Degradation of di-2-ethylhexyl phthalate in aqueous solution by advanced oxidation process

Aims: This study was conducted to compare the effectiveness of conventional technologies, UV irradiation and ozonation process, and UV/O₃ as advanced oxidation processes to remove phthalate from aqueous solutions. Materials and Methods: The initial concentration of di-2-ethylhexyl phthalate (DEHP) was 5 mg/L. The photolysis, ozonation, and UV/O₃ processes were conducted separately at different contact times (5-30 min). Then, the DEHP residuals in the solutions were analyzed by gas chromatography mass spectrometry. The effect of ozone dosage was also evaluated in the range of 50-400 mg/h on DEHP degradation. Kinetic and the rate constants were determined. Results: The results indicated that using UV and ozonation alone, the maximum DEHP removal efficiency were 43% and 50%, respectively. The UV/O₃ process considerably improved the degradation of DEHP up to 80%. The synergistic effect observed in the combined processes mainly due to the effects of UV in enhancing the ozone decomposition, led to higher degradation for 30 min treatment. A kinetic study showed the degradation in UV/O₃ followed the first-order model. In addition, the maximum DEHP removal rate was 74% with 200 mg/h ozone dosage by ozonation alone process, but it was 93% at same condition by UV/O₃ process. Conclusion: It could be found that the UV/O₃ process is a method for DEHP degradation in aqueous solution and may be recommended as a supplement with other processes for treatment of solutions containing low DEHP concentrations.