Study On The Removal Of N,N-Dimethylformamide By Plasma

With the development of the society,the progress of science and technology human industry,the demand for dimethylformamide in the leather,medicine,chemical industry and other industries is increasing,However,due to the better chemical stability and strong toxicity of dimethylformamide itself.So,for DMF wastewater disposal has always been a difficult problem in the field of water treatment,and it has also been paid more and more attention and research by a large number of scholars at home and abroad.Biochemical method is the most widely used and low-cost water treatment method in the traditional water treatment process.It is difficult to directly treat the toxic dimethylformamide wastewater.If there is no pretreatment and it enters the biochemical tank directly,it will cause a great impact on the activated sludge in the biochemical tank.Therefore,for this kind of refractory wastewater,developing new technology and improving the efficiency and impact resistance of traditional treatment technology,the combination of multiple technologies has become the hotspot in the field of water treatment.Low-temperature plasma water treatment technology is a means with high efficiency and no secondary pollution.A large number of hydroxyl radicals,superoxide radicals,ozone and other strong oxidizing active substances generated by low-temperature plasma technology can degrade DMF efficiently and rapidly,which is especially suitable for DMF and other organic wastewater with strong toxicity and difficult biodegradation.At present,a large number of scholars have introduced plasma technology to the treatment of water environment pollution,especially the treatment of organic wastewater.In this paper,a dielectric barrier plasma reactor was used to conduct a more comprehensive experimental study on the degradation of dimethylformamide.The main results are as follows:(1)Taking the degradation rate of DMF as the evaluation index,the influence of the two main parameters of the discharge voltage and frequency of the dielectric barrier plasma reactor power supply on the degradation effect of DMF was investigated.The experiments show that the higher the discharge frequency and discharge voltage,the more effective the treatment of DMF is.Well,the experimental study determined that the power supply experimental parameters discharge voltage is 15 kV and discharge frequency is 20 kHz.(2)The influence of initial concentration,initial pH value,initial conductivity,circulating flow rate and ventilation rate on the degradation effect of DMF was investigated by using the single-factor control variable method,and the degradation rate was used as the evaluation index.The experimental results showed that: the lower the initial concentration was,the better the degradation effect of DMF was.The higher the circulation and gas flow,the better the degradation effect of DMF.DMF degradation was best at an initial conductivity of 1689μs/cm.Under neutral conditions,the degradation rate of DMF is not as good as that under acidic and alkaline conditions.(3)Kinetic analysis shows that the degradation process of DMF by plasma technology conforms to first-order reaction kinetics;through comparative analysis of its rate constant changes,among the five factors of initial concentration,initial conductivity,initial pH,gas flow rate and circulation flow rate The initial concentration,initial conductivity,and initial pH have significant effects on the degradation of dimethylformamide.(4)Through the analysis of response surface,the optimal conditions of plasma technology for the degradation test of dimethylformamide are the initial concentration of 50mg/L,the initial conductivity of 570.01μs/cm,and the initial pH of 9.99.Under these conditions,the degradation rate of dimethylformamide was 47.86%.Under the same conditions,the degradation rates of dimethylformamide,phenol and methylene blue were 29.8%,42.89% and 83.98%.(5)During the treatment of dimethylformamide by plasma technology,the content of the components in the solution changed,the total nitrogen(TN)continued to increase,the pH value continued to decline,the conductivity of the solution continued to rise,and the B/C value basically maintained at about 0.3.(6)In the plasma treatment of dimethylformamide,many kinds of active substances were produced.Studies have shown that: active substances ·OH and ·O2-play a major role in oxidation.Comparing with these two active substances,·O2-contributed more to the degradation of DMF.