Recovering gaseous Hg0 using sulfureted phosphotungstic acid modified γ-Fe2O3 from power plants burning Hg-rich coal for centralized control.

Conversion of gaseous elemental mercury (Hg0) to particulate-bound mercury (HgP) by the injection of disposable sorbents or to gaseous oxidized mercury (Hg2+) by catalysts is not suitable to control Hg0 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-Fe2O3 (HPW/γ-Fe2O3) was employed as a magnetic and reproducible sorbent to recover gaseous Hg0 in coal-fired flue gas for the centralized control. Sulfureted HPW/γ-Fe2O3 showed an excellent capacity to enrich gaseous Hg0 from low concentrations to ultra-high concentrations (>10 mg m-3), which benefited to condensing it into liquid Hg. Moreover, sulfureted HPW/γ-Fe2O3 exhibited excellent para-magnetism, enabling it to be magnetically reclaimed after Hg0 capture; this magnetization did not disappear after multiple thermal desorption of Hg0 due to its excellent thermal stability. Furthermore, sulfureted HPW/γ-Fe2O3 was regenerated by re-sulfuration without decreasing the Hg0 capture performance. Therefore, gaseous Hg0 recovery using sulfureted HPW/γ-Fe2O3 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.