Mercury removal from flue gas by magnetospheres present in fly ash: Role of iron species and modification by HF.

The Hg 0 removal capacities of magnetospheres from fly ash collected from different power plants were investigated at a wide temperature range of 100–400 °C. The relationship between Hg 0 removal efficiency ( η T ) and iron content/species of magnetospheres was investigated. The magnetospheres attained the optimal Hg 0 removal capacity at 250 °C. The reaction temperature played an important role in Hg 0 adsorption and oxidation behaviors. At low reaction temperature (100 °C and 150 °C), the adsorption of Hg 0 played a predominant role in Hg 0 removal, while the Hg 0 removal mainly depended on the Hg 0 oxidation capacity at high temperature (200–400 °C). The Hg 0 removal capacity increased with the increase of iron content. The percentage of ferrospinel and hematite in magnetospheres is a key factor for determining the Hg 0 removal capacity as well. Hydrogen fluoride (HF) could remove the glass-phase materials on the magnetospheres and the active iron species embedded in the glass phase could be exposed and accessible. After fluorinated by HF, the Hg 0 removal capacity increased in different degree for different magnetospheres, which depended on the content of active iron species in raw magnetospheres. [ABSTRACT FROM AUTHOR]