Analysis of hydroxyl radical formation in a gas‐liquid electrical discharge plasma reactor utilizing liquid and gaseous radical scavengers

Abstract

Production rates of hydroxyl radical (•OH) formation in a gas‐liquid plasma discharge reactor with pure water and argon were quantified using gas (carbon monoxide: CO) and liquid (ethanol) radical scavengers. The major oxidation products were acetaldehyde from ethanol and carbon dioxide (CO2) from CO. Total •OH production rates were estimated from the •OH required to form these products and hydrogen peroxide (H2O2). Ethanol completely depleted H2O2 suggesting that it is formed in or near the plasma‐liquid interface. •OH production rates were higher with CO, and CO had a smaller effect on H2O2 suggesting additional •OH is available for other reactions at the plasma‐gas interface. The best case total •OH production was approximately 25% of the thermodynamic limit for water dissociation based upon measured CO2 from CO.