Análise quantitativa dos teores de lignina e celulose em materiais de biomassa por RMN de 13C no estado sólido

• Ano de defesa: 2015
• Autor(a) principal: Cipriano, Daniel Fernandes
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Física; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Física
• Palavras-chave em Português: Solid-state NMR; Lignocellulosic materials; Quantitative analysis; RMN no estado sólido; Materiais lignocelulósicos; Física; 53
• Link de acesso: http://repositorio.ufes.br/handle/10/7462

This work is dedicated to the study and development of an experimental method that allows the use of solid state 13C nuclear magnetic resonance (NMR) spectroscopy, with cross polarization (CP) and magic angle spinning (MAS), to determine the lignin and cellulose contents in lignocellulosic materials. The validity of the method was tested on di erent biomass materials by comparison to the corresponding contents obtained by the Klason method. The method was also used in a comparative study of sugarcane bagasse samples subjected to acid treatments for di erent times. For the development of the method, standard samples of cellulose and lignin as well as mixtures of both materials in known proportions were analyzed by 13C CP/MAS NMR. After acquiring the NMR spectra, graphs were constructed relating the intensity of selected spectral regions to the mass of the component responsible for that intensity. It was observed that the lignin contents of most of the analyzed lignocellulosic materials agreed well with the contents determined directly by chemical analysis. On the other hand, the cellulose contents were not correctly predicted, possibly due to the overlap of hemicellulose and cellulose signals in the NMR spectra. Regarding the acid-treated sugarcane bagasse samples, an increase in the lignin contents of the samples subjected to longer acid treatments was observed, concomitantly with the increase in the fraction of structurally ordered cellulose.