e MgSO4*7H2O (1,0 g/L), em que se obteve um fator de rendimento em etanol YP/S igual a 0,38 g/g e produtividade volumétrica igual a 0,41 g/L.h, em 60 horas de fermentação. / This work evaluated the sugar cane straw xylose extration under different diluted sulfuric acid hydrolysis conditions aiming at the attainment of hemicellulosic hydrolysate rich in xylose and their fermentability for ethanol bioconversion by Pichia stipitis Y 7124. Previous assays for chemical characterization of the sugar cane straw has been carried. The hemicellulosic fraction represented 30.79% of the dry straw mass, whereas the cellulose represented 40.84% and the lignin represented 25,80%. It was verified despite 26,57% of the straw corresponded to xylose, representing 86,27% of its hemicellulosic fraction. The acid hydrolysis was carried out using an experimental design 24-1 aiming at it the xylose concentration (g/L) response on the hemicellulosic hydrolysate regarding the factors: time, temperature, acid solution concentration and the ratio solid:liquid. The best result for the xylose concentration has been found on the center point conditions, with concentration of 31,70 g/L. The analysis of variance was carried out to one screening of the design and it was observed that only the parameters temperature and acid solution concentration has been significant at 95% reliable level. After that acid hydrolysis assays has been carried regarding the factors temperature and acid solution concentration aiming the acid hydrolysis optimization. The optimum point conditions were 130 ºC and the sulfuric acid solution of 2,9% m/v, carried with the ratio solid:liquid of 1:4 (g/mL) at 30 minutes of reaction. Later, fermentation assays was carried out with the hemicellulosic hydrolysate obtained in 250 mL Erlenmeyer flasks containing 100 mL of hydrolysate to evaluate the hydrolysate fermentability obtained as well tha needless of nutritional supplementation and for it used an experimental design 23 of face centered to verify the influence of the factors: urea concentration, MgSO4*7H2O concentration and yeast extract concentration. Assays has been carried at 30 ºC and 200 rpm. It was verified that the yeast extract (5 g/L) exerts greater influence on the fermentation and the MgSO4*7H2O (0,5 g/L) did not present statistic significance. The best conditions were achieved using yeast extract (5 g/L), urea (5 g/L) and MgSO4*7H2O (0,5 g/L). with ethanol yield and volumetric productivity of 0,38 g/g and 0,41 g/L.h, respectively, after 60 hours of fermentation.

Este trabalho avaliou a extração de xilose da palha de cana-de-açúcar sob diferentes condições de hidrólise por ácido sulfúrico diluído visando à obtenção de um hidrolisado hemicelulósico rico em xilose e ainda a fermentabilidade deste para a bioconversão a etanol por Pichia stipitis Y-7124. Inicialmente caracterizou-se a palha de cana e a fração hemicelulósica representou 30,79% da massa seca da palha, enquanto que a celulose representou 40,84% e a lignina 25,80%. Verificou-se ainda que 26,57% da palha corresponde à xilose, representando 86,27% de sua fração hemicelulósica. As hidrólises ácidas foram realizadas de acordo com um planejamento experimental fatorial fracionado 24-1 visando-se à resposta concentração de xilose (g/L) no hidrolisado hemicelulósico. Levou-se em consideração os fatores: tempo, temperatura, concentração da solução ácida e a relação sólido:líquido. A melhor resposta para a concentração de xilose foi encontrada nas condições do ponto central, com a média da concentração igual a 31,70 g/L. A análise de variância foi realizada para um screening do planejamento e observou-se que apenas os fatores concentração da solução ácida e temperatura foram significativos ao nível de 95% de confiança. Em seguida realizou-se ensaios para otimização da hidrólise ácida considerando os fatores temperatura e concentração da solução ácida. As condições de ótimo encontradas foram 130 ºC e a solução de ácido sulfúrico em 2,9% m/v, empregadas com uma relação sólido:líquido igual a 1:4 (g/mL) por 30 minutos de reação. Estas condições de ótimo permitiram a obtenção de um hidrolisado hemicelulósico com concentração igual a 56,5 g/L de xilose, correspondendo à extração de 85,1% da xilose da palha. Posteriormente, ensaios de fermentação foram conduzidos com o hidrolisado hemicelulósico obtido, visando à produção de etanol por P. stipitis em frascos Erlenmeyer de 250 mL com 100 mL de meio hidrolisado para avaliar a fermentabilidade do hidrolisado obtido bem como a necessidade de suplementação nutricional e utilizou-se um planejamento experimental fatorial 23 de face centrada para verificar a influência dos fatores: concentração de ureia, concentração de MgSO4*7H2O e concentração de extrato de levedura. Os ensaios foram conduzidos a 200 rpm e 30 ºC. Verificou-se que o extrato de levedura (5 g/L) exerceu maior influência sobre o processo fermentativo e que o MgSO4*7H2O (0,5 g/L) não apresentou significância estatística. A melhor condição na fermentação para produção de etanol por P. stipitis encontrada foi empregando-se extrato de levedura (5 g/L), ureia (5 g/L) e MgSO4*7H2O (1,0 g/L), em que se obteve um fator de rendimento em etanol YP/S igual a 0,38 g/g e produtividade volumétrica igual a 0,41 g/L.h, em 60 horas de fermentação. / This work evaluated the sugar cane straw xylose extration under different diluted sulfuric acid hydrolysis conditions aiming at the attainment of hemicellulosic hydrolysate rich in xylose and their fermentability for ethanol bioconversion by Pichia stipitis Y 7124. Previous assays for chemical characterization of the sugar cane straw has been carried. The hemicellulosic fraction represented 30.79% of the dry straw mass, whereas the cellulose represented 40.84% and the lignin represented 25,80%. It was verified despite 26,57% of the straw corresponded to xylose, representing 86,27% of its hemicellulosic fraction. The acid hydrolysis was carried out using an experimental design 24-1 aiming at it the xylose concentration (g/L) response on the hemicellulosic hydrolysate regarding the factors: time, temperature, acid solution concentration and the ratio solid:liquid. The best result for the xylose concentration has been found on the center point conditions, with concentration of 31,70 g/L. The analysis of variance was carried out to one screening of the design and it was observed that only the parameters temperature and acid solution concentration has been significant at 95% reliable level. After that acid hydrolysis assays has been carried regarding the factors temperature and acid solution concentration aiming the acid hydrolysis optimization. The optimum point conditions were 130 ºC and the sulfuric acid solution of 2,9% m/v, carried with the ratio solid:liquid of 1:4 (g/mL) at 30 minutes of reaction. Later, fermentation assays was carried out with the hemicellulosic hydrolysate obtained in 250 mL Erlenmeyer flasks containing 100 mL of hydrolysate to evaluate the hydrolysate fermentability obtained as well tha needless of nutritional supplementation and for it used an experimental design 23 of face centered to verify the influence of the factors: urea concentration, MgSO4*7H2O concentration and yeast extract concentration. Assays has been carried at 30 ºC and 200 rpm. It was verified that the yeast extract (5 g/L) exerts greater influence on the fermentation and the MgSO4*7H2O (0,5 g/L) did not present statistic significance. The best conditions were achieved using yeast extract (5 g/L), urea (5 g/L) and MgSO4*7H2O (0,5 g/L). with ethanol yield and volumetric productivity of 0,38 g/g and 0,41 g/L.h, respectively, after 60 hours of fermentation.

In this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation. Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber. The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50. Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD. Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed. Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD. <b>Keywords:</b>cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission

<p>In this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation.</p><p>Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber.</p><p>The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50.</p><p>Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD.</p><p>Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed.</p><p>Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD.</p><p><b>Keywords:</b>cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission</p>

Present state of art related to biomass conversion technology so far was found to concentrate on an enzymatic process, coupled with thermal pretreatment on biomass rich in cellulose. Biomass that rich in crude starch is also important in terms of strategic and economic point of view. The main objective of this study is to adopt a new strategy for a single step conversion of a crude starch material into oligosaccharide and glucose utilizing DIC technology. In contrast to existing thermal based pretreatment, DIC technology involves two vacuum cycles; first vacuum cycle was to increase steam accessibility on biomass and to reduce generation of steam condensate thus avoid losing of monosaccharide and hemicelluloses, while second vacuum cycle was to reduce potential thermal degradation of glucose. Distributions of products formed were found to be closely associated with severity of treatment on crude starch material. At lower DIC severity, pretreatment favors the formations of high oligosaccharide composition with small fraction of glucose; while at high DIC severity, pretreatment favors formation of high glucose as a major end product. During an exploratory study to establish the relevant reaction factors; vacuum cycle and moisture content were the two main factors influencing the conversion of crude starch into glucose.DIC starch conversion into glucose was found to be moisture dependent. Both factors were combined together to optimize the other three factors: pressure/temperature, treatment times, and acid concentration. High DIC severity treatment alone could convert nearly 50% of crude starch into glucose. During DIC optimization, an experimental design was developed and tested with DIC pretreatment in order to obtain a second order polynomial mathematical model that was then applied for response surface methodology (RSM). The interaction nature of above factors was examined and was found they depend on DIC treatment severity. Two experimental designs with low and high DIC severity were developed; Low DIC severity (acid: 0.01-0.05 molar, time: 0.5-3.0 min) and High DIC severity (acid: 0.05-0.20 molar, time: 3.0-10.0 min) with similar temperature range (144-165oC) were used. Data mining operation was done on RSM model to develop a kinetic model at both treatment severities. Kinetic data, including rate constant and activation energy were calculated from kinetic models of both severities to compare with actual dilute acidhydrolysis kinetic studies on two DIC treated samples. It was found that activation energy (Ea)for glucose generation at High DIC severity (Ea: 59.44 kJ/mol) was lower than at optimum dilute acid hydrolysis (Ea: 91.30 kJ/mol); while for glucose degradation, Ea was higher with High DIC severity (Ea: 144.12 kJ/mol) if compared to dilute acid hydrolysis (Ea: 45.14 kJ/mol).This indicates that glucose generation with DIC requires less energy while its degradation needs high energy. This combination was required to maximize glucose generation and minimize glucose degradation. Further studies with non-isothermal state during DIC and dilute acid hydrolysis support this finding. In normal polysaccharide conversion to low molecular weight (LMW) oligosaccharides and glucose procedures; two process steps were involved, namely the first process involved thermal pretreatment followed by a second process with dilute acid hydrolysis. In the present work, attempt was made to exclude dilute acid hydrolysis stage in order to establish that DIC process alone is sufficient for total polysaccharides conversion into LMW mainly glucose fraction. Information gathered from quantitative and statistical analysis on (i) exploratory studies, (ii) kinetic models from RSM of DIC process and (iii) kinetic data based on experimental works during dilute acid hydrolysis study; support the assumption that DIC treatment alone is sufficient for the total conversion required.

Present state of art related to biomass conversion technology so far was found to concentrate on an enzymatic process, coupled with thermal pretreatment on biomass rich in cellulose. Biomass that rich in crude starch is also important in terms of strategic and economic point of view. The main objective of this study is to adopt a new strategy for a single step conversion of a crude starch material into oligosaccharide and glucose utilizing DIC technology. In contrast to existing thermal based pretreatment, DIC technology involves two vacuum cycles; first vacuum cycle was to increase steam accessibility on biomass and to reduce generation of steam condensate thus avoid losing of monosaccharide and hemicelluloses, while second vacuum cycle was to reduce potential thermal degradation of glucose. Distributions of products formed were found to be closely associated with severity of treatment on crude starch material. At lower DIC severity, pretreatment favors the formations of high oligosaccharide composition with small fraction of glucose; while at high DIC severity, pretreatment favors formation of high glucose as a major end product. During an exploratory study to establish the relevant reaction factors; vacuum cycle and moisture content were the two main factors influencing the conversion of crude starch into glucose.DIC starch conversion into glucose was found to be moisture dependent. Both factors were combined together to optimize the other three factors: pressure/temperature, treatment times, and acid concentration. High DIC severity treatment alone could convert nearly 50% of crude starch into glucose. During DIC optimization, an experimental design was developed and tested with DIC pretreatment in order to obtain a second order polynomial mathematical model that was then applied for response surface methodology (RSM). The interaction nature of above factors was examined and was found they depend on DIC treatment severity. Two experimental designs with low and high DIC severity were developed; Low DIC severity (acid: 0.01-0.05 molar, time: 0.5-3.0 min) and High DIC severity (acid: 0.05-0.20 molar, time: 3.0-10.0 min) with similar temperature range (144-165oC) were used. Data mining operation was done on RSM model to develop a kinetic model at both treatment severities. Kinetic data, including rate constant and activation energy were calculated from kinetic models of both severities to compare with actual dilute acidhydrolysis kinetic studies on two DIC treated samples. It was found that activation energy (Ea)for glucose generation at High DIC severity (Ea: 59.44 kJ/mol) was lower than at optimum dilute acid hydrolysis (Ea: 91.30 kJ/mol); while for glucose degradation, Ea was higher with High DIC severity (Ea: 144.12 kJ/mol) if compared to dilute acid hydrolysis (Ea: 45.14 kJ/mol).This indicates that glucose generation with DIC requires less energy while its degradation needs high energy. This combination was required to maximize glucose generation and minimize glucose degradation. Further studies with non-isothermal state during DIC and dilute acid hydrolysis support this finding. In normal polysaccharide conversion to low molecular weight (LMW) oligosaccharides and glucose procedures; two process steps were involved, namely the first process involved thermal pretreatment followed by a second process with dilute acid hydrolysis. In the present work, attempt was made to exclude dilute acid hydrolysis stage in order to establish that DIC process alone is sufficient for total polysaccharides conversion into LMW mainly glucose fraction. Information gathered from quantitative and statistical analysis on (i) exploratory studies, (ii) kinetic models from RSM of DIC process and (iii) kinetic data based on experimental works during dilute acid hydrolysis study; support the assumption that DIC treatment alone is sufficient for the total conversion required.