Transport Mechanism of Chemical Species in a Pin-water Atmospheric Discharge driven by Negative Voltage

The influence of sodium carbonate on the decomposition of formic acid by discharge inside bubbles in water was investigated experimentally. Oxygen or argon gases were injected into the water through a vertically positioned glass tube, in which the high-voltage wire electrode was placed to generate plasmas at low applied voltage. The concentration of formic acid was determined by ion chromatography. In the case of sodium carbonate additive, the pH increased owing to the decomposition of the formic acid. In the case of oxygen injection, the percentage of conversion of formic acid increased with increasing pH because the reaction rate of ozone with formic acid increased with increasing pH. In the case of argon injection, the percentage of conversion was not affected by the pH owing to the high rate loss of hydroxyl radicals.

Section: Argon Injectionmentioning

confidence: 98%

Influence of sodium carbonate on decomposition of formic acid by pulsed discharge plasma inside bubble in water

Iwabuchi

Takahashi

Takaki

et al. 2016

“…9, since such a flow was observed when a pulsed plasma was generated over the water surface. 20,22) The simulation was conducted in three steps. First, the distributions of the electron density and the reaction rates of the electron-impact reactions during the application of pulsed voltage were obtained.…”

Section: Model Descriptionmentioning

confidence: 99%

“…In addition to the decomposition of organic compounds, many experimental studies have been conducted to understand important physical and chemical processes such as water evaporation, 16) electron and ion irradiation to a liquid surface, 17,18) 1OH generation in a gas phase, 19) the dissolution of 1OH, 20) postdischarge chemistry in a liquid phase, 21) and the generation of a liquid-phase flow. 20,22,23) However, it is difficult to fully understand the overall processes with only experimental work because it is impossible to measure the time and space distributions of all the species involved. Therefore, numerical simulation is a powerful tool to improve the understanding of plasmas in contact with a liquid.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the loss mechanisms of hydroxyl radicals in the decomposition of organic compounds using plasma generated over water

Takeuchi¹,

Ando²,

Yasuda³

2015

Many types of plasma processes have been investigated as potential agents for decomposing persistent organic compounds in water using hydroxyl radicals (∙OH), and a wide range of energy efficiency in the reduction of total organic carbon (TOC) has been observed. In this study, loss mechanisms of ∙OH that limit the energy efficiency were investigated using a plasma generated over an acetic acid solution. Various experiments, including the analysis of the decomposition process, a parametric study, and a numerical simulation, revealed that there are two main loss mechanisms: (i) a self-quenching reaction that generates hydrogen peroxide (H2O2) and (ii) a reaction of ∙OH with H2O2 and hydroperoxyl radicals (HO2∙). In the solution, ∙OH reacts with these scavengers rather than target compounds. A pulsed plasma with a low current density, low repetition rate, and short pulse duration can be utilized to achieve high efficiency.

“…Therefore, some sort of liquid flow is necessary to exchange the chemicals in the thin surface layer of a liquid for the promotion of efficient reactions. 23,24) In a dc corona discharge or a dc glow discharge in contact with a liquid, the ion wind will promote the liquid flow in the direction parallel to the liquid surface. In our previous research, we observed the generation of a specific downward liquid flow immediately below the dc glow discharge in contact with the liquid during metallic nanoparticle synthesis.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of liquid flow induced by atmospheric-pressure DC glow discharge in contact with liquid

Tochikubo

Aoki

Shirai

et al. 2017

In this work, we investigated the characteristics of liquid flow induced by atmospheric-pressure dc glow discharge in contact with a liquid. The spatiotemporal development of liquid flow was visualized by the schlieren method, and the temperature distribution was measured using microencapsulated thermotropic liquid crystal particles dispersed in a liquid. We confirmed the appearance of specific downward liquid flow immediately below the dc glow discharge. The characteristics of downward liquid flow were reproduced by fluid simulation considering a downward driving force at the plasma–liquid interface. Our results suggest that the probable driving force for the downward liquid flow was the momentum transfer of charged species at the liquid surface.