Highly stable activated carbon composite material to selectively capture gas-phase elemental mercury from smelting flue gas: Copper polysulfide modification

Gaseous elemental mercury removal from high SO2 flue gas is an urgent environmental problem. In this study, a new sorbent, copper polysulfide modification activated carbon (CuxSy@AC), was synthesized. CuxSy@AC demonstrated better Hg-0 capture performance than copper-impregnated (Cu@AC) and sulfur-modified (S@AC) materials. The mercury adsorption capacity of CuxSy@AC from high-concentration SO2 smelting flue gas could reach 3924 mu g/g in optimal conditions, and this adsorption capacity was superior to that of common modified sorbents. The physical and chemical characteristics of CuxSy@AC were analyzed through several characterization methods, including X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, and fourier transform infrared spectroscopy. Thermo-gravimetric and Raman analyses confirmed that CuxSy@AC had high thermal stability and consisted of short-chain sulfur that had a strong affinity to Hg-0. Hg(0)was physically adsorbed on the material surface. Then, the adsorbed Hg-0 bonded with active sulfur in copper polysulfide to form stable HgS, which was confirmed by X-ray photoelectron spectroscopy and temperature-programmed desorption analysis. CuxSy@AC may be a promising sorbent for Hg-0 removal from high-SO2-concentration flue gas due to its outstanding Hg-0 capture performance and high sulfur resistance, and it may be used as a method to recover mercury resources.