The enhancing energy efficiency of sulfadiazine degradation using a DBD-contact plasma treatment process

Nonthermal plasma has attracted extensive attention because of its ability to remove emerging organic micropollutants. However, its high amount of energy consumption severely limits its economic feasibility. In this study, sulfadiazine degradation was achieved in an optimized dielectric barrier discharge (DBD)-Contact system. The sulfadiazine removal in the DBD-Contact/peroxymonosulfate (PMS) system reached 91.8% within 15 min. Compared to a conventional DBD system, the energy efficiency (G50) of the DBD-Contact/PMS system was 4.37 times greater, which meant a saving of 77.17% in electricity consumption. The reactive species generated by discharge plasma were identified as mostly excited nitrogen species in the gas phase, and after transferred to the water phase, OH and SO4− played an important role in the sulfadiazine removal. The hydroxylation of the S-N bond and the nucleophilic reaction of the pyrimidine ring were proposed as mechanisms for the sulfadiazine degradation, and the developmental and acute toxicity was significantly reduced after treatment. Furthermore, the DBD-Contact/PMS system showed good applicability in a wide pH range and complex practical water samples. This study finds that the DBD-Contact/PMS system can degrade antibiotics with high efficiency and low energy consumption and provides new insights for the practical application of DBD technology in water treatment.