Characteristics of water volatilization and oxides generation by using positive and negative corona

The physical and chemical properties have significant differences for the positive and negative charged particles generated by discharge. In this work, a positive and negative corona discharge system was established, and two discharge reactors for charged particles restraining and acting were designed by a needle electrode covered with a quartz tube and a plate electrode filled with water. The corona discharges happened within the needle-plate electrodes were excited by a positive and negative high voltage source, and the characteristics of both water volatilization and oxides generation were examined within influence of the distances of both quartz tube inside and outside. The results show that the characteristics of both the water volatilization and oxides generation can be affected by the distances of both quartz tube inside and outside. When the distances of tube inside were increased from 5.00 to 13.00 mm, the water volatilizations decreased under negative corona, and increased firstly and declined immediately under positive corona. The maximum value of the water volatilization appeared in the distances of tube inside with 6.00–8.00 mm. In addition, the concentrations of the HNO_x and H₂O₂ in treated water decreased with increasing the distances of tube inside. Moreover, with increasing the distances of tube outside from 4.00 to 14.00 mm, the change trends of both the water volatilizations and oxides presented the same as the distances of tube inside, and the maximum value of the water volatilization and oxides appeared in the distance of tube outside with about 9.00 mm. Overall, the positive corona can generate more water volatilizations and oxides in water than negative corona, and non H₂O₂ can be produced by negative corona. The results reflect the difference between positive and negative corona interaction with water, which can provide reference for plasma application.