| With the acceleration of urbanization and the continuous improvement of people’s living standards,the problem of water pollution has become increasingly prominent,and it has exacerbated the shortage of water resources and severely restricted the sustainable development of the economy and society.Low temperature plasma technology is an environmentally friendly water treatment technology,which can generate ozone,hydrogen peroxide,ultraviolet light,etc.in situ,combining the advantages of a variety of advanced oxidation technologies.The study of pulse power has greatly promoted the development of atmospheric pressure plasma.Nanosecond pulse corona discharge can generate a large area of uniform plasma,with higher energy efficiency and more active substances.Therefore,it has become a hot spot in the field of water treatment research.In this paper,a set of high-voltage repetition frequency nanosecond pulse power supply system based on 2-stage TLT(Transmission Line Transformer)was constructed and can be operated stably.An experimental study of water treatment applications was carried out using acid red 73 dye as the target pollutant.The research was carried out from the aspects of discharge characteristics,reactor structure design,pollutant degradation effect,energy efficiency,active oxidizing particles,etc.,and provides references for the industrial application of plasma water treatment.The main research contents and conclusions are as follows:a)The high-voltage nanosecond pulse corona discharge plasma water treatment system consisted of a primary microsecond charging power supply,a high-voltage energy storage capacitor,a three-electrode LCR triggered gas spark switch,a transmission line transformer,a water treatment reactor,and a wastewater circulation system.The pulse power supply can output a nanosecond pulse signal with a peak voltage of 50 kV,a pulse width of 40 ns,and a rising edge of 20 ns,and it operates stably at a discharge frequency of 500 Hz.b)An experimental study on the treatment of acid red 73 solutions with nanosecond pulse power under different conditions was carried out.Under the same treatment time,increasing the discharge voltage and frequency can increase the degradation rate of Acid Red 73.Increasing the discharge voltage increases the energy of a single pulse,and increasing the frequency increases the number of discharges per second,which essentially increases the energy injected into the reactor.When the discharge voltage is maintained at 44.26 kV,the discharge frequency is increased from 50 Hz to 400 Hz,the degradation rate of pollutants is increased from 46.87%to more than 90%;the discharge frequency is fixed at 200 Hz,and the discharge voltage is increased from 30.42 kV to 52.73 kV,the degradation of pollutants was significantly improved,which increased from 14.39%to 97.15%.c)The distance between the high-voltage electrode and the liquid surface affects the energy injected into the reactor,the degradation effect of pollutants and the concentration of active particles.The smaller the discharge interval,the easier the formation of plasma channels and the more energy injected into the reactor.Therefore,the higher the concentration of hydrogen peroxide in the liquid phase,the higher the conductivity of the solution.However,if the discharge interval is properly increased,the output voltage was higher.The discharge form was mainly a primary streamer discharge.The degradation of AR73 was improved.When the discharge distance was increased from 5mm to 20mm,AR73 degradation rate increased from 26.71%to 90%.(d)Under different voltages and different frequencies,the degradation process of Acid Red 73 conforms to the first-order kinetics equation,and the reaction rate coefficient increases with the increase of discharge voltage and discharge frequency.The active particles(such as hydroxyl radicals,ozone,hydrogen peroxide,etc.)generated by nanosecond pulsed discharge plasma can oxidize the azo double bond,benzene ring,naphthalene ring,etc.in acid red 73 molecule. |
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