Solar photocatalytic decolorization of azo dyes in water and textile wastewater on N-(Cr3+,Fe3+) doped-TiO2 nanoparticle films: optimization of some operational parameters

摘要

The photocatalystic decolorization of the mixture of three textile azo dyes, i.e. Reactive Red (RR) 193, RR 198 and RR 239, with N, or Cr3+ or Fe(3+)doped TiO2 film photocatalysts under solar light irradiation was studied. The effect of different factors, i.e. concentration of dopant, pH of the solution, additive of H2O2 and irradiation source on the photocatalytic decolorization efficiency of the TiO2 film catalysts, was investigated. The optimal doping concentration is 0.2 at.% with N- or Cr3+, with larger than 96% of the decolorizing efficiencies after 4h irradiation time. The decolorization of the dyes was strongly enhanced by the addition of hydrogen peroxide in the pH of 3.0. Under solar light irradiation in the presence of H2O2, both N-doped and Cr3+-doped TiO2 thin film were also applied to photocatalytically decolorize a textile wastewater sample.