Photochemical Removal of Gaseous Elemental Mercury in a Dielectric Barrier Discharge Plasma Reactor

The plasma process has the potential to serve as a low cost mercury oxidation technology that will facilitate elemental mercury removal in a downstream of Flue Gas Desulfurization system. The performance of the main gas constituents, such as H2O, O-2 and HCl on elemental mercury oxidation under plasma atmosphere was investigated in simulated flue gas. Experiments were carried out in a dielectric barrier discharge reactor operated at 140 A degrees C. Photochemical effects of nanocrystalline titania on oxidation of elemental mercury were also tested. The results indicated that both H2O and O-2 promote the oxidation of elemental mercury significantly. Active radicals generated by ionization, such as O, O-2 and OH, play the crucial roles in oxidation process. The presence of HCl in N2/O2 stream in plasma system is a very effective way of oxidizing elemental mercury, the nearly complete oxidation of elemental mercury was observed by 4 kV of applied voltage only. The best photocatalytic activity of anatase TiO2 which was calcined at 600 A degrees C was found in our tests. Compared with the plasma process alone, the oxidation efficiency increased 18.7-26.3 % with the addition of photocatalyst.