Achieving Large-Capability Adsorption of Hg0 in Wet Scrubbing by Defect-Rich Colloidal Copper Sulfides under High-SO2 Atmosphere

This paper reports on a novel method to remove Hg0 in the wet scrubbing process using defect-rich colloidal copper sulfides for reducing mercury emissions from non-ferrous smelting flue gas. Unexpectedly, it migrated the negative effect of SO2 on mercury removal performance, while also enhancing Hg0 adsorption. Colloidal copper sulfides demonstrated the superior Hg0 adsorption rate of 306.9 μg·g−1·min−1 under 6% SO2 + 6% O2 atmosphere with a removal efficiency of 99.1%, and the highest-ever Hg0 adsorption capacity of 736.5 mg·g−1, which was 277% higher than all other reported metal sulfides. The Cu and S sites transformation results reveal that SO2 could transform the tri-coordinate S sites into S22− on copper sulfides surfaces, while O2 regenerated Cu2+ via the oxidation of Cu+. The S22− and Cu2+ sites enhanced Hg0 oxidation, and the Hg2+ could strongly bind with tri-coordinate S sites. This study provides an effective strategy to achieve large-capability adsorption of Hg0 from non-ferrous smelting flue gas.