Radical-Induced Oxidation Removal Of Mercury By Ozone Coupled With Bromine

Ozone oxidation and absorption is an effective technique for air pollutant removal from industrial flue gas. However, it is hard to remove Hg-0 because of the competition reaction between O-3 and NOx. In order to enhance the mercury removal by O-3 in the presence of NO, SO2, and other flue gas components, bromine was used as the oxidation promoter in this research. The experimental data showed that the mercury removal efficiency was improved significantly when Br-2 was introduced into the reaction system. The mechanism and main factors of mercury removal by O-3 and Br-2 were studied. The box model calculation showed that the O radical inspired the generation of Br and BrO radicals. And, the Br and BrO radicals were the key factors which enhanced the Hg-0 oxidation by O-3 in the presence of NO. In the full-scale experiments, mercury removal efficiency was near 90% when only 0.68 ppmv bromine was injected into the real coal-fired flue gas with 101 ppmv O-3. Therefore, it is helpful through introducing bromine to enhance the mercury removal by excess ozone during the NOx removal process.