Organic pollutants degradation using plasma with simultaneous ammonification assisted by electrolytic two-cell system

Atmospheric non-thermal dielectric barrier discharge (DBD) plasma has gained considerable attention due to its cost-efficiency, environmental friendliness, and simplicity. However, certain deficiencies restrict its broad application. Herein, the DBD plasma was used to disrupt three model pharmaceutically active compounds (PhACs), sulfamethoxazole (SMX), ibuprofen (IBP), and norfloxacin (NFX), by varying parameters, such as gas type (Ar, N₂, O₂, and air) and flow rate (1-4 L min^-1). The air plasma discharge had the highest degradation efficiency, and the air flow rate was optimized at 2 L min^-1. However, only 10% of IBP was removed by the sole plasma, whereas NFX and SMX were entirely removed after 30 min. Since the air plasma discharge generates reactive oxygen and nitrogen species in a chained reaction, the remaining NO₂^- and NO₃^- in the aqueous phase were problematic. Therefore, by coupling plasma with electrolysis using Cu/reduced Cu nanowire (R-CuNw) as the anode/cathode, all three PhACs were removed within 30 min, and NO₂^- and NO₃^- were completely reduced to NH₃ with cathodic reduction. Moreover, the electrical energy per order (E_EO, 0.04 kWh L^-1) and treatment cost (0.003 USD L^-1) were much lower than those of the single system. This system demonstrates great potential for water remediation, and the production of NH₃ as a value-added by-product remarkably improves its practicality and is of great importance in agriculture and energy-related industries.