Plasma re-activation: A promising approach to enhance chemical activity for plasma activated water

Plasma activated water (PAW) is a green prospective solution for a wide range of biotechnology applications. However, the drawback for the transient chemical activity of PAW would make it lose versatility in possible applications. Herein, we propose a promising approach for plasma re-activation aimed at enhancing the chemical activity of PAW again before it entirely decays. Our results indicate that the PAW generated by re-activation displays superior physicochemical properties and higher production of RONS. Especially, the concentrations of ONOO-/O2- and H2O2 by re-activation can remarkably increase by 17.88% and 34.83% compared to the initial activation, respectively. Furthermore, the low temperature storage shows excellent synergetic effects with re-activation, indicating that the re-activation actually enhances the chemical activity of PAW to a higher level. The possible reasons for high chemical activity of PAW by plasma re-activation may be affected by the synergistic effect of multi-factors including the residual RONS in stored PAW and the lower pH value, temperatures of electrode and liquid during re-activation. This study provides good insight into the nature of liquid chemistry for PAW prepered by plasma re-activation, and demonstrates a new alternative for improving the chemical activity of PAW.