Aqueous reactive species induced by a surface air discharge: Heterogeneous mass transfer and liquid chemistry pathways

Abstract

Plasma-liquid interaction is a critical area of plasma science and a knowledge bottleneck for many promising applications. In this paper, the interaction between a surface air discharge and its downstream sample of deionized water is studied with a system-level computational model, which has previously reached good agreement with experimental results. Our computational results reveal that the plasma-induced aqueous species are mainly H+, nitrate, nitrite, H2O2 and O3. In addition, various short-lived aqueous species are also induced, regardless whether they are generated in the gas phase first. The production/loss pathways for aqueous species are quantified for an air gap width ranging from 0.1 to 2 cm, of which heterogeneous mass transfer and liquid chemistry are found to play a dominant role. The short-lived reactive oxygen species (ROS) and reactive nitrogen species (RNS) are strongly coupled in liquid-phase reactions: NO3 is an important precursor for short-lived ROS, and in turn OH, O2− and HO2 play a crucial role for the production of short-lived RNS. Also, heterogeneous mass transfer depends strongly on the air gap width, resulting in two distinct scenarios separated by a critical air gap of 0.5 cm. The liquid chemistry is significantly different in these two scenarios.

Nonthermal Plasma–Liquid Interactions in Food Processing: A Review

“…Water is a polar liquid and its conductivity changes when exposed to high voltage (Šunka, ), thus making the application of NTP to a wet surface or a liquid substrate a more complicated process (Bruggeman et al., ; Liu et al., ). It has been reported that the inactivation of microorganisms by plasma in a liquid substrate is mediated by the liquid phase and it is important to understand the complete NTP–liquid interactions to optimize food and medical applications (Bruggeman et al., ; Liu et al., ). Presence of humidity in the carrier gas also leads to modifications in the reactive species of the NTP system and acts as a barrier for the NTP reactive species to penetrate within the liquid substrate (Gorbanev, O'Connell, & Chechik, ; Krohmann et al., ).…”

“…After exposing to the gas plasma, the reactive species in the liquid initiate many postdischarge reactions within the liquid. The liquid chemical reaction pathways and the diffusion coefficients of NTP reactive species in the liquid phase are presented in Figure (Liu et al., ; Verlackt, Van Boxem, & Bogaerts, ) and Table , respectively. In Figure , the blue lines indicate the diffusion process, whereas the black lines represent the chemical reactions.…”

Promoting lentil germination and stem growth by plasma activated tap water, demineralized water and liquid fertilizer

“…One advantage of direct treatment is that the short-lived species such as O, OH, NO, and even the electric field or UV produced by the plasma [11,12] could be possibly effective; some reports indicate this type of plasma treatment could enhance or modify the germination and/or growth of the oilseed rape seeds [13], bean and wheat seeds [14][15][16]. Direct plasma treatments on tomato, radish and mulungu gave also positive effects [17][18][19][20].…”

Synergistic Effect of Atmospheric-pressure Plasma and TiO2 Photocatalysis on Inactivation of Escherichia coli Cells in Aqueous Media

“…To date, most of the studies have focused on the activity of species generated in the gas phase, however, the lifetime of chemical species generated in the gas phase is relatively short, as they are quenched rapidly during their frequent collisions with molecules or other species. High reactivity and short lifetime also means that only a fraction of the species generated during plasma treatment are able to penetrate the gas−liquid interface to reach the intended target4, potentially limiting the efficiency of gas phase plasma inactivation against microorganisms in a moist environment or in bulk liquids.…”