Mechanisms of Elemental Mercury Transformation on α-Fe₂O₃(001) Surface from Experimental and Theoretical Study:...

The reaction mechanisms of a mixture gas of HCl, O₂, and SO₂ in Hg⁰ adsorption on α-Fe₂O₃(001) surface are clarified by a group of adsorption experiments and theoretical calculations based on the density functional theory. The role of O₂ in removing Hg⁰ is greatly influenced by the reaction temperature, meanwhile, the O atom coverage could affect the adsorption performance of Hg⁰. The dissociated O₂ competes with the active sites of Cl species on Fe surface at low temperature, however, at medium temperature HCl and O₂ could simultaneously facilitate the Hg⁰ transformation. Combined with the theoretical calculations, the role of SO₂ and the probable pathways in removing Hg⁰ are discussed. Lower concentration of SO₂ as well as HCl could dissociate on α-Fe₂O₃(001) surface, and the intermediates combine with gaseous Hg⁰, forming mercury-sulfur, mercury-chlorine compounds, and so forth. In addition, the different concentrations of SO₂ are also discussed, and the corresponding X-ray photoelectron spectroscopy analysis on contrasted samples is conducted to research the morphological characterization, providing a reliable basis for judging the probable pathways of Hg⁰ transformation.