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Subject: Ozone × WGL Institute: INP ×

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Now showing 1 - 3 of 3
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    How activated carbon improves the performance of non-thermal plasma removing methyl ethyl ketone from a gas stream
    ([Amsterdam] : Elsevier B.V., 2021) Schmidt, Michael; Kettlitz, Manfred; Kolb, Juergen F.
    The combination of non-thermal plasma (NTP), operated at room temperature and at atmospheric pressure in air and in combination with activated carbon filters offers a more efficient removal of VOCs from gas streams than each individual method alone. Efficiencies, synergies and mechanisms of this combination were investigated by means of comprehensive quantitative Fourier transform infrared spectroscopy analysis. Therefore, dry and wet synthetic air containing about 90 ppm of methyl ethyl ketone (MEK) were treated with non-thermal plasma (NTP) and an intentionally undersized activated carbon (AC) filter, separately and in combination. As a result, removal of about 50 % was achieved for NTP or AC alone but a removal close to 95 % was found for the combination. Ozone, generated by the NTP, was reduced by 55 % with the AC-filter. For the operation of the NTP with humid air, a decomposition of the pollutant on AC was observed even after the plasma was switched off.
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    Differential influence of components resulting from atmospheric-pressure plasma on integrin expression of human HaCaT keratinocytes
    (New York, NY : Hindawi, 2013) Haertel, B.; Straßenburg, S.; Oehmigen, K.; Wende, K.; Von Woedtke, T.; Lindequist, U.
    Adequate chronic wound healing is a major problem in medicine. A new solution might be non-thermal atmospheric-pressure plasma effectively inactivating microorganisms and influencing cells in wound healing. Plasma components as, for example, radicals can affect cells differently. HaCaT keratinocytes were treated with Dielectric Barrier Discharge plasma (DBD/air, DBD/argon), ozone or hydrogen peroxide to find the components responsible for changes in integrin expression, intracellular ROS formation or apoptosis induction. Dependent on plasma treatment time reduction of recovered cells was observed with no increase of apoptotic cells, but breakdown of mitochondrial membrane potential. DBD/air plasma increased integrins and intracellular ROS. DBD/argon caused minor changes. About 100 ppm ozone did not influence integrins. Hydrogen peroxide caused similar effects compared to DBD/air plasma. In conclusion, effects depended on working gas and exposure time to plasma. Short treatment cycles did neither change integrins nor induce apoptosis or ROS. Longer treatments changed integrins as important for influencing wound healing. Plasma effects on integrins are rather attributed to induction of other ROS than to generation of ozone. Changes of integrins by plasma may provide new solutions of improving wound healing, however, conditions are needed which allow initiating the relevant influence on integrins without being cytotoxic to cells.
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    Quantification of the ozone and singlet delta oxygen produced in gas and liquid phases by a non-thermal atmospheric plasma with relevance for medical treatment
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2018-8-15) Jablonowski, Helena; Santos Sousa, Joao; Weltmann, Klaus-Dieter; Wende, Kristian; Reuter, Stephan
    In the field of plasma medicine, the identification of relevant reactive species in the liquid phase is highly important. To design the plasma generated species composition for a targeted therapeutic application, the point of origin of those species needs to be known. The dominant reactive oxygen species generated by the plasma used in this study are atomic oxygen, ozone, and singlet delta oxygen. The species density changes with the distance to the active plasma zone, and, hence, the oxidizing potential of this species cocktail can be tuned by altering the treatment distance. In both phases (gas and liquid), independent techniques have been used to determine the species concentration as a function of the distance. The surrounding gas composition and ambient conditions were controlled between pure nitrogen and air-like by using a curtain gas device. In the gas phase, in contrast to the ozone density, the singlet delta oxygen density showed to be more sensitive to the distance. Additionally, by changing the surrounding gas, admixing or not molecular oxygen, the dynamics of ozone and singlet delta oxygen behave differently. Through an analysis of the reactive species development for the varied experimental parameters, the importance of several reaction pathways for the proceeding reactions was evaluated and some were eventually excluded.