Prediction of Photocatalytic Degradation and Mineralization Efficiencies of Basic Blue 3 Using $${{\rm TiO}_{2}}$$ TiO 2 by Nonlinear Modeling Based on Box–Behnken Design

Abstract

In the present study, nonlinear modeling of color and chemical oxygen demand (COD) removal of Basic Blue 3 as a fairly toxic textile dye by photocatalytic degradation using \({{\rm TiO}_{2}}\) was investigated. A three replicates and one duplicate of Box–Behnken design with 45 runs, with three factors and three levels of catalyst concentration of 0.5–1.5 g/L, initial dye concentration of 20–100 mg/L, and initial pH of 3–11 were set to quantify the explanatory variables. ANOVA results showed that the best-fit multi-nonlinear regression models were cross-validated \({(R^{2}_{\rm pred})}\) accounting for 99.98–99.79 % and were expressed \({(R^{2}_{\rm adj})}\) accounting for 99.88–99.85 % of variation in decolorization (color removal) and mineralization (COD removal), respectively. In total, 0.51 g/L of \({{\rm TiO}_{2}}\), 100 mg/L of initial dye concentration, and initial pH of 7 were established as optimum operating parameters by leave-one-out optimization that resulted in 88.61 and 79.03 % for color and COD removal, respectively. 88.78 % of color removal and 76.95 % of COD removal were determined by cross-validation experiments at optimum conditions. Results showed that optimum point determination was successful.