Dual-Electrode Configuration for Enhanced Plasma Activated Water Production: Optimizing RONS Generation and Energy Efficiency

The production of plasma activated water (PAW) enriched with reactive oxygen and nitrogen species (RONS) is a prerequisite for high-efficient application of PAW in chemical fields. To address the limitations of conventional single-electrode PAW systems, this study innovatively designs a dual-electrode structure consisting of an upper - liquid electrode and a submerged electrode to effectively compensate for the low mass - transfer efficiency of the upper - liquid discharge mode and the instability of the products in the under - liquid discharge mode, thereby improving the discharge stability. The upper - liquid electrode adopts a four - needle T - shaped structure to adapt to the turbulent liquid surface, while the submerged electrode is covered in a quartz tube to ensure stable plasma discharge. Optimized at 171 \(\:\text{V}\) (input voltage), 0.019 mol/L NaCl, and 30 min, the system achieves nonlinear RONS generation (172.11, 5.11, 3.25 and 0.81 µmol/L for \(\:{\text{NO}}_{\text{2}}^{\text{−}}\), \(\:{\text{NO}}_{\text{3}}^{\text{−}}\), \(\:\text{H}\text{₂}\text{O}\text{₂}\), and \(\:\text{O}\text{₃}\), respectively). The total energy consumption is 145.9\(\:\text{}\text{J}\), and the energy efficiency reaches 10.74 \(\:\text{g}\text{/(}\text{KW}\text{×}\text{ℎ)}\). The device performance of the PAW generator is satisfactory, with temperature fluctuations confined to 7.67–8.33 \(\:\text{°}\text{C}\), a final pH of 3.07, and a production volume of 2.4 \(\:\text{L}\) out of a rated capacity of 3\(\:\text{}\text{L}\). These results underscore the potential of this design to establish a foundation for highly effective, low-energy PAW production across industrial applications.