Comparison of Photochemical Oxidation of Diethyl Phthalate by UV/H2O2 and UV/TiO2/Glass Films in Aqueous Solution

The decomposition of diethyl phthalate (DEP) has been carried out in UV/H₂O₂ and UV/TiO₂/glass films process separately. The effects of reaction pH, applied H₂O₂ dose and initial concentration of DEP have been studied. The optimal conditions at an initial DEP concentration of 20 mg.L-1 were acidic and 15mmol.L^-1 H₂O₂ in UV/H₂O₂ system, and pH3.0 in UV/TiO₂/glass films system under 254nm UV irradiation. Under the optimal conditions, DEP photodegradation during the initial period of 60 min in UV/H₂O₂ and UV/TiO₂/glass films systems reached 97 and 49%, respectively. In both systems, DEP photodegradation decreased with increasing initial concentration of DEP. While DEP photodegradation rates increased with increasing dosage of H₂O₂ (5-15 mmol.L^-1), further increase in the dosage of H₂O₂ (20mmol.L^-1) adversely reduced the DEP photodegradation. Pseudo first-order kinetics with regard to DEP concentration can be used to describe the DEP photodegradation in both systems.