The Study On Decomposition Of Xylene By Nonthermal Plasma With Photocatalytic Technique

Volatile organic compounds(VOCs)are important components of air pollutants,can damage the ozone layer,and are important precursors of ozone pollution and secondary particulate matter.Low temperature plasma technology is an effective VOCs removal method.Compared with traditional VOCs treatment technologies,low temperature plasma technology has the advantages of high speed,high degradation rate and high applicability to pollutants.However,the low energy utilization and incomplete degradation,as the problems of a single cryogenic plasma technology,still exist.In this paper,a low temperature plasma with photocatalytic technique was developed for the degradation of xylene-one of the typical VOCs.The properties and mechanism of nonthermal plasma photocatalytic degradation of xylene were investigated by studying the factors of voltage,frequency,initial concentration,gas flow,length of catalyst filling and length of effective discharge area.The main findings were as follows:(1)Low temperature plasma can degrade xylene rapidly and effectively.In the same situation,the degradation rate of xylene increased with the increase of appliedvoltage and power frequency,with a degradation rate of 77.04%when the discharge point area was 120 mm long,the discharge voltage was 20 kV,the power frequency was 11 kHz,and the gas flow rate was 1L/min and the initial concentration was 1100 mg/m3.(2)The degradation efficiency of dimethylbenzene in the reactor can be improved obviously by filling the catalyst with 5 mm diameter glass beads under two different methods.Under the same conditions,the more the catalyst fills,the better the degradation efficiency of P xylene.When the voltage was 20 kV,11 kHz,the gas flow was lL/min and the initial concentration was 1100 mg/m3,the degradation rate was 82.7%.(3)After adding additional ultraviolet light to the reactor,4 ultraviolet lights were switched on,and the degradation rate of xylene reached 97.3%.(4)The degradation of xylene by low-temperature plasma is coordinated with photocatalysis.The main products are small molecular substances such as CO2,CO,and H2O.