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

Abstract Gaseous elemental mercury removal from high SO 2 flue gas is an urgent environmental problem. In this study, a new sorbent, copper polysulfide modification activated carbon (Cu x S y @AC), was synthesized. Cu x S y @AC demonstrated better Hg 0 capture performance than copper-impregnated (Cu@AC) and sulfur-modified (S@AC) materials. The mercury adsorption capacity of Cu x S y @AC from high-concentration SO 2 smelting flue gas could reach 3924 μg/g in optimal conditions, and this adsorption capacity was superior to that of common modified sorbents. The physical and chemical characteristics of Cu x S y @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 Cu x S y @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. Cu x S y @AC may be a promising sorbent for Hg 0 removal from high-SO 2 -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.