Photocatalytic ozonation of municipal wastewater for degradation of phenol using Fe doped TiO2 nanoparticles: optimization using RSM

Photocatalytic ozonation using Fe-doped titanium dioxide nanoparticles (FeT) prepared by the molten salt method was investigated for the degradation of phenol in synthetic solution and real secondary municipal wastewater. Photocatalytic ozonation using UV radiation (UV/FeT/O-3) and solar radiation (solar/FeT/O-3) were compared and optimized using response surface methodology (RSM). The ozone dose, initial pH, catalyst concentration, reaction time, and phenol degradation efficiency as process response were explored to build up a mathematical correlation using the central composite design of RSM. The regression model was tested for statistical significance using analysis of variance. The high value of the coefficient of determination (R-2 = 0.9837 for UV/FeT/O-3 and R-2 = 0.9637 for solar/FeT/O-3) shows that the model was statistically significant showing an excellent correlation between the experimental and predicted value of phenol degradation efficiency. The RSM predicted phenol degradation efficiency of 95.73% for UV/FeT/O-3 and 86.46% for solar/FeT/O-3 obtained under optimized condition (ozone concentration = 70 mg/L; pH = 10; catalyst concentration = 0.5 g/L; reaction time = 20 min) was comparable with the experimental result. Synergy index values of 1.02-1.25 were observed between ozonation and photocatalysis using solar and UV photocatalytic ozonation.