Selective Removal of Elemental Mercury from High-Concentration SO2 Flue Gas by Thiourea Solution and Investigation of Mechanism

Nonferrous metals smelting industry is a major anthropogenic Hg emission source in China. A new method using transition metal-Tu (thiourea) solution was, proposed to selectively remove Hg-0 from high SO2 concentration flue gas. It is found that this solution displays significantly high Hg removal efficiency, up to above 88.7%, under optimal conditions, whereas the loss of SO2 is only 6:8%. High Tu concentration, low solution pH, and low temperature are helpful for Hg-0 removal.The promoting effect of Fe3+ is better than that of Cu2+. The mechanisin of selective Hg-0 removal Was studied by various methods. First, the cyclic Voltammetry (CV) curves show that part of Tu could be oxidized to PDS (formanuditte disulfide), which could combine with Hg to form Hg Tu complex. Additionally; the UV-vis spectra indicate H2SO3 could improve the stability of FDS and facilitate Hg-0 removal. In summary, the use of transition metal-Tu solution to selectively remove Hg-0 from smelting flue gas displays excellent efficiency, and the proposed mechanism. of Hg-0 selective removal is persuasive.