Metal selenides have been demonstrated as promising Hg0 remediators, while their inadequate adsorption rate primarily impedes their application feasibility. Based on the critical role of coordinatively unsaturated selenide ligands in immobilizing Hg0, this work proposed a novel strategy to enhance the Hg0 adsorption rate of metal selenides by magnitudes by purposefully adjusting the selenide saturation. Copper iron diselenide (CuFeSe2), in which the surface reconstruction tended to occur at ambient temperature, was adopted as the concentrator of unsaturated selenides. The adsorption rate of CuFeSe2 reached as high as 900.71 μg·g–1·min–1, far exceeding those of the previously reported metal selenides by at least 1 magnitude. The excellent resistance of CuFeSe2 to flue gas interference and temperature fluctuation warrants its applicability in real-world conditions. The theoretical investigations and mechanistic interpretations based on density functional theory (DFT) calculation further confirmed the indispensable role of unsaturated selenides in Hg0 adsorption. This work aims not only to develop a Hg0 remediator with extensive applicability in coal combustion flue gas but also to take a step toward the rational design of selenide-based sorbents for diverse environmental remediation by the facile surface functionalization of coordinatively adjustable ligands.

The paramount challenge in design and synthesis of materials for vapor-phase elemental mercury (Hg0) immobilization is to achieve a balance between performance and economy for practical applications. Herein, a newly designed electroless plating coupled with an in situ selenization method was developed to construct a copper selenide (Cu2Se)-functionalized commercial polyurethane sponge (PUS) as an efficient Hg0 trap. Intrinsic features such as easy availability of the raw material, facile preparation, and excellent performance guarantee the Cu2Se/PUS to be applicable in industrial uses. The Cu2Se/PUS exhibits a maximum adsorption capacity (Q m,Cu2Se/PUS) of 25.90 mg·g–1, while this value is 758.80 mg·g–1 when normalized to the Cu2Se coating amount. This value of Q m,Cu2Se is equal to 79.7% of its corresponding theoretical value (Q t,Cu2Se), far exceeding the availability of Cu2Se anchored on other supports. Meanwhile, the Cu2Se/PUS exhibited a quick response for Hg0, with an extremely high uptake rate of 1275.84 μg·g–1·min–1. Even under harsh conditions, the Cu2Se/PUS still immobilizes Hg0 effectively, which is crucial for real-world applications. This work not only provides a promising trap for permanent Hg0 sequestration from industrial sources but also illustrates a versatile platform for the economic fabrication and practical application of advanced functional sponges in diverse environmental remediation.

No abstract

No abstract

Mercury and selenium are two typical heavy metal pollutants in coal combustion flue gas. The adsorption mechanism of Se0 and SeO2 over an activated carbon (AC) adsorbent and the specific role of selenium species in Hg0 elimination were systematically studied by density functional theory calculation. The adsorption complex structures of a single Se0 atom and SeO2 molecule on the AC surface were optimized. The adsorption energy in a range of −238.97 to −545.80 kJ/mol indicated that chemisorption was the main adsorption mechanism. The adsorption properties of multiple Se0 atoms and SeO2 molecules on the AC surface were studied, and the most possible adsorption pathway was given. Multi-Se0 atoms preferred to adsorb on neighboring active sites of the AC surface to share their atomic orbitals. Instead, multi-SeO2 molecules preferred to occupy the active sites of the AC surface without any interaction. The multicomponent adsorption processes of Hg0 and selenium species on the AC surface were studied by calculating adsorption energies, electron charge transfer, and atomic bond populations. For the coadsorption of Hg0 and Se0, they preferred to adsorb on different carbon atoms in a separate way. In contrast, SeO2 tends to decompose into Se and SeO ions, and Hg0 can achieve stable configuration through interacting with the SeO ion and AC surface with an adsorption energy of −354.92 kJ/mol. This study indicated future potential for applying activated carbon in multicomponent adsorption of selenium and mercury in coal combustion flue gases.