Optimization and modeling of photocatalytic degradation of Direct Blue 71 from contaminated water by TiO2 nanoparticles: Response surface methodology approach (RSM)

Abstract

In the current survey, the removal of dye from contaminated water was studied by photocatalytic degradation using TiO₂ nanoparticles with respect to pH, TiO₂ dosage, reaction time, temperature and initial dye concentration. TiO₂ nanoparticles were investigated by XRD, FESEM and FT-IR.The RSM was chosen to study the composition effects of input independent factors and one dependent output response (removal efficiency). The P-value (2.2 × 10⁻¹⁶), F-value (1832), R² (multiple R-squared: 0.9985, adjusted R-squared: 0.9972), and lack of fit (0.432) indicate that the reduced full second order model is highly significant for dye removal by TiO₂ nanoparticles.The maximum percentage removal of dye, 90.2%, was achieved at optimum operating conditions including pH=6.5, TiO₂ dose (1.2 g L^-1), contact time (67.5 min), temperature ( ), and dye concentrations (55 mg L^-1)), respectively.The maximum removal efficiency was calculated to be 100%, using regression coefficients derived from the model and the Solver “Add-ins".The results indicated that the TiO₂ photocatalyst was very proper for the removal dye from contaminated water, and it had good efficiency in eliminating textile dyes.