Oddelenie environmentálnej fyziky - Prihlásený: student
Katedra astronómie, fyziky Zeme a meteorológie, FMFI UK, Bratislava,

Solvation of Gaseous Nitrous Acid, Hydrogen Peroxide, and Ozone in the Bulk Water

Hassan M.E., Janda M., Machala Z.
Second International Conference on Advances in Plasma Science and Technology (ICAPST-21), Coimbatore, India - Virtual, May 27-29, p. 70 (2021)

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Abstrakt:

Atmospheric air plasmas created in contact with water generate “plasma-activated water” (PAW) containing various reactive oxygen and nitrogen species (RONS), e.g., hydrogen peroxide (H2O2), nitrate (NO3-) and nitrite (NO2-) anions, and ozone (O3), as well as other shortlived species. It has been reported by several groups that the PAW solutions are effective in killing and inactivating bacteria, having potential applications in biomedicine. PAW is considered as an example of the outcome of plasma-liquid interaction, where the RONS from plasma are transported into the water. The solvation potential of gases into liquids is given by Henry’s law solubility coefficient 𝑘𝐻 which describes the solubility of the gas species in liquids, e.g., water. Plasma long-lived RONS: H2O2, HNO2, and O3 have 𝑘𝐻 of ≈ 9 × 102, 4.8 × 10−1, and 10−4 mol m3 ⁄ Pa, respectively. It means that the solubility of RONS generated in the gas phase varies markedly and even if their gaseous concentrations are equal, concentrations achievable in the aqueous phase differ significantly. The transport mechanism of HNO2, H2O2, and O3 into the bulk water is investigated here. The comparison of highly soluble H2O2 with the medium and weakly soluble HNO2 and O3 species can lead to a better understanding of the transport mechanism of gaseous RONS into the water and will enable optimization of the plasma-liquid interaction systems. The concentration of the transported HNO2 into the water as (NO2-) is measured using the UV-Vis absorption spectroscopic technique. In the gas phase, HNO2 is partially decomposed into NO and NO2 (NOx). The concentration of HNO2 and NOx in the gas phase is measured using electrochemical gas sensors and the UV-Vis absorption spectroscopic technique. Due to the transport of HNO2 into the water (aqueous phase), there is a depletion in the gas phase. The theoretical highest decrease of HNO2 concentration in the gas is determined by Henry’s law coefficient. It was found out that the measured concentration of HNO2 in the bulk water is 3 orders of magnitude higher than that of O3. This result corresponds to the ratio of HNO2 and O3 Henry’s law coefficients.