Elemental Mercury Removal from Flue Gas over Silver-Loaded CuS-Wrapped Fe3O4 Sorbent

In this study, CuS-wrapped Fe3O4 was selected as the support for Ag loading to prepare a recyclable magnetic Agbased sorbent for zero-valent mercury (Hg-0) removal. The synthesized Ag/CuS@Fe3O4 sorbent showed outstanding Hg-0 removal activity and SO2 resistance at 50 degrees C. The Hg-0 capture capacity of Ag/CuS@Fe3O4 was 18.72 mu g g(-1) for 5 min, which was about 3.40 and 1.11 times higher than those of bare Fe3O4 and CuS@Fe3O4. Exposure of Ag/CuS@Fe3O4 to the simulated gas containing SO2 (0.05 v/v%) at 50 degrees C achieved the Hg-0 removal efficiency of >84% during 3 h activity test. Characterization results indicated that both Cu and S sites of CuS were active sites in the reaction process, providing high Hg-0 capture capacity. Meanwhile, the Ag species not only provided new activity sites but also improved the reactive activity of Cu sites due to the formation of ternary amalgam. In addition, the S sites were supplemented by SO2, which prevented the Ag active sites from being destructed by the formation of Ag2S.

Automated summary

In this study, a recyclable magnetic Ag-based sorbent for zero-valent mercury (Hg-0) removal was successfully prepared using CuS-wrapped Fe3O4 as the support and Ag as the loading material. The synthesized Ag/CuS@Fe3O4 sorbent exhibited excellent Hg-0 removal activity and resistance to SO2 at 50 degrees C. Characterization results showed that both Cu and S sites of CuS were active sites in the reaction process, providing high Hg-0 capture capacity. Meanwhile, the Ag species not only provided new activity sites but also improved the reactivity of Cu sites.