Photocatalytic ozonation of dibutyl phthalate over TiO2 film

A novel carbon black modified nano-TiO2 film photocatalyst (CB-TiO2) was prepared by a sol–gel method and used for degrading and mineralizing dibutyl phthalate. The film was characterized by XRD, SEM, and DRS techniques. Carbon black modification could make TiO2 film more pores, looser structure, smaller crystal sizes and longer excitation wavelength. The photocatalytic activity of the CB-TiO2 films was 1.4 times higher than that of TiO2 films in degrading dibutyl phthalate. The results showed that ozone concentrations had an important effect on degradation and mineralization of dibutyl phthalate. The combined photocatalysis with UV irradiation and ozonation (TiO2/UV/O3) process considerably improved mineralization and degradation of dibutyl phthalate compared to combined photocatalysis with UV irradiation (TiO2/UV) process, combined ozonation with UV irradiation (UV/O3) process and ozonation alone (O3) process. Dibutyl phthalate can be quickly mineralized in TiO2/UV/O3 and UV/O3, its mineralization followed pseudo-zero-order kinetics dependent upon ozone concentration and indicated its concentration did not affect the kinetics during TiO2/UV, UV/O3 and TiO2/UV/O3 processes. The kinetic study showed the mineralization rate constants of dibutyl phthalate with TiO2/UV/O3 are 1.2–1.8 times higher than that of UV/O3 with the same ozone concentration and 3.5 times higher than that of TiO2/UV.