Tuning the ONOOH of plasma-activated water: Effect of the N2/O2 ratio and post-discharge duration

Plasma activated water (PAW) contains a variety of reactive oxygen and nitrogen species (RONS). Among them, ONOOH has an impact on the activity and function of cells in the biological system, and also has a pharmacological inhibitory on many human diseases. However, since ONOOH in PAW is a transient species that is difficult to determine, most of the current research is still mainly focused on its determination or basic applications. There is no in-depth study and discussion on its regulation mechanism. Therefore, this research mainly investigates the two aspects mentioned above. In this study, the dielectric barrier discharge (DBD) is used to treat phosphate buffer solution (PBS) for preparing PAW. The effect of different gas ratios of N2 to O
2
on the product characteristics and the lifetime of ONOOH with its precursors is studied, and the pH value of the solution is also tested. The result shows that the maximum yield of ONOOH is at a gas ratio of N2:02=6:4. Then, PAW prepared under different conditions is preserved, in which the products are detected on the different periods. The result shows that the concentration of ONOOH rises briefly after the treatment with the gas ratio of N2:02= 9:1, 8:2 and 7:3, which indicates that the generation of ONOOH can be more than the consumption under these conditions at 0–15 minutes.