High-efficient adsorption and removal of elemental mercury from smelting flue gas by cobalt sulfide

Nonferrous metal smelting produces a large amount of Hg0 in flue gas, which has caused serious damage to the environment and human health. In this work, amorphous cobalt sulfide was synthesized by a liquid-phase precipitation method and was used for capturing gaseous Hg0 from simulated smelting flue gas at low temperatures (50~150 °C). In the adsorption process, Hg0 can be transformed into the stable mercury compound, which is confirmed to be HgS by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption of Hg (Hg-TPD) analysis. Meanwhile, XPS results also demonstrate that S22− species on the surface of cobalt sulfide play an important role in Hg0 transformation. At the temperature of 50 °C (inlet Hg0 concentration of 214 μg·m−3), the Hg0 adsorption capacity of cobalt sulfide (penetration rate of 25%) is as high as 2.07 mg·g−1, which is much higher than that of popular adsorbents such as activated carbons and metal oxides. In addition, it was found that the Hg0 removal efficiency by cobalt sulfide in the flue gas with high concentration of SO2 (5%) remained more than 94%. The good adsorption and Hg0 removal performance guarantee cobalt sulfide the great superiority and application potential in the treatment of Hg0 in smelting flue gas with high concentration of SO2.