Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect
Autor(a) principal: | |
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Data de Publicação: | 2005 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Journal of the Brazilian Chemical Society (Online) |
Texto Completo: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000200019 |
Resumo: | This work reports the effect of pH on the process of mullite formation from mixtures of alumina and silica sols. The pH of the mixtures determines the charges of particle surfaces and affects their interactions and distributions. Mullite formation from amorphous precursors with an Al:Si molar ratio of 1:3, prepared from the sols mixture, was not affected by pH. In this case, the higher concentration of silica determined its distribution around alumina, which led to tetragonal mullite formation, according to the Sundaresan and Aksay mechanism. However, for mullite formation from precursors with Al:Si = 3:1, the pH played an important role on the interactions between alumina and silica particles, as well as on the predominant aluminum species. At pH 1, octahedrically coordinated Al3+ ions predominated in the alumina sol while tetrahedrically coordinated Al3+ ions predominated in the sol at pH ~6. The interactions between silica and alumina particles and their distributions in these precursors determined the minimum temperature required for orthorhombic mullite formation. |
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Mullite formation from mixtures of alumina and silica sols: mechanism and pH effectpH effectmullite formationalumina solsilica solThis work reports the effect of pH on the process of mullite formation from mixtures of alumina and silica sols. The pH of the mixtures determines the charges of particle surfaces and affects their interactions and distributions. Mullite formation from amorphous precursors with an Al:Si molar ratio of 1:3, prepared from the sols mixture, was not affected by pH. In this case, the higher concentration of silica determined its distribution around alumina, which led to tetragonal mullite formation, according to the Sundaresan and Aksay mechanism. However, for mullite formation from precursors with Al:Si = 3:1, the pH played an important role on the interactions between alumina and silica particles, as well as on the predominant aluminum species. At pH 1, octahedrically coordinated Al3+ ions predominated in the alumina sol while tetrahedrically coordinated Al3+ ions predominated in the sol at pH ~6. The interactions between silica and alumina particles and their distributions in these precursors determined the minimum temperature required for orthorhombic mullite formation.Sociedade Brasileira de Química2005-04-01info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersiontext/htmlhttp://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000200019Journal of the Brazilian Chemical Society v.16 n.2 2005reponame:Journal of the Brazilian Chemical Society (Online)instname:Sociedade Brasileira de Química (SBQ)instacron:SBQ10.1590/S0103-50532005000200019info:eu-repo/semantics/openAccessOsawa,Carla C.Bertran,Celso A.eng2005-05-24T00:00:00Zoai:scielo:S0103-50532005000200019Revistahttp://jbcs.sbq.org.brONGhttps://old.scielo.br/oai/scielo-oai.php||office@jbcs.sbq.org.br1678-47900103-5053opendoar:2005-05-24T00:00Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ)false |
dc.title.none.fl_str_mv |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
title |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
spellingShingle |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect Osawa,Carla C. pH effect mullite formation alumina sol silica sol |
title_short |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
title_full |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
title_fullStr |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
title_full_unstemmed |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
title_sort |
Mullite formation from mixtures of alumina and silica sols: mechanism and pH effect |
author |
Osawa,Carla C. |
author_facet |
Osawa,Carla C. Bertran,Celso A. |
author_role |
author |
author2 |
Bertran,Celso A. |
author2_role |
author |
dc.contributor.author.fl_str_mv |
Osawa,Carla C. Bertran,Celso A. |
dc.subject.por.fl_str_mv |
pH effect mullite formation alumina sol silica sol |
topic |
pH effect mullite formation alumina sol silica sol |
description |
This work reports the effect of pH on the process of mullite formation from mixtures of alumina and silica sols. The pH of the mixtures determines the charges of particle surfaces and affects their interactions and distributions. Mullite formation from amorphous precursors with an Al:Si molar ratio of 1:3, prepared from the sols mixture, was not affected by pH. In this case, the higher concentration of silica determined its distribution around alumina, which led to tetragonal mullite formation, according to the Sundaresan and Aksay mechanism. However, for mullite formation from precursors with Al:Si = 3:1, the pH played an important role on the interactions between alumina and silica particles, as well as on the predominant aluminum species. At pH 1, octahedrically coordinated Al3+ ions predominated in the alumina sol while tetrahedrically coordinated Al3+ ions predominated in the sol at pH ~6. The interactions between silica and alumina particles and their distributions in these precursors determined the minimum temperature required for orthorhombic mullite formation. |
publishDate |
2005 |
dc.date.none.fl_str_mv |
2005-04-01 |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000200019 |
url |
http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532005000200019 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
10.1590/S0103-50532005000200019 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
text/html |
dc.publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
publisher.none.fl_str_mv |
Sociedade Brasileira de Química |
dc.source.none.fl_str_mv |
Journal of the Brazilian Chemical Society v.16 n.2 2005 reponame:Journal of the Brazilian Chemical Society (Online) instname:Sociedade Brasileira de Química (SBQ) instacron:SBQ |
instname_str |
Sociedade Brasileira de Química (SBQ) |
instacron_str |
SBQ |
institution |
SBQ |
reponame_str |
Journal of the Brazilian Chemical Society (Online) |
collection |
Journal of the Brazilian Chemical Society (Online) |
repository.name.fl_str_mv |
Journal of the Brazilian Chemical Society (Online) - Sociedade Brasileira de Química (SBQ) |
repository.mail.fl_str_mv |
||office@jbcs.sbq.org.br |
_version_ |
1750318166166208512 |