Studies on Degradation of Phthalate by Ozonation and Ozonation Combined with Ultraviolet Radiation Using Capillary Electrophoresis

Using dimethyl phthalate (DMP) as a phthalic acid esters (PAEs) probe, two candidate processes, ozonation (O₃) and O₃ combined with ultraviolet radiation (O₃/UV), were evaluated for their efficiency in removing DMP and mineralizing the degradation products. The DMP degradation intermediates and final products were determined by capillary electrophoresis (CE). The results showed that the removal of dimethyl phthalate in the aqueous solution by ozonation was efficient, and the oxidation of side-chains of DMP was the dominant mechanism of the process. The major intermediate-phthalic acid (PA) in the ozonation process could be degraded to the minor aliphatic acids. These aliphatic acids could not be decomposed by ozonation very well. In the O₃/UV process, it was believed that the ester chain and the benzene ring of DMP concur to be oxidized by hydroxyl radical (-OH) and the aliphatic acids such as succinic acid and oxalic acid were produced. These aliphatic acids can be oxidized further to H₂O and CO₂ by hydroxyl radical (-OH).