Decolorization of methyl violet in simulated wastewater by dielectric barrier discharge plasma

Abstract

In this study, the decolorization ratio of methyl violet and energy consumption were individually investigated in dielectric barrier discharges of O 2 , He, and He + O 2 gases. The results showed that the highest decolorization ratio was achieved in the O 2 gas discharge, followed by the He + O 2 and He gas discharges, and the decolorization was almost the same in the He + O 2 and O 2 gas discharges. For the He gas discharge, the energy consumption was lowest but the decolorization ratio was also lower than 50%. For the O 2 gas discharge, a decolorization ratio of 99.5% was achieved but a high energy density of 32.5 kJ/L was required. For the He + O 2 discharge, a decolorization ratio of 96% was achieved and the required energy density was only 7.7 kJ/L. Therefore, from the experimental results, the discharge in a mixture of He + O 2 gases is optimal for the decolorization of methyl violet. When He is mixed into O 2 , a high decolorization ratio can be achieved and a low energy density is required.

Spectral characteristics of cotton seeds treated by a dielectric barrier discharge plasma

“…In the last ten years, atmospheric-pressure plasmas have emerged as a competitive alternative to other methods of enhancing seed and seedling vigor and disease resistance, with the potential to combine efficacy, low cost, speed, simplicity, one-step processing, and low impact on human health and environment 2 – 5 . Initially building on advances in plasma-assisted material fabrication 6 – 9 , 10 , exhaust gas purification 11 , and wastewater treatment 12 , 13 , significant progress has been made in the use of plasmas to selectively induce apoptosis in cancer cells 14 – 16 , to eliminate bacterial biofilms on living surfaces and promote wound healing 17 , 18 , for pathogenic microorganism inactivation and removal from solid and liquid media 19 , 20 , for mutation breeding 21 and for agricultural production 4 , 22 , 23 . The unique advantage of using plasmas over other methods of biological stimulation stems from its multi-modal activity, specifically the simultaneous production of chemical species, including reactive oxygen species (ROS) and reactive nitrogen species (RNS) noted for their catalytic activity and biological significance, highly-energetic electrons, electromagnetic radiation and thermal effects, which individually and synergistically affect the treated target 24 , 25 .…”

Non-equilibrium plasma prevention of Schistosoma japonicum transmission

“…The electric characteristics of discharge show the electrons frequently run and the frequent collisions that occur among the particles result in the production of high levels of excited reactive species. The presence of these reactive species and the chemistry is confirmed from the emission spectra for these discharges, in which the spectral lines correspond to various active particles 28 29 32 .…”

“…1 ) was designed to use tap water as one of the electrodes for several reasons. In addition to being abundant and affordable, the use of tap water not only cools down the dielectric efficiently but also avoids the dielectric breakdown due to the different thermal expansions between the metal electrode and the dielectric 32 33 34 . Second, the solution electrode is in a tight contact with the quartz tube, which makes the electric field distribution more uniform and the plasma more homogeneous, also reduces the power consumption 31 35 .…”

“…The biological and chemical activity of plasmas is inherently linked to the amount and reactivity of chemical species produced in plasmas, as well as the nature and extent of plasma-generated physical effects, such as photons, electric fields, shock waves, and others 36 37 38 39 . There are a large number of reactive species that can form in atmospheric plasma, such as the high-energy electrons, the excited N atoms, OH radical, N 2 molecules and O atoms, and the oxygen ions 28 32 40 41 42 43 . At a sufficient concentration, these species can attack the unsaturated fatty acid component of cell membranes to the extent that cells can no longer maintain membrane integrity and function, eventually leading to cercariae death.…”

Electrical and spectral characteristics of a tube-to-plate helium plasma generated using dielectric barrier discharge in water

“…Currently, the electrical discharge of DBD in water used to remove organic contaminants could be divided into two main groups, namely electrical discharge inside the reactor immersed in water and direct electrical discharge in water. The plasmas need to transfer a section of distance before reacting with organic pollutants for the electrical discharge inside the reactors which are immersed in water [9][10][11][12], leading to disappear of short lifetime active species before chemical reactions. It could seriously affect the degradation efficiency of organic pollutants in water, because the short lifetime active species such as OH* and O* play an important role for organic pollutants removal.…”