Assessment of the physicochemical properties and biological effects of water activated by non-thermal plasma above and beneath the water surface

Abstract

A direct current atmospheric pressure cold plasma microjet (PMJ) was used to produce plasma activated water (PAW) in two generation modes above (PAW-A) and beneath (PAW-B) the water surface. The physicochemical characteristics and biological effects of them were measured respectively. Results showed that PAW-B exhibited stronger disinfection efficiency than PAW-A, which was associated with ORP and conductivity, but not pH value, temperature, H2O2, NO3- or NO2-. Furthermore, the cell membrane integrity and membrane potential of S. aureus were destroyed more severely by PAW-B. More importantly, a significant increase of intracellular ROS was induced by PAW-B, which was supposed to contribute most to the sterilization. This work provides valuable guidance for the production and wide applications of PAW.