H2S-Modified Fe–Ti Spinel: A Recyclable Magnetic Sorbent for Recovering Gaseous Elemental Mercury from Flue Gas as a Co-Benefit of Wet Electrostatic Precipitators

The nonrecyclability of the sorbents used to capture Hg0 from flue gas causes a high operation cost and the potential risk of exposure to Hg. The installation of wet electrostatic precipitators (WESPs) in coal-fired plants makes possible the recovery of spent sorbents for recycling and the centralized control of Hg pollution. In this work, a H2S-modified Fe–Ti spinel was developed as a recyclable magnetic sorbent to recover Hg0 from flue gas as a co-benefit of the WESP. Although the Fe–Ti spinel exhibited poor Hg0 capture activity in the temperature range of flue gas downstream of flue gas desulfurization, the H2S-modified Fe–Ti spinel exhibited excellent Hg0 capture performance with an average adsorption rate of 1.92 μg g–1 min–1 at 60 °C and a capacity of 0.69 mg g–1 (5% of the breakthrough threshold) due to the presence of S22– on its surface. The five cycles of Hg0 capture, Hg0 recovery, and sorbent regeneration demonstrated that the ability of the modified Fe–Ti spinel to capture Hg0 did not degrade ...