Development of Recyclable Iron Sulfide/Selenide Microparticles with High Performance for Elemental Mercury Capture from Smelting Flue Gas over a Wide Temperature Range

Fast and effective removal of elemental mercury in a wide temperature range is critical for the smelting industry. In this work, a recyclable magnetic iron sulfide/selenide sorbent is developed to capture and recover Hg⁰ from smelting flue gas. Benefiting from Se doping, the Hg⁰ capture performance of prepared FeSSe is significantly enhanced compared with traditional iron sulfide, especially at high temperatures. Considering the recyclability and working temperature, FeS_1.32Se_0.11 exhibits the best Hg⁰ capture performance. The average capture rate of FeS_1.32Se_0.11 is 3.661 μg/g/min at 80 °C and its saturation adsorption capacity is 20.216 mg/g. The flue gas compositions have almost no effect on Hg⁰ capture. X-ray photoelectron spectroscopy and mercury thermal programmed desorption suggest that the stable active Se-S_n^2- adsorption site can combine with Hg⁰ to form HgSe, consequently improving Hg⁰ capture performance at high temperatures. After Hg⁰ capture, the spent FeSSe can be collected by magnetic separation and regenerated through selective extraction, which facilitates harmless treatment and resource reuse of mercury. With the advantages of excellent Hg⁰ capture performance, wide operating temperature range, and remarkable recycling property, FeSSe microparticles may be a promising sorbent for Hg⁰ capture in industrial applications, while opening a new avenue to realize the resource utilization toward toxic elements.