Please use this identifier to cite or link to this item: http://hdl.handle.net/10316/5208
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dc.contributor.authorHäger, Maria-
dc.contributor.authorHolmberg, Krister-
dc.contributor.authorGonsalves, António M. d'A. Rocha-
dc.contributor.authorSerra, Arménio C.-
dc.date.accessioned2008-09-01T15:05:48Z-
dc.date.available2008-09-01T15:05:48Z-
dc.date.issued2001en_US
dc.identifier.citationColloids and Surfaces A: Physicochemical and Engineering Aspects. 183-185:(2001) 247-257en_US
dc.identifier.urihttp://hdl.handle.net/10316/5208-
dc.description.abstractHydrogen 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.en_US
dc.description.urihttp://www.sciencedirect.com/science/article/B6TFR-42XB6YN-S/1/352062a0cb1c2de6c2c5b2c0de5f428cen_US
dc.format.mimetypeaplication/PDFen
dc.language.isoengeng
dc.rightsopenAccesseng
dc.subjectSurfactanten_US
dc.subjectMicroemulsionen_US
dc.subjectTwo-phaseen_US
dc.subjectReactionen_US
dc.subjectOxidationen_US
dc.subjectHydrogen peroxideen_US
dc.subjectPorphyrinen_US
dc.subjectLipophilic aciden_US
dc.subjectPhase behavioren_US
dc.titleOxidation of azo dyes in oil-in-water microemulsions catalyzed by metalloporphyrins in presence of lipophilic acidsen_US
dc.typearticleen_US
item.fulltextCom Texto completo-
item.languageiso639-1en-
item.grantfulltextopen-
crisitem.author.deptFaculdade de Ciências e Tecnologia, Universidade de Coimbra-
crisitem.author.deptFaculdade de Ciências e Tecnologia, Universidade de Coimbra-
crisitem.author.parentdeptUniversidade de Coimbra-
crisitem.author.parentdeptUniversidade de Coimbra-
crisitem.author.researchunitCoimbra Chemistry Center-
crisitem.author.researchunitCentre for Mechanical Engineering-
crisitem.author.orcid0000-0001-9987-7301-
crisitem.author.orcid0000-0001-8664-2757-
Appears in Collections:FCTUC Química - Artigos em Revistas Internacionais
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