Physicochemical Properties and Time Stability of Plasma Activated Water by a Liquid-Cathode Glow-Type Discharge in Air: The Effect of Air Confinement.
Date
2023
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Abstract
Nonthermal discharges in atmospheric pressure air
in contact with water produce large amounts of reactive species in the gas phase that can enter into the water by diffusion, thus inducing the formation of secondary reactive species in the
liquid phase, including those long-lived species such as NO2
NO3, and H2O2. Depending on the controllable parameters of the discharge, the plasma activated water (PAW) may acquire differ 8 ent physicochemical properties, resulting in various applications.
Physicochemical measurements of PAW obtained by means of a
water-cathode glow-type discharge in atmospheric pressure air
operating in open and closed reactor conditions are reported.
The discharge was operated in a millisecond pulsed-dc regime
at an rms current value of 100 mA and a power of 100 W.
A large volume of 1 L of distilled water was treated for 30 min.
In both cases, low pH values of ∼2.5 and very high levels of
NO3(up to 250 mg/L) in PAW were obtained; however, in the
closed system, no H2O2 was found and high concentrations of
nitrite (120 mg/L) were measured, while in the open system,
large levels of H2O2 were observed (45 mg/L) and no NO 2 was
found. Likewise, the electrical conductivity value for the closed
reactor (≈2000 µS/cm) was significantly higher than for the open
reactor (≈1000 µS/cm). The reasons for these different behaviors
in terms of PAW chemistry are discussed. Also, the time stability
of PAW was measured.
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Keywords
Nonthermal discharges., Plasma activated water (PAW)., Reactive species in water.
Citation
IEEE TRANSACTIONS ON PLASMA SCIENCE
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