Alkaline pre-treatments and different parameters as facilitators for obtaining cellulose nanofibrils
Autor(a) principal: | |
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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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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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por |
language |
por |
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info:eu-repo/semantics/openAccess |
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openAccess |
dc.format.none.fl_str_mv |
application/pdf |
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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reponame:Repositório Institucional da UFLA instname:Universidade Federal de Lavras (UFLA) instacron:UFLA |
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Universidade Federal de Lavras (UFLA) |
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UFLA |
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UFLA |
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Repositório Institucional da UFLA |
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Repositório Institucional da UFLA |
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Repositório Institucional da UFLA - Universidade Federal de Lavras (UFLA) |
repository.mail.fl_str_mv |
nivaldo@ufla.br || repositorio.biblioteca@ufla.br |
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1815438949021122560 |