Outstanding Performance of Chalcopyrite (CuFeS ₂ ) for Gaseous Elemental Mercury Adsorption: Mechanism, Kinetics, and Structure–Activity Relationship

Metal sulfides are promising for gaseous Hg 0 capture from flue gas, but further improvement is limited by the lack of a structure–activity relationship and comparable evaluation parameters. Herein, chalcopyrite (CuFeS 2 ) was developed for Hg 0 adsorption, and its structure–activity relationship was revealed via mechanism analysis, DFT, and kinetics. The adsorption capacity was defined by the number of adsorption configurations (φ 0 ), closely related to the number of unsaturated surface S sites and their combinations. The initial adsorption rate was equal to the product of φ 0, the intrinsic adsorption affinity ( k ), and the gaseous Hg 0 concentration. Thus, two comparable parameters of φ 0 and k, which reflected the intrinsic properties of metal sulfides for gaseous Hg 0 adsorption, were developed to evaluate the ability for Hg 0 adsorption and to predict Hg 0 removal efficiency with experiment conditions. Owing to the huge φ 0 of CuFeS 2, it exhibited superior performance for Hg 0 adsorption, with a theoretical capacity of 283 mg g –1 and an initial rate of 104 μg g –1 min –1, significantly outperforming other metal sulfides. Meanwhile, CuFeS 2 displayed an excellent resistance to high concentrations of H 2 O and SO 2 . Therefore, CuFeS 2 may be a superior sorbent to capture gaseous Hg 0 from smelting flue gas.