Oxidation of elemental mercury with non-thermal plasma coupled with a wet process

The oxidation of the elemental mercury (Hg-0) by non-thermal plasma (NTP) coupled with a wet process has been studied. Effects of oxygen content, supplied voltage, gas temperature, wet process and NO/SO2 concentration on Hg-0 oxidation were investigated using a dielectric barrier discharge reactor. Results indicate that both O and O-3 generated by O-2 during the discharge process contribute to the oxidation of Hg-0. The increase of O-2 content improves the Hg oxidation efficiency. It was noted that the Hg oxidation efficiency declines when the supplied voltage is too high, there was an optimal voltage level for Hg-0 oxidation. High temperatures promote oxidation of Hg-0. The main reason for this is that the high temperature increases the generation of O atoms and the reaction rate of O-3 with Hg-0. Compared with the NTP process only, the Hg oxidation efficiency increases from 43 to 82% after adding a wet process when the supplied voltage was 8 kV at room temperature. The presence of NO hindered mercury oxidation due to competitive consumption of O-3. However, at the level of 100 ppm NO, more than 50% Hg oxidation efficiency could be achieved in the NTP combined with wet process system. It is found SO2 enhance oxidation of Hg-0, because of the positive effect of SO3 generated in the NTP environment. (C) 2017 Elsevier Ltd. All rights reserved.