Remarkable improvement of Ti incorporation on Hg0 capture from smelting flue gas by sulfurated γ-Fe2O3: Performance and mechanism

Abstract

Except for the dangerous Boliden-Norzink technology, recovering gaseous Hg⁰ as liquid Hg⁰ using recyclable sorbents was an achievable method to control Hg⁰ emissions from smelting flue gas. In this study, Ti was incorporated into sulfurated γ-Fe₂O₃ to improve its performance for capturing Hg⁰ from smelting flue gas, and the mechanism of Ti incorporation on Hg⁰ adsorption onto sulfurated γ-Fe₂O₃ was investigated by comparing the kinetic parameters. The kinetic analysis showed that the Hg⁰ adsorption rate primarily depended on the amounts of surface adsorption sites for the physical adsorption of Hg⁰ and surface S₂^2- for Hg⁰ oxidation. Since the amounts of both adsorption sites and S₂^2- on sulfurated γ-Fe₂O₃ increased remarkably after Ti incorporation, Hg⁰ adsorption onto sulfurated γ-Fe₂O₃ was notably improved by 190-350%. The capacity of sulfurated Fe-Ti spinel for Hg⁰ capture could reach 48.6 mg g^-1 and its average adsorption rate could reach 43.3 μg g^-1 min^-1 in 3 h. Meanwhile, the used sulfurated Fe-Ti spinel could be easily regenerated without any apparent degradation. Thus, sulfurated Fe-Ti spinel offered a significant advantage in recovering Hg⁰ from smelting flue gas.

Keywords: Hg(0)capture; Kinetic analysis; Smelting flue gas; Sulfurated γ-Fe(2)O(3); Ti incorporation.