Efficient mineralization of dimethyl phthalate by catalytic ozonation using TiO 2/Al 2O 3 catalyst

Abstract

The removal of dimethyl phthalate (DMP), which is a pollutant of concern in water environments, was carried out by catalytic ozonation with TiO 2/Al 2O 3 catalysts. The heterogeneous catalytic ozonation was an ozonation process combined with the catalytic and adsorptive properties of the TiO 2/Al 2O 3 catalysts to significantly accelerate the mineralization efficiency. Semi-batch ozonation was performed under various experimental conditions including the fed ozone concentration, catalyst type, catalyst dosage, and ultraviolet radiation on the degradation of DMP. The complete removal of DMP was efficiently achieved by both sole and catalytic ozonation; meanwhile, the presence of the catalysts slightly accelerated the elimination rate of DMP. On the other hand, the mineralization efficiency, in terms of total organic carbon (TOC) removal, was substantially enhanced by employing the TiO 2/Al 2O 3 catalyst. The mineralization efficiency using the TiO 2/Al 2O 3 catalyst was the highest, followed in decreasing order by the Al 2O 3 catalyst, the TiO 2 catalyst, and sole ozonation. In addition, the use of the TiO 2/Al 2O 3 catalyst would increase the utilization efficiency of the fed ozone, especially in the late ozonation period. Furthermore, the decrease in the catalytic activity of the TiO 2/Al 2O 3 catalyst after multi-run experiments can be mostly recovered by an incineration process at a high temperature.