Dual Roles of Nano-Sulfide in Efficient Removal of Elemental Mercury from Coal Combustion Flue Gas within a Wide Temperature Range

Environ Sci Technol. 2018 Nov 6;52(21):12926-12933. doi: 10.1021/acs.est.8b04340. Epub 2018 Oct 23.


Nanostructured zinc sulfide (Nano-ZnS) has been demonstrated to be an efficient adsorbent for removal of elemental mercury (Hg0). However, the Hg0 removal performance deteriorates once the flue gas temperature deviates from the optimal temperature of 180 °C. In this study, ultraviolet (UV) light, which is generally generated through corona discharge in electrostatic precipitators (ESPs), was adopted to enhance Hg0 removal by Nano-ZnS. With the UV irradiation, Nano-ZnS exhibited excellent performance in Hg0 removal within a much wide temperature range from room temperature to 240 °C. A Hg0 removal efficiency of 99% was achieved at 60 °C even under extremely adverse conditions, that is, gas flow with an extremely high gas hourly space velocity but without hydrogen chloride. At low temperatures, Hg0 was mainly oxidized by superoxide radicals (•O2-) and hydroxyl radicals (•OH) generated by UV photostimulation to form mercuric oxide (HgO). At high temperatures, most Hg0 was immobilized as mercuric sulfide (HgS), as both the enhanced chemisorption and the accelerated transformation of HgO to HgS facilitated the formation of HgS. Compared with commercial activated carbon, injection of Nano-ZnS can utilize the UV in ESPs to warrant a higher Hg0 removal efficiency within a much wider temperature range.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Air Pollutants*
  • Coal
  • Mercury*
  • Sulfides
  • Temperature


  • Air Pollutants
  • Coal
  • Sulfides
  • Mercury