Efficient Removal of Elemental Mercury from Coal-Fired Flue Gas in a Wide Temperature Range by Fe₃O₄ Attached to the CuSe Surface

The adsorbent technique is one of the common methods used to capture elemental mercury from industrial flue gases. In this paper, CuSe/Fe₃O₄ (CF) was constructed by the hydrothermal method, and the surface area of the adsorbent (CF-25) reached 138.7626 m² g^–1 when the mass ratio of Fe₃O₄ was 25 wt %, and its performance for mercury removal was also optimal. The diselenide ligand (Se₂^2–) from CuSe and the oxygen functional group (O_L) from Fe₃O₄ contributed to the immobilization of Hg⁰. The mercury removal efficiency of CF-25 could reach 92% on average at 40–300 °C, and the adsorption capacity of CF-25 for mercury at 240 °C was 56.0224 mg g^–1. In the cycling experiments, CF-25 was able to absorb 92.7% of the mercury and possessed a high recovery rate. In addition, the adsorbent exhibited excellent sulfur resistance. The outstanding mercury removal performance, high recyclability, and excellent sulfur resistance make CF-25 a promising adsorbent.