Electrostatically directed assembly of macroporous skeleton structured copper selenide for elemental mercury sequestration from coal-fired flue gas

Abstract

Decontamination of Hg0 from coal-fired flue gas remains an enormous challenge. It is an imperative pursuit to design adsorbents bearing an abundance of accessible chelating sites with a high affinity toward mercury, thus achieving both rapid uptake and high capacity for Hg0. Herein, an electrostatically directed assembly strategy was designed to construct Cu2Se decorated commercial polyurethane sponge (Cu2Se/PUS) as an efficient Hg0 trap. The surface coverage of Cu2Se on the Cu2Se/PUS can be rationally adjusted by turning the charge density of Cu2Se and PUS. The saturated Hg0 adsorption capacity of Cu2Se/PUS was achieved at 217.04 mg g−1 (normalized to the Cu2Se coating amount), which was much higher than that of powdery Cu2Se (43.66 mg g−1). Multiform selenium active sites (Se- and Se2-) and copper-terminated active centers of Cu2Se/PUS co-participated in Hg0 adsorption, instead of the individual role of Se- over powdery Cu2Se. The macroporous skeleton structure and the highly dispersed Cu2Se boosted the diffusion of mercury to the active sites for immobilization, thus accelerating the consumption of multiple active sites on the Cu2Se/PUS. This work not only provided an efficient Hg0 trap but also showed great inspiration for the potential of electrostatically directed assembly methods in constructing adsorbents for diverse environmental remediations.