The reaction apparatus consists of a high-frequency AC power supply with a frequency range of 5–35 kHz, avoltage range of 0–250 V and a current range of 0–1.2 A, and a reaction tank, which is used for treatment of the pesticide solution (Fig.1). The reaction tank composed of two parts is put in the center of two stainless steel electrodes.The upper part of the reaction tank is a quartz plate(110 mm 9 1 mm) and the bottom part is a glass culture dish (150 mm 9 2 mm920mm), which contains the working solution. The gap between the quartz plate and the pesticide solution surface is filled with air. Various reactive oxygen species that facilitated the degradation of pesticide,are generated within the air-gap in the discharging process.Moreover, the electric field is enhanced if the air-gap is set at a shorter distance, consequently leading to a higher amount of reactive oxygen species generated that may come into contact with the solution during the discharging process (Zhao et al. 2010). Similarly, DBD can generate more reactive species when the discharge power is set at a higher degree, i.e. the higher the discharge power injected into the reactor, the larger amount of reactive species,
consequently boosting the degradation of contaminants(Feng et al. 2008). In each run, 40 mL solution was poured into the glass culture dish, and the liquid layer thickness