Recovering gaseous Hg using sulfureted phosphotungstic acid modified γ-FeO from power plants burning Hg-rich coal for centralized control.

Conversion of gaseous elemental mercury (Hg) to particulate-bound mercury (Hg) by the injection of disposable sorbents or to gaseous oxidized mercury (Hg) by catalysts is not suitable to control Hg emissions from power plants burning Hg-rich coal because removed Hg may be released as secondary pollution, particularly during the employment of fly ash and desulfurization gypsum. In this study, sulfureted phosphotungstic acid modified γ-FeO (HPW/γ-FeO) was employed as a magnetic and reproducible sorbent to recover gaseous Hg in coal-fired flue gas for the centralized control. Sulfureted HPW/γ-FeO showed an excellent capacity to enrich gaseous Hg from low concentrations to ultra-high concentrations (>10 mg m), which benefited to condensing it into liquid Hg. Moreover, sulfureted HPW/γ-FeO exhibited excellent para-magnetism, enabling it to be magnetically reclaimed after Hg capture; this magnetization did not disappear after multiple thermal desorption of Hg due to its excellent thermal stability. Furthermore, sulfureted HPW/γ-FeO was regenerated by re-sulfuration without decreasing the Hg capture performance. Therefore, gaseous Hg recovery using sulfureted HPW/γ-FeO is a promising, economical-effective, and eco-friendly technology for the centralized control of Hg pollution emitted from power plants that burn coal with a high Hg content.