Characterization of a Multiple Bubble Jet With a Streamer Discharge

Plasma Chem Plasma Process

Niinuma

Shinoki

et al. 2015

Self Cite

The oxidation potential of ozone (2.07 V) is not sufficient to achieve the efficient decomposition of persistent organic pollutants in the conventional water treatment process. Strong oxidizing agents such as OH and O radicals (oxidation potential 2.80 and 2.42 V, respectively) were successfully generated using multiple bubble jets with pulsed electrical discharge and used for the decomposition of acetic acid (CH 3 COOH), as a model pollutant. The flow dynamics of this novel water treatment process was clarified experimentally. The dynamic behavior of bubble jets with pulsed electrical discharge, streamer propagation along the bubble interface, and radical generation were investigated by highspeed visualization and spectroscopic measurements. The decomposition characteristics of CH 3 COOH were determined such as applied frequency, the duty ratio of applied voltage, gas flow rate, the initial CH 3 COOH concentration to achieve the maximum decomposition of CH 3 COOH, and higher energy efficiency compared to the previous electrical discharge gas-liquid processes.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decomposition of Acetic Acid Using Multiple Bubble Jets with Pulsed Electrical Discharge

Plasma Chem Plasma Process

Niinuma

Shinoki

et al. 2015

Self Cite

“…The flow rate of argon is totally 4.0 Sℓ/min. The decolorization is completely achieved in 30 min by OH radical with strong oxidization potential and the H 2 O 2 (15) . Figure 10 shows the effect of swirling of the argon and oxygen bubble jets on the time evolution of the normalized concentration of methylene blue solution.…”

Section: Decolorization Characteristicsmentioning

confidence: 99%

“…In the present study, a multiple bubble jet system encapsulating O 3 in small bubbles, O and OH radicals generated by a DC pulsed discharge was successfully constructed for decolorizing a methylene blue solution (12)- (15) . Bubble jet dynamics with luminescence and complex streamer behavior inside an argon bubble were successfully visualized.…”

Section: Introductionmentioning

confidence: 99%

Characterization of DBD Multiple Bubble Jets for Methylene Blue Decolorization

Niinuma

Takana

2013

JFST

Self Cite

The discharge characteristics and bubble dynamics of argon multiple bubble jets, in which a streamer is generated by a DC pulsed discharge, have been experimentally clarified through visualization analysis. The decolorization characteristics of a methylene blue solution and the properties of a treated solution using multiple bubbles jets, including argon, oxygen and air, have also been clarified. There is complex streamer behavior in a bubble in which streamer propagation is along the interface of an issuing bubble. O and OH radicals during streamer discharge in Ar and O 2 bubbles were detected clearly near the interface of a breaking up bubble by spectroscopic measurement. Finally, the decolorization efficiency by O and OH radicals and ozone in a pulsed discharge multiple bubble jets are estimated.

“…Although the life times of free radicals are very short, OH and O radicals are still of interest because they have higher oxidation potentials than ozone. Therefore, many types of discharge in contact with water such as direct discharge in water [4,5], above water [6], in bubbles [7,8], and spraying water into a discharge [9,10], are studied to utilize these free radicals for water treatment. Because high voltage is needed to breakdown water, attention has been paid to discharge in gas-liquid two-phase flow systems with the aim of overcoming this barrier.…”

Section: Introductionmentioning

confidence: 99%

Acetic Acid Decomposition in a Coaxial Dielectric Barrier Discharge Tube with Mist Flow

Shibata

Plasma Chem Plasma Process

2014

Self Cite

Non-thermal plasmas can be used for water treatment system because they allow free radical generation without heating. Advanced oxidation processes using nonthermal plasmas have been developed to decompose persistent organic pollutants. In this study, a water treatment method that involves spraying a solution into a coaxial dielectric barrier discharge (DBD) tube using an air, argon or oxygen carrier gas was investigated. The alumina DBD tube had an inner high-voltage electrode and an outer ground electrode. Acetic acid was used as the decomposition target because acetic acid is a known persistent organic material. An acetic acid solution, diluted 10,000 times in purified water, was atomized by an ultrasonic atomizer unit and introduced into the DBD tube. The residence time of the droplets sprayed into the discharge area was almost 7 ms. Acetic acid was effectively decomposed and the decomposition ratio reached almost 80 % when Ar was employed as the carrier gas. This is due to the very fine droplets in the sprayed mist having a large specific surface area and OH radicals being able to react directly in solution. Furthermore, the results suggest that the chemical processes involved in acetic acid decomposition can be controlled by varying the carrier gas composition.