Plasma catalysis: A solution for environmental problems

Whitehead, J. Christopher

doi:10.1351/pac-con-10-02-39

Cited by 158 publications

(99 citation statements)

References 15 publications

(15 reference statements)

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“…[1][2][3][4][5][6][7][8] It has also been widely documented that the exposure of organic molecules dissolved in water to various forms of plasma discharges leads to their oxidation. [2][3][4][9][10][11] These oxidation phenomena find applications ranging from environmental remediation [9,[11][12][13][14] to water cleaning [10,15] and sterilization. [1,10] Oxidation also plays an important role in many industrial processes such as the conversion of methanol to formaldehyde.…”

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confidence: 99%

Retraction: Plasma Acid: Water Treated by Dielectric Barrier Discharge

Shainsky

Dobrynin

Ercan

et al. 2012

Plasma Processes & Polymers

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It is demonstrated that direct exposure of deionized water to a dielectric barrier discharge (DBD) plasma creates an acid (pH % 2) and is in fact, a strong oxidizer (providing, e.g., peroxidation of a cell membrane). This study addresses the question: which acid is created in water by plasma treatment. Two major possibilities are considered: nitric/nitrous acid and an acid which consist of a hydrogen cation (H þ ) and a superoxide anion (O À 2 ), which, for the lack of a better term, we call plasma acid. The presence of nitric/nitrous acid in the water after plasma treatment in air is confirmed, although the observed pH % 2 cannot be completely explained by the production of nitric acid. Moreover, experiments with oxygen-plasma treatment of water also lead to high acidity, without production of nitrogen based acids at all. Therefore, O À 2 , the conjugate base of the plasma acid, is at least partially responsible for both lowering of the pH and the increase in the oxidizing power of the solution. Experiments indicate that peroxides such as H 2 O 2 and O À 2 , together with an acidic environment are likely to be responsible for the oxidation properties of the plasma treated water. This plasma acid remains stable for at least a day, depending on the gas where plasma is generated, but the effect is temporal. Existence of a temporal and stable oxidizer created using the plasma treatment of pure water not only raises interesting scientific questions and possibilities, but is also likely to provide many applications in situations where direct plasma treatment may be difficult to achieve. Plasma Process. Polym. 2012,

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confidence: 99%

Retraction: Plasma Acid: Water Treated by Dielectric Barrier Discharge

Shainsky

Dobrynin

Ercan

et al. 2012

Plasma Processes & Polymers

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“…Plasma catalysis is gaining increasing interest for various environmental applications, such as gaseous pollutant removal, the splitting of CO 2 , hydrogen generation and O 3 production [1][2][3][4][5][6][7][8][9]. Plasma catalysis can be regarded as the combination of a plasma with a catalyst, and often results in improved performance, in terms of selectivity and energy efficiency of the process.…”

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confidence: 99%

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

et al. 2018

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Abstract:We investigated the mode transition from volume to surface discharge in a packed bed dielectric barrier discharge reactor by a two-dimensional particle-in-cell/Monte Carlo collision method. The calculations are performed at atmospheric pressure for various driving voltages and for gas mixtures with different N 2 and O 2 compositions. Our results reveal that both a change of the driving voltage and gas mixture can induce mode transition. Upon increasing voltage, a mode transition from hybrid (volume+surface) discharge to pure surface discharge occurs, because the charged species can escape much more easily to the beads and charge the bead surface due to the strong electric field at high driving voltage. This significant surface charging will further enhance the tangential component of the electric field along the dielectric bead surface, yielding surface ionization waves (SIWs). The SIWs will give rise to a high concentration of reactive species on the surface, and thus possibly enhance the surface activity of the beads, which might be of interest for plasma catalysis. Indeed, electron impact excitation and ionization mainly take place near the bead surface. In addition, the propagation speed of SIWs becomes faster with increasing N 2 content in the gas mixture, and slower with increasing O 2 content, due to the loss of electrons by attachment to O 2 molecules. Indeed, the negative O − 2 ion density produced by electron impact attachment is much higher than the electron and positive O + 2 ion density. The different ionization rates between N 2 and O 2 gases will create different amounts of electrons and ions on the dielectric bead surface, which might also have effects in plasma catalysis.

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“…Packed bed dielectric barrier discharge (DBD) is being increasingly used as a chemical reactor for remediation of environmental pollutants (e.g., NOx, SOx, and VOCs), and conversion of greenhouse gases to useful chemicals. [1][2][3] The non-equilibrium nature of DBD provides major advantage, by allowing operation at atmospheric pressure and ambient conditions. This helps to overcome the thermodynamic barriers in chemical reactions and provides high reactivity at room temperatures.…”

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confidence: 99%

“…2,6 Additional features such as easy operation, moderate capital cost, and simple scalability have led to extensive research on packed bed DBDs. 7 Several studies which have used packing material in conjunction with plasma in a DBD have found enhanced performance in comparison to a plasma alone system; 2,3,6,[8][9][10][11][12] however, many studies have also reported a negative impact on the performance. 9,[13][14][15] This unfavorable response has been shown to be related to packing configuration and the void fraction of the discharge in the packed bed DBD.…”

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confidence: 99%

Fluid model for a partially packed dielectric barrier discharge plasma reactor

Gadkari

2017

Physics of Plasmas

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In this work, a two-dimensional numerical \ud fluid model is developed for a partially\ud packed dielectric barrier discharge (DBD) in pure helium. In\ud fluence of packing on\ud the discharge characteristics is studied by comparing the results of DBD with partial\ud packing with those obtained for DBD with no packing. In the axial partial packing\ud configuration studied in this work, the electric field strength was shown to be en\ud hanced at the top surface of the spherical packing material and at the contact points\ud between the packing and the dielectric layer. For each value of applied potential,\ud DBD with partial packing showed an increase in the number of pulses in the current\ud profile in the positive half cycle of the applied voltage, as compared to DBD with\ud no packing. Addition of partial packing to the plasma-alone DBD also led to an\ud increase in the electron and ion number densities at the moment of breakdown. The\ud time averaged electron energy profiles showed that a much higher range of electron\ud energy can be achieved with the use of partial packing as compared to no packing\ud in a DBD, at the same applied power. The spatially and time averaged values over\ud one voltage cycle also showed an increase in power density and electron energy on\ud inclusion of partial packing in the DBD. For the applied voltage parameters studied\ud in this work, the discharge was found to be consistently homogeneous and showed\ud the characteristics of atmospheric pressure glow discharge

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Plasma catalysis: A solution for environmental problems

Cited by 158 publications

References 15 publications

Retraction: Plasma Acid: Water Treated by Dielectric Barrier Discharge

Retraction: Plasma Acid: Water Treated by Dielectric Barrier Discharge

Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges

Fluid model for a partially packed dielectric barrier discharge plasma reactor

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