The Role of Gas-Liquid Interface in Controlling the Reactivity of Air Dielectric Barrier Discharge Plasma Activated Water

Plasma activated water (PAW) has been prepared using atmospheric pressure air dielectric barrier discharge with the bubbling method. This study aims to elucidate the crucial role of gas-liquid interface in determining the physicochemical properties and biological reactivity of PAW, as well as describe the process of mass transfer for reactive oxygen and nitrogen species (RONS) during the PAW generation. Gas-liquid interfacial area is regulated by varying the airflow rate. When the airflow rate increases from 0.5 to 16.0 SLM, the concentrations of \(\:\text{N}{\text{O}}_{\text{2}}^{\text{-}}\), \(\:\text{N}{\text{O}}_{\text{3}}^{\text{-}}\), \(\:{\text{O}}_{\text{3}}\) and activated oxygen in PAW increase significantly, and the water-activated time for complete E. coli inactivation can be shortened from more than 320 s to 40 s. The numerical simulation result shows that when the airflow rate increases from 0.5 to 16.0 SLM, the gas-liquid interfacial area increases from 0.014 to 0.3 m²/600 mL. The analysis shows that the dependence of the chemical reactivity and the biological reactivity on the interface area is mainly attributed to the change of the mass flux with the interface area.