title: Optimised photocatalytic degradation of a mixture of azo dyes using a TiO(2)/H(2)O(2)/UV process.
abstract: The aim of the present study was to optimise the photocatalytic degradation of a mixture of six commercial azo dyes, by exposure to UV radiation in an aqueous solution containing TiO(2)-P25. Response surface methodology, based on a 3(2) full factorial experimental design with three replicates was employed for process optimisation with respect to two parameters: TiO(2) (0.1-0.9 g/L) and H(2)O(2) (1-100 mmol/L). The optimum conditions for photocatalytic degradation were achieved at concentrations of 0.5 g TiO(2)/L and 50 mmol H(2)O(2)/L, respectively. Dye mineralisation was confirmed by monitoring TOC, conductivity, sulfate and nitrate ions, with a sulfate ion yield of 96% under optimal reactor conditions. Complete decolorisation was attained after 240 min irradiation time for all tested azo-dyes, in a process which followed a pseudo-first kinetic order model, with a kinetic rate constant of approximately 0.018 min(-1). Based on these results, this photocatalytic process has promise as an alternative for the treatment of textile effluents.
authors.affiliation: Postgraduate Program of Chemical Engineering, Paraná West State University, Toledo, PR, Brazil.
authors.forename: Soraya Moreno
authors.initials: SM
authors.lastname: Palácio
authors.forename: Fernando Rodolfo
authors.initials: FR
authors.lastname: Espinoza-Quiñones
authors.forename: Aparecido Nivaldo
authors.initials: AN
authors.lastname: Módenes
authors.forename: Diego Ricieri
authors.initials: DR
authors.lastname: Manenti
authors.forename: Cláudio Celestino
authors.initials: CC
authors.lastname: Oliveira
authors.forename: Juliana Carla
authors.initials: JC
authors.lastname: Garcia
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry* / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007220:Industrial Waste; D007700:Kinetics; D010782:Photolysis; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays; D014865:Waste Disposal, Fluid / Q000379:methods; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D001391:Azo Compounds; D007220:Industrial Waste; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D006861:Hydrogen Peroxide; D014025:Titanium