Submitted in fulfillment of the academic requirements for the degree of Master of Applied Sciences (Chemistry), Durban University of Technology, Durban, South Africa, 2016. / Globally there is a drive for the use of renewable materials for the production of biofuels or high-end value chemicals. The current production of chemicals from crude oil refining is unsustainable and leads to global warming effects. Biomass is the most attractive renewable energy source for biofuel or fine chemical production. Sugarcane bagasse is a by-product of the sugar milling industry and is abundantly available. In this study lignin was sequentially extracted using ionic liquids. The ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) and triethylammonium hydrogen sulfate ([HNEt3][HSO4]) were used to fractionate the sugarcane bagasse. The pre-treatment of sugarcane bagasse was carried out at different temperatures ranging from 90 - 150 0C and reaction times ranging from 1 - 24 h in a convection oven at a 10 % biomass loading. Both ILs were able to dissolve the raw bagasse samples at 120 0C with [Emim][OAc] giving a lignin maxima of 28.8 % and a low pulp yield of 57 % after 12 h; [HNEt3][HSO4] gave a lignin recovery of 17.2 % and low pulp yield of 58.5 % after 6 h. Regenerated lignin was obtained by adding ethanol/ water to the mixture followed by vacuum filtration. The regenerated pulp materials were characterized by Scanning Electron Microscope (SEM) to study the morphology; Fourier Transform Infrared Spectroscopy (FTIR) to study the characteristic bands and thermal analysis to study the thermal stability. / M

Submitted in fulfillment of the academic requirements of the degree of Master of Applied Sciences in Chemistry, Durban University of Technology, Chemistry Department, Durban, South Africa, 2016. / Cellulose is a sustainable, abundant biopolymer derived from a variety of living species such as plants, animals, bacteria and some amoebas. An attractive source of cellulose for industrial uses is agricultural waste, as this use does not jeopardize food supplies and improves the local rural economy. Sugarcane bagasse (SCB) is one of the main biomass wastes from sugar production and represents 30–40 wt % of sugar production waste. In 2008, South Africa produced on average 22 million tons of sugar cane each season from 14 sugar mill supply areas which resulted in 7,9 million tons of “waste” bagasse. In this study cellulose nanocrystals were prepared from soda pulped sugarcane bagasse by acid hydrolysis followed by separation using centrifugation, ultrasonication and dialysis. Transmission Electron Microscopy (TEM) images showed nanocrystals of approximately 300 nm in length and 20 nm in width. Thermogravimetric Analysis and Differential Thermogravimetry (TGA and DTG) profiles of FD CNC, MCC and Pulped bagasse all had characteristic onset and decomposition temperatures indicating a change in the structure after chemical treatments. Particle size distribution measurements corroborated with the TEM and FE - SEM results and showed that the majority of the nanocrystals were in the 100 – 300 nm range. Attenuated Total Reflectance – Fourier Transform Infra Red (ATR - FTIR) analysis showed functional group changes as the amorphous regions of the polymer were removed revealing the ordered crystalline portions. These were further confirmed by an increase in the Lateral Orientation Index (LOI) of the samples as the nanocrystals were isolated. X - Ray Diffraction (XRD) Crystallinity Index (CrI) calculations showed a steady increase in the crystallinity of the materials from pulped bagasse to MCC to FD CNC. / M

L’incorporation de sous-produits agricoles ou de matériaux naturels dans la matrice cimentaire confère des propriétés intéressantes aux composites élaborés. L’objectif de cette thèse est d’élaborer un matériau pouvant répondre aux exigences mécaniques, thermiques et de durabilité des matériaux de construction en zone tropicale humide. Dans un premier temps, l’activité pouzzolanique d’une pouzzolane naturelle, de cendres de tronc de bambou et de cendres de bagasse de canne à sucre ont été évaluées. L’influence de leur incorporation a été ensuite étudiée sur les propriétés mécaniques et la durabilité des mortiers exposés à des ions chlorures et sulfates. Dans un second temps, l’influence de l’ajout de fibres de bagasse sur les propriétés thermiques et mécaniques des composites a été étudiée en fonction de différents paramètres (teneur en fibres, environnement de vieillissement, type de matrice cimentaire).Les résultats obtenus ont permis de montrer que les matériaux étudiés possèdent une activité pouzzolanique et qu’il est possible de les incorporer au ciment afin de lutter contre la corrosion. De plus, les composites élaborés avec des fibres de bagasse sont plus isolants que ceux élaborés sans fibres. Cependant, du point de vue des propriétés mécaniques, l’incorporation de fibres de bagasse diminue les contraintes à la flexion des composites. / The incorporation of crop wastes or natural materials in the cement matrix confers interesting properties to composites prepared. The aim of this thesis is to develop a material that can reach the mechanical, thermal and durability requirements for building materials in the humid tropical zone. Firstly, pozzolanic activity of a natural pozzolan, bamboo stem and sugar cane bagasse ashes has been determined. Influence of their incorporation on mechanical properties and durability of mortars exposed to chloride and sulphate ions was studied. Secondly, influence of addition of bagasse fibers on thermal and mechanical properties of composites was studied as a function of various parameters (fibers content, curing, type of cement matrix).These results has shown that the materials studied have pozzolanic activity and it is possible to incorporate them into the cement to fight against corrosion. Moreover, composites elaborated with bagasse fibers are more insulating than those elaborated without fibers. However, from the viewpoint of mechanical properties, incorporation of bagasse fibers decreases flexural strength of composites in the present work and under the conditions producing procedures that were adopted.

O objetivo deste trabalho foi caracterizar a farinha do bagaço da cana-de-açúcar (FBCA) e avaliar o efeito de sua aplicação, como fonte de fibra insolúvel, em bolo. A FBCA foi caracterizada com relação a sua composição química (teor de umidade, cinzas, proteínas, carboidratos, fibras solúveis, fibras em detergente ácido e neutro e lipídeos), atividade de água (Aw), composição de minerais pela técnica de Espectrometria de Fluorescência de Raios-X (TXRF), determinação do tamanho e distribuição das partículas, avaliação da cor instrumental e contagem de bolores e leveduras e de coliformes totais. A FBCA foi aplicada em bolo tipo cupcake nas proporções de 3 e 6%. Os bolos recém-preparados foram avaliados com relação à umidade, atividade de água (Aw), densidade, cor instrumental e pH. Os bolos foram estocados durante 42 dias e em 5 pontos deste período foram avaliados com relação a umidade, Aw, perfil de textura (parâmetros dureza, elasticidade e coesão), contagem de bolores e leveduras e aceitação sensorial (atributos aparência, sabor, aroma, textura e aceitação global). Todas as análises foram realizadas também em uma amostra controle, preparada sem a adição de FBCA, para efeito de comparação. A FBCA demonstrou ser excelente fonte de fibra insolúvel, com 81,92% entre celulose, lignina e hemicelulose, bem como de minerais como o ferro, manganês e cromo. Todavia é uma fonte pobre de fibra solúvel, proteína, carboidratos e lipídeos. Em torno de 60% das partículas da FBCA possuem tamanho inferior a 80µm. A FBCA apresentou contagem alta de bolores e leveduras e cor tendendo para o amarelo e vermelho. Os bolos apresentaram em torno de 15% de umidade e Aw na faixa intermediária. Bolos com FBCA foram ligeiramente mais úmidos, escuros e densos que o controle. Porém, foram menos elásticos e tão coesos e duros quanto. Os bolos adicionados de 3% de FBCA apresentaram a mesma aceitação que o produto tradicional, com a vantagem do maior valor nutricional em função da presença das fibras e dos minerais oriundos da FBCA. / The aim of this study was to characterize the flour from sugarcane bagasse (FSB) and to evaluate the effect of its application as a source of insoluble fiber in cake. The FSB was characterized in respect to the chemical composition (moisture content, ash, proteins, carbohydrates, soluble fiber, fiber in acid and neutral detergent, cellulose, hemicellulose, lignin and lipids), water activity (Aw), mineral composition by Fluorescence spectrometry technique X-ray (TXRF), size and distribution of particles, evaluation of the instrumental color and counts of molds and total coliforms. The FSB was applied in cupcakes, in proportions of 3% and 6%. The freshly prepared cakes were evaluated in respect to moisture content, water activity (Aw), density, pH and instrumental color. The cakes were stored for 42 days and during this period were evaluated for moisture content, Aw, instrumental texture (hardness, elasticity and cohesion), counts of molds and sensory acceptance (appearance, taste, flavor, texture and overall acceptance). All analysis were also carried out in a control sample, prepared without the addition of FSB, for comparison. The FSB demonstrated to be an excellent source of insoluble fiber, containing 81.92% between cellulose, lignin and hemicellulose, and is source of minerals such as iron, manganese and chromium. However, it is a poor source of soluble fiber, protein, carbohydrates and lipids. Around 60% of the particles of FSB are smaller than 80µm. The FSB presented high counts of molds and the color tends to yellow and red. The cakes showed around 15% of moisture content and Aw in the middle range. Cakes with FSB were slightly damper, darker and denser than traditional. However were less elastic, but so cohesive and hard as the traditional one. Cakes added with 3% of FSB presented the same acceptance that the traditional product, with the advantage of greater nutritional value due to the presence of fibers and minerals from FSB.

A fermentação de hidrolisados hemicelulósicos tem como principal dificuldade a presença de compostos inibidores ao metabolismo microbiano, derivados da degradação parcial da lignina, degradação dos açúcares e liberação de radicais acetil durante a etapa de hidrólise dos materiais lignocelulósicos. O presente trabalho teve por objetivo avaliar a influência de diferentes tratamentos de destoxificação sobre a composição e fermentabilidade do hidrolisado hemicelulósico de bagaço de cana-de-açúcar na produção de etanol e xilitol. Foram avaliados os seguintes tratamentos: a) alteração de pH com óxido de cálcio e ácido fosfórico seguido de adsorção com carvão ativo; b) utilização de resinas de troca iônica (A-860, A-500PS e C-150 - Amberlite); e c) extração líquido-líquido com interface imobilizada em membrana de fibra oca (Membrana, Charlote, NC - USA), na qual a fase orgânica foi uma mistura de octanol e Alamina 336 e a fase aquosa foi o próprio hidrolisado. De acordo com os resultados, os tratamentos aplicados (a, b e c) promoveram uma redução na concentração de ácido acético de 46,74%, 64,15% e 44,71% e uma redução na absorbância relativa (A.R.) de 82,0%, 94,59% e 46,07%, respectivamente. Na fermentação dos hidrolisados tratados, pela levedura Candida guilliermondii FTI 20037, após 48h de fermentação, os resultados para o fator de rendimento foram de 0,57g/g, 0,42g/g e 0,33 g/g após os tratamentos a, b e c, respectivamente. Quanto à produtividade volumétrica, na mesma ordem dos tratamentos foram obtidos os seguintes resultados: 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 e 0,16 g.L-1.h-1. Nas fermentações dos hidrolisados tratados (a) e (b) pela levedura Pichia stipitis IMH 43.2, visando a produção de etanol, após 48h os resultados do fator de rendimento foram 0,38 g/g e 0,23 g/g, respectivamente, enquanto a produtividade volumétrica foi de 0,09 g.L-1.h-1 para o tratamento (a) e para o tratamento (b). Para o tratamento (c) não se observou a produção de etanol nas condições de fermentação utilizadas. Considerando os resultados obtidos, sugere-se que, para as condições experimentais empregadas, o hidrolisado seja tratado por alteração de pH seguido de tratamento com carvão ativado, uma vez que este tratamento resultou nos melhores resultados para o fator de rendimento tanto na produção de xilitol quanto na produção de etanol. / The fermentation of hemicellulosic hydrolysates has as main difficult the presence of compounds derived from partial degradation of lignin, sugars and release of acetyl groups, which are inhibitors of microbial metabolism, during the hydrolysis process of lignocellulosic materials. This study aimed to evaluate the influence of different detoxification treatments on the composition and fermentability of the sugarcane bagasse hemicellulosic hydrolyzate in the production of xylitol and ethanol. The following treatments were evaluated: a) change of pH with calcium oxide and phosphoric acid followed by adsorption with activated charcoal, b) use of ion exchange resins (A-860, A-500 PS and C-150 - Amberlite) and c) liquid-liquid extraction with immobilized interface in hollow-fiber membrane (Membrana, Charlote, NC - USA), in which the organic phase was a mixture of octanol and Alamine 336, and the aqueous phase was the hydrolyzate. According to the results, the employed treatments (a, b and c) promoted a reduction of 46.74%, 64.15% and 44.71% in the acetic acid concentration, and a reduction in the relative absorbance (RA) of 82.0%, 94,59% and 46.07% respectively. In the fermentation of the treated hydrolyzates by the Candida guilliermondii FTI 20037 yeast, aiming xylitol production, after 48h of fermentation, the results for xylitol yield were 0.57g/g, 0.42g/g and 0.33g/g, after the treatments a), b) and c), respectively. The volumetric productivity obtained was 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 and 0,16 g.L-1.h-1, in the same order of treatments. In fermentation by Pichia stipitis IMH 43.2 of the hydrolyzates that used treatments (a) and (b), aiming the production of ethanol, after 48h, the results for yield were 0.38g/g and 0.23g/g, respectively, while the volumetric productivity was 0,09 g.L-1.h-1 for both treatments. For treatment (c) there was no ethanol production using the fermentation conditions applied in this work. Considering these results, it is suggested that for the experimental conditions used at this work, the hydrolyzate should be treated by pH change followed by treatment with activated charcoal, since this treatment resulted in better results of yield in the production of xylitol and ethanol.

Orientador: Camila de Almeida Melo / Coorientador: Altair Benedito Moreira / Banca: Maurício Boscolo / Banca: Odair Pastor Ferreira / Resumo: O processamento da cana-de-açúcar para a produção do etanol e do açúcar vem crescendo a cada ano no Brasil, gerando grandes quantidades de subprodutos de biomassa, a destacar a vinhaça e o bagaço de cana. O principal uso dessas biomassas é na geração de energia (bagaço de cana) e na fertirrigação (vinhaça). Porém a busca por novas alternativas de utilização do bagaço de cana e da vinhaça são necessárias na tentativa de agregar ainda mais valor a estes subprodutos. Sendo assim, estes subprodutos podem ser utilizados no processo de carbonização hidrotérmica (CHT), uma técnica capaz de converter termicamente a biomassa úmida em um material sólido rico em carbono, denominado carvão hidrotérmico. Devido às características físico-químicas do carvão hidrotérmico, diversas aplicações têm sido sugeridas, sendo umas delas o uso como possível fertilizante. No processo de CHT, também é gerada uma fração líquida denominada água de processo. Conhecer a composição orgânica do carvão hidrotérmico e da água de processo é fundamental para entender os efeitos do uso do carvão hidrotérmico como um fertilizante e para propor um destino adequado para a água de processo. Neste contexto, o presente trabalho teve como objetivo fazer um screening inicial dos principais compostos orgânicos presentes no carvão hidrotérmico e na água de processo, utilizando um espectrômetro de massas com ionização por electrospray (ESI-MS), seguido da identificação dos compostos orgânicos não voláteis, utilizando... / Abstract: The processing of sugarcane for ethanol and sugar production has been growing every year in Brazil, generating large quantities of biomass by-products, including vinasse and sugarcane bagasse. The main use of these biomasses is for energy generation (sugarcane bagasse) and fertigation (vinasse). However the search for new alternatives of sugarcane bagasse and vinasse uses are necessary in an attempt to add even more value to these byproducts. Thus, these by-products can be used in the hydrothermal carbonization (HTC) process, a technique capable to convert thermally the wet biomass into a solid carbon-rich material called hydrochar. Due to the physical-chemical characteristics of the hydrochar, several applications have been suggested, one of them being the use as a possible fertilizer. In the HTC process, a liquid fraction called process water is also generated. Knowing the organic composition of hydrochar and process water is fundamental to understand the effects of the use of hydrochar as a fertilizer and to propose a suitable destination for process water. In this context, the present work aimed to perform an initial screening of the main organic compounds present in hydrochar and process water using an electrospray ionization mass spectrometer (ESI-MS), followed by the identification of the non-volatile organic compounds, using gas chromatography coupled to mass spectrometry (GC-MS). From the results obtained by ESI-MS analysis, it can be concluded that the conditions of ... / Mestre

A utilização de cana-de-açúcar para geração de açúcar, energia e etanol é uma das atividades mais importantes do Brasil. Esta intensa produção gera grandes quantidades de bagaço que podem ser utilizadas para aumentar a produção de etanol. Neste sentido, é de grande interesse técnico-científico o estudo de pré-tratamentos desta matéria prima, dentre os quais se inserem os processos de polpação. No presente trabalho buscou-se estudar a utilização da polpação hidrotrópica do bagaço de cana-de-açúcar para separação de seus principais componentes macromoleculares. Para tanto foram utilizados dois hidrótropos distintos, o benzoato de sódio e xilenossulfonato de sódio. Como referência, realizaram-se também polpações apenas com água, com soluções etanol/água e com soluções de hidróxido de sódio.O estudo foi realizado a partir de planejamento fatorial de experimentos, utilizando-se a influência das variáveis temperatura e tempo de reação. As respostas consideradas foram o rendimento de polpa e a quantidade de lignina residual. Este estudo exploratório revelou que o xilenossulfonato de sódio foi mais efetivo que o benzoato de sódio. Entretanto, o uso dos agentes hidrotrópicos foram menos eficiente quando comparado aos sistemas etanol/água e hidróxido de sódio. As ligninas extraídas nos processos de polpação hidrotrópica foram analisadas por diversas técnicas de caracterização. As ligninas extraídas na polpação com benzoato de sódio apresentaram menores massas molares quando comparado ao uso de xilenossulfonato de sódio. A análise das polpas obtidas nos diferentes processos revelou que as condições de maiores tempos e temperaturas produziram polpas com maiores índices de cristalinidade. / The production of sugar, energy and ethanol from sugar cane is one of the most important activities of Brazil and generates a enormous quantity of bagasse which can be used to increase the ethanol production. In this sense, the study of sugarcane bagasse is a very important task, in both technical and scientific approaches. Thus, the pre-treatment of sugar cane bagasse by using pulping/delignification processes constitutes a important step to recovery the main macromolecular components of the vegetal tissues of this raw material. In the present work it was studied the utilization of hydrotropic agents to promote the delignification of sugarcane bagasse. The study was carried out by using two different hydrotropes: sodium benzoate and sodium xylenosulfonate. As standard for comparison, it was also studied the pulping of sugarcane bagasse by using only water and ethanol/water and sodium hydroxide solutions. The pulping processes were carried out from factorial planning experiments employing two different levels (and a central point) for reaction time and temperature. As response it was determined the correspondents pulping yield and residual lignin contents. The results indicated that sodium xylenosulfonate was more effective than benzoate sodium in the promotion of the delignification. However, the utilization of hydrotropic systems were less efficient to promote the delignification, when compared with ethanol/water or sodium hydroxide aqueous solution. The lignins extracted in the pulping with sodium benzoate presented lower molar masses when compared with the use of sodium xylenesulfonate. The analysis of the pulps showed that the higher temperatures and reaction times produced pulps with higher crystallinity.

Orientador: Michelle Leali Costa / Coorientador: Mario de Oliveira Neto / Banca: Edson Cocchieri Botelho / Banca: Mirabel Cerqueira Rezende / Resumo: Neste trabalho encontra-se apresentada a produção via misturador termocinético e injeção de compósitos de polipropileno reforçados com bagaço de cana de açúcar deslignificado e com bagaço hidrolisado por enzimas, em diferentes concentrações (5%, 10% e 25%, massa/massa, (m/m)). Em seguida, os compósitos poliméricos foram caracterizados via ensaios mecânicos de tração, flexão em três pontos e impacto Izod. Além disso, ensaios para a determinação das propriedades térmicas (temperaturas de fusão e de cristalização por calorimetria exploratória diferencial (DSC), temperatura de degradação por termogravimetria (TGA) e temperatura de transição vítrea (Tg) por análise dinâmico-mecânica (DMA)) foram realizadas. Análises de infravermelho (FTIR) e microscopia eletrônica de varredura (MEV) também foram realizadas nos compósitos produzidos. As amostras foram também submetidas ao condicionamento em câmara de radiação ultravioleta (UV) para avaliar a influência do intemperismo nas propriedades mecânicas e térmicas dos compósitos poliméricos produzidos. Os resultados de FTIR mostram a presença de boa interface entre a matriz (PP) e os materiais lignocelulósicos. As análises de DSC e TGA mostram que as temperaturas de fusão, de cristalização e degradação térmica estão dentro dos valores relatados na literatura, indicando que o processamento termocinético e a injeção não afetaram as propriedades térmicas dos compósitos. A temperatura de transição vítrea (Tg) medida por DMA não foi afetada pela introdução dos reforços. Porém, quando os compósitos foram submetidos à exposição a radiação UV os valores da Tg dos compósitos foram aumentados. As propriedades mecânicas avaliadas no presente trabalho não sofreram alterações ou ganhos significativos com a introdução dos reforços nos compósitos, ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work is presented the production via kinetic term mixing and injection of polypropylene composites reinforced with both delignified and enzymatic hydrolyzed residue bagasse from sugarcane, at different concentrations (5%, 10% and 25%, (w / w)). Polymeric composites were characterized via mechanical tests of tensile, three points bending flexural and Izod impact. Furthermore, tests for determining the thermal properties were done (melting and crystallization temperatures by differential scanning calorimetry (DSC), temperature of degradation by thermogravimetric analysis (TGA) and glass transition temperature (Tg) by dynamic mechanical (DMA)). Analyses of Fourier transform infra-red spectroscopy (FTIR) and scanning electron microscopy (SEM) were done for the composites. After this, the polymeric composites were subjected to conditioning in the ultraviolet radiation camera (UV) to evaluate the wheathering influence on the mechanical and thermal properties. FTIR results showed the presence of interface between the matrix (PP) and lignocellulosic materials. DSC and TGA analyzes showed that the melting temperatures of crystallization and thermal degradation are within the values reported on literature, indicating that the kinetic term processing and injection did not affect the thermal properties of the composites. Tg was not affected by the introduction of reinforcement agents. However, when the composites were subjected to exposure to UV radiation, the values of Tg of the composites were increased. The mechanical properties evaluated in this study did not change or significant gains with the introduction of reinforcements in composites, however, when exposed to UV radiation for conditioning such properties suffered less significant reductions when compared with the samples of the polypropylene / Mestre

A fermentação de hidrolisados hemicelulósicos tem como principal dificuldade a presença de compostos inibidores ao metabolismo microbiano, derivados da degradação parcial da lignina, degradação dos açúcares e liberação de radicais acetil durante a etapa de hidrólise dos materiais lignocelulósicos. O presente trabalho teve por objetivo avaliar a influência de diferentes tratamentos de destoxificação sobre a composição e fermentabilidade do hidrolisado hemicelulósico de bagaço de cana-de-açúcar na produção de etanol e xilitol. Foram avaliados os seguintes tratamentos: a) alteração de pH com óxido de cálcio e ácido fosfórico seguido de adsorção com carvão ativo; b) utilização de resinas de troca iônica (A-860, A-500PS e C-150 - Amberlite); e c) extração líquido-líquido com interface imobilizada em membrana de fibra oca (Membrana, Charlote, NC - USA), na qual a fase orgânica foi uma mistura de octanol e Alamina 336 e a fase aquosa foi o próprio hidrolisado. De acordo com os resultados, os tratamentos aplicados (a, b e c) promoveram uma redução na concentração de ácido acético de 46,74%, 64,15% e 44,71% e uma redução na absorbância relativa (A.R.) de 82,0%, 94,59% e 46,07%, respectivamente. Na fermentação dos hidrolisados tratados, pela levedura Candida guilliermondii FTI 20037, após 48h de fermentação, os resultados para o fator de rendimento foram de 0,57g/g, 0,42g/g e 0,33 g/g após os tratamentos a, b e c, respectivamente. Quanto à produtividade volumétrica, na mesma ordem dos tratamentos foram obtidos os seguintes resultados: 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 e 0,16 g.L-1.h-1. Nas fermentações dos hidrolisados tratados (a) e (b) pela levedura Pichia stipitis IMH 43.2, visando a produção de etanol, após 48h os resultados do fator de rendimento foram 0,38 g/g e 0,23 g/g, respectivamente, enquanto a produtividade volumétrica foi de 0,09 g.L-1.h-1 para o tratamento (a) e para o tratamento (b). Para o tratamento (c) não se observou a produção de etanol nas condições de fermentação utilizadas. Considerando os resultados obtidos, sugere-se que, para as condições experimentais empregadas, o hidrolisado seja tratado por alteração de pH seguido de tratamento com carvão ativado, uma vez que este tratamento resultou nos melhores resultados para o fator de rendimento tanto na produção de xilitol quanto na produção de etanol. / The fermentation of hemicellulosic hydrolysates has as main difficult the presence of compounds derived from partial degradation of lignin, sugars and release of acetyl groups, which are inhibitors of microbial metabolism, during the hydrolysis process of lignocellulosic materials. This study aimed to evaluate the influence of different detoxification treatments on the composition and fermentability of the sugarcane bagasse hemicellulosic hydrolyzate in the production of xylitol and ethanol. The following treatments were evaluated: a) change of pH with calcium oxide and phosphoric acid followed by adsorption with activated charcoal, b) use of ion exchange resins (A-860, A-500 PS and C-150 - Amberlite) and c) liquid-liquid extraction with immobilized interface in hollow-fiber membrane (Membrana, Charlote, NC - USA), in which the organic phase was a mixture of octanol and Alamine 336, and the aqueous phase was the hydrolyzate. According to the results, the employed treatments (a, b and c) promoted a reduction of 46.74%, 64.15% and 44.71% in the acetic acid concentration, and a reduction in the relative absorbance (RA) of 82.0%, 94,59% and 46.07% respectively. In the fermentation of the treated hydrolyzates by the Candida guilliermondii FTI 20037 yeast, aiming xylitol production, after 48h of fermentation, the results for xylitol yield were 0.57g/g, 0.42g/g and 0.33g/g, after the treatments a), b) and c), respectively. The volumetric productivity obtained was 0,39 g.L-1.h-1, 0,20 g.L-1.h-1 and 0,16 g.L-1.h-1, in the same order of treatments. In fermentation by Pichia stipitis IMH 43.2 of the hydrolyzates that used treatments (a) and (b), aiming the production of ethanol, after 48h, the results for yield were 0.38g/g and 0.23g/g, respectively, while the volumetric productivity was 0,09 g.L-1.h-1 for both treatments. For treatment (c) there was no ethanol production using the fermentation conditions applied in this work. Considering these results, it is suggested that for the experimental conditions used at this work, the hydrolyzate should be treated by pH change followed by treatment with activated charcoal, since this treatment resulted in better results of yield in the production of xylitol and ethanol.

The rapid development of the bioethanol industry globally demonstrates the importance of bioethanol as an alternate energy source to the depleting fossil fuels. To decrease costs and avoid undue pressure on the global food supply, the renewable lignocelluloses appear to be a better substrate for bioethanol production compared to others being investigated. This study investigated the conversion of lignocellulosic material, sugarcane bagasse, to ethanol by the use of Zymomonas mobilis and Pichia stipitis. The investigation of fermentation characteristics of the two strains revealed that their performance on the ethanol production was closely related to the viable cell concentration in the medium. The increase of inoculum size to five fold resulted in an increase in the system co-efficiency to 2.2 fold and 5.2 fold respectively for Z. mobilis and P. stipitis. A theoretical value de (the cell instantaneous ethanol production rate) was introduced to describe the ethanol productivity based on biomass. System co-efficiency proved to be only affected by the viable cell concentration (xC) and de, regardless of ethanol re-assimilation. Immobilized culture of Z. mobilis and P. stipitis showed distinct differences in their characteristics. The bacterium acclimatized to the interior of gel beads; the biomass concentration within the beads increased greater than 10 fold during the reuse of the beads, resulting in an improved fermentation performance. The immobilized P. stipitis gave a similar system co-efficiency level of approximately 0.5 g/l/h under different culture conditions; cell growth in the medium was considerably more vigorous compared to that within the beads. P. stipitis sole-culture on the glucose/xylose medium with a high inoculum size showed a comparable fermentation efficiency with the best result of the co-culture processes. Fermentation of 50.0 g/l of sugar mixture (30.0 g/l glucose and 20.0 g/l xylose) was completed in 20 h with an ethanol yield of 0.44 g/g. No catabolite repression due to glucose was observed for the xylose assimilation. Co-culture of immobilized Z. mobilis and free cells of P. stipitis proved to be the best fermentation scheme on the glucose/xylose sugar mixture co-fermentation. The removal of Z. mobilis after the utilization of glucose improved the stability of the performance. The best result showed that 50.0 g/l sugars were fully converted to ethanol within 19 h, giving an ethanol yield of 0.49 g/g, which is 96% of the theoretical rate. When co-cultured, viable cells of Z. mobilis inhibited the cell activity of P. stipitis, and were capable of growing to high concentration levels without an appropriate carbon source. Acid and enzymatic hydrolysates of sugarcane bagasse showed similar fermentability, but the hydrolysate without overliming significantly inhibited both cell growth and ethanol production of P. stipitis. The co-culture process on the hydrolysate medium successfully utilized 53.56 g/l sugars (32.14 g/l glucose and 21.42 g/l xylose) in 26 h with a yield of 0.43 g/g; this value further increased to 0.49 g/g when ethanol peaked at 40 h. A high cell density proved to be an effective method to improve the system co-efficiency for ethanol production. For the fermentation processes on the sugar medium, results achieved in this study, 10.54 g/l/h for Z. mobilis free cell culture on glucose, 0.755 g/l/h for P. stipitis free cell culture on xylose, 1.092 g/l/h for P. stipites free cell culture on the glucose/xylose mixture and 1.277 g/l/h for glucose/xylose co-fermentation using co-culture, are higher than the best values reported in the literature in batch culture. In the fermentation of the hydrolysate, the system co-efficiency of 0.879 g/l/h achieved with co-culture is comparable to the best values reported for the fermentation of lignocellulosic hydrolysates. / Master of Science (Hons)