To overcome the limitations of starch-based and sugar-based ethanol, scientists propose to expand the use of cellulosic ethanol. Cellulosic ethanol is a biofuel produced from wood, grasses, or the non-edible parts of plants. As the U.S. has a large cellulosic biomass production base (Perlack et al., 2006), production of ethanol from cellulosic feedstock and use of ethanol as a substitute for gasoline could help promote rural development, reduce green house gases emissions, and increase energy independence. This study focuses on the cost of producing cellulosic ethanol along with the amount of carbon sequestered and emitted using switchgrass as a feedstock. In the first part of this study, willingness to adopt (WTA) switchgrass is evaluated. The amount of farmland available for growing switchgrass was estimated using Probit and Tobit models of switchgrass production survey data developed in the University of Tennessee’s Department of Agricultural and Resource Economics. The estimated results from these two models show that when switchgrass prices increase, the probability of farmers to grow switchgrass and land acreages used for switchgrass production will increase. In the second part of this study, based on the results of estimated, farmland availability within an optimal draw area of 50 miles of a biorefinery and a switchgrass delivery schedule could be determined from the biorefinery’s perspective considering different bale types and storage methods. A cost minimization programming model was developed to estimate the year-round switchgrass delivery schedule within fifty miles of three selected biorefinery locations in the southeastern U.S. Also in this study, the carbon credit effect was considered in the model. The results from the programming model suggest that with the carbon credit paid to biorefineries, more marginal land will be used for growing switchgrass, and carbon will be sequestered in the soil at a level that exceeds emitted carbon by at least 1.5 times. Lower feedstock costs would be available to the biorefineries if a carbon payment was available to producers for net carbon sequestered.

On the forefront of the recent expansion in biofuels research is the production of cellulosic ethanol, or ethanol produced from a cellulose containing feedstock. Cellulose is a six-carbon polysaccharide found in most plant life and is one of the most abundant organic compounds on the planet. While the first generation of ethanol facilities uses sugar and starch based (corn kernels) plants as their feedstock, the next generation will use cellulosic sources such as wood chips, switchgrass, and forest residues. These cellulosic sources require far less energy and resources to grow and harvest, and are also much more abundant. A cellulosic source widely available in Georgia and much of the southeastern US is southern pine. This study involves the modeling of a complete 2000 dry ton per day pine to ethanol production facility with the AspenTech3 software Aspen Plus, which outputs a mass and energy balance as well as the capital cost of the equipment. A key parameter which affects the competitiveness of cellulosic ethanol is the internal processing energy required to convert the pine to ethanol. As a result, the heat and electrical load of every component within the facility is modeled and then quantified through the Aspen Plus simulation. After this base case energy analysis is developed, various alternate plant configurations are integrated in an attempt to reduce this process energy requirement. The material that is not fermented into ethanol is burned on-site to provide steam and electricity to the plant, as well as excess electricity to be sold to the grid as a byproduct. As the facility processing energy requirement is decreased, more excess electricity is available for sale. The implementation of the alternate distillation scenarios effectively reduce the internal processing energy in a manner as to increase the amount of excess electricity sold to the grid by 13.5%. The additional equipment required in this alternate scenario returns a simple payback period of 1.1 years through the additional revenue of the increased electricity sale.

Low cost cellulosic wastes like paper sludge, municipal wastes, solid wastes from food, packing etc. contain a high amount of cellulose which can be converted to bioethanol by two steps: (1) solubilization of cellulosic fibers to monosaccharides (2) conversion of monosachharides to bioethanol via fermentation. At present the implementation of this technology has been deterred by high cost for enzymes. Enzymatic hydrolysis of cellulosic fibers shows a biphasic behavior with an initial fast step followed by a slow step leading to low cellulose conversion rates. Low hydrolytic conversion rates necessitate the use of a high enzyme dosage to obtain meaningful cellulose conversion rates which make the implementation of this entire technology economically infeasible. The objective of this study is to get a better understanding of the mechanism of enzymatic hydrolysis of fibers to glucose and to investigate the effect of cationic polymers on enzymatic hydrolysis rates. To achieve the first objective, we performed experiments so as to study changes in morphological and physiochemical properties like fiber length, percentage of fines, crystallinity index, kink angle, kink index, mean curl, total organic carbon and glucose production with time. We used bleached kraft softwood, hardwood, and unbleached softwood fiber as cellulosic substrate and pergalase as cellulase enzyme. All of the experiments were carried out at experimental conditions of a temperature of 50 .C and a pH of 5.0 which maximize enzymatic activity. We studied the impact of recycling and refining on hydrolysis rates by measuring total organic carbon and glucose production. We found that refining increases enzymatic conversion rates by about as much as 20 %, however refining being energy intensive makes its implementation economically unfavorable. We found a novel way of enhancing hydrolysis rates by the use of cationic polyacrylamides. The effect of cationic polacrylamides was studied on both hardwood and softwood fibers at similar experimental conditions. Cationic polyacrylamides produced a maximum rate increase of 20 % in hydrolytic conversion rates for hardwood fibers. Even though, the increase in hydrolysis rates for softwood fibers was smaller than hardwood fibers, it was still significant. We further studied the effect of parameters like polymer concentration, cationicity and molecular weight to find a relation between properties of polymers and the increase in enzymatic hydrolysis.

Understanding the energy input and emissions resulting from the development of biofuels is important to quantify the overall benefit of the biofuel. As part of the On-Farm Biomass Processing project, a life cycle assessment (LCA) was conducted on the process to harvest and transport agricultural crop residues ready for processing into biofuel. A Microsoft Excel model was developed that inventories the entire life cycle of the process, including incorporation of stochastic analysis within the model. The LCA results of the agricultural equipment manufacture are presented, along with the results of each step of the process, including fertilizer addition, single pass harvest, double pass harvest, and transport from the field to processing facility. Various methods of analyzing co-products are also presented for the single pass harvesting step, in which comparisons between market based, mass based and process-purpose based allocation methods are reviewed. The process-purpose based method of fuel consumption difference between combine operation in conventional harvest versus single pass harvest is determined to be the most realistic of the process. A detailed comparison of the energy and emission differences between single pass and double pass harvesting is given, along with the total LCA results of harvesting and transporting the biomass.

in the current context of searches for Bioproducts from renewable sources and the concern with environmental conditions makes biofuels, which are produced from biomass, an alternative to the global dependence on petroleum products. In this way, there is a growing appreciation of wastes from agro-industry as a source of lignocellulosic feedstock for ethanol 2 g (second-generation ethanol). In this sense, the aim of this study was to evaluate the steps of hydrolysis and fermentation of straw and hydrolytic stock corn cob for second-generation ethanol production, testing various process conditions. For this purpose, the corn residues were pretreated with 0.5% H2SO4 at 121ºc for 15 minutes in enzymatic hydrolysis tests in table rotating type incubator shaker to 50ºc and 150rpm, using 20FPU/mL of enzyme Cellic Ctec 2 ®, varying the load of biomass hydrolysis time and type of biomass according to the experimental planning, which made the study of the best operation conditions of hydrolysis through observation of the effects and combinations of parameters, where the best ART index (g/L) was for straw with 5 g of biomass for 48 hours getting 30, 68 g/L, in the range investigated. Fermentation was conducted in shaker to 30ºc, 200 rpm for 24 hours with 90.97% fermentation efficiency, obtaining 3, 9 g/L of alcohol. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / No contexto atual da procura por bioprodutos a partir de fontes renováveis e a preocupação com as condições ambientais torna os biocombustíveis, que são produzidos a partir de biomassa, uma alternativa à dependência mundial por produtos derivados de petróleo. Desta forma, há uma crescente valorização de resíduos provenientes da agroindústria como fonte de matéria-prima lignocelulósica para obtenção de etanol 2G (etanol de segunda geração). Neste sentido, o objetivo desse estudo foi avaliar as etapas de hidrólise e fermentação do caldo hidrolítico da palha e do sabugo de milho para produção de etanol de segunda geração, testando diferentes condições de processo. Para tanto, foram utilizados resíduos de milho pré-tratados com H2SO4 0,5% a 121ºC por 15 minutos em ensaios de hidrólise enzimática em mesa incubadora rotativa tipo shaker à 50ºC e 150rpm, utilizando 20FPU/mL de enzima Cellic Ctec 2®, variando a carga de biomassa, tempo de hidrólise e tipo de biomassa de acordo com o planejamento experimental, o qual viabilizou o estudo das melhores condições de operação da hidrólise, através da observação dos efeitos e combinações dos parâmetros, onde o melhor índice de ART (g/L) foi para a palha com 5 g de biomassa por 48 horas obtendo 30,68g/L, na faixa investigada. A fermentação foi conduzida em shaker à 30ºC, 200rpm por 24hs com eficiência de fermentação de 90,97%, obtendo-se 3,9g/L de álcool.

Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-13Bitstream added on 2014-06-13T20:38:20Z : No. of bitstreams: 1 colombari_fm_me_sjrp.pdf: 821418 bytes, checksum: 6fa62a325554a5e7485ea5403112c41e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O material lignocelulósico do qual o bagaço é formado contém principalmente açúcares polimerizados na forma de celulose e hemiceluloses, e compostos fenólicos polimerizados na forma de lignina. Tais polímeros podem ser hidrolisados via química e/ou enzimática, dando origem a, entre outros compostos, açúcares fermentescíveis. O objetivo desse trabalho foi investigar alguns tratamentos físico-químicos aplicados ao bagaço de cana de açúcar que favoreçam o aumento da liberação de açúcares fermentescíveis por hidrólise enzimática, com a mínima produção possível de compostos inibidores da fermentação alcoólica. Diferentes condições de pré-tratamento foram testadas, como utilização de H2SO4 ou NaOH em diferentes concentrações, concomitantemente com a utilização de tratamentos combinados de ozônio, ultrassom e micro-ondas. Os resultados mostraram que tais processos promoveram certa desestruturação do complexo lignocelulósico da parede celular do bagaço, a qual foi relacionada com a concentração de compostos fenólicos e açúcares redutores. O bagaço pré-tratado foi então submetido à ação de enzimas celulolíticas e o teor de açúcares redutores totais formados foi analisado. As condições nas quais maiores quantidades destes açúcares foram liberados foram: H2SO4 0,1 M, irradiado por ultrassom durante 5 minutos (81,7 ± 0,2 mg de glicose por grama de bagaço) e H2SO4 0,1 M saturado com ozônio, irradiado por micro-ondas por 4 minutos (86,0 ± 0,2 mg de glicose por grama de bagaço), que representam um ganho significativo frente aos 6,8 ± 0,2 mg de glicose por grama de bagaço não tratado. As análises por Calorimetria Exploratória Diferencial (DSC) e por Espectrofotometria no Infravermelho (FTIR-ATR) possibilitaram comparar as modificações no sistema estrutural da parede... / The lignocellulosic material of which the sugarcane bagasse is made contains, mainly, polymerized sugars as cellulose and hemicelluloses and polymerized phenolic compounds as lignin. These polysaccharides can be hydrolyzated chemically or enzymatically, giving rise to, among other compounds, fermentable sugars. The aim of this work is to investigate some physicochemical treatments applied to the sugarcane bagasse that favors the release of the maximum amount of fermentable sugars by enzymatic hydrolysis, with a minimal production of alcoholic fermentation inhibitor compounds. Different pre-treatment conditions were tested as different concentrations of sulfuric acid or sodium hydroxide concomitantly with the combinated treatments of ozone, ultrasound and microwaves. Results showed that such processes promoted certain disruption of lignocellulosic complex of the bagasse cell wall, which was related to the concentration of phenolic compounds and reducing sugars. Then, the bagasse was subjected to the action of cellulolytic enzymes and the reducing sugars content was quantified. The conditions in what the maximum amount of these sugars were released were: H2SO4 0.1 M, irradiated by ultrasound for 5 minutes (81.7 ± 0,2 mg/g bagasse) and H2SO4 0.1 M irradiated by microwaves for 4 minutes (86.0 ± 0,2 mg/g bagasse), that represents a significative gain compared to untreated bagasse. Strucural analysis by Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectrophotometry Atennuated Total Reflectance (FTIR-ATR) analysis allowed comparing the structural modifications in the wall after the pretreatments, indicating that ultrasound pretreatments were effective for hemicelluloses desestruturation and decrease in the cellulose crystallinity index while microwave pretreatments were... (Complete abstract click electronic access below)

Orientador: Roberto da Silva / Coorientador: Prof. Dr. Mauricio Boscolo / Banca: Maria de Lourdes T. P. Polizeli / Banca: Eleni Gomes / Resumo: O material lignocelulósico do qual o bagaço é formado contém principalmente açúcares polimerizados na forma de celulose e hemiceluloses, e compostos fenólicos polimerizados na forma de lignina. Tais polímeros podem ser hidrolisados via química e/ou enzimática, dando origem a, entre outros compostos, açúcares fermentescíveis. O objetivo desse trabalho foi investigar alguns tratamentos físico-químicos aplicados ao bagaço de cana de açúcar que favoreçam o aumento da liberação de açúcares fermentescíveis por hidrólise enzimática, com a mínima produção possível de compostos inibidores da fermentação alcoólica. Diferentes condições de pré-tratamento foram testadas, como utilização de H2SO4 ou NaOH em diferentes concentrações, concomitantemente com a utilização de tratamentos combinados de ozônio, ultrassom e micro-ondas. Os resultados mostraram que tais processos promoveram certa desestruturação do complexo lignocelulósico da parede celular do bagaço, a qual foi relacionada com a concentração de compostos fenólicos e açúcares redutores. O bagaço pré-tratado foi então submetido à ação de enzimas celulolíticas e o teor de açúcares redutores totais formados foi analisado. As condições nas quais maiores quantidades destes açúcares foram liberados foram: H2SO4 0,1 M, irradiado por ultrassom durante 5 minutos (81,7 ± 0,2 mg de glicose por grama de bagaço) e H2SO4 0,1 M saturado com ozônio, irradiado por micro-ondas por 4 minutos (86,0 ± 0,2 mg de glicose por grama de bagaço), que representam um ganho significativo frente aos 6,8 ± 0,2 mg de glicose por grama de bagaço não tratado. As análises por Calorimetria Exploratória Diferencial (DSC) e por Espectrofotometria no Infravermelho (FTIR-ATR) possibilitaram comparar as modificações no sistema estrutural da parede... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The lignocellulosic material of which the sugarcane bagasse is made contains, mainly, polymerized sugars as cellulose and hemicelluloses and polymerized phenolic compounds as lignin. These polysaccharides can be hydrolyzated chemically or enzymatically, giving rise to, among other compounds, fermentable sugars. The aim of this work is to investigate some physicochemical treatments applied to the sugarcane bagasse that favors the release of the maximum amount of fermentable sugars by enzymatic hydrolysis, with a minimal production of alcoholic fermentation inhibitor compounds. Different pre-treatment conditions were tested as different concentrations of sulfuric acid or sodium hydroxide concomitantly with the combinated treatments of ozone, ultrasound and microwaves. Results showed that such processes promoted certain disruption of lignocellulosic complex of the bagasse cell wall, which was related to the concentration of phenolic compounds and reducing sugars. Then, the bagasse was subjected to the action of cellulolytic enzymes and the reducing sugars content was quantified. The conditions in what the maximum amount of these sugars were released were: H2SO4 0.1 M, irradiated by ultrasound for 5 minutes (81.7 ± 0,2 mg/g bagasse) and H2SO4 0.1 M irradiated by microwaves for 4 minutes (86.0 ± 0,2 mg/g bagasse), that represents a significative gain compared to untreated bagasse. Strucural analysis by Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectrophotometry Atennuated Total Reflectance (FTIR-ATR) analysis allowed comparing the structural modifications in the wall after the pretreatments, indicating that ultrasound pretreatments were effective for hemicelluloses desestruturation and decrease in the cellulose crystallinity index while microwave pretreatments were... (Complete abstract click electronic access below) / Mestre

Orientador: Mauricio Boscolo / Banca: Vanildo Luiz Del Bianchi / Banca: George Jackson de Moraes Rocha / Resumo: Utilizando o bagaço de cana como matéria prima para a produção do etanol brasileiro pode-se aumentar a produção em 50% deste combustível sem o aumento de área cultivada com a cana de açúcar. A hidrólise química deste material demonstrou ser ineficiente à medida que gera um grande número de substâncias inibidoras do processo fermentativo alcoólico, como aldeídos furânicos e fenóis. A hidrólise enzimática vem se destacando como a forma mais viável de sacarificação do bagaço, em função de não gerar tais inibidores, mas a recalcitrância da fibra vegetal impede tal processo. A ação das enzimas hidrolíticas é muito dificultada pela forma como se encontra naturalmente a fibra vegetal: regiões de alta cristalinidade e a presença de lignina revestindo as fibras. O preparo do bagaço para a ação enzimática, normalmente denominado de pré-tratamento, utiliza condições extremas de temperatura e pressão que podem formar produtos tóxicos para a fermentação alcoólica e apresentam sérios riscos operacionais. O objetivo deste trabalho é avaliar o grau de desestruturação do bagaço após pré-tratamentos em soluções ácidas e alcalinas em glicerol e irradiadas com micro-ondas (MO) em dois modos: estático e rotativo. A melhor condição para a ação hidrolítica do complexo enzimático empregado foi obtida em meio não tamponado (água destilada) durante 24 horas. As maiores liberações de açúcares redutores totais (ART) após a hidrólise enzimática foram alcançadas quando o bagaço foi pré-tratado com irradiação de MO por dois minutos em modo rotativo em meio ácido (0,07 mol/L H2SO4) em 100% glicerol (617 ± 24 mg de ART/g de bagaço) e em meio alcalino (0,05 mol/L NaOH) em 100% glicerol... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The production of the Brazilian bioethanol can be increased in 50% without expanding the area cultivated with sugarcane by using sugarcane bagasse as raw material. Its recalcitrance is an obstacle to enzymatic hydrolysis, which can be overcome by physical-chemical treatments. Common pre-treatments using extreme conditions of temperature and pressure are dangerous, promote the generation of toxic compounds (phenols and aldehydes) besides being potentially inhibitory for yeast. The aim of this work is to assess the degree of disruption of the bagasse after pre-treatment in acidic and alkaline glycerol, irradiated with microwaves both in the static and rotational modes. The enzyme complex showed the best results with the reactions promoted in a non-buffered (distilled water) at 24 hours. The best results for the pre-treatment were found after inserting a rotation system in the microwave oven inasmuch as the samples were subjected to irradiation in a more homogeneous way. The best pre-treatment was obtained after enzymatic hydrolysis in sulfuric acid (0.07 mol/L), in pure glycerol, with the rotation of the balloon inside the microwave oven (617 ± 24 mg of ART/g bagasse). In alkaline medium, the best result was found in the absence of water in the reaction medium (0.05 mol/L NaOH) with the rotation of the balloon inside the microwave oven (601 ± 58 mg of ART/g of bagasse). Differential Scanning Calorimetry (DSC) allows to evaluate the degree of disruption of bagasse comparing the enthalpy change, which can be associated with disruption of bounds in pre-treated bagasse. Among the pre-treated bagasse, it is observed that the bagasse treated with NaOH 0.05 mol/L and 5% of water in glycerol had the lowest ΔH, suggesting greater breakdown of carbohydrates after pre-treatment / Mestre

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Atualmente, o material utilizado para o tratamento endoscópico é o Deflux, porém este é um material não-biológico. Sabe-se que a substância ideal deve ser atóxica, biocompatível, não-migratória, não-antigênica e deve causar o mínimo possível de inflamação no local do implante. A bactéria Zoogloea sp. produz um exopolissacarídeo celulósico (CEP) com baixa citotoxicidade e alto biocompatibilidade. O objetivo deste estudo é investigar, na bexiga de coelho, a biocompatibilidade de implantes de exopolissacarídeo de celulose, produzidos pela Zooglea sp. Foram utilizados como modelo experimental, 20 coelhos adultos da raça Califórnia, com média de seis meses de idade. Os animais foram divididos em dois grupos, sendo o grupo G1, composto por animais mortos três dias após a aplicação do implante (n=9), e o grupo G2, composto por animais mortos três meses após a aplicação do implante (n=11). Cada animal recebeu, no total, quatro implantes, sendo dois de gel de biopolímero e dois de gel Deflux. Foram realizadas as técnicas imunohistoquímicas para marcação de colágeno tipos I e III, alfa-actina de músculo liso, PCNA e reação química TUNEL. Nas amostras de três dias, os implantes de CEP e deflux, eram estruturalmente homogêneos e livres de células inflamatórias ou vasos sanguíneos. Por outro lado, nas amostras de três meses, com exceção de algumas áreas, o CEP estava organizado como feixes curtos que eram sugestivos de um tecido fibroso. Apesar disso, o implante de CEP corou negativamente para colágenos tipos I e III, fibras elásticas, enquanto que o tricrômico de masson, não indicou a presença de colágeno. Em contraste as áreas de implante de deflux nas amostras de três meses estavam fragmentadas, mas ainda eram homogêneas, e ainda não havia nenhuma célula nem vaso sanguíneo em seu interior. As células positivas para PCNA podiam ser claramente percebidas dentro dessas ilhotas, dessa forma indicando um processo inflamatórioproliferativo, em curso. No grupo sacrificado aos três meses, os implantes de deflux ainda estavam negativos, mas em torno das áreas de CEP algumas células positivas para a técnica do TUNEL eram perceptíveis. Nos implantes de CEP de três meses, muitos vasos sanguíneos eram visualizados, e a sua densidade era de 23.865.48. A densidade de microvasos na lâmina própria (41.5111.19) foi significativamente diferente (p<0.001) daquela no implante de CEP. Nossos resultados mostraram que o CEP possui pouca imunogenicidade e se integra melhor no tecido hospedeiro quando comparado ao deflux. Portanto o CEP deve ser um material eficiente em casos em que a incorporação ao tecido é desejada como por exemplo em estruturas de suporte na cirurgia de reconstrução / Actually the material used for the endoscopic treatment is the Deflux, however this is a non-biological material. It is known that the ideal substance should be non-toxic, biocompatible, non-antigenic, non-migratory and must cause the least possible inflammation. Zoogloea SP. bacteria produces a cellulosic exopolysaccharide (CEP) with low cytotoxicity and high biocompatibility.The aim of this study is to investigate, in rabbit bladder, the biocompatibility of CEP implants produced by Zooglea sp.Were used as experimental model, 20 adult rabbits California race, with an average of six months of age. The animals were divided into two groups, being the G1 group, composed of fallen three days after application of the implant (n=9), and the Group G2, composed of animals dead three months after the application of implant (n=11). Each animal received, in total, four implants, being two of biopolymer gel and two of Deflux gel. Imunohistochemistry techniques were performed for marking of collagen types I and III, Alpha-smooth muscle actin, PCNA and chemical reaction tunnel.In samples of three days, the CEP and deflux implants were structurally homogenous and free of inflammatory cells or blood vessels. On the other hand, in samples of three months, with the exception of a few areas, the CEP was organized as short beams that were suggestive of a fibrous tissue. Despite this, the implant of CEP blushed adversely to collagen type I and III, elastic fibers, while the masson, not indicated the presence of collagen. In contrast the areas of deflux implant in samples of three months were fragmented, but were still homogeneous, and still there was no cell or blood vessel in his heart. PCNA positive cells could be clearly seen inside these islets, thus indicating a proliferative-inflammatory process ongoing. In three months, group sacrificed that received deflux implants were still negative, but around the areas of CEP some cells positive for the technique of TUNEL were seen. In the CEP implants carried out three months apart, many blood vessels were viewed, and its density was of 23.86 5.48. The microvascular density in the bladder wall (41.51 11.19) was significantly different (p 0.001) of that in the CEP implant.Our results showed that the CEP has low immunogenicity and integrates better in host tissue when compared to deflux. So CEP must be an efficient material in cases where the incorporation to the tissue is desired such as support structures in reconstructive surgery

A carbonatação acelerada é um processo químico que têm se tornado muito atrativa para a indústria do fibrocimento, por mitigar a degradação das fibras vegetais utilizadas nos materiais e por melhorar o desempenho físico-mecânico dos compósitos. Nesse contexto, o presente trabalho avaliou a influência da umidade no processo de carbonatação acelerada, em fibrocimentos reforçados com polpas celulósicas de eucalipto. Para o desenvolvimento das atividades experimentais foi realizado primeiramente um estudo da evolução da carbonatação nos compósitos de fibrocimento, considerando diferentes concentrações de umidade relativa (60, 70, 80 e 90%). Posteriormente, foi realizada a caracterização dos compósitos de fibrocimento por meio da avaliação do desempenho físico-mecânico, com ensaio mecânico de flexão em quatro pontos que determinou o módulo de ruptura (MOR), módulo elástico (MOE), limite de proporcionalidade (LOP) e energia específica (EE); e ensaios físicos para obtenção dos valores de absorção de água (AA), densidade aparente (DA) e porosidade aparente (PA). Os compósitos foram também avaliados quanto à durabilidade e microestrutura, através de ensaios de envelhecimento acelerado, composição mineralógica e análise microestrutural. A partir dos resultados obtidos, os compósitos carbonatados com 60% de umidade relativa apresentaram maior formação de carbonato de cálcio, maior densificação da matriz cimentícia e, consequentemente, menor quantidade de espaços vazios logo nas primeiras horas de carbonatação. Em relação ao desempenho dos compósitos de fibrocimento, as umidades de 60 e 70% permitiram que a carbonatação proporcionasse maiores valores de MOR, LOP e MOE, diferindo estatisticamente dos demais compósitos. Os ensaios físicos complementaram os ensaios mecânicos, mostrando que os compósitos carbonatados com 60 e 70% de umidade apresentaram menores valores de AA e PA, junto de maiores valores de DA. O processo de carbonatação acelerada foi favorecido pelas menores concentrações de umidade relativa, como apresentado também pelas análises de TG e DRX, que permitiram que o processo acontecesse de forma mais efetiva, melhorando a interface fibra-matriz. / The accelerated carbonation is a process that can be made very feasible for the fiber cement industry, for mitigating the degradation of the vegetable fibers used in the materials and for improving the physico-mechanical performance of composites. In this context, the present work evaluated the influence of relative humidity in the accelerated carbonation process in fiber cement composites reinforced with eucalyptus cellulosic pulps. For the development of experimental activities, a study of the evolution of carbonation in fiber cement composites was carried out, considering different concentrations of relative humidity (60, 70, 80 e 90%). Subsequently, the characterization of fiber cement composites was evaluated through the physical-mechanical performance evaluation, with a four-point mechanical test that determined the modulus of rupture, modulus of elasticity, limit of proportionality and specific energy; and physical tests to obtain the values of water absorption, bulk density and apparent void volume. The composites were also evaluated for durability and microstructure, through accelerated aging, mineralogical composition and microstructural analysis. From the results obtained, the carbonate composites with 60% relative humidity showed a higher calcium carbonate formation, a higher densification of the cementitious matrix and, consequently, a lower amount of voids in the first few hours of carbonation. In relation of the performance of fiber cement composites, the 60 and 70% humidity allowed the carbonation to provide higher values of mechanical analysis, differing statistically from the other composites. The physical tests complemented the mechanical tests, showing that the carbonated composites with 60 and 70% humidity presented lower values of water absorption and apparent void volume, with a greater filling of the empty spaces of the composites. The accelerated carbonation process was favored by the lower concentrations of relative humidity, as also shown by the TG and XRD analyzes, which allowed the process to happen more effectively, improving the fiber-matrix interface.