Photocatalytic Degradation of Azo Dyes Over Semiconductors Supported on Polyethylene Terephthalate and Polystyrene Substrates

The discharge of effluents from the textile industry into water bodies has a severe impact on water quality. The photocatalytic degradation of two typical azo dyes used in the textile industry (Acid Brown 83 and Direct Blue 1) was studied using the catalysts titanium dioxide (TiO2) and zinc oxide (ZnO) supported on polyethylene terephthalate (PET) and polystyrene (PS) substrates. For these dyes, degradation reactions using different initial pH values and supported catalysts were carried out. Adsorption isotherms were obtained and analyzed. No significant statistical differences were found between the use of PET and PS as substrates on degradation rate constants for both dyes. For Acid Brown 83 the highest rate constant was obtained at pH 2.5 using TiO2. For Direct Blue 1, the rate constant showed a significant difference only between the treatment at pH 2.5 using TiO2 and the treatment al pH 11.0 using ZnO. The adsorption of both dyes was higher on TiO2 than on ZnO.