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Titolo:
Photooxidative N-demethylation of methylene blue in aqueous TiO2 dispersions under UV irradiation
Autore:
Zhang, TY; Oyama, T; Aoshima, A; Hidaka, H; Zhao, JC; Serpone, N;
Indirizzi:
Meisei Univ, Frontier Res Ctr Global Environm Protect, Hino, Tokyo 1918506, Japan Meisei Univ Hino Tokyo Japan 1918506 Protect, Hino, Tokyo 1918506, Japan Chinese Acad Sci, Inst Chem, Beijing 100080, Peoples R China Chinese Acad Sci Beijing Peoples R China 100080 100080, Peoples R China Concordia Univ, Dept Chem & Biochem, Montreal, PQ H3G 1M8, Canada Concordia Univ Montreal PQ Canada H3G 1M8 m, Montreal, PQ H3G 1M8, Canada Tianjin Univ, Coll Chem Engn & Technol, Dept Appl Chem, Tianjin 300072, Peoples R China Tianjin Univ Tianjin Peoples R China 300072 njin 300072, Peoples R China
Titolo Testata:
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
fascicolo: 2, volume: 140, anno: 2001,
pagine: 163 - 172
SICI:
1010-6030(20010510)140:2<163:PNOMBI>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
VISIBLE-LIGHT IRRADIATION; HETEROGENEOUS PHOTOCATALYSIS; SEMICONDUCTOR SURFACES; ELECTRON-TRANSFER; EXCITED-STATE; AZO DYES; DEGRADATION; PARTICLES; PHOTOCHEMISTRY; SUSPENSIONS;
Keywords:
methylene blue; photocatalytic reaction; titanium dioxide; N-demethylation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
33
Recensione:
Indirizzi per estratti:
Indirizzo: Hidaka, H Meisei Univ, Frontier Res Ctr Global Environm Protect, 2-1-1 Hodokubo, Hino, Tokyo 1918506, Japan Meisei Univ 2-1-1 Hodokubo Hino Tokyo Japan 1918506 18506, Japan
Citazione:
T.Y. Zhang et al., "Photooxidative N-demethylation of methylene blue in aqueous TiO2 dispersions under UV irradiation", J PHOTOCH A, 140(2), 2001, pp. 163-172

Abstract

Methylene blue (MB) is a representative of a class of dyestuffs resistant to biodegradation. Its decomposition was examined in aqueous TiO2 dispersions under W illumination to assess the influence of temperature, pH, concentration of dissolved oxygen (DOC), initial concentration of R IB, and light intensity on the kinetics of decomposition. Hypsochromic effects (i.e. blueshifts of spectral bands) resulting from N-demethylation of the dimethylamino group in MB occurs concomitantly with oxidative degradation. The maximum quantity of MB adsorbed on TiO2, and the kinetics of degradation of MB and of total organic carbon (TOC) removal were also measured at constant pH 4. Photobleaching of MB solutions takes place at low DOCs and is caused by areversible reductive process involving photogenerated electrons on TiO2. The rate of degradation of MB remains fairly constant regardless of whether the dispersion was purged with oxygen prior to irradiation or with air during the light irradiation period, The photocatalytic process depends on light intensity, but not on the total light energy absorbed. The photoreaction followed pseudo-first-order kinetics even at high MB concentrations (0.3 mM). The temperature dependence of the photodegradation kinetics was assessed(E-a = 8.9 kJ/mol), as well as the relative photonic efficiency, xi (r), relative to phenol (0.48). (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 23/09/20 alle ore 06:11:08