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

The present work showed the role of plasma-forming gases (air, nitrogen (N-2), argon (Ar), helium (He), and their mixture with oxygen (O-2)) 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 O-2 in N-2, Ar and He plasma suppresses the emission lines intensity of NO. band in N-2 plasma, OH band in Ar and He plasma, and N-2 second positive system in He plasma. Also, adding O-2 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 O-2 showed improved physicochemical properties and RONS concentration in it compared to other plasma forming gases and their mixture with O-2. 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.

Automated summary

This study investigates the impact of plasma-forming gases on the properties of plasma-activated water (PAW) and characterizes the plasma and plasma radicals/species using electrical diagnosis and optical emission spectroscopy. The results show that different plasma-forming gases and plasma-water exposure time significantly affect the physicochemical properties and RONS concentration in PAW.