Novel Synergistic Effect of Fe and Mo in FeMoSx/TiO2 for Recovering High Concentrations of Gaseous Hg0 from Smelting Flue Gas: Reaction Mechanism and Kinetics.

There is a high demand for developing a more effective and environment-friendly technology to substitute the complicated and hazardous Boliden-Norzink technology for recovering gaseous Hg0 from smelting flue gas. In this work, a low-cost and reproducible sorbent (FeMoSx/TiO2) was developed to recover gaseous Hg0 from smelting flue gas. FeMoSx/TiO2 exhibited a superior ability for capturing high concentrations of Hg0, with an adsorption rate of 72.2 μg g-1 min-1 and a capacity of 41.8 mg g-1 at 60 °C. These were generally larger than the sums of those of FeSx/TiO2 and MoSx/TiO2. The kinetic model of Hg0 adsorption by FeSx/TiO2, MoSx/TiO2, and FeMoSx/TiO2 were constructed according to the adsorption mechanism. Then, the structure-activity relationship of FeMoSx/TiO2 for Hg0 capture was determined by comparing the kinetic parameters. The intrinsic adsorption of Hg0 by MoSx/TiO2 (i.e., physically adsorbed Hg0 was oxidized by MoS3 to HgS) was inhibited marginally after FeSx was incorporated. However, another Hg0 adsorption route (i.e., physically adsorbed Hg0 was oxidized by FeS2 to HgS) appeared on FeMoSx/TiO2. Its rate was significantly higher than that of FeSx/TiO2. Thus, a novel synergistic effect of Fe and Mo in FeMoSx/TiO2 for Hg0 capture was observed.