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Titolo:
Photophysical properties of Ag(I)-exchanged zeolite A and the photoassisted degradation of malathion
Autore:
Kanan, SM; Kanan, MC; Patterson, HH;
Indirizzi:
Univ Maine, Dept Chem, Orono, ME 04469 USA Univ Maine Orono ME USA 04469Univ Maine, Dept Chem, Orono, ME 04469 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 31, volume: 105, anno: 2001,
pagine: 7508 - 7516
SICI:
1520-6106(20010809)105:31<7508:PPOAZA>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
AG+-EXCHANGED ZEOLITE; ELECTRON-SPIN-RESONANCE; ALKALI-HALIDE CRYSTALS; LUMINESCENT HOMOATOMIC EXCIPLEXES; PARAMAGNETIC SILVER CLUSTERS; GAMMA-IRRADIATION; MOLECULAR-MODELS; ZSM-5 ZEOLITES; SURFACE SITES; NITRIC-OXIDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
70
Recensione:
Indirizzi per estratti:
Indirizzo: Patterson, HH Univ Maine, Dept Chem, Orono, ME 04469 USA Univ Maine OronoME USA 04469 ept Chem, Orono, ME 04469 USA
Citazione:
S.M. Kanan et al., "Photophysical properties of Ag(I)-exchanged zeolite A and the photoassisted degradation of malathion", J PHYS CH B, 105(31), 2001, pp. 7508-7516

Abstract

Three colored derivatives of Ag(I) doped A-type zeolite were prepared and analyzed spectroscopically at 77 K. These compounds have luminescence spectra containing several emission bands that become dominant at characteristicexcitation wavelengths. The white AgA zeolite shows luminescence bands at 290, 350, 423, 500, and 550-650 nm, whereas the yellow- and red-colored zeolites show bands at 500, 545, and 625 nm. These bands are attributed to thepresence of different silver clusters in zeolite A. Both the experimental and theoretical results suggest the formation of Ag-Ag bonded excimers and exciplexes in the zeolite host. The photodecomposition of malathion in dichloromethane at room temperature shows different decomposition products in the presence and absence of the AgA zeolite catalyst. In addition, the decomposition rates depend on the color of the AgA zeolite. The white, yellow, and red AgA zeolites produce photodecomposition rates with malathion that are 35, 18, and 20 times faster, respectively, than malathion alone in solution. The increase in decomposition rates is due to the different reactivities of the silver clusters of various sizes and charges on the white, yellow,and red A-A zeolite derivatives. The large size of malathion prevents its entrapment in the zeolite channels; therefore, the photodecomposition process and the catalytic silver clusters must occur on the AgA surface.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 08/07/20 alle ore 07:26:22