电极材料对脉冲等离子体降解有机废气的影响分析

Analysis of electrode material effect on organic exhaust gas decomposition by pulse plasma.

用脉冲等离子体降解有机废气，对甲苯、二甲苯的降解率达７３％～９１％，对二氯甲烷的降解率达８２％。在实验中发现电极材料的不同会影响分解效果，其中钨电极的降解率最高。本文运用等离子体化学中放电气体电子碰撞电离和化学自由基产生的机理以及阴极电子学中带电粒子轰击电极表面激发二次电子发射的理论，通过比较不同金属电极的二次电子发射系数δ，研究电极材料对脉冲等离子体降解有机废气影响的机理，发现主要是由于不同电极材料δ值的差异引起降解率的差异，电极稳定性对降解率和电极寿命也有重要影响。在实验的三种电极材料中钨的δ值最大，其最大二次电子发射系数δｍ为１．４，铜其次为１．２９，不锈钢最小约为１．２４，这成为导致三者降解率差异的主要原因。

猅he technique of pulse plasma has been applied to decompose organic exhaust gases. The decomposition efficiency of toluene and xylene can be 73% to 91%, and that of dichloromethane can be up to 82%. In the experiments, it has been found that difference in electrode materials could affect decomposition effects of exhaust gases, and wolfram electrode could induce the highest decomposition efficiency. By applying the mechanisms of electron impact ionization and chemical free radical generation in gas discharge theories of plasma chemistry and the secondary electron emission theories in cathode electronics, and by comparing the secondary electron emission coefficients (δ) of different electrodes, the influence mechanism of organic exhaust gas decomposition by electrode materials has been studied and analyzed in this paper. It has been concluded that the difference in decomposition effects came mainly from the difference in δ values of different electrodes, and stability of electrode also has important influences on decomposition efficiency and electrode life-span. In the three experimental electrode materials, δ of wolfram is the highest, whose maximum δ m is 1.4; the next is of copper (δ m is 1.29); and the lowest is of stainless steel (δ m is 1.24 or so), which has been the main reason for their different decomposition efficiency.