Manufacturing of anodic porous alumina for barriers in a dielectric barrier discharge reactor

The simultaneous treatment of gaseous pollutants and suspended particulate matter exhausted from a diesel engine is one of the most serious problems in our living environment. A dielectric barrier discharge (DBD) reactor, which is one of the non-thermal plasma generators, skillfully combined with porous ceramics and/or catalysts is very attractive for the simultaneous treatment. In this study, anodic porous alumina, which has many pores with nanometer-order diameter and high aspect ratio, has been focused as the barrier of a DBD reactor. However, there have been a few reports on the DBD using the anodic porous alumina barrier. In this paper, the anodizing conditions were optimized from a view point of the stable DBD generation in atmospheric pressure air, using only anodic porous alumina as the barrier. A 99.99% pure Al substrate was anodized under a constant voltage condition in sulfuric acid solution. As a result, it was found that the anodic porous alumina with a film thickness between 150 μm and 220 μm, prepared in 1.0 M sulfuric acid at 10 °C, is suitable for the barrier of the DBD reactor, and the stable DBD can be generated in atmospheric pressure air using it.