# Water Modification by Cold Plasma Jet with Respect to Physical and Chemical Properties
## Appendix A
[PERSON] et al. [66] investigated the mutual interaction between the plasma and plasma treated water, using a pin-to-liquid discharge system. It was found that plasma treated water affects not only the chemical properties but also the physical properties of the plasma, such as the breakdown voltage and the concentration of the plasma column. The decrease of the liquid surface tension of plasma treated water due to nitric oxide electrolyte ion from the plasma resulted in the increase of plasma current onto the surface of plasma treated water and vice versa. It was claimed that the feedback process is continued until the transition from normal discharge to abnormal discharge takes place. [PERSON] et al. [55] presented the combination of a 0D chemical kinetics and a 2D fluid dynamics model to investigate the plasma treatment of a buffered water solution with the kINPen(r) plasma jet. Using this model, they calculated the gas and liquid flow profiles and the transport and chemistry of all species in the gas and liquid phases. Moreover, they evaluated the stability of the reactive oxygen and nitrogen species after plasma treatment. They found that of all species, only H\({}_{2}\)O\({}_{2}\), HNO\({}_{2}\)/NO\({}_{2}^{-}\) and HNO\({}_{3}\)/NO\({}_{3}^{-}\) are stable in the buffered solution after plasma treatment. This is because both their production and loss processes in the liquid phase are dependent on short-lived radicals (e.g., \"OH, NO\", and \"NO\({}_{2}\)). [PERSON] et al. [56] studied the interaction of an argon microwave plasma jet with a benzene layer on water. They found that the main products formed upon treatment were phenol, catechol, and nitrobenzene, proving that the jet was a source of radicals \"OH and \"NO\({}_{2}\), inducing benzene oxidation and nitration. [PERSON] et al. [67] investigated the formation of aqueous hydrogen peroxide (H\({}_{2}\)O\({}_{2 aq}\)) in a DC discharge plasma-liquid system with liquid as the anode. The theoretical analysis and experimental results showed that the H\({}_{2}\)O\({}_{2 aq}\) formation process was mostly controlled by the aqueous electron-induced reactions in the liquid zone directly affected by the plasma. It was shown that the low H\({}_{2}\)O\({}_{2 aq}\) yield in this system was caused by quenching the dissolved OH radicals through aqueous electrons and alkalization in the plasma-directly-affected liquid zone. [PERSON] et al. [57] stated that multiphase transfer of \"OH radicals is highly transport limited and, to overcome transport limits, the plasma activation of aerosols, small liquid droplets interspersed in the plasma, has been proposed. Thus, they reported a combined experimental and modeling study of a controlled plasma-droplet interaction experiment using a diffuse RF glow discharge in He:0.2%H\({}_{2}\)O with detailed plasma diagnostics, ex-situ analysis of the plasma induced chemistry in the droplet containing formate, droplet trajectory, and size measurements. This enabled a quantitative study of the reactivity transfer of OH from the gas phase plasma to the liquid phase and how its diffusion limitations impact formate decomposition in the water droplet. For a droplet with a diameter of 36 \(\upmu\)m, they observed 50% reduction in formate concentration in the droplets after plasma treatment for droplet residence times in the plasma of about 10 ms. These short droplet residence times in the plasma allowed, in some cases, for droplet size reductions of about 5% in spite gas temperatures of 360 K. A one dimensional reaction-diffusion model was used to calculate the OH transport and formate oxidation inside the droplet and was able to predict the conversion of formate by plasma in a droplet without any fitting parameters. The model further showed that formate conversion is dominated by near-interfacial reactions with OH radicals and is limited by diffusion of formate in the droplet. [PERSON] et al. [68] realized two distinct discharge compositions by modifying the location of the ground electrode in a pin-to-liquid plasma system.