Hierarchical microsphere Flower-like SnIn4S8 with active sulfur sites for adsorption and removal of mercury from coal-fired flue gas

Mercury pollutants in coal-fired power plants pose a serious impact on the environment and human health, and sulfur active sites are particularly important in the removal of Hg0 from metal sulfides. Herein, a novel SnIn4S8 adsorbent with active sulfur sites was prepared by a simple one-step hydrothermal method for the removal of gaseous Hg0. SEM, BET and other characterization results showed that the microsphere flower-like structure of SnIn4S8 can make the active sulfur sites evenly distributed. Its excellent specific surface area greatly enhances the reaction rate of Hg0 on the SnIn4S8 surface. It was found that SnIn4S8 has a remarkable efficiency of 100 % and a high stability in the range of 40–120 °C. Its special structural properties make it resistant to SO2 and NO. Its equilibrium adsorption capacity of 28.84 mg/g is much higher than most commercial adsorbents. The adsorption kinetics of bimetallic sulfides was calculated innovatively, and the reaction path and adsorption mechanism of Hg0 on the surface of SnIn4S8 were clarified by combining XPS analysis and thermodynamic calculations. Hg-TPD confirmed the production of stable species HgS. Thus, the microsphere flower-like SnIn4S8 is a prospective adsorbent for mercury removal and provides direction for the future development of adsorbents rich in sulfur sites.