Václav Babický

GENERATION OF CHEMICALLY ACTIVE SPECIES BY ELECTRICAL DISCHARGES IN WATER

Pulse positive streamer corona discharges in water solution with a different conductivity have been investigated in reactors with the needle-plate and coaxial electrode geometry. A special composite anode was used in the coaxial geometry. With such an anode hundreds of streamers were generated at each voltage pulse. Production of H, O and OH radicals by the discharge was proved by emission spectroscopy and formation of H2O2 and degradation of phenol was demonstrated by chemical methods. Assuming that the broadening of the line profile was caused by the dynamic Stark effect, plasma with an electron density over 1018 cm-3 was generated during the initial phase of voltage pulse in the both reactors in spite of the very different electrode geometry and wave-forms of voltage pulses. Production of OH radicals was most effective at solution conductivity below .

Excitation of ) and ) states in a pulsed positive corona discharge in , - and -NO mixtures

Time resolved multichannel emission spectroscopy has been applied to study emission in the 200-500 nm spectral range produced by a pulsed positive corona discharge. The discharge was driven in coaxial geometry by an HV power supply (100 kV/1 kA) at atmospheric pressure in nitrogen, and in and mixtures. Emission of NO- (-) and 2.PG (-) bands has been studied in order to trace the development of and electronic states during both discharge and post-discharge periods. Analysis of spectroscopic data indicates an evolution of the electron mean energy during the discharge pulse in the range 20-1 eV and post-discharge kinetics of the NO and electronic states which is predominantly controlled by , v = 0,1) metastable species.

Time and space resolved analysis of N 2 (C 3 Π u ) vibrational distributions in pulsed positive corona discharge

Time- and space-resolved emission spectroscopy was applied to study the N2(C 3 � u → B 3 � g) and NO(A 2 � + → X 2 � r) emission induced by pulsed positive primary streamers in coaxial geometry generated in high-purity

Production of reactive species by atmospheric pressure streamers in N 2 -O 2 mixtures*

Streamer discharges in atmospheric gases are currently receiving increased attention in connection with environmental issues or new material treatment technologies. The chemical reactivity of streamer-produced plasma, created by various active atomic and molecular species, is a critical parameter for most application areas. Recently, advanced diagnostics based on optical and energy transfer methods have been applied to study dynamics and spatial distribution of several important streamer-produced species. This paper presents an overview of the most recently reported experimental achievements to monitor and detect reactive species, such as, e.g., NO, OH, and O3 radicals, nitrogen and oxygen atoms, or N2(A3Σ) metastables.

Organic synthetic dye degradation by modified pinhole discharge

The aim of this work was to investigate the possibility of applying a high voltage pulsed electrical discharges for dye wastewater treatment. Commercial organic monochlorotriazine reactive dye of the anthraquinone type C.I. Reactive Blue 49 (RB49) was chosen as a representative of persistent and recalcitrant wastewater pollutant. The modified pinhole discharge flow-through reactor was used to treat such type of contaminant. Applying HV pulses 30 kV, 3.15 J/pulse, 50 Hz repetition rate, complete decolorisation and partial mineralization of RB49 has been reached and demonstrated by means of UV/VIS absorption, TOC and AOX measurements.

Ozone formation by gaseous corona discharge generated above aqueous solution

Production of ozone generated in oxygen by the gas phase discharge above aqueous solution was studied for different applied pulse high voltage and discharge gap heights between gas phase high voltage electrode and water surface. The ozone production increased with higher gap and higher applied voltage, while the efficiency decreased with higher voltage for fixed gap height and increased with higher gap height. The appearance of the gas phase discharge occurring above the water significantly differed with the change of discharge gap height. The formation of ozone was affected by the presence of water vapor formed through the vaporization of water surface by the gas phase discharge, which was in direct contact with aqueous solution.