Fixed-Bed Study of Elemental Mercury Removal from Flue Gas Using a SiO2-TiO2 Nanocomposite

摘要

As a highly toxic pollutant, mercury (Hg) tends to bioaccumulate in the food chain and exerts adverse effects on human health. Coal-fired utility boilers are currently the largest single-known source of anthropogenic Hg emissions in the United States. In 2005, the U.S. EPA issued the Clean Air Mercury Rule (CAMR) to permanently cap and reduce Hg emissions from coal-fired power plants. Consequently, various technologies have been developed to offer high levels of Hg control for utility boilers burning different types of coal. Hg speciation studies showed that elemental Hg (Hg~0) is the dominant species present in flue gas burning low-rank coals, but oxidized Hg [Hg(II)] is preferable to Hg~0 in that Hg(II) is water soluble and is readily collected in air pollution control devices (APCDs) such as SO2 scrubbers. Thus, the need exists for a low cost Hg oxidation and capturing process that can be applied for the flue gas treatment.