Contrastive study on organic contaminated soils remediated using dielectric barrier discharge (DBD) plasma

• Soil pH significantly affected degradation because of pollutant acidity coefficient. • Active species that play roles in DBD degradation reactions of PFOA and gasoline from soil were analyzed. • DFT calculations combining plasma generation principle were further used to explore DBD degradation mechanisms. • Contrastive research illustrated remediation of DBD plasma on organic polluted soil is highly effective and high-universality. Non-thermal plasma is an emerging technology in the field of soil remediation. In this research, a dielectric barrier discharge (DBD) reactor was employed to degrade gasoline and perfluorooctanoic acid (PFOA) in soil. Higher removal rates were performed under higher discharged power, smaller electrode gap, lower initial pollutant concentration and soil moisture. The optimal soil moisture for gasoline degradation was 10%, while it was 2% for PFOA removal because of adsorption by hydrophobic interaction. Compared to higher degradation efficiencies of gasoline achieved in alkaline soil condition, the acidic environment was more conducive to PFOA removal due to the low acidity coefficient of PFOA. Degradation promoted in argon atmosphere confirms that high-energy electrons play an important role in organic pollutants degradation during DBD process. Reactive nitrogen species (RNS) significantly promotes gasoline removal, while PFOA degradation is initiated by electrons and reactive oxygen species (ROS) participates in the following reactions during the DBD degradation process. Density functional theory (DFT) calculation further combining plasma generation and organic reaction mechanisms was used to infer the degradation mechanisms of gasoline and PFOA. This contrastive research show that DBD technology is a high-universality and efficient method to remediate organic-polluted soil.