Controllable synthesis of Cu-Co bimetallic sulfide nanosheets for efficient Hg0 removal

Abstract

Transition metal sulfide adsorption is a promising method to remove Hg⁰, which can oxidize Hg⁰ forming HgS by chemisorption. The performance of adsorbents in Hg⁰ removal is determined not only by its morphological structure, but also by the quantity of active sites. With this inspiration, Cu-Co bimetallic sulfide nanosheets containing heterogeneous interface were synthesized utilizing the hydrothermal approach. By changing the ratio of Cu/Co, a range of Cu-Co bimetallic sulfide adsorbents were obtained. The characterization results show that Cu/Co ratio can seriously affect the size of the nanosheets and the quantity of active sites. Cu_0.33Co_0.67S_x has a suitable nanosheet size and the most active sites on the surface. Furthermore, there is obvious heterogeneous interface in Cu_0.33Co_0.67S_x, which can improve electron transfer during Hg⁰ oxidation. Hence, the Hg⁰ removal efficiency of Cu_0.33Co_0.67S_x is nearly 100 % at 60 and 80 °C and even more than 96 % at a high temperature of 100 °C within 200 min. In addition, Cu_0.33Co_0.67S_x has a strong stability of Hg⁰ removal process under different flue gas conditions, especially in SO₂ and H₂O environments.