Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils

Detalhes bibliográficos
Autor(a) principal: Dias, Matheus Cordasso
Data de Publicação: 2017
Tipo de documento: Dissertação
Idioma: por
Título da fonte: Repositório Institucional da UFLA
Texto Completo: http://repositorio.ufla.br/jspui/handle/1/28312
Resumo: Cellulose nanofibrils are promising to replace materials of synthetic origin and in macroscale due to their differentiated properties and the fact of being of natural and renewable origin. However, it presents as disadvantage the high energy consumption that is necessary for its production, being this the main limiting factor to produce cellulose nanofibrils on an industrial scale. The objective of this work was to evaluate the effect of the concentration variation (5 and 10%) and the reaction time (1 and 2 h) of alkaline pre-treatments of cellulosic fibers from commercial bleached pulps of Eucalyptus sp. and Pinus sp. as facilitators in mechanical defibrillation. The pre-treatments were performed with sodium hydroxide (NaOH) solutions in 5% concentration and 2 h of reaction and 10% with 1 and 2 h of reaction. The nanofibrils were obtained by means of a mechanical process using a grinder and the energy consumption during the defibrillation process of the cellulosic fibers for each pre-treatment was evaluated. Chemical and morphological analyzes of the fibers were conducted without and with pre-treatments. It was observed that the alkaline pre-treatment was efficient in the removal of the hemicelluloses, especially of the xyloses where the concentration of the alkaline solution and the reaction time influenced the amount of extractives, lignin and carbohydrates removed. The pre-treatments also caused a decrease in the length and diameter of the fibers mainly in Eucalyptus pulps. The degree of defibrillation was also influenced by the removal of hemicelluloses, there was less defibrillation when excessive removal occurred (hemicelluloses in the range of 2 to 7%). The treatment of the fibers with NaOH 5% 2 h was shown to increase the water retention value (WRV) and effective to facilitate the obtaining of cellulose nanofibrils, with lower energy consumption. This treatment caused partial removal of hemicellulose (keeping them in a range of about 8.5 and 12%) and led to nanofibrils with lower diameter. With the passes through the grinder, cellulose nanofibrils with average diameters of 42 ± 16 nm and 36 ± 14 nm were obtained for the controls; 25 ± 13 nm and 22 ± 11 nm for treatments with NaOH 5% 2h for Eucalyptus and Pinus respectively. Treatments with higher concentrations of NaOH were not effective for the defibrillation of the cellulosic fibers. Fibers treated with NaOH 5% 2 h also promoted a lower energy consumption during the mechanical defibrillator, where for Eucalyptus energy savings were around 23% and 25% for Pinus. The results show that the hemicelluloses contents of the fibers influence the degree of defibrillation and that their excessive removal of the fiber composition impairs the process of obtaining the nanofibrils and the treatment of the fibers with 5% NaOH solution 2 h has been effective as a facilitator of defibrillation process. The present work contributes with information for the optimization of the process of obtaining nanofibrils on an industrial scale and its application in new products for the most diverse uses. We also sought to contribute to the understanding of the inherent chemical and morphological characteristics of the fibers that interfere in the mechanical defibrillation process.
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spelling Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrilsPré-tratamentos alcalinos e diferentes parâmetros como facilitadores na obtenção de nanofibrilas de celuloseNanofibrilas de celulose – Pré-tratamentosDesfibrilação mecânica – Consumo de energiaMicrofibrillated cellulose – Pre-treatmentsMechanical defibrillation – Energy consumptionProcessamento Mecânico da MadeiraCellulose nanofibrils are promising to replace materials of synthetic origin and in macroscale due to their differentiated properties and the fact of being of natural and renewable origin. However, it presents as disadvantage the high energy consumption that is necessary for its production, being this the main limiting factor to produce cellulose nanofibrils on an industrial scale. The objective of this work was to evaluate the effect of the concentration variation (5 and 10%) and the reaction time (1 and 2 h) of alkaline pre-treatments of cellulosic fibers from commercial bleached pulps of Eucalyptus sp. and Pinus sp. as facilitators in mechanical defibrillation. The pre-treatments were performed with sodium hydroxide (NaOH) solutions in 5% concentration and 2 h of reaction and 10% with 1 and 2 h of reaction. The nanofibrils were obtained by means of a mechanical process using a grinder and the energy consumption during the defibrillation process of the cellulosic fibers for each pre-treatment was evaluated. Chemical and morphological analyzes of the fibers were conducted without and with pre-treatments. It was observed that the alkaline pre-treatment was efficient in the removal of the hemicelluloses, especially of the xyloses where the concentration of the alkaline solution and the reaction time influenced the amount of extractives, lignin and carbohydrates removed. The pre-treatments also caused a decrease in the length and diameter of the fibers mainly in Eucalyptus pulps. The degree of defibrillation was also influenced by the removal of hemicelluloses, there was less defibrillation when excessive removal occurred (hemicelluloses in the range of 2 to 7%). The treatment of the fibers with NaOH 5% 2 h was shown to increase the water retention value (WRV) and effective to facilitate the obtaining of cellulose nanofibrils, with lower energy consumption. This treatment caused partial removal of hemicellulose (keeping them in a range of about 8.5 and 12%) and led to nanofibrils with lower diameter. With the passes through the grinder, cellulose nanofibrils with average diameters of 42 ± 16 nm and 36 ± 14 nm were obtained for the controls; 25 ± 13 nm and 22 ± 11 nm for treatments with NaOH 5% 2h for Eucalyptus and Pinus respectively. Treatments with higher concentrations of NaOH were not effective for the defibrillation of the cellulosic fibers. Fibers treated with NaOH 5% 2 h also promoted a lower energy consumption during the mechanical defibrillator, where for Eucalyptus energy savings were around 23% and 25% for Pinus. The results show that the hemicelluloses contents of the fibers influence the degree of defibrillation and that their excessive removal of the fiber composition impairs the process of obtaining the nanofibrils and the treatment of the fibers with 5% NaOH solution 2 h has been effective as a facilitator of defibrillation process. The present work contributes with information for the optimization of the process of obtaining nanofibrils on an industrial scale and its application in new products for the most diverse uses. We also sought to contribute to the understanding of the inherent chemical and morphological characteristics of the fibers that interfere in the mechanical defibrillation process.Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Nanofibrilas de celulose mostram-se promissoras para substituir os materiais de origem sintética e em macroescala devido suas propriedades diferenciadas e pelo fato de ser de origem natural e renovável. Entretanto, apresenta como desvantagem o alto consumo energético que é necessário para a sua produção, sendo este o principal fator limitante para a produção de nanofibrilas de celulose em escala industrial. Objetiva-se com este trabalho avaliar o efeito da variação da concentração (5 e 10%) e do tempo de reação (1 e 2 h) de pré-tratamentos alcalinos de fibras celulósicas provenientes de polpas branqueadas comerciais de Eucalyptus sp. e Pinus sp. como facilitadores na desfibrilação mecânica. Os pré-tratamentos foram realizados com soluções alcalinas de hidróxido de sódio (NaOH) em concentração de 5% e 2 h de reação e 10% com 1 e 2 h de reação. As nanofibrilas foram obtidas por meio de processo mecânico utilizando um grinder e avaliou-se o consumo energético durante o processo de desfibrilação das fibras celulósicas para cada pré-tratamento. Conduziram-se análises química e morfológica das fibras sem pré-tratamento (controle) e com os pré-tratamentos. Foi observado que o pré-tratamento alcalino foi eficiente na retirada das hemiceluloses, principalmente das xiloses onde a concentração da solução alcalina e o tempo de reação influenciaram na quantidade de extrativos, lignina e carboidratos retirados. Os pré-tratamentos também causaram diminuição no comprimento e diâmetro das fibras principalmente nas polpas de Eucalyptus. O grau de desfibrilação também foi influenciado pela remoção de hemiceluloses, houve menor desfibrilação quando ocorreu remoção excessiva (hemiceluloses na faixa de 2 a 7%). O tratamento das fibras com NaOH 5% 2 h demonstrou aumentar o valor de retenção de água (IRA) e efetivo para facilitar a obtenção de nanofibrilas de celulose, com menor consumo de energia. Este tratamento causou remoção parcial de hemicelulose (mantendo-os em uma faixa de cerca de 8,5 e 12%) e levou a nanofibrillas com diâmetro inferior. Com as passagens pelo grinder, foram obtidas nanofibrilas de celulose com diâmetros médios de 42 ± 16 nm e 36 ± 14 nm para os tratamentos controles; 25 ± 13 nm e 22 ± 11 nm para os pré-tratamentos com NaOH 5% 2h para Eucalyptus e Pinus respectivamente. Pré-tratamentos com concentrações maiores (10%) de NaOH não foram efetivos para a nanofibrilação das fibras celulósicas. Fibras tratadas com NaOH 5% 2h também promoveram menor gasto energético durante a passagem pelo desfibrilador mecânico onde para Eucalyptus houve uma economia de energia em torno de 23% e de 25% para Pinus. Os resultados mostram que os teores de hemiceluloses das fibras influenciam no grau de desfibrilação sendo que sua retirada excessiva da composição da fibra prejudica o processo de obtenção das nanofibrilas. O tratamento das fibras com solução de NaOH 5% 2h demonstrou ser eficaz como facilitador do processo de desfibrilação. O presente trabalho contribui com informações para a otimização do processo de obtenção de nanofibrilas em escala industrial e sua aplicação em novos produtos para os mais diversos usos. Também buscou-se contribuir com o entendimento sobre as características químicas e morfológicas inerentes das fibras que interferem no processo de desfibrilação mecânica.Universidade Federal de LavrasPrograma de Pós-Graduação em Ciência do SoloUFLAbrasilDepartamento de Ciências FlorestaisTonoli, Gustavo Henrique DenzinFerreira, Saulo RochaLucas, Alessandra de AlmeidaFonseca, Camila SoaresDias, Matheus Cordasso2017-12-21T13:08:09Z2017-12-21T13:08:09Z2017-12-212017-08-31info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfDIAS, M. C. Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils. 2017. 62 p. Dissertação (Mestrado em Ciência do Solo)-Universidade Federal de Lavras, Lavras, 2017.http://repositorio.ufla.br/jspui/handle/1/28312porinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFLAinstname:Universidade Federal de Lavras (UFLA)instacron:UFLA2017-12-21T13:08:09Zoai:localhost:1/28312Repositório InstitucionalPUBhttp://repositorio.ufla.br/oai/requestnivaldo@ufla.br || repositorio.biblioteca@ufla.bropendoar:2017-12-21T13:08:09Repositório Institucional da UFLA - Universidade Federal de Lavras (UFLA)false
dc.title.none.fl_str_mv Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
Pré-tratamentos alcalinos e diferentes parâmetros como facilitadores na obtenção de nanofibrilas de celulose
title Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
spellingShingle Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
Dias, Matheus Cordasso
Nanofibrilas de celulose – Pré-tratamentos
Desfibrilação mecânica – Consumo de energia
Microfibrillated cellulose – Pre-treatments
Mechanical defibrillation – Energy consumption
Processamento Mecânico da Madeira
title_short Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
title_full Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
title_fullStr Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
title_full_unstemmed Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
title_sort Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
author Dias, Matheus Cordasso
author_facet Dias, Matheus Cordasso
author_role author
dc.contributor.none.fl_str_mv Tonoli, Gustavo Henrique Denzin
Ferreira, Saulo Rocha
Lucas, Alessandra de Almeida
Fonseca, Camila Soares
dc.contributor.author.fl_str_mv Dias, Matheus Cordasso
dc.subject.por.fl_str_mv Nanofibrilas de celulose – Pré-tratamentos
Desfibrilação mecânica – Consumo de energia
Microfibrillated cellulose – Pre-treatments
Mechanical defibrillation – Energy consumption
Processamento Mecânico da Madeira
topic Nanofibrilas de celulose – Pré-tratamentos
Desfibrilação mecânica – Consumo de energia
Microfibrillated cellulose – Pre-treatments
Mechanical defibrillation – Energy consumption
Processamento Mecânico da Madeira
description Cellulose nanofibrils are promising to replace materials of synthetic origin and in macroscale due to their differentiated properties and the fact of being of natural and renewable origin. However, it presents as disadvantage the high energy consumption that is necessary for its production, being this the main limiting factor to produce cellulose nanofibrils on an industrial scale. The objective of this work was to evaluate the effect of the concentration variation (5 and 10%) and the reaction time (1 and 2 h) of alkaline pre-treatments of cellulosic fibers from commercial bleached pulps of Eucalyptus sp. and Pinus sp. as facilitators in mechanical defibrillation. The pre-treatments were performed with sodium hydroxide (NaOH) solutions in 5% concentration and 2 h of reaction and 10% with 1 and 2 h of reaction. The nanofibrils were obtained by means of a mechanical process using a grinder and the energy consumption during the defibrillation process of the cellulosic fibers for each pre-treatment was evaluated. Chemical and morphological analyzes of the fibers were conducted without and with pre-treatments. It was observed that the alkaline pre-treatment was efficient in the removal of the hemicelluloses, especially of the xyloses where the concentration of the alkaline solution and the reaction time influenced the amount of extractives, lignin and carbohydrates removed. The pre-treatments also caused a decrease in the length and diameter of the fibers mainly in Eucalyptus pulps. The degree of defibrillation was also influenced by the removal of hemicelluloses, there was less defibrillation when excessive removal occurred (hemicelluloses in the range of 2 to 7%). The treatment of the fibers with NaOH 5% 2 h was shown to increase the water retention value (WRV) and effective to facilitate the obtaining of cellulose nanofibrils, with lower energy consumption. This treatment caused partial removal of hemicellulose (keeping them in a range of about 8.5 and 12%) and led to nanofibrils with lower diameter. With the passes through the grinder, cellulose nanofibrils with average diameters of 42 ± 16 nm and 36 ± 14 nm were obtained for the controls; 25 ± 13 nm and 22 ± 11 nm for treatments with NaOH 5% 2h for Eucalyptus and Pinus respectively. Treatments with higher concentrations of NaOH were not effective for the defibrillation of the cellulosic fibers. Fibers treated with NaOH 5% 2 h also promoted a lower energy consumption during the mechanical defibrillator, where for Eucalyptus energy savings were around 23% and 25% for Pinus. The results show that the hemicelluloses contents of the fibers influence the degree of defibrillation and that their excessive removal of the fiber composition impairs the process of obtaining the nanofibrils and the treatment of the fibers with 5% NaOH solution 2 h has been effective as a facilitator of defibrillation process. The present work contributes with information for the optimization of the process of obtaining nanofibrils on an industrial scale and its application in new products for the most diverse uses. We also sought to contribute to the understanding of the inherent chemical and morphological characteristics of the fibers that interfere in the mechanical defibrillation process.
publishDate 2017
dc.date.none.fl_str_mv 2017-12-21T13:08:09Z
2017-12-21T13:08:09Z
2017-12-21
2017-08-31
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv DIAS, M. C. Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils. 2017. 62 p. Dissertação (Mestrado em Ciência do Solo)-Universidade Federal de Lavras, Lavras, 2017.
http://repositorio.ufla.br/jspui/handle/1/28312
identifier_str_mv DIAS, M. C. Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils. 2017. 62 p. Dissertação (Mestrado em Ciência do Solo)-Universidade Federal de Lavras, Lavras, 2017.
url http://repositorio.ufla.br/jspui/handle/1/28312
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dc.publisher.none.fl_str_mv Universidade Federal de Lavras
Programa de Pós-Graduação em Ciência do Solo
UFLA
brasil
Departamento de Ciências Florestais
publisher.none.fl_str_mv Universidade Federal de Lavras
Programa de Pós-Graduação em Ciência do Solo
UFLA
brasil
Departamento de Ciências Florestais
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repository.name.fl_str_mv Repositório Institucional da UFLA - Universidade Federal de Lavras (UFLA)
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