Nanosized Copper Selenide Functionalized Zeolitic Imidazolate Framework-8 (CuSe/ZIF-8) for Efficient Immobilization of Gas-Phase Elemental Mercury

A key challenge in elemental mercury (Hg-0) decontamination from flue gas lies in the design of a sorbent with abundant reactive adsorption sites that exhibit high affinity toward Hg-0 to simultaneously achieve rapid capture and large capacity. Herein, zeolitic imidazolate framework-8 (ZIF-8) supported copper selenide (CuSe) nanocomposites are synthesized by a newly designed two-step surfactant-assisted method. The as-prepared CuSe/ZIF-8 with CuSe to ZIF-8 mass ratio of 80% (0.8NC-ZIF) exhibits unparalleled performance toward Hg-0 adsorption with equilibrium capacity and average rate reaching 309.8 mg g(-1) and 105.3 mu g g(-1) min(-1), respectively, surpassing all reported metal sulfides and traditional activated-carbon-based sorbents. The impressive performance of 0.8NC-ZIF for Hg-0 immobilization is primarily attributed to the adequate exposure of the Se-terminated sites with high affinity toward Hg-0 resulted from the layered structure of CuSe. The adsorbed mercury selenide exhibits even higher stability than the most stable natural mercury ore-that is, mercury sulfide hence minimizing its environmental impact when the CuSe/ZIF-8 sorbent is dumped. This work provides a new mindset for future design of sorbents for efficient Hg-0 capture from industrial flue gas. The results also justify the candidature of CuSe/ZIF to be applicable for mercury pollution remediation in real-world conditions.