title: Azo-dyes photocatalytic degradation in aqueous suspension of TiO2 under solar irradiation.
abstract: The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C14H14N3SO3Na) and orange II (C16H11N2SO4Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO2 irradiated by sunlight. Compound parabolic collectors, installed at the "Plataforma Solar de Almería" (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediates were found to be in lower number in respect to those obtained under artificial irradiation. In particular there were no more evidence of the presence of hydroxylated transients. The dependence of dye photooxidation rate on: (i) substrate concentration; (ii) catalyst amount; and (iii) initial pH was investigated. The influence of the presence of strong oxidant species (H2O2, S2O8(2-)) and some ions (Cl-, SO4(2-)) on the process was also studied.
authors.affiliation: Dipartimento di Ingegneria Chimica dei Processi e dei Materiali, Università di Palermo, Viale delle Scienze 90128 Palermo, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Augugliaro
authors.forename: Claudio
authors.initials: C
authors.lastname: Baiocchi
authors.forename: Alessandra Bianco
authors.initials: AB
authors.lastname: Prevot
authors.forename: Elisa
authors.initials: E
authors.lastname: García-López
authors.forename: Vittorio
authors.initials: V
authors.lastname: Loddo
authors.forename: Sixto
authors.initials: S
authors.lastname: Malato
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Marcí
authors.forename: Leonardo
authors.initials: L
authors.lastname: Palmisano
authors.forename: Marco
authors.initials: M
authors.lastname: Pazzi
authors.forename: Edmondo
authors.initials: E
authors.lastname: Pramauro
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D001557:Benzenesulfonates / Q000737:chemistry*; D002384:Catalysis; D004396:Coloring Agents / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry*; D010084:Oxidation-Reduction; D010777:Photochemistry; D013472:Sunlight; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical
chemical_list: D001391:Azo Compounds; D001557:Benzenesulfonates; D004396:Coloring Agents; D007202:Indicators and Reagents; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; C100258:methyl orange; D014025:Titanium; C014722:2-naphthol orange