Surface photochemistry: dibenzo-p-dioxin adsorbed onto silicalite, cellulose and silica

Ferreira, Luís F. Vieira; Silva, José P. da; Machado, I. Ferreira; Branco, T. J. F.; Moreira, J. C.

Publication

Surface photochemistry: dibenzo-p-dioxin adsorbed onto silicalite, cellulose and silica

2007Journal article

dc.contributor.author	Ferreira, Luís F. Vieira
dc.contributor.author	Silva, José P. da
dc.contributor.author	Machado, I. Ferreira
dc.contributor.author	Branco, T. J. F.
dc.contributor.author	Moreira, J. C.
dc.date.accessioned	2015-06-22T14:13:49Z
dc.date.available	2015-06-22T14:13:49Z
dc.date.issued	2007
dc.description.abstract	Laser-induced luminescence of argon purged and air-equilibrated samples of dibenzo-p-dioxin adsorbed onto three different solid powdered supports, silicalite, cellulose and silica, revealed the existence of both fluorescence and phosphorescence emissions at room temperature. A remarkable difference in transient absorption spectra was found when dibenzo-p-dioxin was included within the narrow internal channels of silicalite: triplet-triplet absorption of dibenzo-p-dioxin was detected in the silicalite case as a host, simultaneous with radical cation formation immediately after pulsed laser excitation (in the hundreds of nanoseconds time scale) while in the case of cellulose and silica as adsorbents, absorption transients arising from 2,2'-biphenylquinone and possibly from the spiroketone were found. For all hosts dibenzo-p-dioxin exhibits a transient band peaking at 330-340 nm in the microsecond and millisecond time scales, which we assigned to the biradical of dibenzo-p-dioxin. Diffuse reflectance laser flash photolysis and chromatographic techniques provided complementary information, the former about transient species and the latter regarding the final products formed after laser irradiation at 266 nm. Product analysis and identification clearly show that the photodegradation products are dependent on the host, the photochemistry being much more rich and complex in the cellulose and silica cases, where the main detected photoproduts were 2,2'-dihydroxybiphenyl and 1-hydroxydibenzofuran. In the case of silicalite as host, which has a channel-like internal structure and reduced space available for the guest dioxin, photodegradation reactions are highly reduced or even inhibited and no photodegradation products were detected. (c) 2006 Elsevier B.V. All rights reserved.
dc.identifier.doi	https://dx.doi.org/10.1016/j.jphotochem.2006.08.015
dc.identifier.issn	1010-6030
dc.identifier.uri	http://hdl.handle.net/10400.1/6549
dc.language.iso	eng
dc.peerreviewed	yes
dc.publisher	Elsevier
dc.relation.isbasedon	P-004-BRS
dc.subject	Surface photochemistry
dc.subject	Dibenzo-p-dioxin
dc.subject	Silicalite
dc.subject	Cellulose
dc.subject	Silica
dc.subject	Diffuse reflectance
dc.subject	Flash photolysis
dc.subject	Laser-induced fluorescence
dc.subject	Room temperature phosphorescence
dc.subject	Lifetime distribution spreadsheet
dc.subject	Photodegradation products
dc.title	Surface photochemistry: dibenzo-p-dioxin adsorbed onto silicalite, cellulose and silica
dc.type	journal article
dspace.entity.type	Publication
oaire.citation.endPage	262
oaire.citation.issue	2-3
oaire.citation.startPage	254
oaire.citation.title	Journal of Photochemistry and Photobiology A: Chemistry
oaire.citation.volume	186
person.familyName	Silva
person.givenName	José Paulo da
person.identifier.ciencia-id	3413-C4F4-73F7
person.identifier.orcid	0000-0002-6458-7328
person.identifier.rid	A-4606-2008
person.identifier.scopus-author-id	7201733236
rcaap.rights	restrictedAccess
rcaap.type	article
relation.isAuthorOfPublication	e2004fa2-a47d-44b0-b11c-fc95fe51cbf9
relation.isAuthorOfPublication.latestForDiscovery	e2004fa2-a47d-44b0-b11c-fc95fe51cbf9

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