The influence of liquid conductivity on electrical breakdown and hydrogen peroxide production in a nanosecond pulsed plasma discharge generated in a water-film plasma reactor

Abstract

The influence of liquid conductivity on electrical breakdown and hydrogen peroxide (H2O2) production in a nanosecond pulsed filamentary discharge generated in a water film plasma reactor was investigated over the liquid conductivity range from 0.01 mS cm−1 to 36 mS cm−1 by adding KCl to deionized (DI) water and using helium and argon as carrier gases. The plasma properties, including electron density, gas temperature, and plasma volume, the H2O2 production rate and energy yield, and the energy dissipation into the liquid were determined at different liquid conductivity. The energy dissipation into the bulk liquid increased as the liquid conductivity increased causing the total input energy to increase and resulting in a small decrease in H2O2 energy yield. In addition, the production rate of H2O2 did not change significantly with conductivity for the helium plasma but decreased about 13 percent in the argon plasma. The energy deposited in the helium plasma did not change with conductivity, thereby causing the H2O2 energy yield based upon energy in the plasma to be constant with conductivity. A model based upon the electrical circuit was used to predict the breakdown voltage for a range of liquid conductivity up to 36 mS cm−1. This model also showed that decreasing the rise time of the applied voltage (i.e. faster rising rate) significantly increased the breakdown voltage, and therefore improved the liquid conductivity tolerance of the plasma system allowing it to function at near sea-water conductivity.

Microwave Plasma Jet in Water: Effect of Water Electrical Conductivity on Plasma Characteristics

“…Meanwhile, wastewater has a wide range of electrical conductivity (e.g., up to 30 mS/cm for ballast water [4]), and the degradation of pollutants by plasma under such high conductivity conditions is not investigated. Moreover, the efficiency of direct electrical discharges in water is highly reduced as water conductivity is augmented [14], [16]. In this regard, to maintain a generation of a plasma in a conductive media, advanced technology is usually needed, e.g., high-voltage source with very fast rising time [14], although electrode erosion is always manifesting once it is in contact with plasma.…”

“…Moreover, the efficiency of direct electrical discharges in water is highly reduced as water conductivity is augmented [14], [16]. In this regard, to maintain a generation of a plasma in a conductive media, advanced technology is usually needed, e.g., high-voltage source with very fast rising time [14], although electrode erosion is always manifesting once it is in contact with plasma. Very recently, a MWPJ in TIAGO (Torche à Injection Axiale sur Guide d'Onde, in French) configuration has been studied and it shows very high potential to remove organic pollutants from water at high conductivity [30].…”

“…These can be classified into two categories: thermal (high temperature for all species-thousands of degrees kelvin) and non-thermal (high temperature for electrons-thousands of degrees kelvinand low temperature for neutrals and ions-hundreds of degrees kelvin) [11]. Such (thermal and non-thermal) plasma sources can be powered using direct current (DC) [12], alternative current (AC) [13], and pulsed power [14] electrical excitation, as well as high-frequency electromagnetic fields (microwave and radio frequency) [15] and lasers [16]. Some plasma sources utilize electrodes, such as corona discharge, dielectric barrier discharge, spark, and arc discharge, whereas others are electrodeless, such as radio frequency and microwave discharge that use induced-field, antenna, or wave guide for coupling the power to a gas flowing in a dielectric tube.…”

“…They also showed that, as liquid conductivity is increased from 1 to 700 µS/cm, the breakdown voltage is decreased from ~11 to 1 kV and the electron density is decreased from ~10×1020 to 3×1020 m-3. Recently, Wang et al [14] have investigated the influence of liquid conductivity (by adding KCl), in the range 10-36000 µS/cm, on the properties of a nanosecond pulsed discharge in bubbled water (the used gases are He or Ar). They showed that the production rate of H2O2 was not significantly changed with liquid conductivity when He gas is used, however, it decreased by ~13% when Ar gas is used.…”

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

“…[ 8 ] As such, it is well‐accepted that the electrical characteristics and physiochemical properties of the plasma directly determine the type and concentration of aqueous RONS, thus regulating the bioactivities of plasma‐activated water. In the gas–liquid discharge, the plasma characteristics are affected by various factors [ 9–11 ] of which the type of working gas is one of the most critical.…”