Research on the degradation mechanism of dimethyl phthalate in drinking water by strong ionization discharge

The degradation mechanism of dimethyl phthalate (DMP) in the drinking water was investigated using strong ionization discharge technology in this study. Under the optimized condition, the degradation efficiency of DMP in drinking water was up to 93% in 60 min. A series of analytical techniques including high-performance liquid chromatography, liquid chromatography mass spectrometry, total organic carbon analyzer and ultraviolet–visible spectroscopy were used in the study. It was found that a high concentration of ozone (O₃) produced by dielectric barrier discharge reactor was up to 74.4 mg l^-1 within 60 min. Tert-butanol, isopropyl alcohol, carbonate ions (CO₃^2-) and bicarbonate ions (HCO₃^- ) was added to the sample solution to indirectly prove the presence and effect of hydroxyl radicals (·OH). These analytical findings indicate that mono-methyl phthalate, phthalic acid (PA) and methyl ester PA were detected as the major intermediates in the process of DMP degradation. Finally, DMP and all products were mineralized into carbon dioxide (CO₂) and water (H₂O) ultimately. Based on these analysis results, the degradation pathway of DMP by strong ionization discharge technology were proposed.