Influence of gas components on the oxidation of elemental mercury by positive pulsed corona discharge

Abstract

This study examines the effect of flue gas components on the oxidation of gaseous elemental mercury (Hg-0) to HgO and HgCl2 via pulsed corona discharge (PCD), where the reaction temperature was set to 90 degrees C and the gas stream consisting of 3% H2O and 10% O-2 in N-2 was mixed with 45 mu g m(-3) Hg-0, 108 ppm NOx, 80 ppm HCl, 200 ppm SO2 and 470 ppm NH3. It has been observed that O-2 and HCl components in the gas stream act as oxidizing precursors through the generation of oxidizing species (O, O-3, Cl and Cl-2) in the PCD process. The presence of NO directly hampers Hg-0 oxidation to HgO due to preferential reaction of NO with O and O-3. In contrast, the presence of SO2 indirectly influences the oxidation of Hg-0 to HgCl2 through the fast reaction of SO2 with OH radical, resulting in consuming OH radicals which are partially responsible for the formation of chlorine species, i. e. Cl and Cl-2. It has been also found that NH3 component significantly hinders the oxidation of Hg-0 to HgCl2 through the fast acid-base reaction with HCl.