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

Abstract 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 \(\:V\) (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 \(\:{NO}₂⁻\), \(\:{NO}₃⁻\), \(\:H₂O₂\), and \(\:O₃\), respectively). The total energy consumption is 145.9\(\:J\), and the energy efficiency reaches 10.74 \(\:g/(KW×ℎ)\). The device performance of the PAW generator is satisfactory, with temperature fluctuations confined to 7.67–8.33 \(\:°C\), a final pH of 3.07, and a production volume of 2.4 \(\:L\) out of a rated capacity of 3\(\:L\). These results underscore the potential of this design to establish a foundation for highly effective, low-energy PAW production across industrial applications.