Analysis of Mechanisms at the Plasma-Liquid Interface in a Gas-Liquid Discharge Reactor Used for Treatment of Polluted Water

Aqueous solutions polluted by contaminants different from those generally studied (phenol and chlorophenols) were treated in a falling film gas-liquid dielectric barrier discharge reactor. The lower was the Henry's law constant of a molecule, the better was its removal percentage, regardless of its other chemical properties. In the case of saturated molecules, the removal mechanism is the transfer of pollutants from the liquid phase to the gas phase where they react with the active species of the discharge. For phenol, the reaction with ozone in the liquid phase was estimated to be responsible of about 30% of the removal. A computational fluid dynamic modelling provided a better understanding of the phenomena, indicating that mass transfer of pollutants from liquid to gas is accelerated due to (1) the intense mixing in the liquid film and (2) the reaction of the pollutant with the active species in the gaseous phase.