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Master's Dissertation
DOI
10.11606/D.88.2011.tde-11082011-143629
Document
Author
Full name
Regina Estevam Alves
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2011
Supervisor
Committee
Guimarães, Francisco Eduardo Gontijo (President)
Fiorelli, Juliano
Goncalves, Debora
Title in Portuguese
Caracterização de fibras lignocelulósicas pré-tratadas por meio de técnicas espectroscópicas e microscópicas ópticas de alta resolução
Keywords in Portuguese
Espectroscopia
Etanol
Microscopia
Pré-tratamento
Abstract in Portuguese
Neste trabalho, fibras de eucalipto pré-tratadas diferentemente com ácido e/ou enzima foram investigadas visando se verificar alterações estruturais decorrentes dos pré-tratamentos. Na caracterização foram empregadas técnicas de microscopia eletrônica, de fluorescência (campo de claro), de fluorescência confocal de varredura a laser (CLSM) e de tempo de vida de imagem de fluorescência (FLIM). Além disso, foi também empregada espectrocopia de fluorescência, absorção no ultravioleta e vísivel (UV-Vis), no infravermelho (FT-IR) e ressonância magnética nuclear (RMN). Para a caracterização das fibras via microscopia e espectroscopia de fluorescência foi necessário a produção de filmes de fibras de eucalipto. Os resultados demonstraram um aumento na intensidade da fluorescência das fibras em função dos pré-tratamentos. As imagens de microscopia permitiram conhecer a estrutura morfológica das fibras. Para aumentar a fluorescência das fibras e facilitar a visualização por microscopia de fluorescência, nós depositamos o polieletrólito poli(cloreto de tetraidrotiofeno de xililideno) (PTHT), precursor do poli(p-fenileno vinileno) (PPV). Pelas imagens CLSM observou-se a afinidade do PTHT-PPV pelas as fibras que, foi investigada pelo método arraste. A distribuição de tempos de vida associado à imagem FLIM da fibra de eucalipto indicou a presença do PTHT-PPV nas superfícies da fibra e a lignina no interior da parede da mesma. O PTHT-PPV apresentou um tempo de decaimento de fluorescência mais curto do que a lignina. As análises composicionais das fibras de eucalipto e do bagaço de cana-de-açúcar in natura evidenciaram sinais relacionados à lignina, hemicelulose e celulose.
Title in English
Characterization of pretreated lignocellulosic fibers by means of techniques spectroscopy and high resolution optical microscopy
Keywords in English
Ethanol
Microscopy
Pretreatment
Spectroscopy
Abstract in English
In this dissertation, eucalyptus fibers pretreated with different acid and / or enzyme were investigated in order to study the resulting structural changes of the fibers. The characterization was made using several microscopy techniques such as, electronic microscopy, confocal laser scanning microscopy (CLSM) and fluorescence lifetime imaging microscopy (FLIM). In addition, we used fluorescence spectroscopy, absorption in the ultraviolet and visible (UV-Vis), infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). It was necessary to produce films of eucalyptus fibers for the characterization of fibers via microscopy and fluorescence spectroscopy. The results showed changes in the fluorescence intensity of the fibers as function of the pre-treatments. The microscopy images were used to study the morphological structure of fibers. To increase the fluorescence of the fibers and facilitate its visualization via fluorescence microscopy, e deposited a polyelectrolyte precursor of PPV poly(p-phenylenevinylene), the poly-(xylylidenetetrahydro-thiophenium chloride). CLSM images revealed an affinity between the PTHT-PPV and the fibers. This affinity was investigated by a method consisting of spinning a solution containing the fibers and subsequent optical analysis. The results confirmed the affinity of PTHT-PPV with eucalyptus fibers. The lifetime distribution associated with the FLIM image of eucalyptus fiber indicated the presence of PTHT-PPV on the fiber surface and lignin in the inner wall of the fibers. Also, the PTHT-PPV showed fluorescence decay time shorter than the lignin. The analysis of the composition of eucalyptus fibers, we used sugar cane bagasse in natura to facilitate the identification of functional groups. The results showed signs related to lignin, cellulose and hemicellulose.
 
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Publishing Date
2011-09-05
 
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