Key Physicochemical Parameters Influencing Reactive Species in Plasma-Processed-Air (PPA) Originated From Microwave Discharge

Abstract

Fourier transformation infrared (FTIR) spectroscopy was used to identify the antimicrobial chemical composition of plasma processed air (PPA) generated by a microwave plasma source—MidiPLexc. NO was found to be the first product with maximum concentration of 1030 ppm. NO2 was the dominant long-living species with maximum concentration of 10 520 ppm, which was in equilibrium with its dimer—N2O4. Key physicochemical parameters influencing the concentrations were identified. Elevated input power mainly promoted NO2 generation and 1.5 SLM was determined to be the critical flow rate for the maximum NO2 yield. NO2 concentration was reduced by 40% under humid condition with 50 W power input. A prediction model of NOx generation was made based on specific input energy (SIE).