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 S22− for Hg0 oxidation. Since the amounts of both adsorption sites and S22− 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.