The role of different plasma forming gases on chemical species formed in plasma activated water (PAW) and their effect on its properties

Abstract

Abstract The present work showed the role of plasma-forming gases (air, nitrogen (N2), argon (Ar), helium (He), and their mixture with oxygen (O2)) on the properties of plasma-activated water (PAW). Electrical diagnosis and optical emission spectroscopy were performed to characterize plasma and identify plasma radicals/species. The PAW is characterized by studying its physicochemical properties and dissolved reactive oxygen-nitrogen species (RONS) concentration in it. The results showed introducing O2 in N2, Ar and He plasma suppresses the emission lines intensity of NOϒ band in N2 plasma, OH band in Ar and He plasma, and N2 second positive system in He plasma. Also, adding O2 to Ar and He plasma changes the plasma discharge characteristic from glow discharge to filamentary micro-discharge. The PAW prepared by air and its mixture with O2 showed improved physicochemical properties and RONS concentration in it compared to other plasma forming gases and their mixture with O2. In addition, increasing plasma-water exposure time significantly affects the physicochemical properties and RONS concentration in PAW. Therefore, plasma forming gas and plasma-water exposure time gives better control over the properties of PAW. Hence, these parameters play a significant role in deciding the applications of PAW.