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

Nonferrous metal smelting produces a large amount of Hg-0 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 Hg-0 from simulated smelting flue gas at low temperatures (50150 degrees C). In the adsorption process, Hg-0 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 S-2(2-) species on the surface of cobalt sulfide play an important role in Hg-0 transformation. At the temperature of 50 degrees C (inlet Hg-0 concentration of 214gm(-3)), the Hg-0 adsorption capacity of cobalt sulfide (penetration rate of 25%) is as high as 2.07mgg(-1), which is much higher than that of popular adsorbents such as activated carbons and metal oxides. In addition, it was found that the Hg-0 removal efficiency by cobalt sulfide in the flue gas with high concentration of SO2 (5%) remained more than 94%. The good adsorption and Hg-0 removal performance guarantee cobalt sulfide the great superiority and application potential in the treatment of Hg-0 in smelting flue gas with high concentration of SO2.