Spectroscopic measurements of discharges inside bubbles in water

Miichi, Tomoaki; Ihara, Satoshi; Satoh, Saburoh; Yamabe, Chobei

doi:10.1016/s0042-207x(00)00275-x

Cited by 50 publications

(23 citation statements)

References 2 publications

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“…This type of reactor with artificially produced bubbles has an advantage of significantly reducing of the input power because of absence of Joule heating of liquid medium. Additionally, this discharge can be initiated by DC voltage with much lower voltage compared to direct liquid phase discharge (10)(11). Reducing the rate of erosion of electrode is another advantage of this type of reactor.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Peroxide Generation by DC and Pulsed Underwater Discharge in Air Bubbles

Xiong

Nikiforov

Vanraes

et al. 2012

Journal of Advanced Oxidation Technologies

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Abstract:The generation of H 2 O 2 in underwater discharge in air bubbles is studied with consideration of the influence of electrodes polarity, input power, solution conductivity and the inter-electrode distance. The efficiency of hydrogen peroxide generation strongly depends on the polarity, input power and the inter-electrode distance. Discharges in air bubbles with water as a cathode have significantly higher energy yield of hydrogen peroxide in comparison with negative DC or pulsed discharges. The generation of hydrogen peroxide by DC discharge increases with decrease in the inter-electrode distance, but it is opposite for pulsed discharges. Different efficiency of H 2 O 2 production is explained based on physical processes which result to formation of OH radicals.

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Section: Introductionmentioning

confidence: 99%

Hydrogen Peroxide Generation by DC and Pulsed Underwater Discharge in Air Bubbles

Xiong

Nikiforov

Vanraes

et al. 2012

Journal of Advanced Oxidation Technologies

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“…There are difficulties in the multi-pin electrode case due to as the difficulty of evenly distributing the electric input to each electrode which causes an intermittent discharge and requirements for a high power input to initiate the discharge. In order to further utilize the liquid phase discharge treatment without the disadvantages mentioned above (the high energy and electric field requirements and the needle electrode erosion), another method of externally introducing or thermally generating gas/vapor phase bubbles through the gap between two electrodes in the liquid phase has been investigated under several different setups [38][39][40][41][42][43][44][45]. A detailed review of these apparatus can be found in a previous literature review [14].…”

Section: Introductionmentioning

confidence: 99%

“…A detailed review of these apparatus can be found in a previous literature review [14]. The discharge could be initiated within the added gas bubbles that have a much lower initiation voltage compared to direct liquid phase discharge [32,38].…”

Section: Introductionmentioning

confidence: 99%

Chemical and Physical Characteristics of Pulsed Electrical Discharge Within Gas Bubbles in Aqueous Solutions

Shih¹,

Locke²

2009

Plasma Chem Plasma Process

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The chemical and physical characteristics of pulsed electrical discharge within gas bubbles immersed in an aqueous solution were investigated using a reactor with long protrusion length high voltage needle electrodes. Argon gas was introduced at the base of the needle electrode causing gas bubbles to flow upwards in contact with the needle. The effects of needle protrusion length were evaluated by using 2, 4, and 6 cm length needles under a wide range of power input (3-78 W). No significant differences in chemical or electrical characteristics were found among the different protrusion lengths. H 2 and H 2 O 2 generation rates were proportional to input power and the energy yield efficiency for these species was not affected dramatically by input power. The results of discharge within bubbles in aqueous solution were also compared with those for direct liquid phase discharge and gas phase discharge above the liquid surface.

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“…7 Maximum size and temperature versus irradiation power during and after microwave irradiation (high power) because gas was soon dissolved by the self-pressuring effect of nano-bubbles (bubble contraction) [9]. Microwave energy is stored by nano-bubble formation, and free radicals, which are highly reactive, are released by bubble collapse caused by further self-pressuring [10]. These behaviors should be related with non-equilibrium local heating [11] or super heating [12].…”

Section: Microwave Power [W]mentioning

confidence: 99%

Observation of bubble formation in water during microwave irradiation by dynamic light scattering

2015

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and composites in the field of hydrothermal synthesis, as well as emulsion polymerization for nano-particles with a monodisperse size distribution [3]. Recently, microwave technology has been applied to industrial processes for material characterization to save energy and time. Although nonthermal reaction effects have been reported [4], the mechanism of monodisperse nano-particle formation under microwave irradiation remains unclear, due to the difficulty of direct observation inside reactors.The movement of particles smaller than a few micrometers is governed by Brownian motion, which causes flow around the particles. The force acting upon Brownian particles is measured using a technique called dynamic light scattering (DLS) [5], which provides the diffusion coefficient and particle size. When observation tools are installed within the reactor, the waveguide tube must be carefully designed to prevent microwave leakage. Commercial nano-particle measuring apparatuses are not necessarily suited to such designs, and it is difficult to adjust the light source power and the angle between the light axis and detector probe. Our laboratory has experience with observation of nano-particle movement [6], and measurement techniques we have developed make in situ observation of nano-particle behavior under microwave irradiation possible. This study presents an in situ observation technique for nano-particles or bubbles in a microwave reactor, and clarifies particle movement and bubble formation in water during and after microwave irradiation. Methods MaterialWe used a suspension of monodisperse polystyrene latex (PSL; 100 nm, Duke Scientific Corp.) particles as the Abstract A microwave reactor was designed for in situ observation of nano-and micro-bubbles, and size profiles during and after irradiation were measured with respect to irradiation power and time. Bubble formation in water during irradiation was observed even at temperatures below the boiling point of water. The maximum size strongly depended on radiation power and time, even at a given temperature. Nano-particles in the dispersion medium were found to play an important role in achieving more stable nucleation of bubbles around particles, and stable size distributions were obtained from clear autocorrelation by a dynamic light scattering system. Moreover, a combination of microwave induction heating and the addition of nanoparticles to the dispersion medium can prevent heterogeneous nucleation of bubbles on the cell wall. Quantitative nano-bubble size profiles obtained by in situ observation provide useful information regarding microwave-based industrial processes for nano-particle production.

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Spectroscopic measurements of discharges inside bubbles in water

Cited by 50 publications

References 2 publications

Hydrogen Peroxide Generation by DC and Pulsed Underwater Discharge in Air Bubbles

Hydrogen Peroxide Generation by DC and Pulsed Underwater Discharge in Air Bubbles

Chemical and Physical Characteristics of Pulsed Electrical Discharge Within Gas Bubbles in Aqueous Solutions

Observation of bubble formation in water during microwave irradiation by dynamic light scattering

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