Degradation performance and mechanism of plasma-activated persulfate for environmental persistent pollutants

Abstract

This study comprehensively investigates the degradation performance and mechanism of environmental persistent pollutants (EPs) by combining experimental and theoretical calculations with dielectric barrier discharge (DBD) plasma synergized with persulfate. The findings demonstrated that DBD plasma could generate reactive radicals, including ·OH, ¹O₂ and $·O_2^{-}$, which primarily activate persulfate through ·OH and $·O_2^{-}$ to produce the potent oxidizing radical SO₄⁻·. This process facilitated enhanced degradation and mineralization of MeP wastewater. The performance of DBD/persulfute (PS) in degrading MeP was evaluated by kinetics, energy efficiency, and co-factor calculations, combined with degradation under different influencing factors. The actives in the system were analyzed by free radical scavenging assays and UV spectrophotometric testing to determine their effects. The findings indicated that persulfate was effectively activated by DBD plasma and that $·O_2^{-}$ played a significant role. The presence of persulfate elevated the levels of H₂O₂ and O₃ in the solution. The intermediates formed during the degradation of MeP were detected using LC-MS and then analyzed alongside density-functional theory (DFT) chemical predictions to anticipate the reactive sites and deduce the potential degradation pathways of methylparaben (MeP). Toxicity evaluation software confirmed that the PS/DBD system reduces acute and developmental toxicity in the water column. The study showed that DBD plasma-activated persulfate was successful in addressing newly identified contaminants.