| Tetrabromobisphenol-S(TBBPS)is a new kind of brominated flame retardant,which is widely used in light industrial products.TBBPS is a kind of toxic and refractory organic pollutants,that is quiet harmful to human health.In order to remove these organic pollutants,as one of the advanced oxidation technologies,low-temperature plasma technology has a wide range of research and application in the field of water treatment,and the development of a new type of dielectric barrier discharge(DBD)water treatment reactor has been a research hotspot.In this study,a micro-channel excited DBD plasma water treatment system is proposed to enhance the discharge and gas-liquid mass transfer processes simultaneously.As the core of the reactor,the micro-channel plays a crucial role in the process intensification.On the one hand,the micro-channel can reduce the initial discharge voltage and enhances the discharge intensity,because of the increased space charge density initiated by the transverse electric field formed by the charges accumulated on the micro-channel wall,as a result,the generation efficiency of active particles can be improved.On the other hand,the micro-channel can also reduce the air pressure resistance and enhance the bubbling process,due to the exciting effect of micro-channel discharge on air flow and plasma-water interaction,as a result,the utilization efficiency of active particles can be improved.In order to verify those supposes,the following aspects are studied:Firstly,a water treatment system with micro channel DBD bubbling reactor was established,and the degradation ability of the reactor was evaluated by using methylene blue as a simulated pollutant.The purpose was to improve the reactor and determine the effective operating parameters by verify the pollutant degradation.The final result is that the reactor design with good treatment effect is obtained,and the effective range of several operating parameters is obtained.Secondly,the micro-channel structure can enhance the discharge and bubbling processes.In the initial stage of electric discharge,the discharge in the LMC is always prior to the DBD space,and the discharge intensity in the LMC is larger than that in the DBD space.With the increase in air flow rate,the discharge in the LMC is weakened,and the overall discharge power decreases.The electric discharge improves the bubbling process and induces air flow in the LMC.Through the measurement of the pressure resistance of the LMC,it is found that the pressure resistance decreases during the electric discharge,which is positively related to the applied voltage and discharge frequency,and inversely related to the air flow rate,and is nearly no affected by the water flow rate and solution conductivity.In addition,electric wind may be an important reason for air flow induced by micro-channel discharge,through the measurement of the electric wind in the LMC,it is found that the intensity of the electric wind produced by uniform streamers is greater than that of bright spark-like streamers.Finally,the reactor has a good degradation effect on TBBPS.When 500 m L,2 mmol/L TBBPS is treated at the applied voltage of 18.4 k V in 30 min,the removal rate reached to98%.Applied voltage,air flow and water flow are the key parameters that affect the removal efficiency,especially the appropriate voltage can produce active substances most effectively,thus can have an excellent removal performance.Meanwhile,attention should be paid to avoid the solution in high salinity.In addition,the use of multiple LMCs can conspicuously improve the removal performance and energy efficiency. |
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