Degradation of persistent organic pollutants in soil by parallel tubes-array dielectric barrier discharge plasma cooperating with catalyst

Abstract

Persistent organic pollutants are harmful to the human health and environment due to their toxicity, chemical stability, degradation resistance and high bioaccumulation. In this paper, a parallel tubes-array dielectric barrier discharge reactor is developed to generate homogeneous discharge plasma and degrade the persistent organic pollutants in soil. The effects of applied voltage, initial concentration of pyrene and catalysts on the pyrene degradation efficiency in soil are studied. The results show that the degradation effect can be greatly improved by tuning these influencing parameters. The degradation efficiency of pyrene is significantly enhanced as the applied voltage increases. It reaches 96.23% at 28 kV in simulated soil and 98.26% at 26 kV in actual soil with 100 mg/kg initial concentration, and 10 min plasma treatment time. A significant promotion effect on the degradation efficiency can be obtained with the decrease of the initial pyrene concentration. Likewise, the addition of the catalysts CeO2 and TiO2 significantly improves the pyrene degradation efficiency and presents obvious synergistic effect with plasma. The discharge characteristics are discussed in combination with discharge images, waveforms of current and voltage. And the degradation mechanism of pyrene is analyzed combine with the optical emission spectra.