Effects of flue gas components on the oxidation of gaseous Hg0 by dielectric barrier discharge plasma

• A dielectric discharge barrier reactor was developed for elemental mercury oxidation.
• Active radicals generated in DBD reactor played important roles in Hg0 oxidation process.
• O2, SO2 and HCl had positive effects on Hg0 oxidation.
• NO inhibited Hg0 oxidation due to competing reaction for active radicals.

This study investigated the effects of gas components on the oxidation of Hg0 by dielectric barrier discharge (DBD) non-thermal plasma (NTP) technology. The findings indicated that reactive species such as O and Cl generated by ionization of O2 and HCl played dominant roles during oxidation processes. The presence of 50 ppm of HCl in N2/O2 atmosphere enhanced the Hg0 oxidation, the complete oxidation of Hg0 was observed by 6 kV of applied voltage. The presence of NO in the reactor decreased the Hg0 oxidation efficiency due to the interference by NO reaction with O and O3. The addition of 310 ppm of NO into the flue gas remained in 55% of Hg0 oxidation efficiency. Water vapor inhibited Hg0 oxidation, which was attributed to the consumption of reactive species and decomposition of HgOH. SO2 had a slight promoting effect on Hg0 oxidation, compared with the absence of SO2, the oxidation efficiency increased by 2–8% with the addition of 100–200 ppm of SO2. This study leads to starting the development of a novel promising environmental technology for Hg removal in the flue gas.