Degradation of p-Nitrophenol in Soil by Dielectric Barrier Discharge Plasma

Dielectric barrier discharges (DBDs) were utilized for the remediation of soil contaminated with p-nitrophenol (PNP). The effect of treatment time, applied discharge voltage, initial PNP concentration, pH of contaminated soil, and airflow rate were investigated in this study. The results showed that 63.2 % of the PNP in the contaminated soil was degraded in 50 min with a voltage of 38.2 kV with no airflow. This degradation reaction followed the first order reaction kinetics. The degradation by ozone alone was compared with the plasma treatment to identify the role of ozone. Chromatographic analysis was applied to monitor the intermediates produced during the oxidation process, and the main byproducts were maleic acid, p-benzoquinone, 4-nitrocatechol, methanoic acid, acetic acid, oxalic acid, NO2−, and NO3−. Possible pathways for the degradation of PNP in this system were deduced, which would provide evidence for the researches about the remediation of soils polluted by organic pollutants.