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

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 x 10(-16)), F-value (1832), R-2 (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 (40 degrees C), 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.