The role of water and oxygen impurities on ozone production in a negative corona discharge of CO₂

Abstract

The production of ozone in a negative corona discharge fed by carbon dioxide with embedded traces of oxygen and water has been studied. The presence of traces of oxygen in both pure and dry CO2 leads to an increase in nascent ozone concentrations. In contrast, traces of water vapour (0–800 ppm) are shown to rapidly suppress ozone concentrations with the largest decreases being observed at lowest gas pressures in the discharge (300 Torr). The presence of water vapour did not considerably affect the electrical properties of negative dc corona suggesting that a chemical process is responsible for the ozone loss. We have shown that the addition of water up to a concentration of 1500 ppm has only a marginal effect on the processes of ozone formation but the catalytic cycle of ozone destruction involving OH radicals can be the reason for observed decrease in the total ozone concentration with increasing water concentration.

Advances in non-equilibrium $$\hbox {CO}_2$$ plasma kinetics: a theoretical and experimental review

“…In any case, the avoidance of recombination of O atoms whether in O 2 or CO 2 is a key process to achieve an energy efficient conversion of CO 2 , and the use of membrane to extract O atoms from the plasma could enhance the conversion efficiency [37]. At high pressure, O atoms are also forming O 3 as measured in CO 2 corona discharge [132] which is of importance for planetary atmosphere chemistry. Despite their key role in CO 2 plasma chemistry, very few values of O atoms densities have been measured in plasmas for which CO and CO 2 densities were simultaneously determined [21,93].…”

Hydroxyl Addition to Aromatic Alkenes: Resonance-Stabilized Radical Intermediates

“…Significant production of •OH in a corona discharge has been observed for experiments for which water concentrations were as low as 100 ppm. 16 Alternatively, indanol may be present as an impurity formed by the hydration of indene exposed to humid air. In order to determine the degree of impurity present in the indene sample, characterization by 1 H NMR was undertaken.…”

“…Such a species may form in the electrical discharge whereby traces of water provide the •OH source. Significant production of •OH in a corona discharge has been observed for experiments for which water concentrations were as low as 100 ppm . Alternatively, indanol may be present as an impurity formed by the hydration of indene exposed to humid air.…”

The status of the database for plasma processing

“…For example consider an air based plasma (as used for example in surface treatment of textiles or for sterilization of materials). In such atmospheric pressure plasmas there is evidence of cluster formation, often arising from the presence of trace quantities of water [87,88]. Such clusters demonstrate that, within the discharge, complex ion-molecule reactions occur, reactions for which we have little data and which will be pressure (number density) as well as temperature dependent.…”