Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids
Autor(a) principal: | |
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Data de Publicação: | 2001 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10316/5208 https://doi.org/10.1016/S0927-7757(01)00552-0 |
Resumo: | Hydrogen peroxide oxidation of two aqueous azo dyes, methyl orange and amaranth, catalyzed by manganese porphyrins, have been performed in an oil-in-water microemulsion based on a nonionic surfactant, C12E8. A lipophilic acid was used as cocatalyst in a variable amount. The oxidation was followed by UV spectroscopy. It was shown that the reactions performed in the microemulsion were rapid for both dyes and the reaction rate increased strongly with increasing amount of lipophilic acid added to the reaction mixture. As reference, the same reactions were performed in a two-phase system without surfactant. The reaction profiles in the two-phase system were similar to those in the microemulsion, but the rate was considerably lower. The effect of addition of small amounts of ionic surfactant was also investigated. Addition of anionic surfactant gave a pronounced decrease in reaction rate, whereas a cationic surfactant gave a small reduction in rate. We propose that the rate-limiting step is formation of a metallo-acylperoxy complex at the boundary between oil and water domains. The metallo-acylperoxy complex oxidizes the azo dye in a subsequent step. |
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Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acidsSurfactantMicroemulsionTwo-phaseReactionOxidationHydrogen peroxidePorphyrinLipophilic acidPhase behaviorHydrogen peroxide oxidation of two aqueous azo dyes, methyl orange and amaranth, catalyzed by manganese porphyrins, have been performed in an oil-in-water microemulsion based on a nonionic surfactant, C12E8. A lipophilic acid was used as cocatalyst in a variable amount. The oxidation was followed by UV spectroscopy. It was shown that the reactions performed in the microemulsion were rapid for both dyes and the reaction rate increased strongly with increasing amount of lipophilic acid added to the reaction mixture. As reference, the same reactions were performed in a two-phase system without surfactant. The reaction profiles in the two-phase system were similar to those in the microemulsion, but the rate was considerably lower. The effect of addition of small amounts of ionic surfactant was also investigated. Addition of anionic surfactant gave a pronounced decrease in reaction rate, whereas a cationic surfactant gave a small reduction in rate. We propose that the rate-limiting step is formation of a metallo-acylperoxy complex at the boundary between oil and water domains. The metallo-acylperoxy complex oxidizes the azo dye in a subsequent step.http://www.sciencedirect.com/science/article/B6TFR-42XB6YN-S/1/352062a0cb1c2de6c2c5b2c0de5f428c2001info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleaplication/PDFhttp://hdl.handle.net/10316/5208http://hdl.handle.net/10316/5208https://doi.org/10.1016/S0927-7757(01)00552-0engColloids and Surfaces A: Physicochemical and Engineering Aspects. 183-185:(2001) 247-257Häger, MariaHolmberg, KristerGonsalves, António M. d'A. RochaSerra, Arménio C.info: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:RCAAP2020-11-06T16:59:55Zoai:estudogeral.uc.pt:10316/5208Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T21:01:21.555475Repositório 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 |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
title |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
spellingShingle |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids Häger, Maria Surfactant Microemulsion Two-phase Reaction Oxidation Hydrogen peroxide Porphyrin Lipophilic acid Phase behavior |
title_short |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
title_full |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
title_fullStr |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
title_full_unstemmed |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
title_sort |
Oxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acids |
author |
Häger, Maria |
author_facet |
Häger, Maria Holmberg, Krister Gonsalves, António M. d'A. Rocha Serra, Arménio C. |
author_role |
author |
author2 |
Holmberg, Krister Gonsalves, António M. d'A. Rocha Serra, Arménio C. |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
Häger, Maria Holmberg, Krister Gonsalves, António M. d'A. Rocha Serra, Arménio C. |
dc.subject.por.fl_str_mv |
Surfactant Microemulsion Two-phase Reaction Oxidation Hydrogen peroxide Porphyrin Lipophilic acid Phase behavior |
topic |
Surfactant Microemulsion Two-phase Reaction Oxidation Hydrogen peroxide Porphyrin Lipophilic acid Phase behavior |
description |
Hydrogen peroxide oxidation of two aqueous azo dyes, methyl orange and amaranth, catalyzed by manganese porphyrins, have been performed in an oil-in-water microemulsion based on a nonionic surfactant, C12E8. A lipophilic acid was used as cocatalyst in a variable amount. The oxidation was followed by UV spectroscopy. It was shown that the reactions performed in the microemulsion were rapid for both dyes and the reaction rate increased strongly with increasing amount of lipophilic acid added to the reaction mixture. As reference, the same reactions were performed in a two-phase system without surfactant. The reaction profiles in the two-phase system were similar to those in the microemulsion, but the rate was considerably lower. The effect of addition of small amounts of ionic surfactant was also investigated. Addition of anionic surfactant gave a pronounced decrease in reaction rate, whereas a cationic surfactant gave a small reduction in rate. We propose that the rate-limiting step is formation of a metallo-acylperoxy complex at the boundary between oil and water domains. The metallo-acylperoxy complex oxidizes the azo dye in a subsequent step. |
publishDate |
2001 |
dc.date.none.fl_str_mv |
2001 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10316/5208 http://hdl.handle.net/10316/5208 https://doi.org/10.1016/S0927-7757(01)00552-0 |
url |
http://hdl.handle.net/10316/5208 https://doi.org/10.1016/S0927-7757(01)00552-0 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Colloids and Surfaces A: Physicochemical and Engineering Aspects. 183-185:(2001) 247-257 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
aplication/PDF |
dc.source.none.fl_str_mv |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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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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