Degradation Of Aqeuous Organic Pollutants Using Non-thermal Plasma Above Liquid Surface

Based on the background of widely-concerned problem of water pollution nowadays, this paper focuses on the treatment of wastewaters containing two different pollutants (DMMP which is chemical warfare agent simulant and RhB which is alkaline dye). DMMP belongs to the pollutants which is extremely difficult to degrade. We used the decontamination method of streamer and spark discharge above water assisted by Fenton and found that Fenton could obviously promote the decontamination reaction of plasma. Besides, we compared the decontamination effect of streamer and spark above water and analyzed the influences of pH value, H2O2and energy per pulse to the result. In the research of the reaction kinetics of the decontamination of DMMP, its reaction order was below one and tended to zero with the augment of power. Two kinds of power source, pulsed high voltage and AC/DC were applied in the treatment of RhB solution. AC/DC was found to have better degradation efficiency than pulsed and DC power source at low peak voltage. Moreover, the effects of frequency、pH and the concentration of H2O2to the degradation result and energy efficiency were studied. In order to take foLl advantage of the AC/DC streamer in gas phase, spraying was added into the reaction, which elevated the energy efficiency from3.6g/kWh to5.4g/kWh. Furthermore, the studies of reaction kinetics showed that the reaction order deviated from one to two as the reaction rate decreased. In the experiment with pulsed high voltage power source, we designed the reactor of plasma along water surface and use a dual-channel spark switch module designed to regulate the steepness of pulsed high-voltage with microsecond rise time. Depending on the energy per pulse, a spark along water surface (SPWS) or streamer along water surface (STWS) was formed. STWS was found to have a better degradation effect toward RhB and energy efficiency than SPWS at the same power; however, with similar H2O2amounts, the degradation rate exhibited a greater increase using SPWS. The concentration of RhB also appeared to influence the degradation effect. The probably reaction mechanism of plasma along water surface was obtained by analyzing the inorganic products in liquid and gas phase. Furthermore, the addition of TiO2films to the reaction system were found to enhance degradation performance of SPWS and at similar crystal size, TiO2films doped with Fe and Mn were found to have better strengthening effect to the degradation reaction than undoped. The influence of coating layer to degradation effect and the life of films were also studied.