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

Abstract

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.

Comparison of two cold atmospheric pressure plasma jet configurations in argon

“…In the case of CAPJ II, the flow rates increased from 100 to 500 sccm (Re = 340 and 1,700, respectively) and remained below the transition value as shown by Li et al According to Figure , the length increased almost linearly with the flow rate, which is in accordance with previous studies on plasma jets in laminar flow both in Ar and He . The limited effect of voltage amplitude on the jet length in CAPJ II has also been seen in earlier studies where a similar configuration was used …”

“…Furthermore, Reynolds number, where the maximum occurs, apparently depends on the jet configuration. For CAPJ II, the maximum occurred at higher values of Reynolds number (Re = 1,725) compared to CAPJ I (Re = 250–300) …”

“…The maximum lengths of the plasma jets of two configurations differed considerably even though the ID of the quartz tube was the same. One parameter affecting the maximum jet length has been found to be the Reynolds number, which determines the transition from laminar to turbulent flow . Furthermore, Reynolds number, where the maximum occurs, apparently depends on the jet configuration.…”

Development and characterization of a wire-plate air bubbling plasma for wastewater treatment using nanosecond pulsed high voltage

“…Since the discharge is ignited in air, the energetic electrons generated collide with the background gaseous molecules (such as O2 and N2) to produce primary gas-phase reactive species, such as • OH, • O, H, O3, • N, NO, NO2 and ions [42,43]. These reactive species, in turn, are transferred into the aqueous solution via the bubbles to react with the MB molecules and generate secondary aqueous-phase reactive species [44][45][46], such as H2O2, • OH, O3, NOx, HNO2, and HNO3. Therefore, the decoloration of the MB in the reactor results from the simultaneous contribution of numerous different reactions driven by the primary and secondary reactive species.…”

“…The rather slow increase in the decoloration of the MB at longer treatment time is related to the low concentration of the MB molecules in the solution, which increase the possibility of consuming the generated reactive species to (1) form further reactive species (e.g. nitrogen oxides that reduce the • OH and O3 concentration [44]) undesirable for the decoloration of the MB or (2) react with the intermediate byproducts rather than react with the MB molecules.…”