Avaliação do pré-tratamento hidrotérmico de palhas de cana-de-açúcar para produção de etanol de segunda geração

• Ano de defesa: 2013
• Autor(a) principal: Santos, Fernando Almeida
• Orientador(a): Queiroz, José Humberto de
• Banca de defesa: Queiroz, Maria Eliana Lopes Ribeiro de , Caldas, Celso Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Bioquímica Agrícola
• Departamento: Bioquímica e Biologia molecular de plantas; Bioquímica e Biologia molecular animal
• País: BR
• Palavras-chave em Português: Etanol; Palha de cana-de-açúcar; Pré-tratamento
• Palavras-chave em Inglês: Ethanol; Sugar cane straw; Pretreatment
• Área do conhecimento CNPq: CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::METABOLISMO E BIOENERGETICA
• Link de acesso: http://locus.ufv.br/handle/123456789/331

With the objective of replacing fossil fuels, at least partially, in recent decades the interest in alternative energy sources has increased. In this context, considering the increasing development of the Brazilian sugarcane industry, sugarcane straw has been gaining increasing prominence as a feedstock for biofuel production. Given the close recalcitrant association between the three polymeric components of sugarcane straw (cellulose, hemicellulose and lignin), the release of monosaccharides as a source of fermentable sugars for ethanol production is one of the priorities in the field of cellulosic ethanol research and development. The objective of the present study was to chemically characterize sugarcane straw from different regions of Brazil and optimize a hydrothermal pretreatment step for the production of cellulosic ethanol, via an experimental design. Sugarcane straw of the cultivar RB867515 was collected soon after harvest in the states of São Paulo, Minas Gerais, Paraná, Alagoas and Mato Grosso. The straw was subjected to drying and further milled for analysis of its chemical composition, including contents of cellulose, hemicellulose, total lignin, total extractives, ash, and minerals. Hydrothermal pretreatment was conducted based on a Central Composite Rotational Design (CCRD), with the objective of evaluating the influence of time (min), temperature (oC) and the straw/water ratio (%) on the release of glicose after enzymatic hydrolysis. Enzymatic hydrolysis was conducted at 50 oC using cellulase at a concentration of 15 FPU (filter paper unit) per gram of pretreated straw and was monitored for 72 hours. The results of chemical characterization indicated that the soil and climatic conditions of the regions assessed had little influence on the chemical composition of the straw. The hydrothermal pretreatment proved to be very efficient in the removal of hemicellulose and provides substrates of high susceptibility to enzymatic hydrolysis. Hydrothermal pretreatments at temperatures of 190 and 210 oC resulted in greater cellulose hydrolysis yields, reaching values close to 100%, indicating its efficiency for breaking down sugarcane straw and its potential for the production of cellulosic ethanol.