Degradation of atrazine in river sediment by dielectric barrier discharge plasma (DBDP) combined with a persulfate (PS) oxidation system: response surface methodology, degradation mechanisms, and pathways

Abstract

Single degradation systems based on dielectric barrier discharge plasma (DBDP) or persulfate (PS) oxidation cannot achieve the desired goals (high degradation e ciency, high mineralization rate and low product toxicity) of degrading atrazine (ATZ) in river sediment. In this study, DBDP was combined with a PS oxidation system (DBDP/PS synergistic system) to degrade ATZ in river sediment. A Box-Behnken design (BBD) design including ve factors (discharge voltage, air ow, initial concentration, oxidizer dose and activator dose) and three levels (-1, 0 and 1) was established to test a mathematical model by response surface methodology (RSM). The results con rmed that the degradation e ciency of ATZ in river sediment was 96.5% in the DBDP/PS synergistic system after 10 min of degradation. The experimental total organic carbon (TOC) removal e ciency results proved that 85.3% of ATZ is mineralized into CO 2 , H 2 O and NH 4 + , which effectively reduces the possible biological toxicity of the intermediate products. Active species (sulfate (SO 4 • − ), hydroxy (•OH) and superoxide (•O 2 − ) radicals) were found to exert positive effects in the DBDP/PS synergistic system and illustrated the degradation mechanism of ATZ. The ATZ degradation pathway, composed of 7 main intermediates, was clari ed by fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS).This study indicates that the DBDP/PS synergistic system is a highly e cient, environmentally friendly, novel method for the remediation of river sediment containing ATZ pollution.