Comparative study using design experiment to assess an anionic dye degradation in aqueous solution through the application of different advanced oxidation processes

This study aims to compare the anionic dye degradation (Titan yellow dye: DY9) in synthetic solution using three advanced oxidation processes, namely, Fenton process (FP) (H2O2/Fe2+), photo‐Fenton process (PhFP) (UV/H2O2/Fe2+), and photocatalytic process (PhCP) (TiO2/UV). To perform this study, design of experiments methodology was applied. A full factorial design was used to investigate the effect of operating parameters on the degradation yield. For each process, four parameters were considered, for “FP” and “PhFP,” the initial dye concentration ([DY9]0), the ratio R1 = [H2O2]/[Fe2+], the ratio R2 = [DY9] / [Fe2+], and the pH of solution and for “PhCP,” the initial dye concentration (([DY9]0), initial concentration of hydrogen peroxide [H2O2], dose of titanium oxide [TiO2], and the pH of solution. The averages of degradation yield obtained are 47.1%, 56.7%, and 68.5% for “FP,” “PhFP,” and “PhCP,” respectively. Main and interaction effects plots were constructed. An interaction index (In (%)) was defined, which allowed to quantify the impact of the interaction on the response. Three regression models were proposed and validated on basis of analysis of variance (ANOVA) and statistical criteria as corrected Akaike Information Criterion (AICc), Mallows Cp statistic, coefficient of determination (R2), and adjusted coefficient of determination (R2adj). These models showed that the “PhCP” model was the most statistically significant, including more interaction effect terms. Iso‐responses curves were plotted to predict the optimal conditions for each process. To achieve a full degradation of DY9, the predicting optimal conditions were expressed on intervals. Full factorial design was applied as experimental approach to assess main and interaction effects of process factors. The impact of factor interactions on dye degradation has been quantified using interaction index. The suggestion of methods to improve the degradation of the dye based on the variation of factor interactions.