New insights into elemental mercury removal from flue gas by a MoS2 heterogeneous system

Herein, MoS2 was used in a MoS2/H2O heterogeneous system for the heterogeneously catalyzed removal of Hg-0 from flue gas. Hg-0 removal efficiency reached 77.6% at 25 ?degrees C when the dosage of MoS2 was 0.200 g/L in aqueous suspension. The observed effects of MoS2 dosage and inlet Hg-0 concentration on Hg-0 removal efficiency revealed that the gas-liquid mass transfer process is the limiting step of Hg-0 removal. Low pH and low temperature were conducive to Hg-0 removal. SO2 in the flue gas was absorbed by MoS2, and the simultaneous decrease in solution pH resulted in a slight increase in Hg-0 removal efficiency. The presence of NO in the flue gas enhanced Hg-0 removal efficiency. Common anions, such as NO3-, SO42-, and CO32-, have no obvious effect on Hg-0 removal. However, Cl- improved Hg-0 removal efficiency by 11% because of the production of HgCln2-n. The kinetics and mechanism of Hg-0 removal were studied, and the results indicated that Mo acted as a bridge and catalyst for Hg-0 oxidation, while S immobilized Hg2+ by formation of HgS on MoS2.

Automated summary

In this study, MoS2 was used as a catalyst for the heterogeneous removal of Hg-0 from flue gas. The results showed that the dosage of MoS2 and the inlet Hg-0 concentration had significant effects on Hg-0 removal efficiency, with gas-liquid mass transfer being the limiting step. Additionally, low pH and low temperature were beneficial for Hg-0 removal, while the presence of Cl- greatly enhanced the removal efficiency.