Design Optimization And Performance Study Of Dye Wastewater Degradation Device Based On Low-temperature Plasma

The pollution of dye wastewater in actual industrial production has seriously affected people’s daily life,and the traditional treatment methods have many shortcomings.Low-temperature plasma technology has been attracting attention for its good application in dye wastewater treatment.The main content of this paper revolves around low-temperature plasma degradation of dye wastewater with methyl violet,a typical organic dye,as the target pollutant,and its main work is divided into two parts:The first part is the improvement of the existing coaxial medium-blocking discharge device using nano-Ti O2 with the aim of enhancing its degradation effect on methyl violet solution.In this part,the effects of input voltage,treatment time and discharge gas on the degradation effect of methyl violet were investigated,and the comparison of decolorization capacity,voltage and current waveforms and emission spectra of the device before and after the improvement was also carried out to analyze the effects of nano-Ti O2 on the dielectric barrier discharge plasma device.The experimental results showed that the degradation rate of methyl violet solution increased with the increase of treatment duration.The degradation effect of methyl violet was significantly different at different input voltages,and the higher the input voltage the better the degradation effect.The degradation effect of the discharge device on methyl violet also differed greatly under different working gases,and the best degradation effect was achieved when the working gas was oxygen,followed by air.It was found that the degradation rate of methyl violet solution was faster with the improved device using nano-Ti O2.When the working gas was oxygen,the time required to reach90 % decolorization rate was 33.3 % shorter than that of the pre-modified device.When the working gas was air,the decolorization rate was increased by 7 % after 2 minutes of treatment.A novel array-type underwater bubbling plasma reactor was designed in the second part.The effect of input voltage,frequency and treatment time on the degradation rate of methyl violet was investigated along with the effect of solvent as deionized water and tap water on the degradation rate,and the effect of input voltage,frequency and treatment time on the degradation of methyl violet was investigated using the response surface method,and finally the energy efficiency of this device in degrading methyl violet was studied.The experimental results showed that: the degradation rate of methyl violet increased with the increase of treatment time;the degradation rate of methyl violet increased with the increase of input voltage of power supply;the degradation rate of methyl violet showed a trend of increasing and then decreasing within the input power supply frequency of 8-10 k Hz;the methyl violet solution with tap water as the solvent was easier to degrade.The response surface method was used to investigate the degradation effect of input voltage,frequency and treatment time on methyl violet.The results showed that the order of significance of each factor was: treatment time>input voltage>frequency;the optimal parameters were obtained from the model as input voltage 40 V,frequency 8.97 k Hz and treatment time 11.24 min.The validation experiments were conducted under these conditions,and the average degradation rate of methyl violet was 96.15%,which was only 2.21% error from the predicted value of the mathematical model.Subsequently,the power and energy consumption of the array-type underwater bubble discharge device for degradation of methyl violet were investigated,and the experimental results showed that the actual discharge power of the discharge device increased with the increase of voltage;the energy consumption of the discharge device for degradation of methyl violet was negatively correlated with the treatment time and discharge voltage,and the best energy efficiency was 11.11g/k Wh when the voltage input was 30 V,the frequency was 9k Hz,and the solvent was tap water,which is higher than other studies under comparable experimental conditions.