Multivariate analysis of photocatalytic-mineralization of Eriochrome Black T dye using ZnO catalyst and UV irradiation

The photocatalytic decolorization and mineralization of reactive azo-based dye, Eriochrome Black T (EBT) using ZnO catalyst were investigated under UV-irradiation. In the present study, response surface methodology (RSM) based on central composite design (CCD) was applied for optimizing three independent variables (e.g., ZnO dosage, initial concentration of EBT dye and solution pH), which significantly affected the removal efficiency of EBT. Then the adequacy of the developed model was further evaluated via analysis of variance (ANOVA). In the optimum processing conditions (0.3 g/L of ZnO loading, initial concentration of EBT of 25 mg/L and solution pH of 7.91), this proposed method was successfully decolorized 83% of EBT using ZnO catalyst under 96 W of UV-irradiation for 20 min. In addition, it was found that a highly significant quadratic model (p-value<0.0001, R2=0.9743) was derived from the response surface. According to our ANOVA results, first-order and second-order effects of ZnO loading, EBT concentration and pH of reaction medium played a crucial role in photocatalytic-mineralization of EBT.