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Titolo:
PHOTOASSISTED DEGRADATION OF DYE POLLUTANTS - V - SELF-PHOTOSENSITIZED OXIDATIVE TRANSFORMATION OF RHODAMINE-B UNDER VISIBLE-LIGHT IRRADIATION IN AQUEOUS TIO2 DISPERSIONS
Autore:
WU TX; LIU GM; ZHAO JC; HIDAKA H; SERPONE N;
Indirizzi:
CHINESE ACAD SCI,INST PHOTOG CHEM BEIJING 100101 PEOPLES R CHINA CHINESE ACAD SCI,INST PHOTOG CHEM BEIJING 100101 PEOPLES R CHINA MEISEI UNIV,FRONTIER RES CTR EARTH ENVIRONM PROTECT HINO TOKYO 191 JAPAN CONCORDIA UNIV,DEPT CHEM & BIOCHEM MONTREAL PQ H3G 1M8 CANADA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 30, volume: 102, anno: 1998,
pagine: 5845 - 5851
SICI:
1089-5647(1998)102:30<5845:PDODP->2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOTOCATALYTIC OXIDATION; EXCITED-STATE; SURFACTANTS; PHOTODEGRADATION; PHOTOCHEMISTRY; DECOMPOSITION; SURFACES; SYSTEMS; BENZENE; IONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
38
Recensione:
Indirizzi per estratti:
Citazione:
T.X. Wu et al., "PHOTOASSISTED DEGRADATION OF DYE POLLUTANTS - V - SELF-PHOTOSENSITIZED OXIDATIVE TRANSFORMATION OF RHODAMINE-B UNDER VISIBLE-LIGHT IRRADIATION IN AQUEOUS TIO2 DISPERSIONS", JOURNAL OF PHYSICAL CHEMISTRY B, 102(30), 1998, pp. 5845-5851

Abstract

Chemical oxygen demand (CODCr) and proton NMR, UV-vis, and spin trapping EPR spectroscopic evidence is presented to demonstrate the inversephotosensitized oxidative transformation of tetraethylated rhodamine (RhB) under visible illumination of aqueous titania dispersions. Both de-ethylation and oxidative degradation take place with the former proceeding in a stepwise manner to yield mono-, di-, tri-, and tetra-de-ethylated rhodamine species. Intermediates present after each de-ethylation step remain in a fast dynamic equilibrium between the titania particle surface and the bulk solution. The concentration of (OH)-O-. radicals, formed from the inverse photosensitization process through the superoxide radical anion, increases upon addition of the anionic dodecylbenzene sulfonate surfactant (DBS) because a larger number of RhB excited states are able to inject an electron into the conduction band of the TiO2 particles. Also, intermediates that can no longer absorb the visible light, (i.e., once the dye solution is competely bleached) are unable to drive the photosensitized degradation further. A mechanism for the competitive photoreactions between degradation and de-ethylation is described, in which de-ethylation {zeta similar to 0.0035} is mostly a surface occurring process, whereas degradation {zeta similar to 0.0015} of the RhB chromophore is predominantly a solution bulk process.

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Documento generato il 26/09/20 alle ore 14:11:08