Novel Synergetic Effect of Fe and W in FeWS<sub><i>x</i></sub>/TiO<sub>2</sub> on Capturing High Concentrations of Gaseous Hg<sup>0</sup> from Smelting Flue Gas: Adsorption Kinetics and Structure–Activity Relationship
Chang Wang, Qixing Hu, Qi Zhang, Jian Mei, Shijian Yang
Abstract
In this work, a regenerable sorbent FeWSx/TiO2 was used to reclaim gaseous Hg0 in smelting flue gas for centralized control. FeWSx/TiO2 exhibited excellent ability to adsorb Hg0, with the adsorption rate of 25.0 μg g–1 min–1. There was a novel synergetic effect of Fe and W in FeWSx/TiO2 for Hg0 adsorption, and the rate of Hg0 adsorption onto FeWSx/TiO2 was generally greater than the total of those onto FeSx/TiO2 and WSx/TiO2. The structure–activity relationship of FeWSx/TiO2 for Hg0 capture was discovered according to the kinetic analysis. FeWSx/TiO2’s capacity for Hg0 adsorption was approximately dependent on the number of S22– on the surface. Meanwhile, the rate of adsorption of Hg0 onto FeWSx/TiO2 was proportional to the product of the number of S22– on the surface and the number of surface adsorption sites for the physical adsorption of gaseous Hg0. Although S22– on FeSx/TiO2 did not increase obviously after W incorporation, the adsorption sites on FeSx/TiO2 obviously increased due to the appearance of WS3. Therefore, the rate of adsorption of Hg0 onto FeWSx/TiO2 was 1.8–2.3 times that on FeSx/TiO2.