Cost-Effective Manganese Ore Sorbent for Elemental Mercury Removal from Flue Gas

Mercury capture from flue gas remains a challenge for environmental protection due to the lack of cost-effective sorbents. Natural manganese ore (NMO) was developed as a cost-effective sorbent for elemental mercury removal from flue gas. NMO sorbent showed excellent Hg-0 removal efficiency (>90%) in a wide temperature window (100-250 degrees C) under the conditions of simulated flue gas. O-2, NO, and HCl promoted Hg-0 removal due to the surface reactions of He with these species. SO2 and H2O slightly inhibited Hg-0 removal under the conditions of simulated flue gas. O-2 addition could also weaken the inhibitory effect of SO2. NMO sorbent exhibited superior regeneration performance for He removal during ten-cycle experiments. Quantum chemistry calculations were used to identify the active components of NMO sorbent and to understand the atomic-level interaction between Hg-0 and sorbent surface. Theoretical results indicated that Mn3O4 is the most active component of NMO sorbent for Hg-0 removal. The atomic orbital hybridization and electrons sharing led to the stronger interaction between Hg-0 and Mn3O4 surface. Finally, a chemical looping process based on NMO sorbent was proposed for the green recovery of Hg-0 from flue gas. The low cost, excellent performance, superior regenerable properties suggest that the natural manganese ore is a promising sorbent for mercury removal from flue gas.