Charge distribution modulation and morphology controlling of copper selenide for an enhanced elemental mercury adsorption activity in flue gas

Abstract

The abatement of elemental mercury (Hg0) emissions from industrial flue gases remains an enormous challenge. Metal selenides have been demonstrated to be promising Hg0 remediators, and the electron-transfer ability of selenide ligands is one of the key factors that determining the uptake capacity and adsorption rate of Hg0. Herein, a charge distribution modulation strategy was developed to generate desired selenide ligands. The selenide ligands on a tutorial sample, copper selenide (Cu2Se), was artificially modulated to −1 valances (Se1-) via electrostatic adsorption of positively charged head groups of cetyltrimethylammonium bromide (CTAB). Unlike other selenide ligand such as Se2-, the Se1- directly acted as an electron acceptor for Hg0 and realize one-step immobilization of Hg0 as environmentally stable mercury selenide (HgSe). Besides, CTAB was beneficial to construct nanosheets with thinner and larger plates, hence facilitated a sufficient exposure of active sites for binding Hg0. Profiting from the above advantages, the Hg0 adsorption capacity of CTAB modulated Cu2Se (Cu2Se-CTAB) was up to 80.2 mg·g−1, about two times higher than that of bare Cu2Se. Meanwhile, the average Hg0 adsorption rate of Cu2Se-CTAB before achieving saturation was 9.99 mg·g−1·h−1, much faster comparing with 6.90 mg·g−1·h−1 for regular Cu2Se. The Cu2Se-CTAB showed superior Hg0 adsorption performance at 40–80 °C and excellent resistance to flue gas interference, which are crucial for real-world applications. This newly designed method not only provides an excellent Hg0 remediator but also offers a tutorial example for a rational modulation of metal selenides for diverse environmental remediations.