平行磁场下电极材料对DBD降解亚甲基蓝的影响

采用介质阻挡放电等离子体技术，以镍，铁，钼，不锈钢4种材料作为电极，分别在有平行磁场和无平行磁场的条件下，考察了不同电极材料对亚甲基蓝降解率和能量利用率的影响.实验中发现电极材料的不同会影响亚甲基蓝的降解效果，其中镍电极在处理8min后亚甲基蓝降解率可达99%，降解效果最好，电极材料还会影响平行磁场对亚甲基蓝降解的促进效果，铁和镍电极的能量利用率相比无磁场时提高了约20%，而钼和不锈钢只有5%~10%.通过研究介质阻挡放电等离子体的产生机理和二次电子发射原理，发现这些差异是由电极材料的二次电子发射系数和磁导率的不同导致的，4种材料中铁的二次电子发射系数最大，电子雪崩过程中产生的高能电子更多，因此降解效果最好，铁和镍的磁导率最大，放电空间内的磁感应强度更高，因此平行磁场对亚甲基蓝降解率和能量利用率的提升更大.

Effect of electrode materials on degradation of methylene blue wastewater by DBD plasma under parallel magnetic field

The methylene blue aqueous solution has been treated by dielectric barrier discharge plasma technique as simulated wastewater. Nickel, iron, molybdenum and stainless steel were used as electrodes. The effects of different electrode materials on the degradation rate and energy efficiency were investigated under parallel magnetic field. It has been found that the difference in electrode materials could affect the degradation of methylene blue. For the nickel electrode, the degradation rate of methylene blue could reach 99% after 8min treatment, which could induce the best effect of degradation. The electrode material could also affect the promotion of parallel magnetic field on the degradation of methylene blue. The energy efficiency of iron and nickel electrodes could increase 20% compared to no magnetic field, while molybdenum and stainless steel only 5%~10%. By applying the mechanism of the dielectric barrier discharge (DBD) plasma and the secondary electron emission theories, it has been found that these differences were caused by the differences in secondary emission coefficient and magnetic permeability of the electrode material. The secondary emission coefficient of nickel is the largest among the four materials, so it has the best degradation effect. Iron and nickel had larger magnetic permeability, and the magnetic induction intensity in the discharge space was higher, which induced the more definite improvement of the parallel magnetic field on the degradation rate and energy efficiency of methylene blue.