Optimization of photocatalytic degradation of real textile dye house wastewater by response surface methodology

This study evaluates the advanced oxidation process for decolorization of real textile dyeing wastewater containing azo and disperse dye by TiO₂ and UV radiation. Among effective parameters on the photocatalytic process, effects of three operational parameters (TiO₂ concentration, initial pH and aeration flow rate) were examined with response surface methodology. The F-value (136.75) and p-value <0.0001 imply that the model is significant. The 'Pred R-Squared' of 0.95 is in reasonable agreement with the 'Adj R-Squared' of 0.98, which confirms the adaptability of this model. From the quadratic models developed for degradation and subsequent analysis of variance (ANOVA) test using Design Expert software, the concentration of catalyst was found to be the most influential factor, while all the other factors were also significant. To achieve maximum dye removal, optimum conditions were found at TiO₂ concentration of 3 g L^-1, initial pH of 7 and aeration flow rate of 1.50 L min^-1. Under the conditions stated, the percentages of dye and chemical oxygen demand removal were 98.50% and 91.50%, respectively. Furthermore, the mineralization test showed that total organic compounds removal was 91.50% during optimum conditions.