Modulating the concentrations of reactive oxygen and nitrogen species and oxygen in water with helium and argon gas and plasma jets

Abstract

We employed UV–vis spectroscopy to monitor real-time changes in the oxygen tension and concentration of reactive oxygen and nitrogen species (RONS) in deionized (DI) water during treatments with helium (He) and argon (Ar) gas plasma jets. He and Ar gas jets are both shown to de-oxygenate DI water with He being more efficient than Ar, whilst the plasma jets deliver and regulate the concentrations of hydrogen peroxide (H2O2), nitrite (NO2−) and nitrate (NO3−) in DI water. The H2O2 and NO3− production efficiency varied between He and Ar plasma jets, but was similar for NO2−. Whilst DI water fully equilibrated with ambient air prior to treatment (de-oxygenated by both plasma jets) when DI water was first de-oxygenated by an inert gas jet treatment, both plasma jets were found to be capable of oxygenating DI water. These insights were then used to show how different combinations of plasma jet and inert gas jet treatments can be used to modulate O2 tension and RONS chemistry. Finally, potential further improvements to improve control in the use of plasma jets in regulating O2 and RONS are discussed.

Direct Treatment of Liquids Using Low-Current Arc in Ambient Air for Biomedical Applications

“…The observed concentrations were two orders of magnitude higher than those of 5 mL DI water treated for 1 min with commercially available NEAPPJ operated with He (0.37 mg/L of H2O2, 0.18 mg/L of NO2 − , and 0.06 mg/L of NO3 − ). Additionally, considerably small concentrations of RONS in water treated using NEAPPJ (up to 890 µg/L of H2O2, up to 180 µg/L of NO2 − , and up to 410 µg/L of NO3 − ) [20][21][22]45,46] and custom plasma jets operated with air or addition of air (up to 9.3 mg/L of H2O2, up to 4 mg/L of NO2 − , and up to 5.5 mg/L of NO3 − ) [14,28,47,48] were reported elsewhere, confirming the high efficiency of the developed AALCA as compared with commonly used nonequilibrium plasma jets.…”

“…Typically, low-temperature nonequilibrium atmospheric pressure plasma jets (NEAPPJs) or dielectric barrier discharges (DBDs) are used for activation of liquids by plasma [5,[12][13][14][15][16]. However, in both the case of atmospheric pressure plasma jet (APPJ) and DBD, the production rate of reactive oxygen and nitrogen species (RONS), which play key roles in bactericidal effect and plant growth promotion, is low and irradiation of the liquid takes a long time (from several minutes to hours) due to the low density of the plasma [5,[12][13][14][15][16][17][18][19][20][21]. Moreover, in most cases, plasma is generated using pure gases (e.g., argon, helium, or oxygen) at a high voltage, so a substantial amount of electrical energy is required to sustain the discharge and only a limited volume (typically several milliliters) of medium can be treated at one time [4,7,17,[19][20][21][22].…”

Scalable Treatment of Flowing Organic Liquids Using Ambient-Air Glow Discharge for Agricultural Applications

“…In most cases, low-temperature nonequilibrium atmospheric-pressure plasma jets (NEAPPJs) or dielectric barrier discharges (DBDs) are used for liquid treatments. However, in the case of NEAPPJ, the production rate of reactive oxygen and nitrogen species (RONS) is low, which plays a key role in the bactericidal effect and plant-growth promotion, and liquid irradiation takes a long time (from several minutes to several hours) due to the low density of the plasma [32][33][34][35]. A high-density nonequilibrium atmospheric-pressure radical source (NEAPRS), reported elsewhere, allowed the problem of low RONS concentration appearing in the case of APPJ to be solved [14,18,36].…”

“…A high-density nonequilibrium atmospheric-pressure radical source (NEAPRS), reported elsewhere, allowed the problem of low RONS concentration appearing in the case of APPJ to be solved [14,18,36]. However, noble gases and high voltages are typically required for plasma generation in the case of NEAPRS (as well as in the case of NEAPPJ), and a substantial amount of electrical energy is required to sustain the discharge, when only a limited volume (typically several milliliters) of the medium can be treated at one time [18,[32][33][34][35][36][37][38][39]. Low energy efficiency, the requirement of noble gases, and the limited volume of liquid that can be treated make a plasma-activated medium (PAM) expensive, and its use in practical agriculture applications impossible [18].…”

Оптическое Излучение Плазменных Струй Атмосферного Давления, Возбуждамых Барьерным Разрядом

“…В последнее время все большее внимание стали привлекать к себе плазменные струи атмосферного давления, которые формируются разными электрическими разрядами, как, например, в работах [1][2][3][4][5][6][7]. Такой способ формирования плазмы практически не приводит к нагреву ее газовой составляющей, в результате чего температура газа в плазме остается на уровне комнатной, а такую плазму называют " холодной".…”