Removal of dimethyl phthalate in water by non-thermal air plasma treatment

In this study, the effect of a non-thermal microplasma array on the degradation of dimethyl phthalate (DMP) solution was investigated using a high pressure liquid chromatograph and mass spectrometer (LC-MS). The degradation pathways of DMP were studied through identification of the intermediates generated during the degradation process of DMP by microplasma. The results indicated that the degradation efficiency of DMP in water was strongly dependent on the discharge power and treatment time. When the discharge power was 17.8 W, the degradation efficiency of 30 mg L-1 DMP can be up to 99.9% at a treatment time of 20 min. The main intermediates during the degradation process of DMP were phthalic acid, benzoic acid, formic acid, etc. The DMP and intermediates were eventually oxidized into stable compounds, such as CO, CO2, and H2O. Measurements confirmed that OH and O-3 generated by plasma were the major reactive species in plasma-activated DMP solution, which attacked many functional groups in DMP.