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

Abstract

Abstract 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 Hg0 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\u202fμg/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 Hg0. Hg0 was physically adsorbed on the material surface. Then, the adsorbed Hg0 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 Hg0 removal from high-SO2-concentration flue gas due to its outstanding Hg0 capture performance and high sulfur resistance, and it may be used as a method to recover mercury resources.