Dimethyl phthalate contaminated soil remediation by dielectric barrier discharge: Performance and residual toxicity

Phthalates, as additives in the plastic production process, were able to enter the soil, causing huge risks to soil environment and human health. The potential of phthalates elimination in soil using dielectric barrier discharge (DBD) plasma was evaluated, with dimethyl phthalate (DMP) as a model pollutant. The experimental results demonstrated that DMP in soil could be decomposed by the DBD plasma oxidation. DMP concentration was reduced from 200 mg kg−1 to 87 mg kg−1 after 60 min's DBD plasma oxidation, and its decomposition process fitted well with the first-order kinetics. Soil moisture was an important parameter affecting DMP decomposition in soil. Lower initial concentration was beneficial for DMP degradation. Analysis on types and action ranges of reactive oxygen species participating in DMP decomposition demonstrated that oxygen-containing species and electron played crucial roles. DMP molecular structure was destroyed in the DBD plasma processing, and phthalic acid monomethyl ester, phthalic acid, acetic acid, and oxalic acid were detected as the main intermediates. DBD plasma oxidation decreased the toxicity of DMP to seed germination and growth. Germination rate of wheat seed and activity of root system both increased, while free radical damage to cell membrane was significantly alleviated after 60 min's DBD plasma oxidation.