| Summary: | This paper reports on a novel method to remove Hg<sup>0</sup> 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 SO<sub>2</sub> on mercury removal performance, while also enhancing Hg<sup>0</sup> adsorption. Colloidal copper sulfides demonstrated the superior Hg<sup>0</sup> adsorption rate of 306.9 μg·g<sup>−1</sup>·min<sup>−1</sup> under 6% SO<sub>2</sub> + 6% O<sub>2</sub> atmosphere with a removal efficiency of 99.1%, and the highest-ever Hg<sup>0</sup> adsorption capacity of 736.5 mg·g<sup>−1</sup>, which was 277% higher than all other reported metal sulfides. The Cu and S sites transformation results reveal that SO<sub>2</sub> could transform the tri-coordinate S sites into S<sub>2</sub><sup>2−</sup> on copper sulfides surfaces, while O<sub>2</sub> regenerated Cu<sup>2+</sup> via the oxidation of Cu<sup>+</sup>. The S<sub>2</sub><sup>2−</sup> and Cu<sup>2+</sup> sites enhanced Hg<sup>0</sup> oxidation, and the Hg<sup>2+</sup> could strongly bind with tri-coordinate S sites. This study provides an effective strategy to achieve large-capability adsorption of Hg<sup>0</sup> from non-ferrous smelting flue gas.
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