Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production

Detalhes bibliográficos
Autor(a) principal: Cadete, Sonia Marisa Silva
Data de Publicação: 2015
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10773/16089
Resumo: Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.
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spelling Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp productionBiotecnologia industrialCelulosePasta de papelXilanasCelulaseGlucanosDissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.Pastas solúveis são normalmente usadas para a produção de derivativos de celulose e celulose regenerada. Alguns dos parâmetros que determinam a qualidade de uma pasta solúvel são: um elevado teor de celulose, baixo teor de material nãocelulósico, elevada brancura, uma distribuição uniforme de pesos moleculares e elevada reactividade da celulose. Na primeira parte deste trabalho, fez-se um estudo de optimização aplicando enzimas, previamente seleccionadas, em diferentes fases de um novo processo de purificação desenvolvido na Novozymes da pasta de eucalipto Kraft em celulose solúvel, como uma alternativa ao processo convencional de pré-hidrólise kraft. Além da purificação, a aplicação de celulases (endoglucanase) no início da sequência possibilitou uma diminuição da viscosidade, enquanto que a aplicação de xilanases das famílias GH11 e GH10 contribuíram também para o aumento da brancura da pasta final. A segunda parte deste trabalho teve como objectivo explorar várias actividades enzimáticas auxiliares conjuntamente com a melhor GH11 xilanase identifcada, de modo a promover a remoção das hemiceluloses mais recalciterantes de uma pasta Kraft de Eucalipto parcialmente branqueada. Todas as combinações das enzimas testadas resultaram numa fracção resistente de xilana residual (ca. 6% na pasta) que não foi possível hidrolisar. A produção de uma pasta solúvel foi possível usando um estágio de extracção alkalino a frio (CCE) no fim de uma sequência composta pelos seguintes estágios: O-X-D-HCE-X-HCE-D-CCE. A aplicação de enzimas melhorou a eficiencia do processo. Com esta sequência,os principais requisitos para a produção de uma pasta solúvel (adequada para producao de viscose) foram cumpridos: 2,7% de xilana residual, 92,4% de brancura, uma viscosidade dentro dos valores de uma pasta solúvel comercial e elevada reactividade.Universidade de Aveiro2018-07-20T14:00:56Z2015-12-15T00:00:00Z2015-12-152017-12-08T15:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10773/16089TID:201594463engCadete, Sonia Marisa Silvainfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-02-22T11:29:51Zoai:ria.ua.pt:10773/16089Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T02:51:17.380815Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
title Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
spellingShingle Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
Cadete, Sonia Marisa Silva
Biotecnologia industrial
Celulose
Pasta de papel
Xilanas
Celulase
Glucanos
title_short Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
title_full Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
title_fullStr Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
title_full_unstemmed Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
title_sort Enzymatic upgrading of eucalypt paper-grade kraft pulp within dissolving pulp production
author Cadete, Sonia Marisa Silva
author_facet Cadete, Sonia Marisa Silva
author_role author
dc.contributor.author.fl_str_mv Cadete, Sonia Marisa Silva
dc.subject.por.fl_str_mv Biotecnologia industrial
Celulose
Pasta de papel
Xilanas
Celulase
Glucanos
topic Biotecnologia industrial
Celulose
Pasta de papel
Xilanas
Celulase
Glucanos
description Dissolving-grade pulps are commonly used for the production of cellulose derivatives and regenerated cellulose. High cellulose content, low content of non-cellulosic material, high brightness, a uniform molecular weight distribution and high cellulose reactivity are the key features that determine the quality of a dissolving pulp. The first part of this work was an optimization study regarding the application of selected enzymes in different stages of a new purification process recently developed in Novozymes for purifying an eucalypt Kraft pulp into dissolving pulp, as an alternative to the pre-hydrolysis kraft (PHK) process. In addition, a viscosity reduction was achieved by cellulase (endoglucanase) treatment in the beginning of the sequence, while the GH11 and GH10 xylanases contributed to boost the brightness of the final pulp. The second part of the work aimed at exploring different auxiliary enzyme activities together with a key xylanase towards further removal of recalcitrant hemicelluloses from a partially bleached Eucalypt Kraft pulp. The resistant fraction (ca. 6% xylan in pulp) was not hydrolysable by the different combinations of enzymes tested. Production of a dissolving pulp was successful when using a cold caustic extraction (CCE) stage in the end of the sequence O-X-DHCE-X-HCE-D-CCE. The application of enzymes improved process efficiency. The main requirements for the production of a dissolving pulp (suitable for viscose making) were fulfilled: 2,7% residual xylan, 92,4% of brightness, a viscosity within the values of a commercial dissolving pulp and increased reactivity.
publishDate 2015
dc.date.none.fl_str_mv 2015-12-15T00:00:00Z
2015-12-15
2017-12-08T15:00:00Z
2018-07-20T14:00:56Z
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 http://hdl.handle.net/10773/16089
TID:201594463
url http://hdl.handle.net/10773/16089
identifier_str_mv TID:201594463
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Universidade de Aveiro
publisher.none.fl_str_mv Universidade de Aveiro
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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instacron_str RCAAP
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reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
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