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Titolo:
Modelling the natural photodegradation of water contaminants - A kinetic study on the light-induced aerobic interactions between riboflavin and 4-hydroxypyridine
Autore:
Pajares, A; Gianotti, J; Stettler, G; Bertolotti, S; Criado, S; Posadaz, A; Amat-Guerri, F; Garcia, NA;
Indirizzi:
Univ Nacl Rio Cuarto, Dept Quim & Fis, RA-5800 Rio Cuarto, Argentina Univ Nacl Rio Cuarto Rio Cuarto Argentina RA-5800 Rio Cuarto, Argentina Univ Nacl Patagonia Austral, Unidad Acad Rio Gallegos, RA-9400 Rio Gallegos, Argentina Univ Nacl Patagonia Austral Rio Gallegos Argentina RA-9400 os, Argentina CSIC, Inst Quim Organ, E-28006 Madrid, Spain CSIC Madrid Spain E-28006CSIC, Inst Quim Organ, E-28006 Madrid, Spain
Titolo Testata:
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
fascicolo: 2-3, volume: 139, anno: 2001,
pagine: 199 - 204
SICI:
1010-6030(20010316)139:2-3<199:MTNPOW>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOLECULAR-OXYGEN; PHOTOSENSITIZED OXIDATION; PHOTOCHEMICAL PROPERTIES; VINYL POLYMERIZATION; AQUEOUS-SOLUTION; SINGLET OXYGEN; RATE CONSTANTS; ROSE-BENGAL; FLAVINS; SYSTEM;
Keywords:
4-hydroxypyridine; photooxidation; photosensitization; riboflavin; singlet molecular oxygen; superoxide anion;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
35
Recensione:
Indirizzi per estratti:
Indirizzo: Garcia, NA Univ Nacl Rio Cuarto, Dept Quim & Fis, RA-5800 Rio Cuarto, Argentina Univ Nacl Rio Cuarto Rio Cuarto Argentina RA-5800 , Argentina
Citazione:
A. Pajares et al., "Modelling the natural photodegradation of water contaminants - A kinetic study on the light-induced aerobic interactions between riboflavin and 4-hydroxypyridine", J PHOTOCH A, 139(2-3), 2001, pp. 199-204

Abstract

Within our current studies on the natural photodegradation of representative aquatic environmental contaminants, the visible Light irradiation of themodel compound 4-hydroxypyridine (4-OHP), in air-equilibrated aqueous solution and in the presence of riboflavin (Rf), has been studied employing stationary photolysis, polarographic detection of oxygen uptake, stationary and time-resolved fluorescence spectroscopy, and laser flash photolysis. The results indicate that 4-OHP - a compound inert towards the attack of singlet molecular oxygen (O-2((1)Delta (g))) generated by Rose Bengal sensitization - quenches excited singlet and triplet states of Rf, with rate constantsof 2.4 x 10(9) M-1 s(-1) and 1.2 x 10(7) M-1 s(-1), respectively, The photodecomposition of Rf, a known process taking place from triplet Rf, has been found to depend on the concentration of dissolved 4-OHP: at greater than or equal to 20 mM limited photodecomposition occurs due to the quenching ofexcited singlet Rf, while at ca. 5 mM triplet Rf is photogenerated and subsequently quenched either by oxygen, giving rise to O-2((1)Delta (g)), or by 4-OHP yielding semireduced Rf through an electron transfer process. Superoxide dismutase inhibition of the oxygen uptake and flash photolysis data indicate that superoxide anion is generated, likely by the reaction of the anion radical from Rf with disserved oxygen, also yielding neutral, ground state Rf. The final result is that both 4-OHP and Rf are photodegraded, probably through oxidation with superoxide anion. (C) 2001 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 07:38:03