Time stability of water activated by different on-liquid atmospheric pressure plasmas

Two atmospheric pressure micro-jets generated in helium or argon and an air micro-arc discharge were used to obtain plasma activated water. The new water properties depend on the plasma gas, treatment time and treated volume. The higher concentration of hydrogen peroxide is associated with the argon discharge while the higher concentration of nitrogen based species and the higher modifications of pH and of electrical conductivity are associated with the air discharge. The properties of the treated water (pH and electrical conductivity) and the concentrations of hydrogen peroxide and of nitric acid show very small variations over three weeks after treatment.