Degradation of di-n-butyl phthalate in aqueous solution by the O3/UV process

Abstract

The degradation of di-n-butyl phthalate (DBP), which is a pollutant of concern in an aqueous environment, was investigated using the combination of ozonation with ultraviolet irradiation (O3/UV) in this study. Compared with either ozonation or UV irradiation, the hybrid system stimulated the O3 molecule photolysis and the hydroxyl radical (OH) generation; therefore, the DBP degradation through the pathway of OH attack was markedly reinforced. Since OH was a more vigorous oxidant than O3, both the kinetics of the DBP removal and the mineralization were increased. With the aqueous O3 fed rate of 4.03 mg/(L min), the spiked DBP molecules almost completely disappeared in 60 min, approximately 70% of which were converted into H2O and CO2. The effects of DBP concentration, aqueous O3 fed rate, and solution pH on the DBP degradation were also investigated. Pseudo-first-order kinetics model was able to depict the experimental data under different conditions. Eight intermediates were identified, and the DBP degradation by the O3/UV process was supposed to be mainly started with the OH attack to the aliphatic chains. Since the combination of O3 with UV benefits the complete decomposition of DBP and reduces the possible toxicity of the treated water, it is a promising process for DBP removal from an aqueous solution.