Characterization of reactive species in water induced by cold atmospheric air plasma: Experimental applications for industrial micropollutant removal from wastewater and seed germination

Cold atmospheric air plasma (CAAP) interaction with liquids produces a variety of reactive oxygen and nitrogen species (RONS) that play crucial role in the oxidation of organic micropollutants (OMPs) in wastewater. In our study, a needle-type plasma source powered by an AC power supply was used to generate CAAP for the production of RONS in plasma-activated water (PAW) and for the treatment of succinic acid (SA). The PAW was characterized using various analytical techniques to determine its physicochemical properties (pH, oxidation-reduction potential, electrical conductivity, and optical absorbance) and to identify RONS (•OH, H 2 O 2 , H 3 O + , NO 3 - , NO 2 - ) in the liquid phase. Quantitative analysis of •OH production was based on the presence of H 2 O 2 in PAW, and associated chemistry for •OH generation was explored. SA used as a probe compound, was treated directly with CAAP, and its mineralization rate was calculated. SA oxidation in water was used to detect the presence of •OH in the liquid phase. The results indicated that CAAP effectively degraded SA in water, achieving 46% mineralization. It was observed that the concentration of RONS increased significantly with longer treatment times and higher input plasma power. Energy consumption for RONS production in PAW was calculated, and the stability of RONS in PAW over a three-day period was measured. Additionally, the study investigated seed germination and plant growth using PAW, exploring its potential application as fertilizer in agriculture. The potential future steps for synergistic combination of CAAP with a pilot-scale continuous hydrodynamic cavitation process for treatment of wastewater containing OMPs are also discussed. • Cold atmospheric plasma generates RONS for wastewater micropollutant oxidation. • PAW was analyzed for physicochemical properties and RONS. • Succinic acid mineralization achieved 46% by direct plasma treatment. • Energy use, RONS stability, and agricultural potential of PAW were investigated. • Future synergy of plasma-cavitation processes for wastewater treatment discussed.