Abstract:203With the glow discharge burning with the electrolyte cathode, there is observed the transfer of both solvent and solutes into the gas phase. The investigation of the kinetics of such nonequilibrium evaporation of a solvent was conducted previously and the accumulation in the condensate of ions of potassium, chlorine, nitrite, and nitrate carried from the solution was proved experimentally [1,2].The study of the solute transfer by comparison of the absorption spectra of the condensate and the initial solutio… Show more
“…During the generation of PAW, the penetration of particles from the discharge areas into the liquid depends on the potential difference between the plasma and liquid. The dependencies of the mass transfer on the electrical parameters between the gas and liquid phases of an atmospheric air pressure DC discharge have been studied previously [33][34][35][36][37]. As opposed to DC excitation, AC excitation causes positive and negative to change places during a discharge.…”
Plasma-activated water (PAW) represents a promising green antibacterial agent for biomedical and agricultural applications. In this study, a novel AC multi-needle-to-water discharge device was developed to investigate the effects of gas flow on the generation and chemical composition of PAW. It is shown that the concentrations of
NO
3
−
and N(III) (
NO
2
−
and
HN
O
2
) in the PAW both increased with an extension of the plasma-processing time and a reduction of the gas-flow rate. The absorption of gas-phase products carried by the gas flow from the discharge chamber was found to be beneficial for the generation of both
NO
3
−
and N(III) in the PAW at a gas flow rate of 20–60 L h−1, yet their concentrations were still lower than those without any feeding gas. As opposed to
NO
3
−
or N(III), the
H
2
O
2
concentration in the plasma-activated phosphate buffer solution (PAPBS) increased under stronger gas flows and was almost unaffected by absorption in PAPBS. The pH value of PAW increased at higher gas flow rates. A comparison of the N(III) in PAW and PAPBS reflects the effects of the reactions of
NO
2
−
and
H
2
O
2
in the two different working liquids. To quantify the effects of gas flow on the discharge characteristics, gas temperatures were calculated from the optical emission spectra and were proven to be flow-independent near the discharge channel. Fourier transform infrared (FTIR) measurements of the gaseous products during the discharge, and further analysis of possible reaction pathways indicated that by controlling the gas flow in the multi-needle-to-water discharge system, the concentration of long-lived species in PAW could be tuned, which might favor the generation of
ONOOH
.
These findings contribute to a better understanding of effective electric discharge-related mechanisms for enhancing the biochemical and chemical activities of PAW.
“…During the generation of PAW, the penetration of particles from the discharge areas into the liquid depends on the potential difference between the plasma and liquid. The dependencies of the mass transfer on the electrical parameters between the gas and liquid phases of an atmospheric air pressure DC discharge have been studied previously [33][34][35][36][37]. As opposed to DC excitation, AC excitation causes positive and negative to change places during a discharge.…”
Plasma-activated water (PAW) represents a promising green antibacterial agent for biomedical and agricultural applications. In this study, a novel AC multi-needle-to-water discharge device was developed to investigate the effects of gas flow on the generation and chemical composition of PAW. It is shown that the concentrations of
NO
3
−
and N(III) (
NO
2
−
and
HN
O
2
) in the PAW both increased with an extension of the plasma-processing time and a reduction of the gas-flow rate. The absorption of gas-phase products carried by the gas flow from the discharge chamber was found to be beneficial for the generation of both
NO
3
−
and N(III) in the PAW at a gas flow rate of 20–60 L h−1, yet their concentrations were still lower than those without any feeding gas. As opposed to
NO
3
−
or N(III), the
H
2
O
2
concentration in the plasma-activated phosphate buffer solution (PAPBS) increased under stronger gas flows and was almost unaffected by absorption in PAPBS. The pH value of PAW increased at higher gas flow rates. A comparison of the N(III) in PAW and PAPBS reflects the effects of the reactions of
NO
2
−
and
H
2
O
2
in the two different working liquids. To quantify the effects of gas flow on the discharge characteristics, gas temperatures were calculated from the optical emission spectra and were proven to be flow-independent near the discharge channel. Fourier transform infrared (FTIR) measurements of the gaseous products during the discharge, and further analysis of possible reaction pathways indicated that by controlling the gas flow in the multi-needle-to-water discharge system, the concentration of long-lived species in PAW could be tuned, which might favor the generation of
ONOOH
.
These findings contribute to a better understanding of effective electric discharge-related mechanisms for enhancing the biochemical and chemical activities of PAW.
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