The Comparison of Photocatalytic Degradation and Decolorization Processes of Dyeing Effluents

Abstract

Treatment of dye effluents resulting from the industrial scale dyeing of cotton, polyacrylic fibres, leather, and flax fabrics by photocatalytic methods was investigated. Photocatalytic processes were initiated by UV-a light (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msub><mml:mi>λ</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow></mml:msub></mml:mrow></mml:math>366 nm) and were conducted in the presence of TiO 2 , TiO 2 /FeCl 3 , or FeCl 3 as photocatalysts. It was found that the photocatalytic process carried out with TiO 2 and TiO 2 /FeCl 3 was the most effective method for decolorization of textile dyeing effluents and degradation of dyes, except for effluents containing very high concentrations of stable azo dyes. During the photocatalytic degradation of anionic dyes, a mixture of TiO 2 /FeCl 3 was more effective, while in the case of cationic dyes, more suitable seems to be TiO 2 alone.