Caracterização e utilização do bagaço de cana-de-açúcar e capim-elefante para produção de polpa solúvel e papel de impressão e escrita

• Ano de defesa: 2014
• Autor(a) principal: Andrade, Marcela Freitas
• Orientador(a): Colodette, Jorge Luiz
• Banca de defesa: Jardim, Carolina Marangon , Gomes, Fernando José Borges , Silva, Vanessa Lopes
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Ciência Florestal
• Departamento: Manejo Florestal; Meio Ambiente e Conservação da Natureza; Silvicultura; Tecnologia e Utilização de
• País: BR
• Palavras-chave em Português: Cana-de-açúcar; Capim-elefante; Celulose
• Palavras-chave em Inglês: Cane sugar; Elephant grass; Cellulose
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS
• Link de acesso: http://locus.ufv.br/handle/123456789/601

In recent years, there has been an increasing trend towards more efficient utilization of agro-industrial residues and crops, such has sugar cane bagasse and elephant grass. Some examples of applications of these materials include bioenergy, bioethanol and pulps for paper and dissolving. Given the great variability of sugarcane bagasse and elephant grass, its applications require a detailed study of the chemical and morphological composition of the fibers, in the particular case of sugar cane bagasse, is also important to know the differences between the main fractions of these fibers, the depithed and pith. One of the least known components of bagasse (depithed and pith) is the lignin, and this lack is the major barrier to the success of the biomass deconstruction processes. The use of the technique of Nuclear Magnetic Resonance dimensional (2D NMR) allows detailed assessment of the lignin these materials and was successfully used in this study. The main goal of this thesis was to characterize in detail the chemistry and morphology of the fibers of bagasse (pith and depithed) and elephant grass and evaluate their potential for production of paper pulp (bagasse and elephant grass) and dissolving pulp (bagasse). The thesis is divided into 5 distinct chapters, namely: (1) Chemical and morphological characterization of sugarcane bagasse (depithed and pith) and elephant grass, (2) detailed characterization of the lignin structure of the depithed bagasse by 2D NMR technical, (3) evaluation of the depithed bagasse for production of dissolving pulp, (4) evaluation of the depithed bagasse for production of printing and writing paper grade pulp, (5) evaluation of elephant grass for production of printing and writing paper grade pulp. On the first chapter the main goals were characterizing the chemical (depithed and pith), morphological (fibers fraction) and the structural composition of the depithed bagasse lignin by 2D NMR. The cellulose, hemicelluloses and lignin contents in the two materials varied significantly, with the depithed fraction presenting more cellulose and hemicellulose and less lignin, extractives and minerals. The lignin composition of the depithed bagasse showed very high contents in PCAs (cinnamic acids contents). The morphological analyses of the depithed bagasse indicated a short fiber material, similar to hardwoods. On the second chapter the main objective was to obtain a lignin preparation (depithed and pith) by technica high yield and analyze the detailed structural with a semi quantitative 2-dimensional spectroscopy. Two lignin fractions were isolated, from the two starting materials: milled wood lignin (MWLc) and cellulolytic enzyme lignin (CEL96) as such and after it has been extracted with alkali to remove the p-coumaric and ferulic acids. The four lignin samples and the two alkaline extracts were analyzed by 2D NMR. The isolation yield of CEL96 was far higher than of MWLc preparations. The p-coumaric acid content was higher than ferulic acid content in the alkali extraction liquor. The β-O-4 ́ linkage correlation peak was the most prominent inter-unit linkage signal found throughout all isolated lignin fractions. Both MWLc and CEL96 from both fractions DB and P contain high amounts of pHCAs. On the third chapter the goal was evaluating the potential of the depithed bagasse for production of dissolving grade pulps. The depithed bagasse was chemically characterized and converted into brown pulp of two different extents of delignification degrees (kappa 16.9 and 9.2) by the pre- hydrolysis soda process (PHS). The resulting pulps were fully bleached by the O-D-(EP)- D-P sequence and evaluated for their main dissolving pulp characteristics. The production of dissolving pulp was possible for PHS process independent of the initial kappa number, being the kappa 16.9 most, due the highest yield of soluble pulp. The depithed bagasse soluble pulp produced by the HSP process in either of two levels kappa has low viscosity and relatively high ash content, which limits their use for certain applications of dissolving pulp, some demineralization of the pulp at the end of the bleaching is required. On the fourth chapter the main goal was evaluating the potential of the depithed bagasse for the production of printing and writing paper. The depithed bagasse was cooked by the soda process to two different degrees of delignification (kappa 17.5 and 10.8). The resulting pulps were fully bleached by the O-D*-(EP)-D sequence and characterized for their beatability, drainability and physical-mechanical properties. The bleached soda pulps cooked to 17.5 and 10.8 kappa number showed similar refinability, resistance to drainage and strength properties (tensile, burst and tear). Both brownstock pulps obtained from depithed sugar cane bagasse were suitable for the production of printing and writing paper grades; however, the higher kappa brownstock was more economically attractive given its higher pulping yield. The main goal of the fifth chapter was characterizing chemically and morphologically the elephant grass, and evaluating the potential of the fibers for production of printing and writing paper grade pulp. The elephant grass was chemically and morphologically characterized and cooked by the soda process to two different degrees of delignification (kappa 17.5 and 10.6). The resulting pulps were fully bleached by the O-D*- (EP)-D sequence and characterized for their beatability, drainability and physical- mechanical properties. The elephant grass was characterized by the low lignin content and relatively high content of minerals and extractives in relation to eucalyptus wood, for example. The morphological analyses of the elephant grass indicated a short fibered material, similar to hardwoods. The bleached soda pulps cooked to 17.5 and 10.6 kappa number showed similar refinability and resistance to drainage, but the tensile and burst index were higher for the 17.5 kappa pulp. Both brownstock pulps obtained from elephant grass biomass were suitable for the production of printing and writing paper grades; however, the higher kappa brownstock was more economically attractive given its higher pulping yield, without significantly increased of chemical demand for bleaching.