On the Possibilities of Straightforward Characterization of Plasma Activated Water

Abstract

Plasma activated deionized water from a hot arc 150 W PAW synthesizer has been analyzed for nitrite, nitrate and peroxide densities. Observed nitrite and nitrate levels are impressive, reaching several millimoles per liter at few hundred kiloJoules per liter energy input. Nitrate levels appear positively influenced by the applied energy density, together with a less pronounced increase in nitrite levels and limiting energy density for maximum peroxide levels. Active PAW cooling during synthesis appears to be essential for obtaining relevant peroxide levels and connected PAW activity. In addition to established laboratory diagnostics, alternative low access tools have been investigated for applicability of PAW characterization in offlab situations. Although no unique parameter exists to properly represent PAW activity, pH, oxidizing-reduction potential and electrical conductivity provide important insight, together with aqueous phase nitrite absorption spectrometry. Finally, classic acid-base titration has been applied to find access to the complex mixture of acidic reactive nitrogen species. Keywords Plasma activated water • Reactive oxygen species (ROS) • Reactive nitrogen species (RNS) • Reactive oxygen and nitrogen species (RONS) • Wet chemical analysis • Atmospheric plasma liquid interaction • Pulsed power plasma technology

Plasma‐activated water: Physicochemical properties, microbial inactivation mechanisms, factors influencing antimicrobial effectiveness, and applications in the food industry

“…When plasma interacts with water, it triggers dynamic chemical reactions and forms a series of aqueous reactive species. Several techniques have been used currently to identify and quantify the reactive species generated in plasma‐treated liquids, including electron paramagnetic resonance (EPR), UV‐vis spectrophotometry, chemical dosimetry, liquid chromatography in addition to colorimetric and fluorescence method (Griess reagent, nitrate assay kit, titanium (IV) oxysulfate, amplex red hydrogen peroxide [H 2 O 2 ] assay kit) (Hoeben et al., 2019; Jo, Joh, Chung, & Chung, 2020; Kučerová, Machala, & Hensel, 2020; Pandiyaraj et al., 2020; Xu et al., 2020). While laser‐induced fluorescence (LIF), Fourier‐transform infrared (FTIR) spectroscopy, mass‐spectrometry, and gas sensors or analyzers are used for product detection in the gas phase (Gorbanev & Bogaerts, 2018; Khlyustova et al., 2019).…”

Antimicrobial Effect of Plasma-Activated Tap Water on Staphylococcus aureus, Escherichia coli, and Candida albicans

“…The differences in the susceptibility of C. albicans to PAW, when compared to bacterial species, can be correlated to other cellular components, notably the fungal cell wall that presents several peculiarities [61]. The antimicrobial effect of PAW has been correlated with reactive oxygen and nitrogen species [62]. Oxidizing species are formed in aqueous solutions and can vary No significant reduction in the C. albicans count was detected after contact with PAW or distilled water with pH 3.5 (p > 0.05) exposed for 10 or 30 min periods (Figure 9).…”

Microsecond pulse gas–liquid discharges in atmospheric nitrogen and oxygen: Discharge mode, stability, and plasma characteristics

“…Reactive oxygen and nitrogen species (RONS) are recognized as the origin of the observed biochemical activity of gas–liquid discharges [ 6,7 ] ; therefore, it is necessary to control and regulate the type and concentration of RONS in the aqueous solution for different biotech applications. Generally, the aqueous RONS are directly derived from the gaseous plasma or via the plasma‐water reactions at the interface of gas and liquid phases.…”