Study On The Device Design And Influencing Factors Of Dye Wastewater Treatment By DBD Non-thermal Plasma

Organic dye wastewater has received considerable attention due to its increasingly negative impact on the environment and human life.Non-thermal plasma based on dielectric barrier discharge(DBD)has been proven to be effective in organic wastewater treatment.This paper conducts a systematic study on the degradation of dye wastewater by surface DBD plasma at atmospheric pressure.A new type of surface DBD non-thermal plasma water treatment reactor was designed.The electrical characteristics,degradation efficiency and influencing factors of the process of degradation of methyl orange by self-made reactor were studied,and the changes of the physical and chemical characteristics of wastewater during the degradation process were discussed.This paper developed a new type of surface DBD non-thermal plasma water treatment device,designed the water treatment device from the electrode parameters,barrier medium material and reactor type.Numerical simulation was carried out using Comsol,the influence of the wire diameter and pitch of the ground electrode on the electric potential distribution is studied,and the distribution of the electron density in the discharge process is calculated by plasma module.The surface DBD electrode structure greatly reduces the discharge start voltage.A large amount of high-quality non-thermal plasma can be generated when the voltage amplitude is only 1.8k V.Under the voltage amplitude of 8.0k V,the degradation rate of 2L 25mg/L methyl orange reached 92.5%in 5 minutes and 99.2%in 25 minutes.Based on Matlab/Simulink,a equivalent circuit model was built to study the discharge process and electrical characteristics of surface DBD.The diagnostic experiment results of the electrical characteristics of the reactor show that the micro-discharge voltage starting point,the discharge power,and the capacitor voltage are generally in line with the simulation expectations.The experiment investigated the effects of initial concentration,initial pH,and pumping rate on the degradation of methyl orange.In the same minutes,the higher the solution concentration,the higher the average degradation rate,but the lower the decolorization rate of the solution.The methyl orange degradation effect is better under acidic conditions,but when the acidity is too strong,it will inhibit the positive progress of the oxidation reaction.Increasing the pumping rate can speed up the degradation process,but when the pumping rate reaches a level that can fill the solution with bubbles,continuing to increase the pumping rate can not increase the degradation efficiency.The experiment investigated the influence of voltage amplitude and frequency on the degradation of methyl orange.The degradation efficiency of methyl orange increased with the increase of the voltage amplitude,first increased and then decreased with the increase of the frequency.Excessive voltage and frequency may heat up the electrode significantly and reduce the energy efficiency.This paper combined TiO₂photocatalysis with DBD.1.5g TiO₂was added to the degradation system,the degradation rate of methyl orange in 10 minutes reached 93.3%,which was 14.2%higher than using the DBD plasma alone.TiO₂used the ultraviolet light generated by DBD.When TiO₂is added alone,methyl orange can not degraded.The photocatalytic method has a synergistic effect on the degradation process of DBD.The changes of pH value and COD of the methyl orange solution during the degradation process was analyzed.The pH value showed a downward trend during the degradation process,which indicated that the methyl orange produced organic acid intermediates during the process.The change trend of COD is not completely synchronized with the degradation of methyl orange,showing a trend of decrease-increase-decrease.COD is more difficult to degrade completely.